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Crystallographic Structure and Ferroelectricity of ( A x La 1− x ) 2 Ti 2 O 7 ( A = Sm and Eu) Solid Solutions with High T c
Author(s) -
Chen Chen,
Gao Zhipeng,
Yan Haixue,
Reece Mike J.
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13970
Subject(s) - pyrochlore , solid solution , raman spectroscopy , monoclinic crystal system , solubility , materials science , crystallography , crystal structure , x ray crystallography , ferroelectricity , analytical chemistry (journal) , dielectric , diffraction , chemistry , phase (matter) , physics , organic chemistry , chromatography , optics , metallurgy , optoelectronics
The solubility and ferroelectric properties of ( A x La 1− x ) 2 Ti 2 O 7 ( 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 ( A x La 1− x ) 2 Ti 2 O 7 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 La 2 Ti 2 O 7 , when x was less than the solubility limit. When x was above the solubility limit the materials were biphase. The biphases of (Sm x La 1− x )Ti 2 O 7 ( x = 0.9) consisted of (Sm x La 1− x ) 2 Ti 2 O 7 with PLS and pure Sm 2 Ti 2 O 7 with pyrochlore structure, and the biphases of (Eu x La 1− x )Ti 2 O 7 ( x = 0.6, 0.7, and 0.8) consisted of (Eu x La 1− x ) 2 Ti 2 O 7 with PLS structure and La 3+ doped Eu 2 Ti 2 O 7 with pyrochlore structure. The effect of A‐site substitution on the properties of La 2 Ti 2 O 7 was investigated by measuring the dielectric permittivity and loss at different frequencies and temperatures. The highest piezoelectric constant d 33 was 2.8 pC/N for (Sm 0.1 La 0.9 )Ti 2 O 7 .