Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7732502 | Journal of Power Sources | 2015 | 7 Pages |
Abstract
Different compositions of apatite-type La10Si6âxWxO27+δ ceramics are prepared successfully by the high-temperature solid state reaction route. Crystal structure and electrical properties of La10Si6âxWxO27+δ ceramics are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). La10Si6âxWxO27+δ (x = 0.1, 0.2, 0.3, 0.4, 0.5) ceramics consist of a hexagonal apatite-type structure and a small amount of La6W2O15 phase of orthorhombic structure but no La2SiO5 phase. The diffraction peaks of the hexagonal apatite-type structure shift to the low angle side with doping the W6+. When the content of hexavalent tungsten is beyond 0.1, rod-like grains of La10Si6âxWxO27+δ ceramics are replaced gradually by equiaxed apatite-type grains, and some fine particles of La6W2O15 are observed at grain boundaries. These La6W2O15 particles are non-conducting materials and lead to the increase in grain impedance and grain boundary impedance of La10Si6âxWxO27+δ ceramics gradually when the content of hexavalent tungsten is beyond 0.2. However, the solid solubility of W6+ in the lattice of apatite-type structure reaches the maximum when the W6+ content is at 0.1, and correspondingly the La10Si5.9W0.1O27.1 ceramic has the highest total conductivity of 4.45 Ã 10â2 S cmâ1 at 1073 K.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
Jun Xiang, Jia-Hu Ouyang, Zhan-Guo Liu,