Author: Miguel Alguero
Publisher: John Wiley & Sons
ISBN: 1118935705
Category : Technology & Engineering
Languages : en
Pages : 984
Book Description
This two volume set reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, the text covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. This set is developed from the high level European scientific knowledge platform built within the COST (European Cooperation in Science and Technology) Action on Single and multiphase ferroics and multiferroics with restricted geometries (SIMUFER, ref. MP0904). Chapter contributors have been carefully selected, and have all made major contributions to knowledge of the respective topics, and overall, they are among most respected scientists in the field.
Nanoscale Ferroelectrics and Multiferroics
Author: Miguel Alguero
Publisher: John Wiley & Sons
ISBN: 1118935705
Category : Technology & Engineering
Languages : en
Pages : 984
Book Description
This two volume set reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, the text covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. This set is developed from the high level European scientific knowledge platform built within the COST (European Cooperation in Science and Technology) Action on Single and multiphase ferroics and multiferroics with restricted geometries (SIMUFER, ref. MP0904). Chapter contributors have been carefully selected, and have all made major contributions to knowledge of the respective topics, and overall, they are among most respected scientists in the field.
Publisher: John Wiley & Sons
ISBN: 1118935705
Category : Technology & Engineering
Languages : en
Pages : 984
Book Description
This two volume set reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, the text covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. This set is developed from the high level European scientific knowledge platform built within the COST (European Cooperation in Science and Technology) Action on Single and multiphase ferroics and multiferroics with restricted geometries (SIMUFER, ref. MP0904). Chapter contributors have been carefully selected, and have all made major contributions to knowledge of the respective topics, and overall, they are among most respected scientists in the field.
Nanoscale Ferroelectrics and Multiferroics
Author: Miguel Alguero
Publisher: John Wiley & Sons
ISBN: 1118935756
Category : Technology & Engineering
Languages : de
Pages : 994
Book Description
Dieses Buch beleuchtet die wichtigsten Aspekte der Verarbeitung und Charakterisierung von Ferroelektrika und Multiferroika auf Nanoebene, präsentiert eine umfassende Beschreibung der jeweiligen Eigenschaften und legt dabei den Schwerpunkt auf die Unterscheidung von Größeneffekten bei extrinsischen Eigenschaften wie Rand- oder Interface-Effekte. Eingegangen wird auch auf neuartige Nanoebene. Das Fachbuch ist in drei Abschnitte unterteilt und beschreibt die Verarbeitung (Nanostrukturierung), Charakterisierung (nanostrukturierter Materialien) und Nanoeffekte. Unter Rückgriff auf die Synergien zwischen Nano-Ferroelektrika und -Multiferroika werden Materialien behandelt, die auf allen Ebenen einer Nanostrukturierung unterzogen werden, von Technologien für keramische Materialien wie ferroelektrische Nanopulver, nanostrukturierte Keramiken und Dickschichten sowie magnetoelektrische Nanokomposit-Materialien bis hin zu freistehenden Nanoobjekten mit spezifischen Geometrien wie Nanodrähte und Nanoröhren auf verschiedenen Entwicklungsstufen. Grundlage des Buches ist die europäische Wissensplattform im Wissenschaftsbereich innerhalb der Aktion von COST (Europäische Zusammenarbeit in Wissenschaft und Technik) zu ein- und mehrphasigen Ferroika und Multiferroika mit begrenzten Geometrien (SIMUFER, Ref. MP0904). Die Autoren der Kapitelbeiträge wurden sorgfältig ausgewählt, haben allesamt ganz wesentlich zur Wissensbasis für das jeweilige Thema beigetragen und gehören vor allem zu den renommiertesten Wissenschaftlern des Fachgebiets.
