We report a non-Pb piezoelectric ceramic system Ba(Ti(0.8)Zr(0.2))O(3)-(Ba(0.7)Ca(0.3))TiO(3) which shows a surprisingly high piezoelectric coefficient of d(33) approximately 620 pC/N at optimal composition. Its phase diagram shows a morphotropic phase boundary (MPB) starting from a tricritical triple point of a cubic paraelectric phase (C), ferroelectric rhombohedral (R), and tetragonal (T) phases. The high piezoelectricity of the MPB compositions stems from the composition proximity of the MPB to the tricritical triple point, which leads to a nearly vanishing polarization anisotropy and thus facilitates polarization rotation between 001T and 111R states. We predict that the single-crystal form of the MPB composition of the present system may reach a giant d(33) = 1500-2000 pC/N. Our work may provide a new recipe for designing highly piezoelectric materials (both Pb-free and Pb-containing) by searching MPBs starting from a TCP.

Large Piezoelectric Effect in Pb-Free Ceramics

An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems' applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related to the reliability of ferroelectric memories, piezoelectric nonlinearity of ferroelectric films which is relevant to microsystems' applications, and permittivity and loss in ferroelectric films-important in all applications and essential in high frequency devices. In the context of properties we also discuss nanoscale probing of ferroelectrics. Finally, we comment on two important emerging topics: multiferroic materials and ferroelectric one-dimensional nanostructures. (c) 2006 American Institute of Physics.

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Ferroelectric thin films: Review of materials, properties, and applications

Theoretical concepts and experimental evidence of heterogeneity in glass-forming liquids and polymers are reviewed. The main purpose is to provide an introduction to theoretical developments and recent experiments which have led to rapidly increasing knowledge. Realizing that there is no consensus in regard to the various scenarios of the glass transition starting from rather different assumptions we try to give a balanced overview although we also compare and interrelate some of the approaches. The experimental part describes recent nuclear magnetic resonance, dielectric, and optical experiments from which dynamically distinguishable subensembles can be selected thus proving the existence of a well defined dynamical heterogeneity.

Heterogeneity at the glass transition: a review

Associate DIETRICH BELITZ, University of Oregon Editors: Condensed Matter Physics (Theoretical) J. IGNACIO CIRAC, Max-Planck-Institut für Quantenoptik Quantum Information RAYMOND E. GOLDSTEIN, University of Cambridge Biological Physics ARTHUR F. HEBARD, University of Florida Condensed Matter Physics (Experimental) RANDALL D. KAMIEN, University of Pennsylvania Soft Condensed Matter DANIEL KLEPPNER, Massachusetts Institute of Technology Atomic, Molecular, and Optical Physics (Experimental) PAUL G. LANGACKER, Institute for Advanced Study, Princeton University Particle Physics (Theoretical) VERA LÜTH, Stanford University Particle Physics (Experimental) DAVID D. MEYERHOFER, University of Rochester Physics of Plasmas and Matter at High-Energy Density WITOLD NAZAREWICZ, University of Tennessee, Oak Ridge National Laboratory Nuclear Physics JOHN H. SCHWARZ, California Institute of Technology Mathematical Physics FRIEDRICH-KARL THIELEMANN, Universität Basel Astrophysics Senior Assistant Editor: DEBBIE BRODBAR, APS Editorial Office American Physical Society

Reviews of Modern Physics

One of the most intriguing protein materials found in nature is bone, a material composed of assemblies of tropocollagen molecules and tiny hydroxyapatite mineral crystals that form an extremely tough, yet lightweight, adaptive and multifunctional material. Bone has evolved to provide structural support to organisms, and therefore its mechanical properties are of great physiological relevance. In this article, we review the structure and properties of bone, focusing on mechanical deformation and fracture behavior from the perspective of the multidimensional hierarchical nature of its structure. In fact, bone derives its resistance to fracture with a multitude of deformation and toughening mechanisms at many size scales ranging from the nanoscale structure of its protein molecules to the macroscopic physiological scale.

On the Mechanistic Origins of Toughness in Bone

The domain-size dependence of the piezoelectric properties of ferroelectrics is investigated using a continuum Ginzburg-Landau model that incorporates long-range elastic and electrostatic interactions. Microstructures with the desired domain sizes are created by quenching from the paraelectric phase by biasing the initial conditions. Three different two-dimensional microstructures with different sizes of the 90\ifmmode^\circ\else\textdegree\fi{} domains are simulated. An electric field is applied along the polar as well as nonpolar directions and the piezoelectric response is simulated as a function of domain size for both cases. The simulations show that the piezoelectric coefficients are enhanced by reducing the domain size, consistent with recent experimental results of Wada and Tsurumi [Br. Ceram. Trans. 103, 93 (2004)] on domain-engineered ${\mathrm{BaTiO}}_{3}$ single crystals.

https://arxiv.org/pdf/cond-mat/0410403.pdf

Domain-size dependence of piezoelectric properties of ferroelectrics

By including the contributions of dipolar defects in the time-dependent Ginzburg-Landau theory, we have simulated the domain switching process in ferroelectrics The model incorporates elastic effects in the form of an anisotropic long-range interaction that is obtained by integrating out the strain fields, subject to the elastic compatibility constraint The defects are simulated by considering an inhomogeneous electric field due to randomly placed coarse-grained dipoles It is shown that these defects act as nuclei for the formation of $90\ifmmode^\circ\else\textdegree\fi{}$ twinned structures, resulting in a lower coercive field compared to the defect-free case Due to these defects, the simulated polarization switching occurs by two successive $90\ifmmode^\circ\else\textdegree\fi{}$ rotations, rather than a single $180\ifmmode^\circ\else\textdegree\fi{}$ flipping as in the defect-free case

Influence of dipolar defects on switching behavior in ferroelectrics

Landau theory for shape memory polycrystals

We propose a Ginzburg–Landau theory for the elastic properties of shape memory polycrystals A single crystal elastic free energy for a system that undergoes a square-to-rectangle transformation is generalized to a polycrystal by introducing a crystal orientational field that is determined from a continuum phase-field model The coupled system is used to study domain morphology and mechanical properties of shape memory alloys in different temperature regimes

Rajeev Ahluwalia

Papers

Domain-size dependence of piezoelectric properties of ferroelectrics

Influence of dipolar defects on switching behavior in ferroelectrics

Landau theory for shape memory polycrystals

Landau Theory for Shape Memory Polycrystals

Dynamic strain loading of cubic to tetragonal martensites