Development of high-pressure topography and application to rheology of mantle minerals

1.高压X射线形貌术的发展：为了更好地了解晶体塑性和压力下的相变，我们利用同步辐射和Kawai型多砧高压装置开发了原位高压X射线形貌术。将单晶样品置于高压池中，用X射线CCD相机通过砧隙观察晶体的衍射斑点。虽然可观察到的斑点受到导向块/WC砧座阴影的限制，并且长的样品到相机的距离使得将斑点引导到相机非常困难，但我们可以在高压和高温条件下观察斑点。2.晶体形貌图像的观察：使用该技术对石英、橄榄石和金红石单晶进行了研究。在室温下初始压缩到几十吨的过程中，观察到斑点变宽。在加热过程中，变宽的斑点恢复原状。在恒温下进一步压缩导致斑点显著增宽。样品是多晶的，可能是由于应力。虽然我们还需要进一步的技术发展，如应力控制，这项技术可以是非常有用的观察晶体缺陷和在压力和温度下的单晶转变。

1.Development of high-pressure X-ray topography : To better understand crystal plasticity and phase transformation under pressure, we developed in-situ high-pressure X-ray topography technique using synchrotron radiation and Kawai-type multi-anvil high pressure device. Single crystal sample is placed in high pressure cell, and diffraction spots from the crystal are obseved using X-ray CCD camera, through anvil gaps. Although observable spots are limited by gude-blocks/WC anvil shadows and long sample-to-camera distance makes guiding spots to the camera very difficult, we could observe spots at high-pressure and temperature conditions.2.Observations of topographic images of crystal : Single crystals of quartz, olivine and rutile have been studied using this technique. During initial compression to few tens tons at room temperature, broadening of spots were observed. During heating, broadened spot reverted to original. Further compression under constant temperataure caused significant broadening of the spots. Recovered samples were polycrystalline, possibly due to stress. Athough we still need further technical developments such as stress control, this technique can be very useful to obsereve crystal defects and transformation of single crystals under pressure and temperature.