Publication Date:
2017-11-10
Description:
Ba 5 RZr 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 P4/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 the A 1 site ion size decreasing. 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 RZr 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 RTi 3 Nb 7 O 30 , Zr substitution at B site enhances the relaxor nature. This article is protected by copyright. All rights reserved.
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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