Microwave Materials and Applications

By Mailadil T. Sebastian

The recent rapid progress in wireless telecommunication, including the Internet of Things, 5th generation wireless systems, satellite broadcasting, and intelligent transport systems has increased the need for low-loss dielectric materials and modern fabrication techniques. These materials have excellent electrical, dielectric, and thermal properties and have enormous potential, especially in wireless communication, flexible electronics, and printed electronics.

Microwave Materials and Applications discusses the methods commonly employed for measuring microwave dielectric properties, the various attempts reported to solve problems of materials chemistry and crystal structure, doping, substitution, and composite formation, highlighting the processing techniques, morphology influences, and applications of microwave materials whilst summarizing many of the recent technical research accomplishments in the area of microwave dielectrics and applications

Chapters examine:

• Oxide ceramics for dielectric resonators and substrates
• HTCC, LTCC and ULTCC tapes for substrates
• Polymer ceramic composites for printed circuit boards
• Elastomer-ceramic composites for flexible electronics
• Dielectric inks
• EMI shielding materials
• Microwave ferrites

A comprehensive Appendix presents the fundamental properties for more than 4000 low-loss dielectric ceramics, their composition, crystal structure, and their microwave dielectric properties.

Microwave Materials and Applications presents a comprehensive view of all aspects of microwave materials and applications, making it useful for scientists, industrialists, engineers, and students working on current and emerging applications of wireless communications and consumer electronics.

• Language: English
• Publisher: Wiley
• Release date: Mar 2, 2017
• ISBN: 9781119208556

Book preview

Wiley Series in Materials for Electronic and Optoelectronic Applications

www.wiley.com/go/meoa

Series Editors

Professor Arthur Willoughby, University of Southampton, Southampton, UK

Dr Peter Capper, SELEX Galileo Infrared Ltd, Southampton, UK

Professor Safa Kasap, University of Saskatchewan, Saskatoon, Canada

Published Titles

Bulk Crystal Growth of Electronic, Optical and Optoelectronic Materials, Edited by P. Capper

Properties of Group-IV, III--V and II--VI Semiconductors, S. Adachi

Charge Transport in Disordered Solids with Applications in Electronics, Edited by S. Baranovski

Optical Properties of Condensed Matter and Applications, Edited by J. Singh

Thin Film Solar Cells: Fabrication, Characterization, and Applications, Edited by J. Poortmans and V. Arkhipov

Dielectric Films for Advanced Microelectronics, Edited by M. R. Baklanov, M. Green, and K. Maex

Liquid Phase Epitaxy of Electronic, Optical and Optoelectronic Materials, Edited by P. Capper and M. Mauk

Molecular Electronics: From Principles to Practice, M. Petty

CVD Diamond for Electronic Devices and Sensors, Edited by R. S. Sussmann

Properties of Semiconductor Alloys: Group-IV, III--V, and II--VI Semiconductors, S. Adachi

Mercury Cadmium Telluride, Edited by P. Capper and J. Garland

Zinc Oxide Materials for Electronic and Optoelectronic Device Applications, Edited by C. Litton, D. C. Reynolds, and T. C. Collins

Lead-Free Solders: Materials Reliability for Electronics, Edited by K. N. Subramanian Silicon Photonics: Fundamentals and Devices, M. Jamal Deen and P. K. Basu

Nanostructured and Subwavelength Waveguides: Fundamentals and Applications, M. Skorobogatiy

Photovoltaic Materials: From Crystalline Silicon to Third-Generation Approaches, Edited by G. Conibeer and A. Willoughby

Glancing Angle Deposition of Thin Films: Engineering the Nanoscale, Matthew M. Hawkeye, Michael T. Taschuk, and Michael J. Brett

Microwave Materials

and Applications

Volume I

Edited by

MAILADIL T. SEBASTIAN

University of Oulu, Finland

RICK UBIC

Boise State University, ID, US

HELI JANTUNEN

University of Oulu, Finland

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This edition first published 2017

© 2017 John Wiley & Sons, Ltd

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Library of Congress Cataloging-in-Publication Data

Names: Sebastian, M. T., 1952-- editor. | Jantunen, Heli, editor. | Ubic, Rick, editor.

Title: Microwave materials and applications / edited by Dr. Mailadil T. Sebastian, Dr. Heli Jantunen, Dr. Rick Ubic.

Description: Chichester, UK ; Hoboken, NJ : John Wiley & Sons, 2017. | Includes bibliographical references and index.

Identifiers: LCCN 2016052142 | ISBN 9781119208525 (cloth) | ISBN 9781119208556 (epub)

Subjects: LCSH: Microwave devices--Materials. | Dielectrics.

Classification: LCC TK7876 .M2545 2017 | DDC 621.381/30284--dc23

LC record available at https://lccn.loc.gov/2016052142

A catalogue record for this book is available from the British Library.

ISBN: 9781119208525

CONTENTS

Volume I

List of Contributors

Series Preface

Preface

1: Measurement of Microwave Dielectric Properties and Factors Affecting Them

1.1 Introduction

1.2 Permittivity (ϵr) and quality factor (Q)

1.3 Measurement of Microwave Dielectric Properties

1.4 Methods of Measurement

1.5 Measurement of EMI Shielding Effectiveness

1.6 Terahertz and Millimeter Wave Measurements

1.7 Measurement of Dielectric Properties of Powder Samples

1.8 Estimation of Dielectric Loss by Spectroscopic Methods

1.9 Factors Affecting Dielectric Loss

1.10 Measurement of Temperature Coefficient of Resonant Frequency

1.11 Tuning of the Resonant Frequency

References

2: Modeling of Microwave Dielectric Properties of Composites

2.1 Introduction

2.2 Connectivity

2.3 Electrostatic Theory

2.4 Mixing Equations

2.5 Effect of Porosity

2.6 Conclusion

References

3: Perovskites

3.1 Introduction

3.2 Lattice Constant Prediction

3.3 Tolerance Factor

3.4 Octahedral Tilting

3.5 Simple Perovskites

3.6 Cation Ordering

3.7 Cation Deficient Perovskites

3.8 Summary

References

4: High Permittivity Materials

4.1 Introduction

4.2 The BaO–Ln2O3–TiO2 System

4.3 The Effect of Processing Parameters on Electrical Properties

4.4 Titania

4.5 Sr1-3x/2CexTiO3 Ceramics

4.6 Pbn(Nb1-xTax)O5+n

4.7 (Pb1-xCax)(Fe1/2B1/2)O3 [B = Nb, Ta]

4.8 Ag(Nb1-xTax)O3

4.9 Summary

References

5: Millimeter-Wave Materials

5.1 Introduction: New Frontiers of Millimeter-Wave Dielectrics

5.2 Dielectric Properties for Millimeter Wave [29]

5.3 Candidates of Millimeter-Wave Dielectrics

5.4 Specialized Study

5.5 Acknowledgments

References

6: Other Important Materials

6.1 Spinel

6.2 Li2ATi3O8 (A = Mg, Zn) Ceramics

6.3 Li2Zn3Ti4O12

6.4 Apatites

6.5 Alumina

6.6 Zirconium Tin Titanate

6.7 Dielectric Materials in the BaO–TiO2 System

6.8 Columbite Niobates (M²+Nb2O6)

6.9 Acknowledgments

References

7: Microwave Dielectric Properties of Glasses and Bulk Glass Ceramics

7.1 Glasses

7.2 Bulk Glass Ceramics

References

8: High Temperature Cofired Ceramic (HTCC), Low Temperature Cofired Ceramic (LTCC), and Ultralow Temperature Cofired Ceramic (ULTCC) Materials

