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Influence of BaTiO 3 Content on the Structure and Properties of Na 0.5 Bi 0.5 TiO 3 Crystals
Author(s) -
Ge Wenwei,
Cao Hu,
DeVreugd Christopher,
Li Jiefang,
Viehland Dwight,
Zhang Qinhui,
Luo Haosu
Publication year - 2011
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/j.1551-2916.2011.04433.x
Subject(s) - tetragonal crystal system , curie temperature , phase boundary , ferroelectricity , dielectric , materials science , coercivity , analytical chemistry (journal) , atmospheric temperature range , phase (matter) , mineralogy , crystallography , condensed matter physics , chemistry , crystal structure , ferromagnetism , thermodynamics , physics , optoelectronics , organic chemistry , chromatography
Lead‐free Na 0.5 Bi 0.5 TiO 3 – x %BaTiO 3 single crystals of different compositions ( x =0, 2, 4, 4.5 and 5.5) were grown using a top‐seeded solution growth method. Temperature‐dependent X‐ray diffraction revealed the presence of a high‐temperature tetragonal phase that existed over a narrow composition range of 0< x <2, at temperatures far in excess of the ferroelectric Curie temperature T c . Polarized light microscopy images confirmed the presence of tetragonal domains in NBT that persisted until T c +250°C; whereas for x >4, rhombohedral domains were found that persisted on heating to only about T c ‐150°C. Investigations of the properties revealed a dramatic increase in the dielectric constant (upto 500%), a decrease in the coercive field (300%), and an increase in the longitudinal piezoelectric constant (1000%) with modest increases in x , as the high‐temperature tetragonal ferroelastic phase was suppressed and as the morphotropic‐phase boundary approached.