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Eu‐substitution‐induced commensurate phase with enhanced ferroelectric property in Ba 4 (Eu x La 1− x ) 2 Fe 2 Nb 8 O 30 multiferroics
Author(s) -
Hong Jiang Sheng,
Huang Yu Hui,
Wu Yong Jun,
Fu Mao Sen,
Li Juan,
Liu Xiao Qiang
Publication year - 2019
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.16020
Subject(s) - ionic radius , ferroelectricity , tetragonal crystal system , materials science , dielectric , tungsten , crystal structure , crystallography , octahedron , phase transition , condensed matter physics , chemistry , ion , metallurgy , physics , optoelectronics , organic chemistry
Effects of Eu‐substitution on the crystal structure, dielectric, ferroelectric, and magnetic properties have been systematically studied for Ba 4 (Eu x La 1− x ) 2 Fe 2 Nb 8 O 30 ( x = 0, 0.3, 0.5, 0.7, 0.9, 0.95, 1) tungsten bronze ceramics. The tetragonal bronze structure is confirmed in all compositions. With the increase of x , Ba 4 (Eu x La 1− x ) 2 Fe 2 Nb 8 O 30 ceramics transform from paraelectric to ferroelectric. The compositions of x = 0.9, 0.95, and 1 show first‐order ferroelectric phase transitions above room temperature (391 K for x = 0.9, 404 K for x = 0.95, and 425 K for x = 1). The ferroelectric behavior is associated with a commensurate octahedral tilting, which is caused by large A 2‐ A 1 ionic‐radius difference. Magnetic hysteresis loops for all compositions at room temperature have been obtained, which could be ascribed to both the secondary phase and tungsten bronze structure per se. It is confirmed that the radius difference between A 2 and A 1 cations plays a critical role on the structure, dielectric, and ferroelectric characteristics.