8.1 High Temperature Cofired Ceramics (HTCC)

8.2 HTCC Alumina

8.3 Aluminium Nitride HTCC

8.4 ZrSiO4

8.5 Low Temperature Cofired Ceramics (LTCC)

8.6 Ultralow Temperature Cofired Ceramics (ULTCC)

8.7 Discussion and Conclusion

References

Index

Volume II

List of Contributors

Series Preface

Preface

9: Voltage Tunable Microwave Dielectrics for Frequency and Phase Agile Devices

9.1 Introduction to Voltage Tunable Materials

9.2 Different Classes of Voltage Tunable Materials

9.3 Importance of Voltage Tunable Materials in Frequency and Phase Agile Devices

9.4 Growth Techniques for Voltage Tunable Thin Films on Various Substrates

9.5 Characterization techniques

9.6 High-Frequency Characterization

9.7 Design and Realization Aspects of Varactors Using Tunable Materials

9.8 Conclusions

9.9 Acknowledgment

References

10: Dielectric Inks

10.1 Introduction

10.2 Methodology

10.3 Dielectric Inks and Their Properties

10.4 Polymer-Based Dielectric Inks, Properties and Applications

10.5 Commercially Available Dielectric Inks, Properties and Applications

10.6 Conclusion

Acknowledgment

References

11: Polymer–Ceramic Composites for Microwave Applications

11.1 Introduction: Microwave Substrates

11.2 Types of Polymer–Ceramic Composites

11.3 Thermoplastic Matrix and Composites

11.4 PTFE/Ceramic Composites

11.5 Polyethylene–Ceramic Composites

11.6 Polystyrene–Ceramic Composites

11.7 Epoxy Ceramic Composites

11.8 Liquid Crystal Polymer (LCP)

11.9 Thermal Conductivity

11.10 Polymer Nanoceramic Composites

11.11 Ultrawideband Antenna Design Using Copper Cladded Ceramic-Filled PTFE Substrates

11.12 Conclusion

References

12: Rubber–Ceramic Composites

12.1 Introduction

12.2 Silicone Rubber

12.3 Butyl Rubber (BR)

12.4 Fabrication of Flexible Microstrip Antenna

12.5 Conclusions

References

13: Designing of Materials for EMI Shielding Applications

13.1 Electromagnetic Shielding and Microwave Absorption Mechanism

13.2 Shielding Effectiveness (SE)

13.3 Measurement of Shielding Effectiveness

13.4 Electromagnetic Shielding Materials

13.5 New Insight into Designing of Materials for Microwave Shielding

13.6 Nanostructured Graphene/Fe3O4 Incorporated Polyaniline for EMI Shielding

13.7 Designing of Polypyrrole–γ-Fe2O3 Nanocomposite Wave Absorber

13.8 Designing of Conducting Polymer Composite by Incorporating Ferrofluid

13.9 Designing of Polypyrrole–Aqueous Ferrofluid (PFF) Nanocomposite Microwave Absorber

13.10 Conclusions

Acknowledgments

References

14: Microwave Ferrites and Applications

14.1 Introduction

14.2 Structure, chemistry, magnetism, and gyromagnetic properties

14.3 Ferrite Materials Processing for Microwave Applications

14.4 Semiconductor Integration of Ferrite Thin and Thick Films for MIC Development

14.5 Ferrite–Based Microwave Device Development

14.6 Outlook

References

15: Applications of Microwave Dielectrics

15.1 General Requirements for Microwave Applications

15.2 LTCC Microwave Components and Materials

15.3 LTCC Application Examples

References

16: Applications of Dielectric Resonators

16.1 Introduction

16.2 Dielectric Resonator Antenna (DRA)

16.3 Applications of Dielectric Resonator in Microwave Oscillators

16.4 Application of Dielectric Resonators in Microwave Filters

References

Appendix: List of Low-Loss Ceramic Dielectric Materials and Their Properties

Abbreviations

References

Index

EULA

List of Tables

Chapter 2

Table 2.1

Chapter 4

Table 4.1

Table 4.2

Chapter 5

Table 5.1

Table 5.2

Table 5.3

Chapter 6

Table 6.1

Table 6.2

Table 6.3

Table 6.4

Chapter 7

Table 7.1

Table 7.2

Table 7.3

Chapter 8

Table 8.1

Table 8.2

Table 8.3

Table 8.4

Table 8.5

Table 8.6

Table 8.7

Table 8.8

Table 8.9

Table 8.10

Table 8.11

Table 8.12

Chapter 10

Table 10.1

Table 10.2

Table 10.3

Table 10.4

Table 10.5

Chapter 11

Table 11.1

Table 11.2

Table 11.3

Table 11.4

Chapter 12

Table 12.1

Table 12.2

Table 12.3

Table 12.4

Table 12.5

Chapter 13

Table 13.1

Table 13.2

Chapter 14

Table 14.1

Chapter 16

Table 16.1

Table 16.2

Table 16.3

List of Illustrations

Chapter 1

Figure 1.1 Plot of number of papers published versus year (as per scopus.com using the keyword microwave materials).

Figure 1.2 The wavelength is reduced by a factor of √ϵ when the wave enters the dielectric.

Figure 1.3 Frequency dependence of polarization processes and peak power losses.

Figure 1.4 The TE01δ resonant peak and associated parameters.

Figure 1.5 Schematic sketch of the Courtney setup for measuring the dielectric constant under an end shorted condition.

Figure 1.6 The TE011 resonance of a ceramic puck with ϵr = 9.8 under an end shorted condition.

Figure 1.7 The cavity setup for the measurement of Q-factor.

Figure 1.8 Microwave resonance spectra of Ba(Mg1/3Ta2/3)O3 ceramic with ϵr = 24: (a) reflection and (b) transmission configuration.

Figure 1.9 The cavity manufactured by QWED for the quality factor measurement.

Figure 1.10 Variation of Qf with ratio of the cavity diameter/sample diameter.

Figure 1.11 Schematic diagram of a DR coupled to (a) a microstrip line and (b) an equivalent circuit. (After Khanna and Garault [38]).

Figure 1.12 Typical resonant curve of a DR coupled to a microstrip line used in determining the quality factor by the strip line method.

Figure 1.13 The experimental setup for measuring the quality factor by the strip line method. The DR is coupled to the strip line.

Figure 1.14 Schematic sketch of SPDR.

Figure 1.15 Photographs of SPDR connected to a Q meter and computer. Source: Reproduced with permission from QWED, Poland.

Figure 1.16 Cylindrical cavities containing (a) a dielectric rod and (b) a dielectric disk.

Figure 1.17 Variation of resonant frequency with an imaginary part of permittivity for the TE011 mode cylindrical cavity with a dielectric disk sample. Dotted line corresponds to the TE011 mode frequency of the empty cavity. Source: Adapted from Krupka 2006 [14].

Figure 1.18 Variation of Q-factor due to dielectric losses as a function of the imaginary part of permittivity for the TE011 mode cylindrical cavity containing a dielectric disk sample. Source: Adapted from Krupka 2006 [14].

Figure 1.19 Setup for free-space by the short-circuited reflection method.

Figure 1.20 Setup for free-space by metal-backing and bistatic reflection.

Figure 1.21 Accurate setup for free-space measurements.

Figure 1.22 Schematic for dielectric measurement by the Kent method.

Figure 1.23 Schematic for dielectric measurement by the Yu–Cullen method.

Figure 1.24 Diagram for the S parameter in the network analyzer.

Figure 1.25 Schematic for the waveguide method.

Figure 1.26 Measurement setup used for cavity methods.

Figure 1.27 Experimental optical arrangement of a THz system.

Figure 1.28 A photoconductive switch integrated in a microstrip transmission line.

Figure 1.29 Schematic for dielectric measurements of powder samples. Source: Tuhkala et al. 2013 [106]. Reproduced with permission of AIP.

Figure 1.30 Variation of tan δ of three different sapphire crystals as a function of temperature on cooling: (a) crystal with disorientation, (b) crystal grown at the rate of 8 mm/h, and (c) crystal grown at the rate of 4 mm/h. Source: Adapted from Braginsky et al. 1987 [17].

Figure 1.31 Experimental setup for τf measurements by an HE11δ frequency shift.

Figure 1.32 The frequency displacement of HE11δ mode frequency as a function of temperature variation.

Figure 1.33 The frequency profile of Hakki–Coleman measurements of a high dielectric loss ceramic in comparison with the measurements using the SFS method.

Figure 1.34 Schematic diagrams showing tuning of the resonant frequency: (a) plug tuning, (b) plate tuning, and (c) disk tuning.

Chapter 2

Figure 2.1 Schematics of connectivity families with two different phases. The number of connectivities is reduced from 16 to 10 due to symmetry involved in the families.

Figure 2.2 Electromagnetic wave traveling through dielectric material (having complex permittivity ϵ*r). The effect of the higher complex permittivity of dielectric material results in a decreased wavelength in the medium (λair versus λdiel) and a corresponding reduced amplitude (ain versus aout).

Figure 2.3 Particle that is affected by the electromagnetic wave also causes scattering. Electric field in a certain direction before (Ei) and after (Eo) passing the particle differs as a consequence of losses in the material but also due to scattering. Either Rayleigh or Mie scattering dominates when the particle is much smaller or the same size as the wavelength, respectively.

Figure 2.4 Sphere- and needle-shaped particles orientated into two different directions with respect to the incident electromagnetic waves Eiz and Eix.

Figure 2.5 Ellipsoid with dimensions of ax, ay and az.

Figure 2.6 Bruggeman symmetric and non-symmetric equations with varying inclusion and matrix permittivities of 2.1 and 30, respectively.

Figure 2.7 Modified Lichtenecker equation with k-factors of 0.1, 0.3, and 0.6 and ϵe = 2.1, ϵi = 30.

Figure 2.8 Dielectric material under E-field in serial and parallel models.

Figure 2.9 Presented mixing equations with ϵe = 2.1, ϵi = 30, and k = 0.3.

Figure 2.10 (a) Random unit cell embedded in the effective media in the EMT model. (b) Composite schematic including filler, interphase and matrix in the Vo–Shi model where a, b, and c represent radii of different constituents.

Figure 2.11 Permittivity of the dielectric can be decreased using low permittivity fillers or increasing porousness.

Figure 2.12 Measured effective permittivities of (1 – x)MgTiO3–xCaTiO3 composite powders with CaTiO3 molar ratios (x) of (a) 0.02, (b) 0.05, and (c) 0.1 and effective permittivities of Bruggeman symmetric and Looyenga mixing models with inclusion permittivities of (a) 13.5, (b) 14.0, and (c) 14.9. Measured effective loss tangents of MgTiO3 and composite powders and theoretical effective loss tangents calculated by the general mixing model. The resonance frequencies of the resonator perturbed by the powder samples were within the range 2.12–3.66 GHz. EPMA figures of calcium distribution (light dots in 100 μm × 100 μm analysis areas) in composite powders as inserts. Source: Reprinted with permission from Journal of Applied Physics. Copyright 2014, AIP Publishing LLC [69].

