Development of anvil with sintered diamond core for high pressure high temperature experiments

本研究项目的目的是开发具有烧结金刚石芯的砧座，并使用新砧座产生高压和高温。我们已经开发了两种Bridgman顶砧，它们由烧结金刚石芯的碳化钨组成。砧的直径为26和20 mm。我们还建造了一台600吨的压机，用于压缩布里奇曼砧以产生高压。使用这些仪器，在本项目期间取得了以下成果。我们已经成功地产生压力高达约20.5 GPa使用新的砧。该产生的压力比由碳化钨制成的Bridgman砧座所获得的压力高得多。新的砧座也已用于高达17 GPa和1400摄氏度的高压高温实验。进行了以下相变实验。确定了KAlSi_3O_8长石与K_2Si_4O_9水铁矿+ Al_2SiO_5蓝晶石+ SiO_2柯石英（或斯石英）及KAlSi_3O_8霍兰石的相界。研究了CaAl_2O_4铁酸钙的稳定场。确定了CaFeSi_2O_6单斜辉石分解为CaSiO_3钙钛矿+ Fe_2SiO_4尖晶石+SiO_2方石英的边界。这些相界在下地幔具有重要的地球物理和地球化学意义.与此相关的是，在高温高压条件下，用原位X射线衍射技术精确地测定了TiO_2中金红石-α-PbO_2的转变边界。该边界对于高温下的压力校准很重要。

The purpose of this research project is to develop anvils with sintered diamond cores and to generate high pressures and high temperatures using the new anvils. We have developed two kinds of Bridgman anvils which consist of tungsten carbide with sintered diamond core. The diameters of tlie anvils are 26 and 20 mm. We have also constructed a 600-ton press, which is used to compress the Bridgman anvils to generate high pressures. Using these apparatus, the following results have been obtained during this project term.1. We have successfully generated pressure up to about 20.5 GPa using the new anvils. This generated pressure is much higher than those attained by Bridgman anvils made of tungsten carbide. The new anvils have also been used for high pressure high temperature experiments up to 17 GPa and 1400 ﾟC.2. The following phase transition experiments have been caried out. Phase boundaries in KAlSi_3O_8 feldspar to K_2Si_4O_9 wadeite + Al_2SiO_5 kyanite + SiO_2 coesite (or stishovite) and further to KAlSi_3O_8 hollandite have been determined. Stability field of CaAl_2O_4 calcium ferrite has been examined. The decomposition boundary of CaFeSi_2O_6 clinopyroxene to CaSiO_3 perovskite + Fe_2SiO_4 spinel +SiO_2 stishovite has also been determined. These phase boundaries are of geophysical and geochemical importance in the lower mantle.3. As a related topic, the rutile-alphaPbO_2 transition boundary in TiO_2 has accurately been determined by in situ x-ray diffraction techniques at high pressure and high temperature. This boundary is important for pressure calibration at high temperatures.