Titanium K-Edge XAS Study on Local Structure of Pb_1-xCa_xTiO₃ Ferroelectric Ceramics

Abstract

Abstract. In order to characterize the local structure of Pb 1-x Ca x TiO 3 (PCT) samples, Ti K-edge XANES measurements were performed and showed that Ca incorporation to PbTiO 3 structure leads to a decreasing of local distortion of Ti atoms in relation to oxygen atoms at the TiO 6 octahedra. Moreover, according to EXAFS measurements, the local structure around Ti atoms exhibits tetragonal symmetry with P4mm space group for samples with x ≤ 0.475, whereas orthorhombic symmetry with Pbnm space group was observed for x equals to 0.50 and 0.55.

Polar orientation and extension in a novel crystallographic model for PbTiO3-based perovskites explaining the experimental ferroelectric thermal anomalies

“…Room temperature Pb1-xCaxTiO3 phase diagrams observed for samples prepared by solid state reaction by Sawaguchi et al (1956); Chemical coprecipitation by Ranjan et al (1997); Solid state reaction by Chandra (2008) and Chandra & Pandey (2003); Sol-gel by Kuo et al (2004); Sol-gel by Singh et al (2007); polymeric precursor method by de Lázaro et al (2007); polymeric precursor method by Longo et al (2010); and solid state reaction by Mesquita et al (2014). Figure S3 shows the results from the comparison between the three sequential refinement runs:…”

“…As a case study of temperature-dependent structural properties, the isovalent substitution of Pb 2+ by Ca 2+ on the A site forming the Pb 1À x Ca x TiO 3 (PCT) system reveals a perovskite structure, although the phase diagram shows uncertainties about the space groups of the compositions in the vicinity of x ' 0.50 (Ranjan et al, 1997;Chandra & Pandey, 2003;Mesquita et al, 2014;Chandra, 2008;Longo et al, 2010;Kato et al, 2007;Eremkin, 1994). The selection of the proposed phase diagram at room temperature is shown in the supporting information (Fig.…”