Figure 2.13 SEM figure of elongated BaTiO3 particles. Source: Adapted from Tuhkala et al. 2015 [75].

Chapter 3

Figure 3.1 Simple ABX3 perovskite structure (e.g., BaTiO3), where A (Ba) and B (Ti) are cations and X (O) is the anion.

Figure 3.2 Schematic representation of octahedral tilting in perovskites: (left) in-phase octahedral tilting about a single axis, (right) antiphase octahedral tilting about a single axis.

Figure 3.3 Variation of ϵr as a function of tolerance factor t in LnAlO3. Source: Cho et al. 2012 [37]. Reproduced with permission from Cambridge University Press.

Figure 3.4 1:1-Ordered double-perovskite A(B1/2'B1/2'')O3 structure viewed along ⟨110⟩c to highlight the doubled ⟨111⟩ repeat of the B′ and B′′ cation sites.

Figure 3.5 Unit-cell parameters for Ba2LnTaO6 reflecting the increase in symmetry of the various members of this series with decreasing lanthanide ionic radius. Source: Saines et al. 2007 [66] Reproduced with permission from Elsevier.

Figure 3.6 The τf as a function of tolerance factor (t) for Ba2LnTaO6 ceramics. Source: Khalam et al. 2008 [68]. Reproduced with permission from John Wiley & Sons.

Figure 3.7 Temperature dependence of the reduced lattice parameters for Ba2NdNbO6 obtained from analysis of synchrotron X-ray diffraction data. Source: Saines et al. 2007 [71]. Reproduced with permission from Elsevier.

Figure 3.8 Calculated tilting angles in Ba2LnNbO6 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Y) as a function of the tolerance factor, t. Source: Fu and Ijdo 2006 72]. Reproduced with permission from Elsevier.

Figure 3.9 Synchrotron X-ray diffraction pattern (crosses) recorded from Sr2YNbO6 powder. The X-ray wavelength was 0.4973 Å. The pattern was fitted (continuous line) assuming a monoclinic structure with P21/n space-group symmetry. The markers below the pattern indicate the expected peak positions and the curve below these markers show the difference between the observed and calculated patterns. The inset shows detail of the fit near the group of reflections indexed as 440 in the doubled (∼ 8.25 Å) pseudocubic perovskite cell. Source: Howard et al. 2005 [78]. Reproduced with permission of the International Union of Crystallography.

Figure 3.10 The variation in the τf of CeO2-added and B2O3-added Sr(B1/2Nb1/2)O3 ceramics versus the tolerance factor. Source: Khalam and Sebastian 2006 [83]. Reproduced with permission from John Wiley & Sons.

Figure 3.11 The variation of ϵr and τf of Ca(B1/2Ta1/2)O3 (B = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, and In) ceramics versus B-site ionic radii. Source: Khalam et al. 2007 [87], reproduced with permission from John Wiley & Sons.

Figure 3.12 The dielectric constant and temperature coefficient of resonant frequency of Ca(B1/2Nb1/2)O3 ceramics versus ionic radii of B-site elements. Source: Khalam and Sebastian 2007 [89]. Reproduced with permission from John Wiley & Sons.

Figure 3.13 SADPs of LZT indexed according to the simple pseudocubic perovskite unit cell (a = 3.9449 Å) corresponding to (a) [100], (b) [010], (c) [001], (d) [111], (e) [110], (f) [101], and (g) [011]. Source: Adapted from Ubic et al. 2006 [113].

Figure 3.14 Ordered cationic arrangement of B-site ions in complex perovskites: 1:1 arrangement (left) and 1:2 arrangement (right). Source: Sagala and Nambu 1992 [137]. Reproduced with permission from Physical Society of Japan.

Figure 3.15 Crystal structure of Ba(Mg1/3Ta2/3)O3. The large spheres represent Ba atoms and the small spheres oxygen atoms. Medium spheres represent Mg in pale [MgO6] octahedra and Ta in dark [TaO6] octahedra. Ta distorts out-of-center towards the octahedral face with O bonded to Mg. Source: Adapted from Lufaso 2004 [143].

Figure 3.16 Variation of quality factor of BMT with glass addition. Source: Adapted from Surendran et al. 2004 [154].

Figure 3.17 (left) X-ray diffraction line profiles of (422) and (266) reflections for Ba(Mg0.33-xTa0.67)O3 for x = (a) 0.03, (b) 0.025, (c) 0.02, (d) 0.015, (e) 0.01, (f) 0.005, (g) 0.0, (h) –0.005, (i) –0.010, and (j) –0.015. (right) X-ray diffraction line profiles of (422) and (266) reflections for Ba1-x(Mg0.33Ta0.67)O3 for x = (a) 0.0025, (b) 0.005, (c) 0.0075, (d) 0.01, (e) 0.015, (f) 0.02, (g) 0.025, (h) 0.03, (i) −0.005, (j) –0.01, and (k) –0.015, Source: Adapted from Surendran et al. 2005 [164].

Figure 3.18 Powder diffraction patterns of some typical non-stoichiometric compositions of BMT: (a) pure Ba(Mg0.333Ta0.667)O3, (b) Ba(Mg0.3233Ta0.667)O3, (c) Ba(Mg0.3183Ta0.667)O3, (d) Ba(Mg0.3133Ta0.667)O3, (e) Ba(Mg0.3033Ta0.667)O3, (f) 0.9925 Ba(Mg0.3183Ta0.667)O3, (g) 0.99 Ba(Mg0.3183Ta0.667)O3, (h) 0.98Ba(Mg0.3183Ta0.667)O3, (i) 0.97 Ba(Mg0.3183Ta0.667)O3. • stands for Ba5Ta4O15, for ❖ BaTa2O6, and ⊗ MgTa2O6. Source: Adapted from Surendran et al. 2005 [164].

Figure 3.19 Variation of unloaded quality factor of Ba(Mg0.33-xTa0.67)O3 and Ba1-x(Mg0.33T0.67) O3 as a function of x. Source: Adapted from Surendran et al. 2005 [164].

Figure 3.20 Variation of the quality factor of BMT with concentration of the dopant. Source: Adapted from Surendran et al. 2005 [182].

Figure 3.21 Plot of ionic radius of the dopant versus quality factor of BMT ceramic. Source: Adapted from Suendran et al. 2005 [182].

Figure 3.22 Variation of unloaded quality factor of pure and doped BMT at cryogenic temperature. Source: Adapted from Surendran 2005 [182].

Figure 3.23 Volume of the subcell versus concentration of BaZrO3 in BMT. Source: Chai et al. 1997 [189]. Reproduced with permission from Elsevier.

Figure 3.24 Illustration of the crystal structure of the disordered cubic perovskite subcell (left, <111> direction vertical) and the ordered trigonal supercell (P3hm1) (right, c-axis vertical) of Ba3ZnTa2O9 showing layers of TaO6 and ZnO6 octahedral. Source: Mallinson et al. 2007 [196]. Reprinted with permission from American Chemical Society, © 2016.

Figure 3.25 Electron diffraction patterns recorded from BZT with the beam perpendicular to a pseudocubic {110} direction obtained from the center of a grain in a sample quenched from (a) 1600 °C and (b) 1625 °C. Source: Qazi et al. 2001 [141]. Reproduced with permission from Elsevier.

Figure 3.26 Variation of quality factor of BZT as a function of the ionic radius of the additive cation. Source: Varma et al. 2005 [209]. © The Japan Society of Applied Physics.

Figure 3.27 The dependence of microwave quality factor of Ba(Zn1/3Ta2/3)O3 on the compositional deviation around xBaO—y1/3ZnO—z2/3TaO5/2 system (x + y + z = 3). Source: Adapted from Ohsato 2016 [272].

Figure 3.28 BaO—ZnO—TaO5/2 partial ternary system in the vicinity of BZT. Synthesized compositions are shown by alphabets A to S. A point is pure BZT. Three areas are shown as (I) for order/single phase, (II) for order/secondary phase, and (III) for disorder/single phase. Source: Adapted from Ohsato 2016 [272].

Figure 3.29 Representation of 1:1 B-site ordering in Ba(Zr, Zn, Ta)O3 crystal. Source: Tamura 2006 [215]. Reprinted with permission from Elsevier.

Figure 3.30 HRTEM image viewed along the [11 ]c zone axis. Higher amplification lattice images of the labeled areas: (b) area I and (c) area II. Simulated unfocused HRTEM images for (d) 1:2 ordered and (f) disordered Ba(B1/3'B2/3'')O3 perovskites; d = 110 nm and thickness t = 4.3 nm along the [11 ]c zone axis. (e) Schematic diagram of [11 ]c projection for ordered Ba((Co, Zn, Mg)1/3Nb2/3)O3 ceramics. Source: Ma et al. 2015 [217] Reprinted with permission from Royal Society of Chemistry.

Figure 3.31 Qf values of stoichiometric Ba(Zn1/3Nb2/3)O3 (BZN) after heat treatments in different ZnO loss-protective environments. Source: Wu and Davies 2006 [221]. Reprinted with permission from John Wiley & Sons.

Figure 3.32 Variation of Qf with ionic radius of dopant for 1 and 0.5 mol% dopant addition in BZN. Source: Varma and Sebastian 2007 [229]. Reprinted with permission from Elsevier.

