R3m: A New High-Pressure and/or High-Temperature Phase of PbCO3, SrCO3, BaCO3, and Possibly of CaCO3,Crystal Growth & Design

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R3m: A New High-Pressure and/or High-Temperature Phase of PbCO3, SrCO3, BaCO3, and Possibly of CaCO3
Crystal Growth & Design ( IF 3.2 ) Pub Date : 2023-08-22 , DOI: 10.1021/acs.cgd.3c00449
Pavel N. Gavryushkin _{1,

2} , Maksim V. Banaev _{1,

2} , Nursultan E. Sagatov _{1,

2} , Dinara N. Sagatova _{1,

2}

Affiliation

In the present study, we use the crystal structure prediction technique to reveal the new high-pressure structures of PbCO₃, SrCO₃, and BaCO₃. As a result, we found the new calcite-like R3m structure thermodynamically stable for PbCO₃, SrCO₃, and BaCO₃. Without consideration of the temperature effect, PbCO₃-R3m is stable in the pressure range of 15–30 GPa. With increasing temperature, the stability field of PbCO₃-R3m in P–T coordinates reduces, and above 2000 K, the aragonite phase directly transforms into the post-aragonite phase without the formation of R3m. SrCO₃-R3m is thermodynamically stable at pressures 10–20 GPa and temperatures above 750 K. BaCO₃-R3m is dynamically stable at ambient pressure and the available experimental data indicate its appearance at temperatures above 1086 K. By analogy with KNO₃, we assume the possibility of the appearance of BaCO₃-R3m during rapid quenching of high-temperature dynamically disordered phases of BaCO₃, as well as metastable crystallization of the R3m phase at ambient pressure.

中文翻译：

R3m：PbCO3、SrCO3、BaCO3 和可能的 CaCO3 的新高压和/或高温相

_{在本研究中，我们利用晶体结构预测技术揭示了PbCO 3}、SrCO ₃和BaCO ₃的新高压结构。结果，我们发现新的类方解石R 3 m结构对于PbCO ₃、SrCO ₃和BaCO ₃具有热力学稳定性。在不考虑温度影响的情况下，PbCO ₃ - R 3 m在15~30 GPa的压力范围内是稳定的。_{随着温度的升高，PbCO 3} - R 3 m在P–T中的稳定场坐标降低，在2000 K以上，文石相直接转变为后文石相，而没有形成R 3 m。SrCO ₃ - R 3 m在压力 10–20 GPa 和温度高于 750 K 时是热力学稳定的。 BaCO ₃ - R 3 m在环境压力下是动态稳定的，可用的实验数据表明它在温度高于 1086 K 时出现。 KNO ₃ ，我们假设BaCO高温动态无序相快速淬火过程中可能出现BaCO ₃ - R 3 m_图3，以及R 3 m相在环境压力下的亚稳态结晶。

更新日期：2023-08-22

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