THE pressure-induced transition of olivine to a denser spinel structure is probably of considerable importance in the Earth's mantle1. Olivineâspinel transitions are known in Mg2GeO4 (refs. 2 and 3) and Fe2SiO4 (ref. 1), while a variety of evidence indicates that Mg2SiO4 will undergo a similar transition around 125,000 atmospheres and 600° C. (refs. 1 and 3). These results suggested the desirability of exploring for olivineâspinel transitions in other substances which normally crystallize with an olivine structure.
Decomposition of Ni2SiO4 in an Oxygen Potential Gradient
作者:Jeff Wolfenstine、Duane Dimos、D. L. Kohlstedt
DOI:10.1111/j.1151-2916.1985.tb15325.x
日期:1985.5
Polycrystalline Ni2SiO4 was exposed to a gradient in oxygenpotential at 1336°C to cause kinetic decomposition into its component oxides, NiO and SO2. At the higher-oxygen-potential side NiO formed, and at the lower-oxygen-potential side SiO2 formed. This spatial distribution of SiO2 and NiO is consistent with diffusion data for silicate olivines which indicate that Ni diffuses much faster than either
多晶 Ni2SiO4 暴露于 1336°C 的氧势梯度下,导致动力学分解为其组分氧化物 NiO 和 SO2。在氧势较高的一侧形成 NiO,在氧势较低的一侧形成 SiO2。SiO2 和 NiO 的这种空间分布与硅酸盐橄榄石的扩散数据一致,这表明 Ni 的扩散速度比 Si 或 O 快得多。