Publisher: John Wiley & Sons
ISBN: 1118935756
Category : Technology & Engineering
Languages : de
Pages : 994
Book Description
Dieses Buch beleuchtet die wichtigsten Aspekte der Verarbeitung und Charakterisierung von Ferroelektrika und Multiferroika auf Nanoebene, präsentiert eine umfassende Beschreibung der jeweiligen Eigenschaften und legt dabei den Schwerpunkt auf die Unterscheidung von Größeneffekten bei extrinsischen Eigenschaften wie Rand- oder Interface-Effekte. Eingegangen wird auch auf neuartige Nanoebene. Das Fachbuch ist in drei Abschnitte unterteilt und beschreibt die Verarbeitung (Nanostrukturierung), Charakterisierung (nanostrukturierter Materialien) und Nanoeffekte. Unter Rückgriff auf die Synergien zwischen Nano-Ferroelektrika und -Multiferroika werden Materialien behandelt, die auf allen Ebenen einer Nanostrukturierung unterzogen werden, von Technologien für keramische Materialien wie ferroelektrische Nanopulver, nanostrukturierte Keramiken und Dickschichten sowie magnetoelektrische Nanokomposit-Materialien bis hin zu freistehenden Nanoobjekten mit spezifischen Geometrien wie Nanodrähte und Nanoröhren auf verschiedenen Entwicklungsstufen. Grundlage des Buches ist die europäische Wissensplattform im Wissenschaftsbereich innerhalb der Aktion von COST (Europäische Zusammenarbeit in Wissenschaft und Technik) zu ein- und mehrphasigen Ferroika und Multiferroika mit begrenzten Geometrien (SIMUFER, Ref. MP0904). Die Autoren der Kapitelbeiträge wurden sorgfältig ausgewählt, haben allesamt ganz wesentlich zur Wissensbasis für das jeweilige Thema beigetragen und gehören vor allem zu den renommiertesten Wissenschaftlern des Fachgebiets.
Nanoscale Ferroelectric-Multiferroic Materials for Energy Harvesting Applications
Author: Hideo Kimura
Publisher: Elsevier
ISBN: 0128145005
Category : Technology & Engineering
Languages : en
Pages : 254
Book Description
Nanoscale Ferroelectric-Multiferroic Materials for Energy Harvesting Applications presents the latest information in the emerging field of multiferroic materials research, exploring applications in energy conversion and harvesting at the nanoscale. The book covers crystal and microstructure, ferroelectric, piezoelectric and multiferroic physical properties, along with their characterization. Special attention is given to the design and tailoring of ferroelectric, magnetic and multiferroic materials and their interaction among ferroics. The fundamentals of energy conversion are incorporated, along with the requirements of materials for this process. Finally, a range of applications is presented, demonstrating the progression from fundamentals to applied science. This essential resource describes the link between the basic physical properties of these materials and their applications in the field of energy harvest. It will be a useful resource for graduate students, early career researchers, academics and industry professionals working in areas related to energy conversion. - Bridges the gap between the fundamentals and applications of ferroelectric and multiferroic materials for energy harvesting - Demonstrates how a range of nanomaterials play an important role in the creation of efficient energy harvesting systems - Provides new solutions for the fabrication of electronic devices for various applications
Publisher: Elsevier
ISBN: 0128145005
Category : Technology & Engineering
Languages : en
Pages : 254
Book Description
Nanoscale Ferroelectric-Multiferroic Materials for Energy Harvesting Applications presents the latest information in the emerging field of multiferroic materials research, exploring applications in energy conversion and harvesting at the nanoscale. The book covers crystal and microstructure, ferroelectric, piezoelectric and multiferroic physical properties, along with their characterization. Special attention is given to the design and tailoring of ferroelectric, magnetic and multiferroic materials and their interaction among ferroics. The fundamentals of energy conversion are incorporated, along with the requirements of materials for this process. Finally, a range of applications is presented, demonstrating the progression from fundamentals to applied science. This essential resource describes the link between the basic physical properties of these materials and their applications in the field of energy harvest. It will be a useful resource for graduate students, early career researchers, academics and industry professionals working in areas related to energy conversion. - Bridges the gap between the fundamentals and applications of ferroelectric and multiferroic materials for energy harvesting - Demonstrates how a range of nanomaterials play an important role in the creation of efficient energy harvesting systems - Provides new solutions for the fabrication of electronic devices for various applications
