Stable compounds in the CaO-Al2O3 system at high pressures

IF 1.2 4区地球科学 Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY

Physics and Chemistry of Minerals Pub Date : 2022-10-27 DOI:10.1007/s00269-022-01221-6

Ekaterina I. Marchenko, Artem R. Oganov, Efim A. Mazhnik, Nikolay N. Eremin

引用次数: 2

Abstract

Using the evolutionary crystal structure prediction algorithm USPEX, we showed that at pressures of the Earth’s lower mantle (24-136 GPa) CaAl₂O₄ is the only stable calcium aluminate. At pressures above 7.0 GPa it has the CaFe₂O₄-type structure with space group Pnma. This phase is one of the prime candidate aluminous phases in the lower mantle of the Earth. We show that at low pressures 5CaO • 3Al₂O₃ (C₅A₃) with space group Cmc2₁, CaAl₄O₇ (with space group C2/c) and CaAl₂O₄ (space group P2₁/m) are stable at pressures of up to 2.1, 1.8 and 7.0 GPa, respectively. The previously unknown structure of the orthorhombic "CA-III" phase is also found in our calculations. This phase is metastable at 0 K and has a layered structure with space group P2₁2₁2.

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高压下CaO-Al2O3体系中的稳定化合物

利用演化晶体结构预测算法USPEX，我们发现在下地幔压力(24-136 GPa)下，CaAl2O4是唯一稳定的铝酸钙。在7.0 GPa以上的压力下，形成具有空间群Pnma的cafe2o4型结构。这个阶段是地球下地幔中主要的候选铝相之一。结果表明，在低压下，空间群为Cmc21的5CaO•3Al2O3 (C5A3)、空间群为C2/c的CaAl4O7和空间群为P21/m的CaAl2O4在高达2.1、1.8和7.0 GPa的压力下都是稳定的。在我们的计算中也发现了以前未知的正交“CA-III”相的结构。该相在0 K时亚稳，具有空间群P21212的层状结构。

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

Physics and Chemistry of Minerals 地学-材料科学：综合

CiteScore

2.90

自引率

14.30%

发文量

审稿时长

3 months

期刊介绍： Physics and Chemistry of Minerals is an international journal devoted to publishing articles and short communications of physical or chemical studies on minerals or solids related to minerals. The aim of the journal is to support competent interdisciplinary work in mineralogy and physics or chemistry. Particular emphasis is placed on applications of modern techniques or new theories and models to interpret atomic structures and physical or chemical properties of minerals. Some subjects of interest are: -Relationships between atomic structure and crystalline state (structures of various states, crystal energies, crystal growth, thermodynamic studies, phase transformations, solid solution, exsolution phenomena, etc.) -General solid state spectroscopy (ultraviolet, visible, infrared, Raman, ESCA, luminescence, X-ray, electron paramagnetic resonance, nuclear magnetic resonance, gamma ray resonance, etc.) -Experimental and theoretical analysis of chemical bonding in minerals (application of crystal field, molecular orbital, band theories, etc.) -Physical properties (magnetic, mechanical, electric, optical, thermodynamic, etc.) -Relations between thermal expansion, compressibility, elastic constants, and fundamental properties of atomic structure, particularly as applied to geophysical problems -Electron microscopy in support of physical and chemical studies -Computational methods in the study of the structure and properties of minerals -Mineral surfaces (experimental methods, structure and properties)