在上部地函中，地函流(mantle flow)與上部地函熱傳輸息息相關。從震波資料觀測到剪力波在上部地函因介質非均向性(anisotropy)使其在水平及垂直分量上波速不同呈現分裂現象(shear wave splitting)。這可以由上部地函擄獲岩中橄欖石、輝石受應力(即地函流)會產生晶體順向排列(LPO)現象解釋。在礦物相晶體順向排列下，必影響岩石之熱傳導性質。所以本研究使用時間域熱反射方法(TDTR)來測量直輝石a、b、c三軸，在一系列不同的鐵鎂比例(Mg#)與含水量(至多接近1000 ppm)等變因，對於在常壓與高壓下的熱傳導率影響，來探討在上部地函輝石其因化學成份差異對於熱傳輸的影響，進而影響地球內部地溫梯度。發現常壓下天然直輝石(En72-En94)，其含鎂量(Mg#)每增加0.1 mol%，熱傳導率值則會上升約0.6 Wm-1K-1至0.8 Wm-1K-1，且上升幅度對於c軸影響是較為顯著。在鎂端成份(En100)合成輝石含水量(少於1000ppm範圍)會不等量地降低熱導率，含水量越多輝石熱導率值下降越多。而c軸與a軸下降幅度較a軸顯著，與羥基缺陷在c軸與a軸有關。本研究發現在常溫高壓下輝石熱導率值隨壓力上升而上升，其中c軸樣品在特定壓力(低於Pbca- P21/c相變壓力)前呈現快速前線性上升，與直輝石常溫高壓拉曼觀察到c軸660與680cm-1兩對振動模異常發生壓力相近，可能暗示輝石矽氧四面體中長鏈O3-Si-O3鍵角變化會影響傳熱行為。

In this study, thermal conductivity of the single crystal orthoenstatite were measured by the time-domain thermoreflectance (TDTR) methods at ambient conditions and high pressure conditions. The orientation of every crystals were identified by Laue diffraction method and polarized Raman spectroscopy. The experimental results showed that at the ambient conditions, the c-axis has the highest thermal conductivity value than other directions. The lowest value direction is the b-axis. Both Mg content and water content have significant influence to the thermal conductivity.
At the high pressure conditions, thermal conductivity increases with the rising pressure. However, the slope (∂⁡(Λ_lat )/∂P) of c-axis are much higher than other orientations. The slope suddenly became flat as the pressure over the specific pressures, which are much lower than the phase transition (Pbca to P21/c) pressure indicated by XRD. We also compared with the Raman data of c-axis at the same conditions. Vibration modes at 660 and 680cm-1 have the abnormal phenomenon at the similar pressure, which may imply that the heat transfer behavior in the orthopyroxenes at the high pressure may be affect by the long tetrahedral chain distortion.

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