Figure 3.33 Change in the Qf of (1 – x)BZN—(x)BW with x after sintering (square data points) and annealing (circles). The highest reported Qf value for pure BZN is indicated by a star. Source: Wu and Davies 2006 [230]. Reprinted with permission from John Wiley & Sons.

Figure 3.34 Qf values of Ba(Zn1/3Nb2/3)O3 (BZN) with an excess and deficiency of Nb2O5. As-sintered samples are indicated by solid squares and annealed samples by open squares. Source: Wu and Davies 2006 [232]. Reprinted with permission from John Wiley & Sons.

Figure 3.35 Schematic illustration of the perovskite subcells in the 1:3-ordered A(B1/4'B3/4'')O3 structure highlighting the different B' and B" sites

Figure 3.36 Plot of ionic radius of dopant versus quality factor of 1 mol%-doped Ca5Nb2TiO12 and Ca5Ta2TiO12 ceramics. Source: Bijumon and Sebastian 2007 [253]. Reproduced with permission from John Wiley & Sons.

Chapter 4

Figure 4.1 Schematic diagram of the tungsten bronze structure. After Subbarao et al. [37] and Jamieson et al. [38].

Figure 4.2 Proposed crystal structure of Ba3.75Pr9.5Ti18O54. Source: Adapted from Matveeva et al. 1984 [14].

Figure 4.3 Microwave dielectric properties of Ba6-3xLn8+2xTi18O54 (Ln = La, Pr, Nd, and Sm), Source: Adapted from Ohsato 2001 [45].

Figure 4.4 Dependence of (a) ϵr and (b) τf on the unit cell volume. Source: Adapted from Ohsato 2001 [45].

Figure 4.5 Variation of quality factor (Qf) and τf of Ba4(Nd28/3-ySmy)Ti18O54 for y = 1. Source: Adapted from Ohsato et al. 1995 [57].

Figure 4.6 Variation of ϵr, Qf, and τf as a function of composition in Ba4Sm (28-y)/3LiyTi18O54 solid solution. Source: Adapted from Ohasto et al. 2004 [102].

Figure 4.7 The microstructure of (Ba0.5Pb0.5)3.75Nd9.5Ti18O54 was sintered in air at 1400 °C for four hours. Source: Adapted from Ubic et al. 1998 [5].

Figure 4.8 Effect of porosity on the quality factor value of sintered TiO2 disks measured at 3 GHz. Source: Adapted from Templeton et al. 2000 [131].

Figure 4.9 Qf versus six coordinate ionic radii for doped TiO2. The lines indicate ideal range for ionic radii [8] for the dopants to get high Q. Source: Pullar et al. 2009 [34]. Reprinted with permission from Elsevier.

Figure 4.10 XPS spectra in the Ce-3d binding energy region for selected samples, from x = 0.400 to 0.133. Peaks linked to Ce³+ and Ce⁴+ cations are indicated. Source: Adapted from Subodh et al. 2007 [144].

Figure 4.11 Selected-area electron diffraction patterns from grains of the x = 0.25 composition corresponding to (a) [001], (b) [101], and (c) [111] pseudocubic directions. Superlattice reflections caused by antiphase tilting of octahedra are denoted with an α in (b). Source: Adapted from Ubic et al. 2008 [145].

Figure 4.12 High-resolution image of the x = 0.25 composition parallel to the pseudocubic [110]. The lower-right inset is a Fourier transform of the image with superlattice spots circled. Source: Adapted from Ubic et al. 2008 [145].

Figure 4.13 Pseudocubic [110] selected area diffraction pattern of the x = 0.4 composition with α and β superlattice reflections indicated. Source: Adapted from Ubic et al. 2009 [146].

Figure 4.14 ToF neutron powder diffraction patterns for d-spacings between 0.5 and 3 Å for Sr1−3x/2CexTiO3 (x = 0.1333, 0.1667, 0.25, 0.4) taken from data obtained with the 46° bank detectors. Observed data are represented by crosses; calculated results are represented by solid lines. The difference curve is illustrated on the same scale. The arrow in the inset (b) shows, as an example, a weak superlattice reflection at ≈2.35 Å corresponding to the pseudocubic ½{311}. Source: Adapted from Ubic et al. 2008 [145].

Figure 4.15 SEM micrographs for the Sr1-3x/2CexTiO3 samples sintered at 1375 °C/2 h, for (a) x = 0.1667, (b) x = 0.2, (c) x = 0.25, (d) x = 0.333. Source: Adapted from Subodh et al. 2007 [144].

Figure 4.16 Dependence of microwave ϵr and Qf with Ce³+ content (x) for the Sr2+nCe2Ti5+nO15+n (renamed as Sr1-3x/2CexTiO3) solid solutions, at optimized sintering temperatures. SrTiO3 values are included for x = 0. Source: Adapted from Subodh et al. 2008 [144].

Figure 4.17 Temperature dependences of real and imaginary parts of complex permittivity in Sr0.75−xPbxCe0.1667TiO3 (x = 0–0.75) ceramics. Data were taken at 100 kHz (y = 0–0.25, 0.75) and at 100 MHz (y = 0.3333–0.6667). Source: Adapted from Kamba et al. 2009 [157].

Figure 4.18 Concentration dependence of microwave permittivity and Qf factor in Sr0.75-xPbxCe0.6667TiO3 (x = 0–0.75) ceramics. Data were collected at room temperature between 0.9 and 3.2 GHz. Source: Adapted from Kamba et al. 2009 [157].

Figure 4.19 High-resolution TEM images and the corresponding SADPs of grains from PbnNb2O5+n ceramics with the nominal compositions (a) n = 1.5, (b) n = 1.6, (c) n = 1.75, (d) and (e) n = 2.0, (f) n = 2.2, (g) n = 2.5, and (h) n = 3.0. A simulation of the n = 1.5 structure is shown inset in (a) and outline unit cells are drawn for both the cubic and trigonal settings. Crystallographic directions are labeled with reference to the cubic unit Cell. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.20 Dynamical dark-field TEM images of a Pb1.6Nb2O6.6 grain near the <111>cubic zone. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.21 XRD traces of crushed pellets with nominal compositions corresponding to PbnNb2O5+n where n = 1.5, 1.6, 1.75, 2.0, 2.2, and 2.5. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.22 A comparison of the simulated XRD patterns for the Pb2Nb2O7 models proposed by Bernotat-Wulf and Hoffmann [172] (marked B), Leroux et al. [166] (marked L), and an experimental trace for a crushed Pb2Nb2O7 pellet (marked E). Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.23 Crystal models of the Pb2Nb2O7 structure as proposed in references [164] (a) and [166] (b), viewed along <100>.

Figure 4.24 The effect of Pb concentration (n) on the τf of PbnNb2O5+n. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.25 The effect of Pb concentration (n) on the ϵr and Q of PbnNb2O5+n. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.26 The effect of Ta⁵+ doping on the τf of Pb1.5Nb2O6.5 and Pb2Nb2O7. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.27 The effect of Ta⁵+ doping on the ϵr and Q of Pb1.5Nb2O6.5. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.28 The effect of Ta⁵+ doping on the ϵr and Q of Pb2Nb2O7. Source: Adapted from Ubic and Reaney 2002 [163].

Figure 4.29 Temperature dependence of relative permittivity for ANT 31:13 end members and composites. Source: Kim et al. 2002 [268].

Figure 4.30 Variation of temperature coefficient of capacitance for Ag(Nb, Ta)O3 end members and composite. Source: Kim et al. 2002 [268].

Chapter 5

Figure 5.1 Millimeter-wave layout list of 30 GHz (1 cm) to 300 GHz (1 mm) of Ministry of Public Management, Home Affairs, Posts and Telecommunications in Japan [2].

Figure 5.2 Usage of millimeter-wave: (a) Non-condense high data transfer digital wireless telecommunications system (LAN/PAN) [3]. (b) Millimeter-wave radar on the pre-crashed safety system [4]. Source: Reproduced with permission of TOYOTA News Release 2009.

Figure 5.3 Direction of development of microwave dielectrics designed on a figure: Qf as a function of ϵr. Source: Adapted from Ohsato et al. 2004 [9].

Figure 5.4 (a) When irradiated by electromagnetic waves, the materials should resonate due to changing dielectric polarization under alternating electromagnetic fields. (b) Dielectric losses increase with an increase in frequency. (c) ϵr causes a shortening of wavelength λ in dielectrics. Source: Adapted from Ohsato [17, 32].

Figure 5.5 Origin of extrinsic losses produced by (a) defects, (b) impurities), and (c) grain boundary.

Figure 5.6 Dielectric constants due to crystal structure: (a) SiO4 tetrahedron, (b) Al2O3, and (c) TiO6 octahedron. Source: Adapted from Ohsato 2005 [17].

Figure 5.7 Qf of high purity forsterite ceramics and commercial forsterite ceramics against ϵr. Dielectric losses of commercial forsterite ceramics and high Q forsterite ceramics against dielectric constants. Source: Adapted from Ohsato 2007 [35].

Figure 5.8 SEM photographs of (a) commercial forsterite ceramics and (b) high purity forsterite ceramics sintered at 1360 °C. Source: Adapted from Ohsato 2007 [35].