Nanostructured Multiferroics
Author: Raneesh Balakrishnan
Publisher: John Wiley & Sons
ISBN: 3527343202
Category : Technology & Engineering
Languages : en
Pages : 274
Book Description
Explore the state of the art in multiferroic materials with this cutting-edge resource Nanostructured Multiferroics delivers an overview of recent research developments in the area of nanostructured multiferroics, along with their preparation, characterization, and applications. Covering single-phase and composite multiferroics, nanomultiferroics, and multiferroic composites, the book explains their physical properties, the underlying physical principles, and the technology and application aspects of the materials, including energy harvesting and spintronics. With multiferroics undergoing a renaissance of renewed interest and development in the past few years, and with promising new breakthroughs in areas like superconductivity, spintronics, and quantum computing, Nanostructured Multiferroics offers both experienced scientists and young researchers inspirational and informative resources likely to spark ideas for further research. Along with chapters discussing topics such as the specific heat and magnetocaloric properties of manganite-based multiferroics for cryo-cooling applications and the multiferroic properties of barium-doped BiFeO3 particles, further topics are: * A comprehensive discussion about the physical properties of multiferroic nanocomposites * An exploration of the basic theory underpinning a variety of multiferroic interactions * An in-depth analysis of the engineering functionality in nanomultiferroics * An introduction to nanostructured multiferroics accompanied by discussions of their synthesis, characterization, and common applications * A treatment of multiferroic materials, as well as single-phase and composite multiferroics * An examination of the use of nanostructured multiferroics in the field of spintronics Perfect for materials scientists, Nanostructured Multiferroics will also earn a place in the libraries of solid-state physicists and chemists who seek to improve their understanding of the fundamentals of, and recent advances made in, multiferroics. The information contained within will inform anyone working in areas involving superconductivity, quantum computing, and spintronics.
Publisher: John Wiley & Sons
ISBN: 3527343202
Category : Technology & Engineering
Languages : en
Pages : 274
Book Description
Explore the state of the art in multiferroic materials with this cutting-edge resource Nanostructured Multiferroics delivers an overview of recent research developments in the area of nanostructured multiferroics, along with their preparation, characterization, and applications. Covering single-phase and composite multiferroics, nanomultiferroics, and multiferroic composites, the book explains their physical properties, the underlying physical principles, and the technology and application aspects of the materials, including energy harvesting and spintronics. With multiferroics undergoing a renaissance of renewed interest and development in the past few years, and with promising new breakthroughs in areas like superconductivity, spintronics, and quantum computing, Nanostructured Multiferroics offers both experienced scientists and young researchers inspirational and informative resources likely to spark ideas for further research. Along with chapters discussing topics such as the specific heat and magnetocaloric properties of manganite-based multiferroics for cryo-cooling applications and the multiferroic properties of barium-doped BiFeO3 particles, further topics are: * A comprehensive discussion about the physical properties of multiferroic nanocomposites * An exploration of the basic theory underpinning a variety of multiferroic interactions * An in-depth analysis of the engineering functionality in nanomultiferroics * An introduction to nanostructured multiferroics accompanied by discussions of their synthesis, characterization, and common applications * A treatment of multiferroic materials, as well as single-phase and composite multiferroics * An examination of the use of nanostructured multiferroics in the field of spintronics Perfect for materials scientists, Nanostructured Multiferroics will also earn a place in the libraries of solid-state physicists and chemists who seek to improve their understanding of the fundamentals of, and recent advances made in, multiferroics. The information contained within will inform anyone working in areas involving superconductivity, quantum computing, and spintronics.
