Ferroelectric ceramics

About: Ferroelectric ceramics is a research topic. Over the lifetime, 4458 publications have been published within this topic receiving 117294 citations.

Giant strain in lead-free piezoceramics Bi0.5Na0.5TiO3–BaTiO3–K0.5Na0.5NbO3 system

Abstract: Piezoelectric actuators convert electrical into mechanical energy and are implemented for many large-scale applications such as piezoinjectors and ink jet printers. The performance of these devices is governed by the electric-field-induced strain. Here, the authors describe the development of a class of lead-free (0.94−x)Bi0.5Na0.5TiO3–0.06BaTiO3–xK0.5Na0.5NbO3 ceramics. These can deliver a giant strain (0.45%) under both unipolar and bipolar field loadings, which is even higher than the strain obtained with established ferroelectric Pb(Zr,Ti)O3 ceramics and is comparable to strains obtained in Pb-based antiferroelectrics.

Ultrahigh piezoelectricity in ferroelectric ceramics by design

Abstract: Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), as rare-earth dopants tend to change the local structure of Pb-based perovskite ferroelectrics. We achieve ultrahigh piezoelectric coefficients d33 of up to 1,500 pC N-1 and dielectric permittivity e33/e0 above 13,000 in a Sm-doped PMN-PT ceramic with a Curie temperature of 89 °C. Our research provides a new paradigm for designing material properties through engineering local structural heterogeneity, expected to benefit a wide range of functional materials.

Current status and prospects of lead-free piezoelectric ceramics

Abstract: Dielectric, ferroelectric and piezoelectric properties of perovskite ferroelectric and bismuth layer-structured ferroelectric (BLSF) ceramics are described as superior candidates for lead-free piezoelectric materials to reduce environmental damages. Perovskite type ceramics seem to be suitable for actuator and high power applications that are required a large piezoelectric constant, d 33 (>300 pC/N) and a high Curie temperature, T c (>200 °C). For BaTiO 3 (BT)-based solid solutions, that is, (1 − x )BaTiO 3 − x (Bi 0.5 K 0.5 )TiO 3 [BTBK − 100 x ] ceramics, the T c increases with increasing the amount of x . BTBK-20 + MnCO 3 0.1 wt.% ceramic shows the high T c than 200 °C and the electromechanical coupling factor, k 33 = 0.35. In the case of a (Bi 1/2 Na 1/2 )TiO 3 − b BaTiO 3 − c (Bi 1/2 K 1/2 )TiO 3 [BNBK (100 a /100 b /100 c )] solid solution ceramics, the d 33 and T c are 191 pC/N and 301 °C for the BNBK (85.2/2.8/12), respectively. On the other hand, BLSF ceramics seem to be excellent candidates as piezoelectric sensors for high temperatures and ceramic resonators with high mechanical quality factor ( Q m ), and low temperature coefficient of resonance frequency (TC- f r ). Donor-doped Bi 4 Ti 3 O 12 ceramics such as Bi 4 Ti 3− x Nb x O 12 [BITN- x ] and Bi 4 Ti 3− x V x O 12 [BITV- x ] show high T c than 650 °C. The k 33 value of the grain-oriented (HF) BITN-0.08 ceramic is 0.39 and is able to keep the same value up to 350 °C. Bi 3 TiTaO 9 (BTT)-based solid solution system, Sr x −1 Bi 4− x Ti 2− x Ta x O 9 [SBTT2( x )] (1 ≦ x ≦ 2), displays the high Q m value (=13500) in (p)-mode at the x = 1.25 composition.

Ferroelectricity in a pure BiFeO3 ceramic

Abstract: The difficulties in synthesizing phase pure BiFeO3 are well known. In this letter we are reporting the optimized synthesis conditions for obtaining phase pure BiFeO3 ceramic. The oxide mixing technique followed by leaching with dilute nitric acid has been used for the synthesis. X-ray diffraction pattern indicated that the sample is phase pure. Scanning electron microscopy along with energy dispersive x-ray fluorescence analysis confirmed the chemical homogeneity of the sample. No segregation of the impurity phase in the matrix was detected. Moreover, Bi/Fe atomic ratio is observed to be ∼1. The ferroelectric transition of the sample at 836 °C has been detected by differential thermal analysis.

