Thermal conductivity measurments of earth materials under high pressure and high temperature

为了研究地幔的热状态，作者在高温高压条件下测量了地幔候选矿物的热导率和热扩散率，并采用一维热流脉冲法同时测量了热扩散率和热导率。以三个相同的薄圆盘的形式制成的样品通过插入堆叠圆盘的一个界面中的薄加热器中的脉冲电流加热。温度变化由另一个接口上的热电偶检测。热扩散率由温度曲线的衰减时间确定，热导率由已知厚度的样品的温度上升和电功率计算。实验使用单轴裂球高压装置进行。边长为18 mm的氧化镁八面体用作截顶为11 mm的碳化钨顶砧中的压力介质。尺寸 ...更多信息 样品的直径为4 mm，高度为1 mm。用一对八面体金属平面炉进行了高温实验，在8.2GPa的压力下对熔融石英、石榴石和橄榄石进行了测量。外推到零压力的热导率或热扩散率值与用其它方法得到的结果一致。测量的重复性在7%以内的热扩散和15%以内的热导率。压力对地幔矿物的热扩散或热导率的依赖性是两个或三个百分点的增加每1GPa的石榴石和5%的增加每1GPa的橄榄石的b轴方向。石榴石和橄榄石的测量温度高达1000 K在8.2 GPa。石榴石的热扩散或热导率随着温度的升高而适度降低，不同于热导率的T-逆定律中的正常绝缘体。这与先前在零压力下的结果相同。少

To investigate the thermal state of the earth's mantle, the author measured the thermal conductivity and the thermal diffusivity of mantle candidate minerals under high pressure and at high temperature.A pulse method using one-dimensional heat flow has been applied to simultaneous thermal diffusivity and thermal conductivity measurements. The sample, made in the form of three identical thin disks, is heated by a pulse current in a thin heater inserted into one interface of the stacked disks. Change of temperature is detected by a thermocouple on the other interface. Thermal diffusivity is determined from decay time of the temperature profile, and thermal conductivity is calculated from the rise of temperature and an electric power for the known thickness of the sample.Experiments were performed using a uniaxial split-sphere high-pressure apparatus. A magnesia octahedron with a edge length of 18 mm was used as a pressure medium in tungsten carbide anvils with a truncation of 11 mm. Size … More s of the samples were 4 mm in diameter and 1 mm in height. A pair of metallic planar furnaces in the octahedron was used for experiments at high temperatures.Measurements were made on fused silica, garnet and olivine under pressures up to 8.2 GPa. Extrapolated values of thermal conductivity or thermal diffusiivity to zero pressure agree with those obtained by other methods. Reproducibilities of measurements are within 7 per cent for thermal diffusively and within 15 per cent for thermal conductivity.Pressure dependences on thermal diffusively or thermal conductivity of mantle minerals are tow or three per cent increase per 1 GPa for garnets and five per cent increase per 1 GPa for the b-axis direction of olivine.Garnet and olivine were measured at temperatures up to 1000 K under 8.2 GPa. The thermal diffusively or the thermal conductivity of garnet decreases moderately with temperature increase unlike normal insulators in the T-inverse law of thermal conductivity. This is the same effect as seen in previous results under zero pressure. Less