The local structure of mixed-ion perovskites

Abstract

The temperature-dependent Nb K-edge absorption spectra of several mixedion Pb-containing perovskite compounds were analysed to determine the Nb displacement and to trace its changes through the phase transitions. Both extended x-ray absorption fine structure (EXAFS) and the pre-edge region of the spectra were involved in the analysis. The results show that, in the compounds studied, Nb occupies an off-centre position with symmetry lower than that implied by macroscopic symmetry. The magnitude and direction of the Nb off-centre displacement do not display any noticeable temperature change and are not affected by the change in macroscopic symmetry. The Nb-O distribution and its temperature evolution do not show any distinct dependence on the degree of compositional ordering and properties of the samples.

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the ZrLaulhé1, Hippert2, Kreisel3 et al. 2006Phys. Rev. B1042651View full textAdd to dashboardCite

“…28,29,30,31). On the other hand, only a few EXAFS studies have been reported for relaxors yet 32,33,34,35,36 . In the following, we report an EXAFS study of three BTZ relaxors (x = 0.25, 0.30 and 0.35) at the Zr K-edge.…”

Electronic structure of Pb1−xLaxTiO3 ferroelectric materials from Ti 2p and O 1s soft x-ray absorption spectroscopy

“…According to x-ray diffraction ͑XRD͒ experiments, a structural phase transition to a cubic structure occurred in this case. [4][5][6] Recently, we studied the composition resulting from the substitution of the Pb ion by La in the Pb 1−x La x TiO 3 system for x ranging from 0 to 30 at. % using XAS and XRD techniques.…”

Local order of Pb1−xLaxZr0.40Ti0.60O3 ferroelectric ceramic materials probed by X-ray absorption and Raman spectroscopies

“…The use of short-range order structure characterization techniques, such as X-ray absorption spectroscopy (XAS) and Raman spectroscopy, has shown the existence of a certain degree of local disorder above and below T m , which is apparently not compatible with the long-range order cubic symmetry detected by XRD [13][14][15]. In fact, XAS technique is a powerful tool for the investigation of local structures and provides meaningful additional structural information on materials [16]. Although the local structural data afforded by XAS are usually not sufficient to construct a whole structural model, they often provide valuable information about the local structural peculiarities [17].…”