Partial molar volume of FeO, NiG and CoO liquid at high pressure

为了测定高压下亲铁氧化物液体的偏摩尔体积，我们发展了高压X射线吸收技术，利用同步辐射X射线和多砧装置测量高压下硅酸盐熔体的密度。密度（ρ）由样品的X射线吸收曲线用公式I= I_0exp（-ρμt）计算，其中I_0分别为透射和入射X射线的强度，μ为样品的质量吸收系数，t为样品厚度。在这项研究中，我们使用单晶金刚石圆柱作为样品胶囊，因为它的低X射线吸收，硬度和惰性与硅酸盐熔体。金刚石膜盒使高压下测量硅酸盐金属的密度成为可能。在日本SPring-8的BL 22 XU实验室，用DIA型六面顶砧装置和高亮度单色X射线进行了高压X射线吸收实验。我们使用具有MORB和含铁二硅酸钠的组合物的玻璃作为起始材料。虽然密度的玻璃，结晶固体，熔体测定高达5 GPa和1873 K，我们还没有确定液体的偏摩尔体积。然而，这种方法可以在高压和高温下产生一系列密度数据，误差在1%以内，足以评估硅酸盐液体的偏摩尔体积。

We have developed the high-pressure X-ray absorption technique to measure density of silicate melts at high-pressure using synchrotron X-ray and a multi-anvil apparatus, in order to determine partial molar volume of siderophile oxide liquid at high pressure. Density (ρ) is evaluated from X-ray absorption profile of a sample using the equation of I=I_0 exp(-ρμt), where land are intensities of transmitted and incident X-rays, respectively, μ is mass absorption coefficient of sample, and t is sample thickness. In this study, we used a single crystalline diamond cylinder as a sample capsule, because its low X-ray absorption, hardness, and inertness with silicate melts. Diamond capsule makes the densiy measurement of silciate metls under pressure possible.High-pressure X-ray absorption experiments were conducted by using a DIA-type cubic anvil apparatus and a highly brilliant monochromatic X-ray at BL22XU of SPring-8,Japan. We used glasses with the compositions both of the MORB and of the Fe-bearing sodium disilicate for starting materials. Although densities of glasses, crystalline solids, and melts were determined up to 5 GPa and 1873 K, we have not determined the partial molar volume of liquid. This method can, however, yield a series of density data at high pressures and temperatures within an error of 1% enough to evaluate the partial molar volume of silicate liquid.