期刊
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
卷 64, 期 3, 页码 627-636出版社
SPRINGER
DOI: 10.1007/s10971-012-2894-4
关键词
Sol-gel methods; Cobalt oxide; Calcination; Thermoelectric properties; Nanostructure
资金
- West Virginia-Energy Materials Program [EPS08-01]
Ca3Co4O9 (CCO) powder precursors were prepared by the chemical sol-gel route and calcined at various temperatures between 923 K (CCO-923 K) and 1,073 K (CCO-1,073 K). The calcination temperature was found to be a critical factor affecting the microstructure and thermoelectric properties of CCO ceramic bulk samples. The grain size increases with calcination temperature. The nano-crystals with size about 100 nm in the powders calcined at 923 K promote large crystal growth and texture development during sintering. Bulk pellets made from CCO-923 K powder have large crystal grains, uniform grain size distribution, and a high degree of crystal alignment. By contrast, pellets made from CCO powders at higher calcination temperatures have a bimodal distribution of large and small grains and a large amount of randomly oriented grains. Transmission electron microscopy analysis shows that each crystal grain (identified in SEM images) consists of bundles of CCO nano-lamellas. The nano-lamellas within one bundle share the same c-axis orientation and have fiber texture. The electrical resistivity of CCO-923 K is weakly dependent on operating temperature. Compared to the CCO-1,073 K sample, the CCO-923 K sample has the highest power factor, a lower thermal conductivity, and higher electrical conductivity.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据