Reply to “Comment on ‘Pb1−xCaxTiO3solid solution (

Elson Longo¹,

E. C. Paris²,

P. S. Pizani³

et al.

Abstract

Chandra ͓Phys. Rev. B 77, 017101 ͑2008͔͒ disagrees with the coexistence of a pseudocubic structure with a long-range tendency for cubic symmetry and tetragonal in a short-range order for the Pb 1−x Ca x TiO 3 ͑PCT͒ system obtained by the polymeric precursor method ͑PPM͒, as proposed in our original paper ͓Phys. Rev. B 75, 144111 ͑2007͔. However, we did not show the Rietveld results for the samples in this paper. The Rietveld refinement results shown clearly the coexistence of the tetragonal-cubic phases for the PCT synthesized by PPM instead of the tetragonal-orthorhombic structures as suggested by Chandra ͓Phys. Rev. B 77, 017101 ͑2008͔͒.

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

“…According to Chandra et al [2,3], X-ray diffraction measurements showed an orthorhombic symmetry with Pbnm space group when x ≥ 0.42. On the other hand, Lázaro et al showed a tendency for the coexistence of cubic and tetragonal symmetries in which the weight percentage of tetragonal and cubic structure for Pb 0.50 Ca 0.50 TiO 3 was equal to 54.81% and 45.19%, respectively [4,5].…”

“…Besides the decreasing of Curie temperature, the addition of Ca 2+ ions to PbTiO 3 compound causes a structural phase transition and the appearance of a relaxor behavior. Although there are controversies about the crystalline symmetry in high Ca content samples [2][3][4][5]8]. According to Chandra et al [2,3], X-ray diffraction measurements showed an orthorhombic symmetry with Pbnm space group when x ≥ 0.42.…”

“…Although the long-range structure and dielectric properties have been well characterized, the local structure of PCT system has been only analyzed through Raman technique [2][3][4][5]8]. As far as we know, there are no studies concerning the effect of Ca substitution on the local structure of Ti atom in PCT compound probed by X-ray absorption spectroscopy (XAS).…”

“…In order to improve the mechanical properties of PbTiO 3 ceramics, Pb 2+ ions have been substituted by Ca 2+ , forming the Pb 1-x Ca x TiO 3 (PCT) system [2][3][4][5][6]. This system has strong piezoelectricity and high values of dielectric permittivity at Curie temperature, becoming a good candidate for pyroelectric sensors and dynamic random access memories depending on the Ca composition [7].…”

“…In order to obtain qualitative information from experimental EXAFS spectra, theoretical spectra were calculated using FEFF8.2 code according the PCT structure that has been previously reported [2][3][4][5]8]. Thus, theoretical EXAFS spectra were calculated considering structural models with a cubic symmetry (Pm-3m space group), tetragonal symmetry with P4mm space group and with an orthorhombic symmetry with Pbnm space group.…”