Ultrafine Barium Titanate Powders via Microemulsion Processing Routes |
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Authors: | John Wang Jiye Fang Ser-Choon Ng Leong-Ming Gan Chwee-Har Chew Xianbin Wang Zexiang Shen |
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Affiliation: | Department of Materials Science, Department of Physics, Department of Chemistry, and Institute of Materials Research and Engineering, National University of Singapore, Singapore 119260 |
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Abstract: | Three processing routes have been used to prepare barium titanate powders, namely conventional coprecipitation, single-microemulsion coprecipitation using diether oxalate as the precipitant, and double-microemulsion coprecipitation using oxalic acid as the precipitant. A single-phase perovskite barium titanate was obtained when the double-microemulsion-derived oxalate precursor was calcined for 2 h at a temperature of as low as 550°C, compared to 600°C required by the single-microemulsion-derived precursor. A calcination for 2 h at >700°C was required for the conventionally coprecipitated precursor in order to develop a predominant barium titanate phase. It was, however, impossible to eliminate the residual TiO2 impurity phase by raising the calcination temperature, up to 1000°C. The microemulsion-derived barium titanate powders also demonstrated much better powder characteristics, such as more refined crystallite and particle sizes and a much lower degree of particle agglomeration, than those of the conventionally coprecipitated powder, although they contained ∼0.2 wt% BaCO3 as the impurity phase. |
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