EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr

Abstract

Extended X-ray absorption fine structure (EXAFS) experiments at the Zr K-edge were carried out on perovskite relaxor ferroelectrics BaTi1−xZrxO3 (BTZ) (x = 0.25, 0.30, 0.35), and on BaZrO3 for comparison. Structural information up to 4.5Å around the Zr atoms is obtained, revealing that the local structure differs notably from the average Pm3m cubic structure deduced from X-ray diffraction. In particular, our results show that the distance between Zr atoms and their first oxygen neighbors is independent of the Zr substitution rate x and equal to that measured in BaZrO3, while the X-ray cubic cell parameter increases linearly with x. Furthermore, we show that the Zr atoms tend to segregate in Zr-rich regions. We propose that the relaxor behavior in BTZ is linked to random elastic fields generated by this particular chemical arrangement, rather than to random electric fields as is the case in most relaxors.

Structural relaxation around substitutionalCr3+inMgAl2O4Juhin1, Calas2, Cabaret3 et al. 2007Phys. Rev. B541340View full textAdd to dashboardCite

“…The improved thermal and mechanical properties of Cr-doped spinel may be explained by remanent local strain fields induced by the full relaxation of the structure around chromium, as it has been observed in other solid solutions. 2 Another important consequence of relaxation concerns the origin of the partition of elements between minerals and liquids in geochemical systems. 5 Finally, the data obtained in this study will provide a structural basis for discussing the origin of color in red spinel and its variation at high Cr-contents.…”

“…For instance, the addition of a minor component can improve significantly the electric, magnetic or mechanical behaviour of a material. 1,2,3 Another evidence for the presence of impurities in crystals comes from the modification of optical properties such as coloration. Transition metal ions like Cr 3+ cause the coloration of wide band gap solids, because of the splitting of 3d-levels under the action of crystal field.…”

Temperature-stable dielectric properties from −20°C to 430°C in the system BaTiO3–Bi(Mg0.5Zr0.5)O3

“…The distinctive properties of classical relaxor dielectrics are broad, frequency-dependent peaks in plots of relative permittivity ( r ) versus temperature, and strong frequency dispersion in dielectric loss tangent (tan ) [1][2][3][4][5]. Relaxor characteristics were first discovered by…”

Fano resonance and dipolar relaxation in lead-free relaxors

“…Owing to their fundamental interest and also technological promise, relaxors have been studied by various techniques since their discoveries. For instance, they have been investigated by Raman, neutron elastic diffuse scattering, extended X-ray absorption fine structure, high-resolution tunnelling electron microscopy, piezoresponse force microscopy, phenomenology and numerical simulations 7,13,19,20,26,27,[36][37][38][39][40][41] . On the other hand, there is an important aspect of their properties that has been much less documented because of experimental and computational challenges to overcome, that is, their terahertz (THz) dynamics 25,27,42,43 .…”