Fundamentals of ceramics

Abstract: INTRODUCTION Introduction Definition of Ceramics Elementary Crystallography Ceramic Microstructures Traditional Versus Advanced Ceramics General Characteristics of Ceramics Applications The Future BONDING IN CERAMICS Introduction Structure of Atoms Ionic versus Covalent Bonding Ionic Bonding Ionically Bonded Solids Covalent Bond Formation Covalently Bonded Solids Band Theory of Solids Summary Appendix 2A: Kinetic Energy of Free Electrons STRUCTURE OF CERAMICS Introduction Ceramic Structures Binary Ionic Compounds Composite Crystal Structures Structure of Covalent Ceramics Structure of Silicates Lattice Parameters and Density Summary Appendix 3A: Ionic Radii EFFECT OF CHEMICAL FORCES ON PHYSICAL PROPERTIES Introduction Melting Points Thermal Expansion Young's Modulus and the Strength of Perfect Solids Surface Energy Summary THERMODYNAMIC AND KINETIC CONSIDERATIONS Introduction Free Energy Chemical Equilibrium and the Mass Action Expression Chemical Stability Domains Electrochemical Potentials Charged Interfaces, Double Layers, and Debye Lengths Gibbs-Duhem Relation for Binary Oxides Kinetic Considerations Summary Appendix 5A: Derivation of Eq. (5.27) DEFECTS IN CERAMICS Introduction Point Defects Linear Defects Planar Defects Summary DIFFUSION AND ELECTRICAL CONDUCTIVITY Introduction Diffusion Electrical Conductivity Ambipolar Diffusion Relationships between Self-, Tracer, Chemical, Ambipolar, and Defect Diffusion Coefficients Summary Appendix 7A: Relationship between Fick's First Law and Eq. (7.30) Appendix 7B: Effective Mass and Density of States Appendix 7C: Derivation of Eq. (7.79) Appendix 7D: Derivation of Eq. (7.92) PHASE EQUILIBRIA Introduction Phase Rule One-Component Systems Binary Systems Ternary Systems Free-Energy Composition and Temperature Diagrams Summary FORMATION, STRUCTURE, AND PROPERTIES OF GLASSES Introduction Glass Formation Glass Structure Glass Properties Glass-Ceramics Summary Appendix 9A: Derivation of Eq. (9.7) SINTERING AND GRAIN GROWTH Introduction Solid-State Sintering Liquid-Phase Sintering Hot Pressing and Hot Isostatic Pressing Summary Appendix 10A: Derivation of the Gibbs-Thompson Equation Appendix 10B: Radii of Curvature Appendix 10C: Derivation of Eq. (10.20) Appendix 10D: Derivation of Eq. (10.22) MECHANICAL PROPERTIES: FAST FRACTURE Introduction Fracture Toughness Strength of Ceramics Toughening Mechanisms Designing with Ceramics Summary CREEP, SUBCRITICAL CRACK GROWTH, AND FATIGUE Introduction Creep Subcritical Crack Growth Fatigue of Ceramics Lifetime Predictions Summary Appendix 12A: Derivation of Eq. (12.24) THERMAL PROPERTIES Introduction Thermal Stresses Thermal Shock Spontaneous Microcracking of Ceramics Thermal Tempering of Glass Thermal Conductivity Summary DIELECTRIC PROPERTIES Introduction Basic Theory Equivalent Circuit Description of Linear Dielectrics Polarization Mechanisms Dielectric Loss Dielectric Breakdown Capacitors and Insulators Summary Appendix 14A: Local Electric Field MAGNETIC AND NONLINEAR DIELECTRIC PROPERTIES Introduction Basic Theory Microscopic Theory Para-, Ferro-, Antiferro-, and Ferrimagnetism Magnetic Domains and the Hysteresis Curve Magnetic Ceramics and their Applications Piezo- and Ferroelectric Ceramics Summary Appendix 15A: Orbital Magnetic Quantum Number OPTICAL PROPERTIES Introduction Basic Principles Absorption and Transmission Scattering and Opacity Fiber Optics and Optical Communication Summary Appendix 16A: Coherence Appendix 16B: Assumptions Made in Deriving Eq. (16.24) INDEX *Each chapter contains Problems and Additional Reading.