In-situ High-Temperature XRD and FTIR for Calcite, Dolomite and Magnesite: Anharmonic Contribution to the Thermodynamic Properties

作     者：Xiang Wang Xiaoxiang Xu Yu Ye Chao Wang Dan Liu Xiaochao Shi Sha Wang Xi Zhu 

作者机构：State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 China Shanghai Key Lab of Chemical Assessment and Sustainability School of Chemical Science and Engineering Tongji University Shanghai 200092 China 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2019年第30卷第5期

页      面：964-976页

核心收录：

学科分类：07[理学] 

基　　金：supported by the National Key Research and Development Program of China(No.2016YFC0600204) the National Natural Science Foundation of China(Nos.41590621,41672041) 

主　　题：calcite dolomite magnesite high-temperature FTIR anharmonicity thermodynamics 

摘      要：In-situ powder X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectra were measured on the natural crystals of calcite(Ca0.996 Mg0.004 CO3), dolomite(Ca0.497 Mg0.454 Fe0.046 Mn0.003 CO3) and magnesite(Mg0.988 Ca0.010 Fe0.002 CO3), with a temperature up to 796 K. The thermal expansion coefficients were evaluated for these carbonate minerals, resulting in the values of 2.7×10^-5, 3.3×10^-5 and 3.5×10^-5 K^-1 for calcite, dolomite and magnesite, respectively. The magnitude of these coefficients is in the same order as those for the isothermal and elastic moduli of these carbonates(e.g., calcitedolomitemagnesite. The Debye model(harmonic approximation) would be valid for magnesite to simulating the thermodynamic properties and isotope fractionation β-factor at high P-T condition.