Bismuth nanoprecipitation at grain boundaries during microstructural evolution in (Sr, Ba)TiO3 ceramics
Bismuth nanoprecipitation at grain boundaries during microstructural evolution in (Sr, Ba)TiO3 ceramics
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DOI：
10.1016/j.actamat.2007.05.022
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发表时间：
2007-09
期刊：
影响因子：
9.4
通讯作者：
J. Xing;H. Gu;A. Gloter;Hui-xian Shen;X. Pan;P. L. Wang
中科院分区：
文献类型：
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作者：
J. Xing;H. Gu;A. Gloter;Hui-xian Shen;X. Pan;P. L. Wang
用分析电子显微镜观察了低温烧结的掺铋系列陶瓷中的金属铋纳米粒子(NPs)在晶界(GBs)的存在。根据其局部结构和化学成分，大多数GB分为两组，一组是NPs，另一组是二氧化钛基非晶膜。Ba在晶格中的固溶量仅为标称值的1/3左右，其余的Ba杂质在烧结过程中被驱入三个口袋或润湿了晶格。较低的Ba掺杂引起的液态较少，形成了核壳结构。铋掺杂与钡共溶，从而抑制了铋在晶界上的偏析。多余的铋不能像二氧化钛薄膜那样快速地通过去湿的GB扩散出去，迫使它们在局部沉淀。这些金属纳米粒子可能会引发几种极化模式，从而增加在1 kHz处检测到的介电常数。
Metallic Bi nanoprecipitates (NPs) were observed at grain boundaries (GBs) in a series of Bi-doped Sr1−xBaxTiO3ceramics sintered at low temperature, using analytical electron microscopy. Most GBs fell into two groups, according to their local structure and chemistry, one with the NPs and the other with titania-based amorphous film. The solution of Ba into the lattice was only about one-third of the nominal value, and the remaining Ba dopants were driven into triple pockets or wetted the GBs during the sintering. Lower Ba doping initiated less liquid, resulting in a core–shell structure. Bi dopants were co-soluted with Ba, thereby suppressing the Bi segregation at GBs. The extra Bi could not diffuse out through the dewetted GB as fast as via the titania-based film, compelling them to precipitate locally. These metallic NPs may initiate several modes of polarization that increase the dielectric constants detected at 1kHz.