Related papers: Finite-Temperature Properties of Ba(Zr,Ti)O$_3$ Re…
We suggest considering the Burns temperature in lead containing relaxor ferroelectrics as the temperature, at which Pb becomes off-center and nearly randomly occupies positions around the center on a sphere with the radius, which increases…
We present here the results of frequency dependent dielectric, polarization and powder X-ray powder diffraction studies in the 300 to 100K temperature range for Ba_0.55Sr_0.45TiO_3. The dielectric results indicate a succession of three…
We study a minimal model for a relaxor ferroelectric including dipolar interactions, and short-range harmonic and anharmonic forces for the critical modes as in the theory of pure ferroelectrics together with quenched disorder coupled…
\indent It is a generally accepted fact that the unique dielectric properties of relaxor ferroelectrics are related to the formation of polar nanoregion (PNRs). Less well recognized is the corollary that, because they are polar and…
A first-principles-derived scheme, that incorporates ferroelectric and antiferrodistortive degrees of freedom, is developed to study finite-temperature properties of PbZr1-xTixO3 solid solutions near its morphotropic phase boundary. The use…
It is now well established that the unique properties of relaxor ferroelectrics are due to the presence of polar nanoregions (PNR's). We present recent results from Neutron and Raman scattering of single crystals of PZN, PZN-xPT, and PMN.…
Detailed Raman spectroscopy studies on polycrystalline Sr1-xPrxTiO3 (x=0.01, 0.025, 0.05, 0.075, 0.09, 0.13, 0.15, 0.17) samples are reported elucidating the microscopic mechanism of relaxor ferroelectrics. The polar mode was observed upto…
The electrocaloric effect (ECE) in normal and relaxor ferroelectrics is investigated in the framework of a thermodynamic approach based on the Maxwell relation and a Landau-type free energy model. The static dielectric response of relaxors…
The relaxor ferroelectric PbMg1/Nb2/3O3 was investigated by means of broad-band dielectric and Fourier Transform Infrared (FTIR) transmission spectroscopy in the frequency range from 1 MHz to 15 THz at temperatures between 20 and 900 K…
Neutron and x-ray scattering studies on relaxor ferroelectric systems Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$ (PZN), Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ (PMN), and their solid solutions with PbTiO$_3$ (PT) have shown that inhomogeneities and disorder play…
In an attempt to understand the origin of relaxor ferroelectricity, it is shown that interesting behaviour of the onset of non-ergodicity and of precursor nanodomains found in first principles simulations of the relaxor alloy $\mathrm…
Machine learning has been establishing its potential in multiple areas of condensed matter physics and materials science. Here we develop and use an unsupervised machine learning workflow within a framework of first-principles-based…
Introducing structural and/or chemical heterogeneity into otherwise ordered crystals can dramatically alter material properties. Lead-based relaxor ferroelectrics are a prototypical example, with decades of investigation having connected…
Relaxor behavior and lattice dynamics have been studied for a single crystal of K$_{1-x}$Li$_x$TaO$_3$ $(x=0.05)$, where a small amount of a Ca impurity ($\sim 15$~ppm) was incorporated. The dielectric measurements revealed Debye-like…
The response of polar nanoregions (PNR) in the relaxor compound Pb[(Zn$_{1/3}$Nb$_{2/3}$)$_{0.92}$Ti$_{0.08}$]O$_3$ subject to a [111]-oriented electric field has been studied by neutron diffuse scattering. Contrary to classical…
Epitaxial thin films of relaxor PbMg1/3Nb2/3O3 and PbSc0.5Nb0.5O3, and ferroelectric PbZr0.65Ti0.35O3, Pb0.955La0.045Zr0.65Ti0.35O3, and Ba0.4Sr0.6TiO3 were prepared, and their dielectric properties were studied in a broad range of the…
SrNaBi2Nb3O12 powder was prepared via the conventional solid-state reaction method. X-ray structural studies confirmed the phase to be a three-layered member of the Aurivillius family of oxides. SrNaBi2Nb3O12 (SNBN) ceramics exhibited the…
Via a combination of various experimental and theoretical techniques, a peculiar, identical temperature scale T* is found to exist in all complex lead-based relaxor ferroelectrics. T* corresponds to a nanoscale phase transition due to…
A first-principles-based model is developed to investigate the influence of lead vacancies on the properties of relaxor ferroelectric Pb(Sc1/2Nb1/2)O3 (PSN). Lead vacancies generate large, inhomogeneous, electric fields that reduce barriers…
Low temperature properties of BaZrO3 are revealed by combining experimental techniques (X-ray diffraction, neutron scattering and dielectric measurements) with theoretical first-principles-based methods (total energy and linear response…