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Effect of Sintering Aids on Microstructures and PTCR Characteristics of (Sr 0.2 Ba 0.8 )TiO 3 Ceramics
Author(s) -
Cheng HsiuFung,
Lin TsaiFa,
Hu ChenTi,
Lin INan
Publication year - 1993
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.1151-2916.1993.tb05302.x
Subject(s) - materials science , sintering , eutectic system , microstructure , grain size , grain growth , ceramic , phase (matter) , liquid phase , metallurgy , composite material , mineralogy , chemistry , organic chemistry , physics , thermodynamics
The effects of liquid‐phase sintering aids on the microstructures and PTCR characteristics of (Sr 0.2 Ba 0.8 )TiO 3 materials have been studied. The grain size of sintered materials monotonically decreases with increasing content of Al 2 O 3 –SiO 2 –TiO 2 (AST). The ultimate PTCR properties with ρ ht /ρ rt as great as 10 5.61 are obtained for fine‐grain (10‐μm) samples, which contain 12.5 mol% AST and were sintered at 1350°C for 1.5 h. The quantity of liquid phase formed due to eutectic reaction between AST and (Sr,Ba)TiO 3 is presumably the prime factor in determining the grain size of samples. The grains grow rapidly at the sintering temperature in the first stage until the liquid phase residing at the grain boundaries reaches certain critical thickness such that the liquid–solid interfacial energy dominates the mechanism of grain growth.