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Thermal Diffusivity Measurement of Upper Mantle Minerals at Ultra-high Pressures and Temperatures

超高压和高温下上地幔矿物的热扩散率测量

基本信息

批准号：
09440188
负责人：
KATSURA Tomoo
金额：
$ 8.77万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

In this study, first we constructed a measurement system of thermal diffusivity by Angstrom method We constructed a heating system using a programmable power source which can modulate electric voltage such that electric power sinusoidally changes. Using an external trigger, we measure emf of two thermocouples inserted to a sample to determine phase lag between temperature oscillations at two different points. The positions of two thermocouples are measured opetically. Thermal diffusivity is calculated from these positions and the phase lag.We measured thermal diffusivity of periclase, forsterite, zircona and corundum at high pressures and temperatures. Thermal diffusivity of all of these materials decreases with increasing temperature and increases with increasing temperature. Reciprocal thermal diffusivity of periclase is linearly increases with increasing temperature as is the case of simple materials. Its gradient decreases with increasing pressure. Reciprocal thermal diffusivity of forsterite shows curvature as is the case of Fo89 olivine. This may be due to complex crystal structure of forsterite. Reciprocal thermal diffusivity of corundum shows a linear relation with temperature. However, its gradient does not change with increasing temperature. It is possible that measurement for corundum was failed because thermal diffusivity of corundum is very highThermal diffusivity of forsterite is 30% larger than that of fo89 olivine. Thermal diffusivity of forsterite increases by 40% over 6 GPa. This pressure dependence is about 40% larger than that of fo89 olivine.Thermal diffusivity of zirconia measured at high pressure is more than 50% larger than expected from the measurement at ambient conditions.

在这项研究中，首先我们通过埃法构建了一个热扩散率测量系统。我们使用可编程电源构建了一个加热系统，该电源可以调制电压，使电功率呈正弦变化。使用外部触发器，我们测量插入样品的两个热电偶的电动势，以确定两个不同点的温度振荡之间的相位滞后。两个热电偶的位置通过光学测量。根据这些位置和相位滞后计算热扩散率。我们测量了方镁石、镁橄榄石、氧化锆和刚玉在高压和高温下的热扩散率。所有这些材料的热扩散率随温度升高而降低，并随温度升高而升高。与简单材料的情况一样，方镁石的热扩散率倒数随着温度的升高而线性增加。其梯度随着压力的增加而减小。与 Fo89 橄榄石一样，镁橄榄石的热扩散率倒数也显示出曲率。这可能是由于镁橄榄石复杂的晶体结构所致。刚玉的热扩散系数与温度呈线性关系。然而，其梯度不随温度升高而改变。刚玉的测量可能失败，因为刚玉的热扩散率非常高。镁橄榄石的热扩散率比fo89橄榄石大30%。镁橄榄石的热扩散率在6 GPa以上增加了40%。这种压力依赖性比 fo89 橄榄石大约 40%。在高压下测量的氧化锆的热扩散率比在环境条件下测量的预期值大 50% 以上。