Figure 5.9 (a) Apparent density and (b) temperature coefficient of resonant frequency of the forsterite ceramics with added 30 wt% rutile as a function of the sintering temperature. Source: Adapted from Tsunooka et al. 2004 [20].

Figure 5.10 Rutile added to forsterite located in the 2MgO·SiO2—MgO·2TiO2·MgO·SiO2 compositional triangle. Source: Adapted from Tsunooka et al. 2013 [38].

Figure 5.11 Qf and τf (a) and Da and ϵr (b) of rutile added forsterite as a function of amount of TiO2. (c) A backscattered SEM photograph of the forsterite ceramics composite with 25 wt% rutile sintered at 1,200 °C for 2 hours. Source: Adapted from Tsunooka et al. [20, 38].

Figure 5.12 Qf values of sintered at 1400 °C for 2 hours as a function of calcined hours. Source: Ando et al. [21, 22].

Figure 5.13 XRPD patterns of powders applied: (a) silica A and (b) silica B. XRPD patterns as shown below half way in (a) and (b) represent the difference in calcined powder at 1175 °C for 2, 3, 4, 10, and 24 hours and are indicated as cal nh. Above halfway in (a) and (b), 1175 °C, samples, which are sintered at 1400 °C for 2 hours after, are denoted as sin nh. Source: Ando et al. [21, 22].

Figure 5.14 SEM image of silica A and silica B: (a) raw materials and (b) calcined powder. Source: Ando et al. [21, 22].

Figure 5.15 SEM images of the section of grains calcined at 1175 °C for 2 h with EPMA line analysis of Si and Mg: (a) silica A, (b) silica B, and (c) small grains of silica A. Source: Ando et al. [21, 22].

Figure 5.16 The average grain size of the samples sintered at 1400 °C for 2 hours using silica A and silica B as a function of calcination time. Source: Ando et al. [21, 22].

Figure 5.17 Surface SEM images of specimens prepared by using silica A and silica B sintered at 1400 °C for 2 hours as a function of calcination time and at 1175 °C for (a) 2, (b) 3, (c) 4, (d) 10, and (e) 24 hours. Source: Ando et al. [21, 22].

Figure 5.18 Phase diagram of the MgO—SiO2 binary system. Source: Adapted from Wu et al. 1993 [40].

Figure 5.19 SEM micrograph of willemite ceramic sintered at 1340 °C for 2 h. Source: Adapted from Guo et al. 2006 [23].

Figure 5.20 (a) The τf of rutile added willemite as a function of amount of TiO2. (b) SEM photograph of rutile added willemite. These samples were sintered at 1250 °C for 2 h. After Guo et al. [23].

Figure 5.21 (a) Millimeter-wave dielectric strip resonator with 3 μm thickness electrode on the substrate with 0.2 mm thickness for trial manufacture. (b) Resonant frequency depending on temperature. Source: Adapted from Nakazawa and Shimakata 2011 [8].

Figure 5.22 Transmission loss in the microstrip line using high-Q willemite substrate. The loss is 1/9 that in the current substrates [7].

Figure 5.23 Crystal structure of (a) cordierite and (c) indialite, and (b) ordering/disordering of AlO4/SiO4. Source: Adapted from Ohsato et al. 2013 [25].

Figure 5.24 (a) Qf as a function of Ni-doped cordierite, (b) volume of AlO4 and SiO4 as a function of Ni-doped cordierite, and (c) covalencies of Si—O and Al—O as a function of composition x. Source: Adapted from Ohsato et al. 2013 [25].

Figure 5.25 Crystal structure of Ni-doped cordierite (Mg1-xNix)2Al4Si518, (a) x = 0, (b) 0.05, and (c) 0.1. Source: Adapted from Ohsato et al. 2010 [28].

Figure 5.26 (a) Just-casted glass rod with internal strain under the crossed polars, (b) annealed glass without strain free, and (c) glass pellets cut for resonator. Source: Adapted from Ohsato et al. 2013 [25].

Figure 5.27 (a) Deformation and cracking of crystallized pellets, (b) anisotropic crystal growth of the pellets crystallized from the surface of the glass pellets under the crossed polars, and (c) thermal expansion of crystallographic axes on cordierite. Source: Adapted from Ohsato et al. 2013 [25].

Figure 5.28 Microwave dielectric properties of indialite/cordierite glass ceramics crystallized for (a) 10 and (b) 20 hours, and indialite percentage (b) as a function of the crystallization temperature. Source: Adapted from Ohsato et al. 2013 [25].

Figure 5.29 Estimating the ordering ratios of Si and Al in tetrahedra by (a) volumes and (b) covalencies of Si/AlO4 tetrahedra. Source: Adapted from Ohsato et al. 2013 [25].

Figure 5.30 (a) Optical and (b) and (c) SEM photographs of indialite/cordierite glass ceramics crystallized at 1200 °C for 10 hours; (a) and (c) with 10 wt% TiO2 show no cracks and no deformations, but (b) without TiO2 shows cracks. Source: Adapted from Kagomiya and Ohsato 2014 [56].

Figure 5.31 Microwave dielectric properties of indialite/cordierite glass ceramics with rutile 0, 10, 20 wt% crystallized at 1200 °C for 10 hours. Source: Adapted from Kagomiya and Ohsato 2014 [56].

Figure 5.32 Crystal structure of (a) α-CaSiO3 and (b) SrSiO3 solid solutions. Source: Adapted from Kagomiya et al. 2009 [26].

Figure 5.33 Relative density and microwave dielectric properties, ϵr, Qf, and τf, of (Ca1−x Srx)SiO3 solid solutions as functions of composition x. Source: Adapted from Kagomiya et al. 2009 [26].

Figure 5.34 (a) Qf, (b) ϵr and (c) τf of CaMgSi2O6 ceramics sintered at 1300 °C, as a function of calcining temperature. Source: Adapted from Ohsato et al. 2012 [27].

Figure 5.35 (a) Specific surface area, (b) bulk green density, and (c) relative density of sintering temperature at 1300 °C for 2 h. Source: Adapted from Ohsato et al. 2012 [27].

Figure 5.36 SEM figures of diopside powders calcined at 1100–1300 °C for 2 h. Source: Ohsato et al. 2012 [27].

Figure 5.37 Phase diagram of CaO—MgO—SiO2 ternary system. A part around the diopside and akermanite is magnified including triple points at 1350 and 1357 °C. Source: Adapted from Ohsato et al. 2012 [27].

Figure 5.38 (a) The electronegativity scale of the elements, showing the relation to the periodic table. The electronegativities are plotted against the horizontal scale, and different columns of the periodic table are separated vertically. (b) Curve relating an amount of ionic character of a bond A—B to the difference in electronegativity xA – xB of the atoms [61, 62].

Figure 5.39 The solid solutions in alkali and plagioclase feldspars at high temperature. Source: Adapted from Hurlbut 1971 [67].

Figure 5.40 Sintering process of LFC containing anorthite as the main composition; start composition: •60% Gl60 + ◯40% Al2O3 + 10 wt% B2O3, final composition: anorthite (•B2) + 20%Al2O3(◯Al-220) + glass (•G3:B2O3•SiO2) [70]. Source: Reproduced with permission from Nishigaki 2005.

Figure 5.41 Dielectric properties of plagioclase feldspars NaxCa1-xAl2-xSi2+xO8 s.s: (a) τf and ϵr, (b) Qf as a function of x. Source: Adapted from Krzmanc 2005 [71].

Figure 5.42 Microwave dielectric properties of alumina ceramics: (a) Qf, (b) ϵr, and (c) τf as a function of the sintering temperature. Source: Adapted from Ohsato et al. 2003 [18].

Figure 5.43 (a) Density and (b) mean grain size of alumina ceramics as a function of sintering temperature, and (c) Qf values as a function of mean grain size of alumina ceramics. Source: Adapted from Miyauchi 2008 [30].

Figure 5.44 TiO2—Al2O3 phase diagram. Source: Adapted from Levin 1975 [78].

Figure 5.45 (a) τf, (b) ϵr, (c) Qf, and (d) ρ of TiO2-added alumina as a function of sintering temperature. Solid and open circles show data before and after annealing, respectively. Source: Adapted from Miyauchi et al. 2006 [77].

Figure 5.46 Crystal structure of (a) alumina and (b) new-type corundum.

Figure 5.47 (a) Cluster model used in the calculation: (Mg4M2O22)−26 (M = Nb and Ta). Energy level diagrams and total and partial density state of (b) MN and (c) MT by (Mg18M2O60)−74. Source: Adapted from Ogawa et al. 2003 [80].

Figure 5.48 (a) ϵr, (b) αobs, and (c) Qf of MNT s.s. as a function of composition x. Source: Adapted from Ogawa et al. 2003 [80].

Figure 5.49 (a) Lattice parameters and (b) volumes of MNS s.s. as a function of composition x. Source: Adapted from Ogawa et al. 2005 [81].

Figure 5.50 Normalized covalency of Mg—O and (Nb/Sb)–O bonds as a function of composition x. Source: Adapted from Ogawa et al. 2005 [81].

Figure 5.51 Energy-level diagrams and total and partial density of states of (a) Mg4Nb2O9 and (b) Mg4Sb2O9 by (AMg12O45)−61 (A = Nb and Sb) cluster. Source: Adapted from Ogawa et al. 2005 [81].

