Crystallographic Structure and Ferroelectricity of (AxLa1−x)2Ti2O7 (A = Sm and Eu) Solid Solutions with High Tc

• Published in: Journal of the American Ceramic Society Vol. 99; no. 2; pp. 523 - 530
• Main Authors: Chen, Chen, Gao, Zhipeng, Yan, Haixue, Reece, Mike J.
• Format: Journal Article
• Language: English
• Published: Columbus Blackwell Publishing Ltd 01.02.2016; Wiley Subscription Services, Inc
• Subjects: Crystal structure; Crystallography; Dielectric properties; Dielectrics; Ferroelectric materials; Ferroelectrics; Permittivity; Perovskites; Piezoelectricity; Raman spectroscopy; Samarium; Solid solutions; Solubility; Spectroscopic analysis; X-ray diffraction
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.13970

The solubility and ferroelectric properties of (AxLa1−x)2Ti2O7 (A = Sm and Eu) solid solutions were investigated. The crystallographic structure of the solid solutions was studied using X‐ray diffraction and Raman spectroscopy. The solubility limits of Eu and Sm in (AxLa1−x) 2Ti2O7 were found to be greater than x = 0.5 and 0.8, respectively. The solid solutions had a monoclinic perovskite‐like layered structure (PLS), similar to that of the pure La2Ti2O7, when x was less than the solubility limit. When x was above the solubility limit the materials were biphase. The biphases of (SmxLa1−x)Ti2O7 (x = 0.9) consisted of (SmxLa1−x)2Ti2O7 with PLS and pure Sm2Ti2O7 with pyrochlore structure, and the biphases of (EuxLa1−x)Ti2O7 (x = 0.6, 0.7, and 0.8) consisted of (EuxLa1−x)2Ti2O7 with PLS structure and La3+ doped Eu2Ti2O7 with pyrochlore structure. The effect of A‐site substitution on the properties of La2Ti2O7 was investigated by measuring the dielectric permittivity and loss at different frequencies and temperatures. The highest piezoelectric constant d33 was 2.8 pC/N for (Sm0.1La0.9)Ti2O7.