Pressure dependence of thermal transport properties
Pressure dependence of thermal transport properties
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DOI：
10.1073/pnas.0610734104
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发表时间：
2007-05-29
影响因子：
11.1
通讯作者：
Hofmeister, Anne M.
中科院分区：
文献类型：
--
作者：
Hofmeister, Anne M.
热导率(K)和热扩散率(D)的压力(P)导数对地球物理很重要，但很难准确测量，因为矿物坚硬且部分透明，可能会因界面热损失和虚假辐射传输而引起系统误差。为了评估准确性，对橄榄石[(Mg0.9Fe0.1)(2)SiO4]、石英(SiO_2)和氯化钠进行了详细的重复实验：这些数据和其他关于电绝缘体的数据与理论进行了比较。在环境条件下，D与接触数成正比被低估。随着温度(T)的升高，杂散辐射传输超过了对触点损耗的补偿。孔隙空间的压缩和接触损失影响压力导数，但它们似乎与T无关。用无接触激光闪光法获得了1atm时D(T)的准确(+/-2%)值。其他光学技术不能精确定位D，但提供了有用的压力导数。已发表的关于偏导数(Ink)/偏导数PAT的环境条件的数据与所有可用的模型大致一致，其中最简单的预测偏导数(Ink)/偏导数P类似于偏导数(INKT)/偏导数P，其中K-T是体积弹性系数。然而，经过多次测量验证的导数只有通过有阻尼谐振子模型才能准确再现。需要一个改进的数据库来完善这一模型，并自信地将这些困难的测量结果外推到地球物理相关的条件下。
Pressure (P) derivatives of thermal conductivity (k) and thermal diffusivity (D) are important to geophysics but are difficult to measure accurately because minerals, being hard and partially transparent, likely incur systematic errors through thermal losses at interfaces and spurious radiative transfer. To evaluate accuracy, repeat experiments for olivine [(Mg0.9Fe0.1)(2)SiO4], quartz (SiO2), and NaCl are examined in detail: these and other data on electrical insulators are compared with theory. At ambient conditions, D is underestimated in proportion to the number of contacts. As temperature (T) increases, spurious radiative transfer more than offsets contact loss. Compression of pore space and contact losses affect pressure derivatives, but these seem independent of T. Accurate (+/- 2%) values of D(T) at 1 atm are obtained with the contact-free, laser-flash method. Other optical techniques do not pinpoint D but provide useful pressure derivatives. Published data on partial derivative(Ink)/partial derivative Pat ambient conditions agree roughly with all available models, the simplest of which predicts partial derivative(Ink)/partial derivative P similar to partial derivative(InKT)/partial derivative P, where K-T is the bulk modulus. However, derivatives verified by multiple measurements are reproduced accurately only by the damped harmonic oscillator model. An improved database is needed to refine this model and to confidently extrapolate these difficult measurements to geophysically relevant conditions.