Figure 5.52 (a) The Qf and ϵr values and (b) τf of MNS s.s. as a function of composition x. Source: Adapted from Ogawa et al. 2005 [81].

Figure 5.53 (a) Model of crystal structure of spinel, which is exhibited in KEK Tsukuba, made by Dr Y. Kudoh and students of Professor Y. Takeuchi's group at the University of Tokyo. (b) Illustrated spinel structure from perpendicular to [111] direction with the same angle as (a).

Figure 5.54 Microwave dielectric properties of MgGa2O4. Source: Kan et al. 2013 [91].

Figure 5.55 (a) Lattice parameter of MgGa2O4 and degree of inversion x of Mg1-xGax[MgxGa2-x]O4, (b) volume values and (c) covalency of T- and O-sites of MgGa2O4. Source: Kan et al. 2013 [91].

Figure 5.56 (a) Lattice parameter, (b) volume of MO4 tetrahedron and MO6 octahedron, and (c) covalency of the M–O bond in MO4 tetrahedron and MO6 (M = Mg, Zn, Ga) octahedron as a function of composition x of (1 – x)MgGa2O4–xZnGa2O4 ceramics fired at 1500 °C for 2 h in air. Source: Kan et al. 2014 [88].

Figure 5.57 (a) Relative density, (b) the ϵr values, and (c) Qf of (Mg1-xZnx)Ga2O4 s.s. as a function of the firing temperature. Source: Kan et al. 2014 [88].

Figure 5.58 The effects of Co substitution for Mg on (a) the bulk density, (b) ϵr, (c) Qf, and (d) τf of (Mg3-xCox)(VO4)2 ceramics sintered for 5 h in air. Source: Umemura et al. 2005 [106].

Figure 5.59 (a) Bulk density, (b) ϵr, (c) Qf, and (d) τf of Mg3(VO4)2–xBa3(VO4)2 ceramics sintered at 950, 1000, and 1025 °C for 5 h in air. After Ogawa et al. [107]

Chapter 6

Figure 6.1 Powder diffraction patterns of (1 – x)ZnAl2O4–xTiO2 mixed phases for x = 0.0, 0.12, 0.14, 0.15, 0.16, 0.17, 0.18, 0.2, 0.3, 0.5, 1.0. Source: Adapted from Surendran et al. 2004 [5].

Figure 6.2 Variation of the bulk density of (1 – x)ZnAl2O4–xTiO2 with x. Source: Adapted from Surendran et al. 2004 [5].

Figure 6.3 Variation of the ϵr of (1 – x)ZnAl2O4–xTiO2 with x. Source: Adapted from Surendran et al. 2004 [5].

Figure 6.4 Variation of the temperature coefficient of resonant frequency of (1 – x) ZnAl2O4–xTiO2 with x. Source: Adapted from Surendran et al. 2004 [5].

Figure 6.5 Variation of the unloaded quality factor and resonant frequency of (1 – x)ZnAl2O4–xTiO2 with x. Source: Adapted from Surendran et al. 2004 [5].

Figure 6.6 (a) Backscattered SEM micrographs of 0.83ZnAl2O4–0.17TiO2 sintered at 1450 °C, (b) 0.83ZnAl2O4–0.17TiO2 + 10 wt% BBSZ sintered a 950 °C. Source: Adapted from Thomas et al. 2008 [10].

Figure 6.7 SEM images of (1 – x)ZnAl2O4–xTiO2 ceramics: (a) x = 0.1, (b) x = 0.3, (c) x = 0.5, (d) x = 0.7, and (e) x = 0.9, sintered at 1390 °C/4 h. Source: Huang et al. 2009 [11].

Figure 6.8 Variation of bulk density of MgAl2O4 with mole fraction of TiO2 addition. Source: Adapted from Surendran et al. 2005 [20].

Figure 6.9 Powder diffraction pattern of (1 – x)MgAl2O4–xTiO2 system for x = 0.0, 0.12, 0.14, 0.16, 0.18, 0.20, 0.30, 0.50, 0.70, 0.90, and 1.0. ⊙ represents MgTiO3 and * represents Mg2TiO4 phases. Source: Adapted from Surendran et al. 2005 [20].

Figure 6.10 Variation of ϵr of MgAl2O4 with mole fraction of TiO2 addition. Source: Adapted from Surendran et al. 2005 [20].

Figure 6.11 Variation of Qu and τf of MgAl2O4 with mole fraction of TiO2 addition. Source: Adapted from Surendran et al. 2005 [20].

Figure 6.12 X-ray diffraction patterns of Li2Mg1-xZnxTi3O8 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1) ceramics sintered at 1075 °C/4 h. Source: Adapted from George and Sebastian 2010 [61].

Figure 6.13 Shows the SEM images of thermally etched (25 °C below the sintering temperature): (a) Li2MgTi3O8 and (b) Li2ZnTi3O8 ceramics sintered at 1075 °C/4 h. The figure also shows the SEM micrograph of Li2Mg1-xZnxTi3O8 for (c) x = 0.2, (d) 0.4, (e) 0.6, and (f) 0.8; (g) is the magnified image of a part of (e). Source: Adapted from George and Sebastian 2010 [61].

Figure 6.14 The variation of (a) relative permittivity, (b) quality factor, and (c) temperature coefficient of resonant frequency of Li2MgTi3O8 and Li2ZnTi3O8 ceramics as a function of sintering temperature. Source: Adapted from George and Sebastian 2010 [60].

Figure 6.15 The X-ray diffraction pattern of (a) Li2MgTi3O8 sintered at 1075 °C/4 h, (b) Li2MgTi3O8 + 3 wt% of LMZBS sintered at 925 °C/4 h, (c) Li2MgTi3O8 + 3 wt% of LMZBS + 20 wt% of Ag sintered at 925 °C/4 h, (d) Li2ZnTi3O8 sintered at 1075 °C/4 h, (e) Li2ZnTi3O8 + 3 wt% of LMZBS sintered at 900 °C/4 h, and (f) Li2ZnTi3O8 + 3 wt% of LMZBS + 20 wt% of Ag sintered at 900 °C/4 h. Source: Adapted from George and Sebastian 2011 [62]

Figure 6.16 SEM images thermally etched: (a) 3 wt% of LMZBS glass added to LMT ceramics sintered at 925 °C/4 h, (b) 3 wt% of LMZBS glass added to LZT ceramics sintered at 900 °C/4 h, (c) LMT + 3wt% of LMZBS + 20 wt% of Ag sintered at 925 °C/4 h, and (d) LZT + 3 wt% of LMZBS + 20 wt% of Ag sintered at 900 °C/4 h. Source: Adapted from George and Sebastian 2011 [62].

Figure 6.17 The low magnification image of Li2ZnTi3O8 + 3 wt% of LMZBS glass sintered at 900 °C/4 h. Source: Adapted from George and Sebastian 2011 [62].

Figure 6.18 Variation of relative permittivity and quality factor of (a) LMT and (b) LZT ceramics as a function of LMZBS glass addition. Source: Adapted from George and Sebastian 2011 [62].

Figure 6.19 The variation of temperature coefficient of resonant frequency of LMT and LZT ceramics as a function of LMZBS glass. Source: Adapted from George and Sebastian 2011 [62].

Figure 6.20 XRD of ZnLi2/3Ti4/3O4 (a) powders calcined at 900 °C and (b) ceramic sintered at 1075 °C for 2 h. Source: Zhou et al. 2012 [101]. Reproduced with permission of Elsevier.

Figure 6.21 The apatite crystal structure is shown with (SiO4)4–polyhedra shown as grey tetrahedra, the AII (6h) sites are in orange, the AI (4f) sites are in blue, and the large and small channels. Source: Qu et al. [129].

Figure 6.22 TEM images of (a) (Sr2Tm2)Tm6Si6O26, (b) (Sr2Y2)Y6Si6O26, (c) (Sr2Tb2)Tb6Si6O26, and (d) (Sr2Pr2)Pr6Si6O26. Source: Adapted from Leu et al. 2011 [111].

Figure 6.23 X-ray diffraction patterns of Sr2RE8Si6O26 (RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Er, Tm, Yb, and Y) ceramics. Source: Adapted from Thomas and Sebastian 2009 [112].

Figure 6.24 Electron diffraction patterns of (Sr2Pr2)Pr6Si6O26 ceramic along (a) [001], (b) [100], (c) [120], and (d) [011] zones. Source: Leu et al. 2011 [111].

Figure 6.25 SEM images of (a) Sr2La8Si6O26 sintered at 1325 °C/2 h, (b) Sr2Dy8Si6O26 sintered at 1475 °C/2 h, and (c) Sr2Dy8Si6O26 + 0.5 wt% ZBS sintered at 1450 °C/2 h. Source: Adapted from Thomas and Sebastian 2009 [112].

Figure 6.26 XRD patterns of (A) CaRE4Si3O13 (RE = La, Pr, Nd, Sm, Eu, Tb, Dy, Tm, Yb, and Y) and (B) BaRE4Si3O13 (RE = La, Pr, Nd, Sm) ceramics. Source: Adapted from Thomas 2011 [124].

Figure 6.27 SEM images of (a) Ca2La8Si6O26 sintered at 1325 °C/2 h, (b) Ca2Y8Si6O26 sintered at 1475 °C/2 h, and (c) Ba2La8Si6O26 sintered at 1325 °C/2 h. Source: Adapted from Thomas 2011 [124].

