Kutnohorite CaMn(CO3)2 crystal growth at high pressure-temperature

IF 1.1 4区工程技术 Q4 Engineering

High Temperatures-high Pressures Pub Date : 2020-01-01 DOI:10.32908/hthp.v49.831

Rui Li, Lin Li, J. Bai, Wen Liang, Hongfeng Tang

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引用次数: 1

Abstract

High quality kutnohorite CaMn(CO3)2 single crystals up to 100 μm in size were successfully achieved under high pressure-temperature (P-T) conditions. Electron microprobe analyses revealed the average wt% of CaO was 25.98% and that of MnO was 32.88%, correspondingly well to the ideal formula of Ca1.0Mn1.0(CO3)2. Accurate crystalline structural data were determined from single-crystal X-ray diffraction (XRD), with the R3 space group and R3c space group used to refine the crystal structure of CaMn(CO3)2. The Ca-O and Mn-O bond lengths were slightly different when using the R3 space group, which were clearly distinguished from those in the dolomite structure. Therefore, R3c is the most probable space group for the CaMn(CO3)2 crystal structure. Thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) showed that CaMn(CO3)2 decomposed from 620–750 °C, but only one endothermic peak was observed during the decomposition process. It indicated that the octahedral units in CaMn(CO3)2 have the same thermal stability due to the complete miscibility of Ca and Mn. The results of single crystal XRD and thermal analysis provided direct evidence that CaMn(CO3)2 has a calcitetype structure, not dolomite-type layered structure, which was in good agreement with the rigid model of rhombohedral carbonates.

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高压-高温条件下Kutnohorite CaMn(CO3)2晶体的生长

在高压-高温(P-T)条件下成功制备了高质量的库特霍雷特CaMn(CO3)2单晶，晶粒尺寸可达100 μm。电镜分析表明，CaO的平均wt%为25.98%，MnO的平均wt%为32.88%，符合Ca1.0Mn1.0(CO3)2的理想公式。利用单晶x射线衍射(XRD)获得了精确的晶体结构数据，利用R3空间群和R3c空间群对CaMn(CO3)2的晶体结构进行了细化。使用R3空间群时，Ca-O和Mn-O键长略有不同，这与白云岩结构中的键长有明显区别。因此，R3c是CaMn(CO3)2晶体结构最可能存在的空间群。热重分析(TG)和差示扫描量热分析(DSC)表明，CaMn(CO3)2在620 ~ 750℃范围内分解，但在分解过程中只观察到一个吸热峰。结果表明，由于Ca和Mn的完全混溶，CaMn(CO3)2中的八面体单元具有相同的热稳定性。单晶XRD和热分析结果直接证明了CaMn(CO3)2具有方解石型结构，而不是白云岩型层状结构，这与方解石型碳酸盐的刚性模型吻合较好。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

High Temperatures-high Pressures THERMODYNAMICS-MECHANICS

CiteScore

1.00

自引率

9.10%

发文量

期刊介绍： High Temperatures – High Pressures (HTHP) is an international journal publishing original peer-reviewed papers devoted to experimental and theoretical studies on thermophysical properties of matter, as well as experimental and modelling solutions for applications where control of thermophysical properties is critical, e.g. additive manufacturing. These studies deal with thermodynamic, thermal, and mechanical behaviour of materials, including transport and radiative properties. The journal provides a platform for disseminating knowledge of thermophysical properties, their measurement, their applications, equipment and techniques. HTHP covers the thermophysical properties of gases, liquids, and solids at all temperatures and under all physical conditions, with special emphasis on matter and applications under extreme conditions, e.g. high temperatures and high pressures. Additionally, HTHP publishes authoritative reviews of advances in thermophysics research, critical compilations of existing data, new technology, and industrial applications, plus book reviews.