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Effects of B 2 O 3 on the Phase Stability of Ba 2 Ti 9 O 20 Microwave Ceramic
Author(s) -
Wang SeaFue,
Chung ChiangChuang,
Wang ChaiHui,
Chu Jinn P.
Publication year - 2002
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.1151-2916.2002.tb00323.x
Subject(s) - sintering , eutectic system , materials science , ceramic , phase (matter) , analytical chemistry (journal) , phase boundary , solid solution , mineralogy , liquid phase , solid state , microstructure , metallurgy , thermodynamics , chemistry , organic chemistry , chromatography , physics
Preparation of dense and phase‐pure Ba 2 Ti 9 O 20 is generally difficult using solid‐state reaction, since there are several thermodynamically stable compounds in the vicinity of the desired composition and a curvature of Ba 2 Ti 9 O 20 equilibrium phase boundary in the BaO–TiO 2 system at high temperatures. In this study, the effects of B 2 O 3 on the densification, microstructural evolution, and phase stability of Ba 2 Ti 9 O 20 were investigated. It was found that the densification of Ba 2 Ti 9 O 20 sintered with B 2 O 3 was promoted by the transient liquid phase formed at 840°C. At sintering temperatures higher than 1100°C, the solid‐state sintering became dominant because of the evaporation of B 2 O 3 . With the addition of 5 wt% B 2 O 3 , the ceramic yielded a pure Ba 2 Ti 9 O 20 phase at sintering temperatures as low as 900°C, without any solid solution additive such as SnO 2 or ZrO 2 . The facilities of B 2 O 3 addition to the stability of Ba 2 Ti 9 O 20 are apparently due to the eutectic liquid phase which accelerates the migration of reactant species.