Figure 6.28 Powder XRD patterns of Ca2+xLa8-x(SiO4)6-x(PO4)xO2 with (a) x = 0 sintered at 1475 °C/4 h, (b) x = 2 sintered at 1475 °C/4 h, (c) x = 4 sintered at 1675 °C/4 h, and (d) x = 6 sintered at 1425 °C/4 h. Source: Adapted from Thomas and Sebastian 2011 [113].

Figure 6.29 Lattice parameter variation of Ca2+xRE8−x(SiO4)6−x(PO4)xO2 with the value of x. Source: Adapted from Thomas et al. 2013 [114].

Figure 6.30 SEM images of Ca2+xLa8−x(SiO4)6−x(PO4)xO2 with (a) x = 0 sintered at 1475 °C/4 h, (b) x = 2 sintered at 1475 °C/4 h, (c) x = 4 sintered at 1675 °C/4 h, and (d) x = 6 sintered at 1425 °C/4 h. Source: Adapted from Thomas et al. 2013 [114].

Figure 6.31 (a) Variation of Quf with x for Ca2+xRE8−x(SiO4)6−x(PO4)xO2 ceramics and (b) variation of τf with x for Ca2+xRE8−x(SiO4)6−x(PO4)xO2 ceramics. Source: Adapted from Thomas et al. 2013 [114].

Figure 6.32 SEM images of (a) Sr4La6(SiO4)4(PO4)2O2, (b) Ca4Pr6(SiO4)4(PO4)2O2, (c) Ca4La6(GeO4)4(PO4)2O2, and (d) Ca4La6(SiO4)4(VO4)2O2. Source: Adapted from Thomas et al. 2013 [114].

Figure 6.33 Dependence of Qf on x for (a) (Ca4-xSrx)La6(SiO4)4(PO4)2O2, (b) Ca4La6-xPrx)(SiO4)4(PO4)2O2, (c) Ca4La6(SiO4)4-x(GeO4)x(PO4)2O2, and (d) Ca4La6(SiO4)4(PO4)2-x(VO4)xO2. Source: Adapted from Thomas et al. 2013 [114]

Figure 6.34 Variation of τf with x for (a) (Ca4-xSrx)La6(SiO4)4(PO4)2O2, (b) Ca4(La6-xPrx)(SiO4)4(PO4)2O2, (c) Ca4La6(SiO4)4-x(GeO4)x(PO4)2O2, and (d) Ca4La6(SiO4)4(PO4)2-x(VO4)xO2 ceramics. Source: Adapted from Thomas et al. 2013 [114].

Figure 6.35 Variation of tan δ with time in 42% porous alumina after introduction of dry N2 gas. Source: Adapted from Molla et al. 1999 [132].

Figure 6.36 Variation of tan δ with fractional porosity. Source: Adapted from Alford et al. 2001 [133].

Figure 6.37 Variation of the unloaded quality factor with Sn in ZrxSnzTiyO4 ceramics. Source: Adapted from Wolfram and Gobel 1981 [175].

Figure 6.38 Variation of the temperature coefficient of resonance frequency τf with Sn content. Source: Adapted from Wolfram and Gobel 1981 [175].

Figure 6.39 Simplified defect model for charge deviation of substitution of Ta⁵+ and Fe³+ for tetravalent cations and of oxygen vacancies. M and O denote cation and oxygen, respectively. Source: Adapted from Tamura 2006 [210].

Figure 6.40 Variation of unloaded quality factor at 7 GHz with the amount of Nb2O5 (•) Ta2O5(▴) and Sb2O5 (⧫) for sintered Zr0.8Sn0.2TiO4. Source: Adapted from Yoon et al. 1995 [212].

Figure 6.41 The temperature dependence of tan δ of ZST normalized to 10 GHz. Source: Adapted from Alford et al. 1995 [217].

Figure 6.42 Phase diagram of BaTiO3–TiO2 system. Source: Adapted from Kirby and Wechsler 1991 [228].

Figure 6.43 Columbite octahedral structure (A = M²+, B = Nb⁵+) projected along the c [001] axis. Source: Adapted from Pullar 2009 [289].

Figure 6.44 Unit cell of columbite MgNb2O6. Source: Adapted from Pullar 2009 [289].

Figure 6.45 Variation in Qf with firing temperature of binary niobate (NO = Nb2O6) ceramics. CoNOa and b made with CoO and Co3O4, respectively. Source: Adapted from Pullar et al. 2005 [301].

Figure 6.46 The product Qf for the columbites A1+xNb2O6, where A = Mg (1), Zn (2), and Co (3), as a function of x. The samples were sintered in air for 8 h at 1400 °C (1 and 3) and 1300 °C (2). Source: Belous et al. 2007 [307]. Reproduced with permission of Elsevier.

Figure 6.47 SEM micrograph of Zn1-xMgxNb2O6 ceramic, x = 0.7, sintered at 1300 °C, demonstrating DGG. Source: Zhang et al. 2004 [356]. Reproduced with permission of Elsevier.

Chapter 7

Figure 7.1 A schematic situation is shown where C denotes the targeted crystalline phase one likes to obtain in a glass ceramic and A and B are glass-forming components like, for example, SiO2 or B2O3. The thin solid line shows the boundary of the region where glass formation is observed under standard laboratory conditions and the dashed line shows the field of crystallization of the phase C. In the rare cases where the field of crystallization of C overlaps with the glass-forming area a stable glass can be molten, which crystallizes the phase C under heat treatment.

Chapter 8

Figure 8.1 SEM micrograph of aluminum nitride substrate sintered at 185 °C for different holding times: (A) 2 h, (B) 3 h, (C) 4 h, and (D) 6 h. Source: Luo et al. 2006 [12]. Reproduced with permission of John Wiley & Sons.

Figure 8.2 Variation of thermal conductivity of AlN substrate with sintering duration at 1850 °C. Source: Luo et al. 2006 [12]. Reproduced with permission of John Wiley & Sons.

Figure 8.3 Viscosity analysis of ZrSiO4 slurry. Source: Adapted from Varghese et al. 2015 [17].

Figure 8.4 Microstructure of single layer of Aldrich and IRE ZrSiO4 cast green tape (a) surface of Aldrich zircon tape (b) surface of mineral zircon tape (c) Aldrich tape surface magnified (d) mineral tape surface magnified (e) Aldrich tape cross sectional (f) mineral tape cross sectional. Source: Adapted from Varghese et al. 2015 [17].

Figure 8.5 Surface roughness of Aldrich and mineral ZrSiO4 cast green tape. Source: Adapted from Varghese et al. 2015 [17].

Figure 8.6 Sintering profile of ZrSiO4 HTCC ceramic substrate. Source: Adapted from Varghese et al. 2015 [17].

Figure 8.7 Sintered microstructure of Aldrich and mineral ZrSiO4 HTCC substrates (a) mineral ZrSiO4 (b) Aldrich ZrSiO4 (c) mineral magnified (d) Aldrich magnified (e) mineral cross sectional (f) Aldrich cross sectional. Source: Adapted from Varghese et al. 2015 [17].

Figure 8.8 Variation of relative permittivity as a function of residual carbon in glass–ceramics. Source: Adapted from Tummula 1991 [27].

Figure 8.9 Polymer degradation in neutral atmosphere. Source: Adapted from Tummula 1991 [27].

Figure 8.10 Signal propagation delay as a function of relative permittivity with different ceramic materials. Source: Adapted from Tummula 1991 [27].

Figure 8.11 Variation of Z shrinkage of 9K7 at different heating rates on sintering at 800 °C. Source: Dai 2012 [92]. Reproduced with permission of John Wiley & Sons.

Figure 8.12 Variation of XY and Z shrinkage and bulk density with heating rate sintered at 800 °C. Source: Dai 2012 [92]. Reproduced with permission of John Wiley & Sons.

Figure 8.13 Variation of dielectric constant and quality factor Q with heating rate on sintering at 800 °C. Source: Dai 2012 [92]. Reproduced with permission of John Wiley & Sons.

Figure 8.14 TEM images of the microstructure 9K7 sintered by heating at (a) rate of 1 °C and (b) 5 °C/min. Source: Dai 2012 [92]. Reproduced with permission of John Wiley & Sons.

Figure 8.15 Variation of resonant frequency with and without TiO2 addition in T2000 glass–ceramic system. Source: Dai 2002 [93]. Reproduced with permission of John Wiley & Sons.

Figure 8.16 SEM micrographs of thermally etched: (a) Li2MgTi3O8 ceramics sintered at 1075 °C, (b) Li2ZnTi3O8 ceramics sintered at 1075 °C, (c) Li2MgTi3O8 + 3 wt% LMZBS glass sintered at 925 °C/4 h, (d) Li2ZnTi3O8 + 3 wt% LMZBS glass sintered at 900 °C/4 h and Li2MgTi3O8 + 3 wt% LMZBS glass sintered at 925 °C/4 h, (e) Li2MgTi3O8 + 3 wt% LMZBS glass + 20 wt% Ag sintered at 925 °C/4 h, and (f) Li2ZnTi3O8 + 3 wt% LMZBS glass + 20 wt% Ag sintered at 900 °C/4 h. Source: Adapted from George et al. 2011 [195].