Nanoscale Ferroelectric-Multiferroic Materials for Energy Harvesting Applications
Author: Hideo Kimura
Publisher: Elsevier
ISBN: 9780128144992
Category : Technology & Engineering
Languages : en
Pages : 0
Book Description
Nanoscale Ferroelectric-Multiferroic Materials for Energy Harvesting Applications presents the latest information in the emerging field of multiferroic materials research, exploring applications in energy conversion and harvesting at the nanoscale. The book covers crystal and microstructure, ferroelectric, piezoelectric and multiferroic physical properties, along with their characterization. Special attention is given to the design and tailoring of ferroelectric, magnetic and multiferroic materials and their interaction among ferroics. The fundamentals of energy conversion are incorporated, along with the requirements of materials for this process. Finally, a range of applications is presented, demonstrating the progression from fundamentals to applied science. This essential resource describes the link between the basic physical properties of these materials and their applications in the field of energy harvest. It will be a useful resource for graduate students, early career researchers, academics and industry professionals working in areas related to energy conversion.
Publisher: Elsevier
ISBN: 9780128144992
Category : Technology & Engineering
Languages : en
Pages : 0
Book Description
Nanoscale Ferroelectric-Multiferroic Materials for Energy Harvesting Applications presents the latest information in the emerging field of multiferroic materials research, exploring applications in energy conversion and harvesting at the nanoscale. The book covers crystal and microstructure, ferroelectric, piezoelectric and multiferroic physical properties, along with their characterization. Special attention is given to the design and tailoring of ferroelectric, magnetic and multiferroic materials and their interaction among ferroics. The fundamentals of energy conversion are incorporated, along with the requirements of materials for this process. Finally, a range of applications is presented, demonstrating the progression from fundamentals to applied science. This essential resource describes the link between the basic physical properties of these materials and their applications in the field of energy harvest. It will be a useful resource for graduate students, early career researchers, academics and industry professionals working in areas related to energy conversion.
Ferroelectric Domain Walls
Author: Jill Guyonnet
Publisher: Springer Science & Business Media
ISBN: 3319057502
Category : Science
Languages : en
Pages : 167
Book Description
Using the nano metric resolution of atomic force microscopy techniques, this work explores the rich fundamental physics and novel functionalities of domain walls in ferroelectric materials, the nano scale interfaces separating regions of differently oriented spontaneous polarization. Due to the local symmetry-breaking caused by the change in polarization, domain walls are found to possess an unexpected lateral piezoelectric response, even when this is symmetry-forbidden in the parent material. This has interesting potential applications in electromechanical devices based on ferroelectric domain patterning. Moreover, electrical conduction is shown to arise at domain walls in otherwise insulating lead zirconate titanate, the first such observation outside of multiferroic bismuth ferrite, due to the tendency of the walls to localize defects. The role of defects is then explored in the theoretical framework of disordered elastic interfaces possessing a characteristic roughness scaling and complex dynamic response. It is shown that the heterogeneous disorder landscape in ferroelectric thin films leads to a breakdown of the usual self-affine roughness, possibly related to strong pinning at individual defects. Finally, the roles of varying environmental conditions and defect densities in domain switching are explored and shown to be adequately modelled as a competition between screening effects and pinning.
Publisher: Springer Science & Business Media
ISBN: 3319057502
Category : Science
Languages : en
Pages : 167
Book Description
Using the nano metric resolution of atomic force microscopy techniques, this work explores the rich fundamental physics and novel functionalities of domain walls in ferroelectric materials, the nano scale interfaces separating regions of differently oriented spontaneous polarization. Due to the local symmetry-breaking caused by the change in polarization, domain walls are found to possess an unexpected lateral piezoelectric response, even when this is symmetry-forbidden in the parent material. This has interesting potential applications in electromechanical devices based on ferroelectric domain patterning. Moreover, electrical conduction is shown to arise at domain walls in otherwise insulating lead zirconate titanate, the first such observation outside of multiferroic bismuth ferrite, due to the tendency of the walls to localize defects. The role of defects is then explored in the theoretical framework of disordered elastic interfaces possessing a characteristic roughness scaling and complex dynamic response. It is shown that the heterogeneous disorder landscape in ferroelectric thin films leads to a breakdown of the usual self-affine roughness, possibly related to strong pinning at individual defects. Finally, the roles of varying environmental conditions and defect densities in domain switching are explored and shown to be adequately modelled as a competition between screening effects and pinning.
