Experimental studies on the phase transition and thermoelastic behavior of barite-group minerals are crucial to understand the recycle of sulfur in Earth's interior. Here, we present a high-pressure and high-temperature (high P-T) study on two barite-group mineralsbarite (BaSO4) and celestite (SrSO4) up to similar to 59.5 GPa 700K and similar to 22.2 GPa, 700K, respectively, using in situ synchrotron-based X-ray diffraction (XRD) combined with diamond anvil cells (DACs). Our results show that BaSO4 undergoes a pressure-induced phase transition from Pbnm to P2(1)2(1)2(1) at similar to 20.3GPa, which is different from the previous results. Upon decompression, the high-pressure phase of BaSO4 transforms back into its initial structure, which indicates a reversible phase transition. However, no phase transitions have been detected in SrSO4 over the experimental P-T range. In addition, fitting a third-order Birch-Murnaghan equation of state to the pressure-volume data yields the bulk moduli and their pressure derivatives of BaSO4 and SrSO4. Simultaneously, the thermal expansion coefficients of BaSO4 and SrSO4 are also obtained, by fitting the temperature-volume data to the Fei-type thermal equation of state. Furthermore, the compositional effects on the phase transformation and thermoelastic behavior of barite-group minerals are also discussed, and the results suggest that the bond length of <M-O> (M=Ba, Sr, Pb) is an important factor that causes the phase transition pressure of SrSO4 to be the largest, PbSO4 is the second, and BaSO4 is the lowest. Publication name | PHYSICS AND CHEMISTRY OF MINERALS, 46 (6):607-621; 10.1007/s00269-019-01026-0 JUN 2019 | Author(s) | Ye, Zhilin; Li, Bo; Chen, Wei; Tang, Ruilian; Huang, Shijie; Xu, Jingui; Fan, Dawei; Zhou, Wenge; Ma, Maining; Xie, Hongsen | Corresponding author(s) | ZHOU Wenge zhouwenge@vip.gyig.ac.cn Chinese Acad Sci, Key Lab High Temp & High Pressure Study Earths In, Inst Geochem, Guiyang 550081, Guizhou, Peoples R China. MA Maining mamn@ucas.ac.cn Univ Chinese Acad Sci, Key Lab Computat Geodynam, Coll Earth & Planetary Sci, Beijing 100049, Peoples R China. | View here for the details
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