NiO的高压结构和等温状态方程研究

The High Pressure Structure and Isothermal Equation of State of NiO up to 67 GPa

运用金刚石对顶砧(Diamond Anvil Cell,DAC)技术,以液氩作为传压介质,在最高压力为67 GPa的压力范围内对NiO进行了原位的同步辐射X射线衍射研究。在整个实验过程中,并未发现第一类结构相变,也没有发现T.Sasaki等预测的在60 GPa左右轴比c/a随压力的变化率而突然增大的现象,且此压力范围内NiO的结构畸变程度随压力的变化趋势相比以前的研究结果要平缓一些。用三阶的Brich-Murnaghan方程对实验数据进行拟合,得到的体弹模量及其对压力的一阶导数分别为B0=195(4)GPa和B0′=5.3(2)。

The high-pressure structure and isothermal equation of state of NiO were investigated up to 67 GPa by in situ synchrotron X-ray diffraction in a diamond anvil cell using argon as the pressure medium. No phase transition was found in this pressure range, nor the the pressure coefficient of axial ratio c/a became larger suddenly at about 60 GPa which was predicted by T. Sasaki. Our experiments showed that the distortion of the structure under pressure was slacker than previous results. We fit the data points to the three-order Brich-Murnaghan EOS,which resulted in a bulk modulus of B0 = 195 （4） GPa with its pressure derivative B0 ＇= 5.3（2）.