Crystal chemistry of FeO at high pressure and temperature
Crystal chemistry of FeO at high pressure and temperature
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高温高压下 Fe3O 的晶体化学
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Schaefer
中科院分区：
文献类型：
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作者：
M. Dyar;M. Schaefer
本文用高温金刚石对顶砧装置结合同步辐射X射线衍射研究了Fe、O在100 GPa和1100 K压力下的相关系和状态方程。在静水压力下，Fe.O在16 GPa和300 K时由NaCl型立方结构（B1）转变为菱面体结构。相变压力随温度的变化而增加，压力-温度斜率为0.070（±0.003）GPalK。非化学计量对相变边界没有明显影响。在非流体静力学条件下，转变发生在较低的压力下。随着压力的增加，菱面体相的变形增加。在室温下，在40 GPa以上的压力下，观察到从菱面体细胞到较低对称相的进一步扭曲。在90 GPa和600 K的高压下加热，形成NiAs型六方相（BS）。静水压缩数据的最小二乘拟合得到NaCl型立方相（BI）的室温体积模量KTO = 146（±2）GPa，其压力导数（8 KTOI 8 P）T = 4。的非化学计量的体积模量的程度的影响是小的，在实验的不确定性。虽然菱形相的体积模量不能准确地确定，通过比较结构相关的晶面间距d，很明显，菱形相比立方相的可压缩性更低。的体积模量和它的压力导数的NiAs型六方相（BS），来自静态压缩数据，分别为172 GPa和4.3，在900 K。
AhstractThe phase relations and equations of state of Fe,O have been studied up to a pressure of 100 GPa and a temperature of 1100 K, using a high-temperature diamond-anvil cell combined with synchrotron x-ray diffraction. Under a hydrostatic environment, Fe.O transforms from the NaCl-type cubic structure (Bl) to a rhombohedral structure at 16 GPa and 300 K. The transition pressures increase as a function of temperature with a pressure-temperature slope of 0.070(±0.003) GPalK. No significant effect of non stoichiometry on the transition boundary was observed. The transition occurs at lower pressure under nonhydrostatic conditions. The rhombohedral phase increases its distortion with increasing pressure. Further distortions from the rhombohedral cell to a lower symmetry phase were observed at pressures above 40 GPa at room temperature. Upon heating at high pressure, the NiAs-type hexagonal phase (BS) forms at 90 GPa and 600 K. Least-squares fits of the hydrostatic compression data yielded the room-temperature bulk modulus K TO = 146(±2) GPa with its pressure derivative (8KTOI8P)T = 4 for the NaCI-type cubic phase (Bl). The effect of degree of nonstoichiometry on the bulk moduli is small, within the uncertainty of the experiments. Although the bulk modulus for the rhombohedral phase cannot be determined accurately, by comparing the structurally related interplanar d spacings it is evident that the rhombohedral phase is less compressible than the cubic phase. The bulk modulus and its pressure derivative for the NiAs-type hexagonal phase (BS), derived from the static compression data, are 172 GPa and 4.3 at 900 K, respectively.