Figure 8.17 The variation of sintering temperature and relative density of (a) Li2MgTi3O8 and (b) Li2ZnTi3O8 ceramics as a function of LMZBS glass. Source: Adapted from George and Sebastian 2011 [195].

Figure 8.18 The variation of sintering temperature and relative permittivity and quality factor of Li2MgTi3O8 and (b) Li2ZnTi3O8 ceramics as a function of LMZBS glass addition. Source: Adapted from George and Sebastian 2011 [195].

Figure 8.19 SEM micrographs of sintered (a) Li2MgSiO4 (LMS), (b) LMS + 0.5 wt% LBS, (c) LMS + 1 wt% LBS, (d) LMS + 2 wt% LMZBS, (e) LMS + 1 wt % LBS + 20 wt% Ag, and (f) LMS + 2 wt% LMZBS + 20 wt% Ag. Source: Adapted from George et al. 2009 [210].

Figure 8.20 Variation of relative permittivity (1 MHz) with temperature for Li2MgSiO4 and with the addition of LBS and LMZBS glasses. Source: Adapted from George et al. 2009 [210].

Figure 8.21 XRD pattern of (a) LiMgPO4 sintered at 950 °C/2 h and (b) LiMgPO4 + 0.15 volume fraction of TiO2 + 20 wt% Ag and sintered at 950 °C/6 h. Source: Adapted from Thomas and Sebastian 2010 [219].

Figure 8.22 SEM micrographs of (a) LiMg0.9Zn0.1PO4 sintered at 925 °C/4 h, (b) LiMg0.8Zn0.2PO4 sintered at 900 °C/4 h, (c) LiMg0.2Zn0.8PO4 sintered at 850 °C/4 h, (d) LiZnPO4 sintered at 825 °C/4 h, (d) LiMg0.9Zn0.1PO4 + 0.12 volume fraction of TiO2 sintered at 950 °C/4 h, and (f) LiMg0.9Zn0.1PO4 + 0.12Vf TiO2 +20 wt% Ag sintered at 950 °C/6 h. Source: Adapted from Thomas and Sebastian 2012 [220].

Figure 8.23 SEM images of (a) and (b) cross-sections of thermolaminated tape (four layers) having different magnification; (e) and (f) are surfaces of green and sintered tapes respectively. Source: Adapted from Thomas et al. 2013 [221].

Figure 8.24 SEM images of (a) and (c) cross-section of thermolaminated tape (four layers) having different magnification; (b) and (d) are surfaces of green and sintered Bi4(SiO4)3 tapes, respectively. Source: Adapted from Abhilash et al. 2015 [222].

Figure 8.25 Variation of relative permittivity of Sr2ZnSi2O7 + 15 wt% LMZBS glass sintered at 825 °C having thicknes 0.5 and 0.38 mm as a function of temperature. Source: Adapted from Joseph et al. 2011 [227].

Figure 8.26 Variation of Qf of LTCC materials with relative permittivity.

Figure 8.27 Variation of τf of LTCC materials with relative permittivity

Figure 8.28 Variation of (a) Qf and (b) relative permittivity of LTCC materials with sintering temperature.

Figure 8.29 Variation (a) of glass transition temperature as a function of B2O3 content (O) ZnO—B2O3—SiO2, ▪ BaO—B2O3—SiO2 glasses; (b) relative permittivity as a function of B2O3 content (O) ZnO—B2O3—SiO2, ▪ BaO—B2O3—SiO2 glasses. Source: Wu and Huang 1999 [239]. Reproduced with permission from Elsevier.

Figure 8.30 Variation of (a) glass transition temperature and (b) relative permittivity of PbO—B2O3—SiO2 glasses as a function of PbO content. Source: Wu and Huang 1999 [239]. Reproduced with permission from Elsevier.

Figure 8.31 (a) Scanning electron micrograph of the cross-section of 3ZnO—2B2O3—15 wt% SiO2 ULTCC laminated tape cofired with Ag at 650 °C for 30 min. (b) Dielectric properties of 3ZnO—2B2O3—SiO2 bulk ceramics sintered at different temperatures for 30 min. The inset shows the variation of bulk density. Source: Yu et al. 2014 [243]. Reproduced with permission from Springer.

Figure 8.32 SEM micrograph of (a) Pb2WO5 sintered at 530 °C and (b) PbWO4 sintered at 620 °C. Source: Xie et al. 2015 [269]. Reproduced with permission from John Wiley & Sons.

Figure 8.33 Variation of relative permittivity, Qf and sintering temperature as a function of MoO3 ratio in Na2O—MoO3 system. Source: Zhang et al. 2015 [277].

Figure 8.34 Variation of microwave dielectric properties of (Li0.5Bi0.5)(W1-xMox)O4 as a function x. Source: Zhou et al. 2012 [266]. Reproduced with permission from World Scientific Publishers.

Figure 8.35 Surface morphology of (a) green Zn2Te2O8 + 4wt% TiO2 tapes, (b) tape sintered at 660 °C, and (c) cross-sectional view of the interface between ZT and Al sintered at 660 °C. Source: Adapted from Honkamo et al. 2009 [302].

Figure 8.36 Variation of relative permittivity and loss tangent of Zn2Te2O8 + 4wt% TiO2 laminated tape sintered at 660 °C measured at 1 MHz. Source: Adapted from Honkamo 2009 et al. [302].

Figure 8.37 Variation of dielectric constant and quality factor of MgTe2O5 ceramics at cryogenic temperatures. Source: Adapted from Subodh et al. 2008 [295].

Figure 8.38 Variation of quality factor frequency product with relative permittivity.

Figure 8.39 Variation of τf with relative permittivity.

Figure 8.40 Variation of microwave dielectric properties as a function of sintering temperature: (a) ϵr, (b) Qf, and (c) τf.

Chapter 9

Figure 9.1 A typical voltage tunability characteristics of BST thin films. Source: Sudheendran et al. 2015 [26].

Figure 9.2 Photograph and differential phase shifts with applied DC bias of c-BZN phase shifter fabricated and displayed by Professor Stemmer. Reproduced with permission from Professor Susanne Stemmer UCSB.

Figure 9.3 Room temperature ferroelectric and magnetic characteristics of BST—CFO heterostructures fabricated by the present authors.

Figure 9.4 Schematic diagram of a simple p–n junction diode and a PIN diode. Source: Adapted from Sudheendran 2014 [17].

Figure 9.5 Schematic diagram of a MEMS aractor. Source: Adapted from Sudheendran 2014 [17].

Figure 9.6 Typical ferroelectric varactor used for microwave applications.

Figure 9.7 In situ monitoring of epitaxial growth of BST thin films on MgO substrate using laser MBE.

Figure 9.8 Photograph of (a) the sputtering system, (b) inner view of the triple targets system, (c) the sputtering targets, and (d) RF plasma generated during the functional oxide deposition.

Figure 9.9 Flowchart of the principle steps of the chemical solution deposition (CSD) method. Source: Waser et al. [25]. Reproduced with permission of Springer.

Figure 9.10 Schematic diagram of planar and parallel plate capacitor test structures. Figure from the PhD Thesis of K. Sudheendran submitted to University of Hyderabad.

Figure 9.11 Measured capacitance and polarization of ferroelectric capacitors at low frequencies. Source: Sudheendran et al. 2015 [26].

Figure 9.12 Picture of the cavity perturbation measurement set up with the resonance characteristics of the cavity under different perturbations.

Figure 9.13 (a) Picture of the CPW transmission lines fabricated for on-wafer measurement, mounted on the probe station. (b) The fabricated CPW line. Source: Sudheendran and James Raju 2010 [27].

Figure 9.14 Simulated results for the characteristic impedance of the reference CPW line.

Figure 9.15 Measured S21 phase and magnitude for the test and reference line fabricated for the BST thin films deposited on the sapphire substrate and the extracted dielectric permittivity and loss tangent for the films.

Figure 9.16 Distributed circuit model for the CPW test structure.

Figure 9.17 Calculated distributed line parameters for the test samples.

Figure 9.18 Figure shows the distribution of various loss parameters extracted for the test device.

Figure 9.19 Block diagram of the tunability measurement setup. Figure from the PhD Thesis of K. Sudheendran submitted to University of Hyderabad.

Figure 9.20 Cross-section and microphotograph of the tunable capacitor fabricated using BZN thin films. Source: Adapted from Sudheendran et al. 2010 [50].

Figure 9.21 Measured real and imaginary parts of the S11 parameter of the CPC capacitor fabricated using c-BZN thin films. Source: Adapted from Sudheendran et al. 2010 [50].

Figure 9.22 Schematic diagram of the interdigitated and parallel plate varactor in the GSG configuration. Source: Sudheendran 2014 [17].

Figure 9.23 Microphotograph of the fabricated (a) IDC and (b) CPC varactors. Source: Adapted from Sudheendran et al. 2010 [50].

Figure 9.24 Frequency dependence of capacitance for the IDC varactors fabricated using the c-BZN films measured at different bias fields. Source: Adapted from Sudheendran and James Raju 2010 [50].

Figure 9.25 Variation of capacitance and loss tangent with voltage for the CPC varactors fabricated using the BST thin films. Source: Saravanan et al. 2012 [49].

Figure 9.26 Frequency dependence of capacitance and Q factor for the CPC varactors fabricated using the c-BZN films