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Relaxor nature in Ba 5 RZr 3 Nb 7 O 30 (R = La, Nd, Sm) tetragonal tungsten bronze new system
Author(s) -
Feng Wen Bin,
Zhu Xiao Li,
Liu Xiao Qiang,
Fu Mao Sen,
Ma Xiao,
Jia Shu Jing,
Chen Xiang Ming
Publication year - 2018
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.15332
Subject(s) - tetragonal crystal system , materials science , tungsten , dielectric , ferroelectricity , crystallography , hysteresis , permittivity , analytical chemistry (journal) , condensed matter physics , crystal structure , chemistry , physics , metallurgy , optoelectronics , chromatography
Abstract Ba 5 RZ r 3 Nb 7 O 30 (R = La, Nd, Sm) lead‐free relaxor ferroelectrics were prepared by a standard solid‐state reaction process, and the influence of A and B site ion occupation on the dielectric characteristics especially the relaxor nature were investigated systematically. Tetragonal tungsten bronze structure with space group P 4 /mbm was determined for all compositions, ion cross distribution by Ba 2+ and R 3+ in A 1 site was observed, while A 2 site was only occupied by Ba 2+ . Selected area electron diffraction patterns confirmed the existence of incommensurate superlattice modulation. Furthermore, temperature and frequency dependences of the dielectric properties showed a broad permittivity peak with strong frequency dispersion, following well the Vogel‐Fulcher relationship. The maximum dielectric constant temperature increased gradually with decreasing A 1 site ion size. Slim P‐E hysteresis loops were obtained at room temperature for all compositions. Meanwhile, micro ferroelectric domains were observed in Ba 5 SmZr 3 Nb 7 O 30 . For Ba 4 R 2 Zr 4 Nb 6 O 30 and Ba 5 RZ r 3 Nb 7 O 30 (R = Nd, Sm), the transition from normal ferroelectric to relaxor behavior originates from the increased t A 1 , which is a result of cross distribution at A 1 site. Compared with Ba 5 RT i 3 Nb 7 O 30 , Zr substitution at B site enhances the relaxor nature.