白钨矿的原位高压X射线衍射研究

使用金刚石对顶砧高压装置(DAC)和同步辐射光源,对天然白钨矿进行了原位高压能量色散X射线衍射(EDXD)研究,实验最高压力为16.0 GPa.在实验压力范围内观察到了一次白钨矿结构→钨锰铁矿结构的可逆相变:压力小于5.3 GPa时为白钨矿结构(I4_1/a),在5.3～12.3 GPa压力区间内为白钨矿结构与钨锰铁矿结构(P2/c)并存,大于12.3 GPa时完全相变为钨锰铁矿结构.从键长、配位数和配位多面体角度对白钨矿→钨锰铁矿结构的相变机制进行了解释.

In-situ High-Pressure X-Ray Diffraction of Natural Scheelite

In-situ high-pressure energy dispersive X-ray diffraction experiments on natural scheelite (CaWO_4) have vbeen carried out at room temperature by using DAC device with a synchrotron radiation source at 4W2 High-Pressure Station of Beijing Synchrotron Radiation Facility. In pressures higher than 16.0 CPa, a reversible phase transition from scheelite-structure to wolframite- structure was observed. With increasing pressure, CaWO_4 kept the scheelite-structure until 5. 3 GPa, and then had a coexistence with scheelite- and wolframite-structures between 5. 3 GPa and 12. 3 GPa, and finally completely transformed to wolframite-structure at pressures above 12.3 GPa. The mechanism of the phase transition from scheelite-to-wolframite was also explained in the views of bond length, coordinate number and coordinate polyhedron.