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Synthesis and Processing Characteristics of Ba 0.65 Sr 0.35 TiO 3 Powders from Catecholate Precursors
Author(s) -
Ali Naseef J.,
Milne Steven J.
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.tb07771.x
Subject(s) - materials science , sintering , microstructure , manganese , grain size , grain growth , ceramic , abnormal grain growth , doping , permittivity , mineralogy , particle size distribution , analytical chemistry (journal) , dielectric , composite material , chemical engineering , metallurgy , particle size , chemistry , optoelectronics , chromatography , engineering
Powders of composition Ba 0.65 Sr 0.35 TiO 3 were prepared from catecholate precursor phases, BaTi(C 6 H 4 O 2 ) 3 and SrTi (C 6 H 4 O 2 ) 3 . The physical and chemical properties of the base powders, and those doped with 0.2 wt% manganese, are reported in detail. The dimensions of the primary particles in the starting powders were of the order of 20–50 nm, but the occurrence of abnormal grain growth during sintering promoted grain sizes in the ceramic of up to ∼100 μm. In some microstructures, coarse grains coexisted with a ∼1‐μm fraction to produce a characteristic bimodal grain size distribution. By contrast, under comparable sintering conditions, namely 1350° or 1400°C for 1 h, grain growth in Mn‐doped samples was suppressed, leading to uniform microstructures with a grain size of only a few micrometers. The pellet densities were nevertheless similar, 97% of theoretical in both doped and undoped samples. No significant difference was observed in the dielectric permittivity of the two compositions: the peak relative permittivity occurred at ∼20°C, with a maximum value of ∼22 000.