Magnetoelectric Composites
Author: Mirza I. Bichurin
Publisher: CRC Press
ISBN: 0429949618
Category : Science
Languages : en
Pages : 297
Book Description
This book is dedicated to modeling and application of magnetoelectric (ME) effects in layered and bulk composites based on magnetostrictive and piezoelectric materials. Currently, numerous theoretical and experimental studies on ME composites are available but few on the development and research of instruments based on them. So far, only investigation of ME magnetic field sensors has been cited in the existing literature. However, these studies have finally resulted in the creation of low-frequency ME magnetic field sensors with parameters substantially exceeding the characteristics of Hall sensors. The book presents the authors’ many years of experience gained in ME composites and through creation of device models based on their studies. It describes low-frequency ME devices, such as current and position sensors and energy harvesters, and microwave ME devices, such as antennas, attenuators, filters, gyrators, and phase shifters.
Publisher: CRC Press
ISBN: 0429949618
Category : Science
Languages : en
Pages : 297
Book Description
This book is dedicated to modeling and application of magnetoelectric (ME) effects in layered and bulk composites based on magnetostrictive and piezoelectric materials. Currently, numerous theoretical and experimental studies on ME composites are available but few on the development and research of instruments based on them. So far, only investigation of ME magnetic field sensors has been cited in the existing literature. However, these studies have finally resulted in the creation of low-frequency ME magnetic field sensors with parameters substantially exceeding the characteristics of Hall sensors. The book presents the authors’ many years of experience gained in ME composites and through creation of device models based on their studies. It describes low-frequency ME devices, such as current and position sensors and energy harvesters, and microwave ME devices, such as antennas, attenuators, filters, gyrators, and phase shifters.
Integrated Multiferroic Heterostructures and Applications
Author: Ming Liu
Publisher: John Wiley & Sons
ISBN: 3527341773
Category : Science
Languages : en
Pages : 258
Book Description
Written by well-known experts in the field, this first systematic overview of multiferroic heterostructures summarizes the latest developments, first presenting the fundamental mechanisms, including multiferroic materials synthesis, structures and mechanisms, before going on to look at device applications. The resulting text offers insight and understanding for scientists and students new to this area.
Publisher: John Wiley & Sons
ISBN: 3527341773
Category : Science
Languages : en
Pages : 258
Book Description
Written by well-known experts in the field, this first systematic overview of multiferroic heterostructures summarizes the latest developments, first presenting the fundamental mechanisms, including multiferroic materials synthesis, structures and mechanisms, before going on to look at device applications. The resulting text offers insight and understanding for scientists and students new to this area.
Multiferroic Materials
Author: Junling Wang
Publisher: CRC Press
ISBN: 148225154X
Category : Science
Languages : en
Pages : 409
Book Description
"a very detailed book on multiferroics that will be useful for PhD students and researchers interested in this emerging field of materials science" —Dr. Wilfrid Prellier, Research Director, CNRS, Caen, France Multiferroics has emerged as one of the hottest topics in solid state physics in this millennium. The coexistence of multiple ferroic/antiferroic properties makes them useful both for fundamental studies and practical applications such as revolutionary new memory technologies and next-generation spintronics devices. This book provides an historical introduction to the field, followed by a summary of recent progress in single-phase multiferroics (type-I and type-II), multiferroic composites (bulk and nano composites), and emerging areas such as domain walls and vortices. Each chapter addresses potential technological implications. There is also a section dedicated to theoretical approaches, both phenomenological and first-principles calculations.
