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Lead‐Free (Ba 0.70 Sr 0.30 )TiO 3 ‐Modified Bi 0.5 (Na 0.80 K 0.20 ) 0.5 TiO 3 Ceramics with Large Electric Field–Induced Strains
Author(s) -
Jaita Pharatree,
Watcharapasorn Anucha,
Kumar Nitish,
Jiansirisomboon Sukanda,
Cann David P.
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.14136
Subject(s) - materials science , tetragonal crystal system , ferroelectricity , analytical chemistry (journal) , raman spectroscopy , dielectric , ceramic , phase transition , phase (matter) , atmospheric temperature range , mineralogy , electric field , crystallography , crystal structure , condensed matter physics , chemistry , thermodynamics , composite material , optics , optoelectronics , physics , organic chemistry , chromatography , quantum mechanics
The dielectric, ferroelectric, and electric field–induced strain behavior of Bi 0.5 (Na 0.80 K 0.20 ) 0.5 TiO 3 ( BNKT ) ceramics modified with (Ba 0.70 Sr 0.30 )O 3 ( BST ) were investigated as a function of composition and temperature. The ceramic samples were synthesized by a solid‐state mixed oxide method and sintered at 1125°C for 2 h. The XRD and Raman spectra showed coexisting rhombohedral and tetragonal phases throughout the entire compositional range with the tetragonal phase becoming dominant at higher BST concentrations. For all compositions, the temperature dependence of the dielectric spectra revealed a frequency dependence that is characteristic of a relaxor mechanism. This suggests that these ceramics lacked long‐range order and it appears that the maximum disorder was observed for the composition with 5 mol% BST ( BNKT –0.05 BST sample). This was evidenced by the observation of pinched hysteresis loops, even at room temperature, and a significant decrease in the P r and E c values which resulted in large electric field–induced strains ( S max ) of 0.40% and a normalized strain coefficient ( < m t e x t > d 33∗= S max / E max ) of 732 pm/V. This significant strain enhancement at the composition of x = 0.05 may be attributed to both a composition‐induced structural phase transition and a field‐induced relaxor to ferroelectric phase transition.