The occurrence of buetschliite, K₂Ca(CO₃)₂, as inclusions in mantle minerals, is considered as one of the keys to understanding phase relationships of dense carbonates and outlines the potential role of potassium carbonates in the Earth's deep carbon cycle. Within this scope, the high-pressure behavior of synthetic buetschliite is characterized by in situ Raman spectroscopy up to 19 GPa and 300°C. Up to 6 GPa, the compression is regular, then the splitting of some of the lattice and internal modes defines the transition to a low-symmetry phase, in analogy to that observed previously in K₂Mg(CO₃)₂. The temperature rise to 300°C shifts the transition pressure from ~6 to ~8 GPa, but on the whole, it does not change the high-pressure behavior of K₂Ca(CO₃)₂. The observed pressure-induced spectral changes are fully reversible at room and elevated temperature. The findings show the expansion of buetschliite baric stability with temperature, which confirms its importance as a constituent of carbonate inclusions in deep minerals.

中文翻译：

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合成硅钙石 K2Ca(CO3)2 在高达 19 GPa 和 300°C 的高压下的行为和稳定性

_{布奇利石（K 2} Ca(CO ₃ ) ₂ ）作为地幔矿物中的包裹体，其出现被认为是了解致密碳酸盐相关系的关键之一，并概述了碳酸钾在地球深层碳循环中的潜在作用。在此范围内，合成硅铝镁石的高压行为通过高达 19 GPa 和 300°C 的原位拉曼光谱进行表征。高达 6 GPa 时，压缩是规则的，然后一些晶格和内部模式的分裂定义了向低对称性相的过渡，类似于之前在 K ₂ Mg(CO ₃ ) ₂中观察到的情况。温度升至300°C将转变压力从~6 GPa转变为~8 GPa，但总体而言，它并没有改变K ₂ Ca(CO ₃ ) ₂的高压行为。观察到的压力引起的光谱变化在室温和高温下是完全可逆的。研究结果表明，钙镁石的气压稳定性随着温度的变化而扩大，这证实了其作为深层矿物碳酸盐包裹体成分的重要性。