Publisher: CRC Press
ISBN: 148225154X
Category : Science
Languages : en
Pages : 409
Book Description
"a very detailed book on multiferroics that will be useful for PhD students and researchers interested in this emerging field of materials science" —Dr. Wilfrid Prellier, Research Director, CNRS, Caen, France Multiferroics has emerged as one of the hottest topics in solid state physics in this millennium. The coexistence of multiple ferroic/antiferroic properties makes them useful both for fundamental studies and practical applications such as revolutionary new memory technologies and next-generation spintronics devices. This book provides an historical introduction to the field, followed by a summary of recent progress in single-phase multiferroics (type-I and type-II), multiferroic composites (bulk and nano composites), and emerging areas such as domain walls and vortices. Each chapter addresses potential technological implications. There is also a section dedicated to theoretical approaches, both phenomenological and first-principles calculations.
Handbook of Advanced Dielectric, Piezoelectric and Ferroelectric Materials
Author: Z-G Ye
Publisher: Elsevier
ISBN: 1845694007
Category : Technology & Engineering
Languages : en
Pages : 1091
Book Description
This comprehensive book covers recent developments in advanced dielectric, piezoelectric and ferroelectric materials. Dielectric materials such as ceramics are used to manufacture microelectronic devices. Piezoelectric components have been used for many years in radioelectrics, time-keeping and, more recently, in microprocessor-based devices. Ferroelectric materials are widely used in various devices such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage and display devices.The book is divided into eight parts under the general headings: High strain high performance piezo- and ferroelectric single crystals; Electric field-induced effects and domain engineering; Morphotropic phase boundary related phenomena; High power piezoelectric and microwave dielectric materials; Nanoscale piezo- and ferroelectrics; Piezo- and ferroelectric films; Novel processing and new materials; Novel properties of ferroelectrics and related materials. Each chapter looks at key recent research on these materials, their properties and potential applications.Advanced dielectric, piezoelectric and ferroelectric materials is an important reference tool for all those working in the area of electrical and electronic materials in general and dielectrics, piezoelectrics and ferroelectrics in particular. - Covers the latest developments in advanced dielectric, piezoelectric and ferroelectric materials - Includes topics such as high strain high performance piezo and ferroelectric single crystals - Discusses novel processing and new materials, and novel properties of ferroelectrics and related materials
Publisher: Elsevier
ISBN: 1845694007
Category : Technology & Engineering
Languages : en
Pages : 1091
Book Description
This comprehensive book covers recent developments in advanced dielectric, piezoelectric and ferroelectric materials. Dielectric materials such as ceramics are used to manufacture microelectronic devices. Piezoelectric components have been used for many years in radioelectrics, time-keeping and, more recently, in microprocessor-based devices. Ferroelectric materials are widely used in various devices such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage and display devices.The book is divided into eight parts under the general headings: High strain high performance piezo- and ferroelectric single crystals; Electric field-induced effects and domain engineering; Morphotropic phase boundary related phenomena; High power piezoelectric and microwave dielectric materials; Nanoscale piezo- and ferroelectrics; Piezo- and ferroelectric films; Novel processing and new materials; Novel properties of ferroelectrics and related materials. Each chapter looks at key recent research on these materials, their properties and potential applications.Advanced dielectric, piezoelectric and ferroelectric materials is an important reference tool for all those working in the area of electrical and electronic materials in general and dielectrics, piezoelectrics and ferroelectrics in particular. - Covers the latest developments in advanced dielectric, piezoelectric and ferroelectric materials - Includes topics such as high strain high performance piezo and ferroelectric single crystals - Discusses novel processing and new materials, and novel properties of ferroelectrics and related materials