We have synthesized the orthocarbonate Sr₃[CO₄]O in a laser-heated diamond anvil cell at 20 and 30 GPa by heating to ≈3000 (300) K. Afterward, we recovered the orthocarbonate with [CO₄]^4– groups at ambient conditions. Single-crystal diffraction shows the presence of [CO₄]^4– groups, i.e., sp³-hybridized carbon tetrahedrally coordinated by covalently bound oxygen atoms. The [CO₄]^4– tetrahedra are located in a cage formed by corner-sharing OSr₆ octahedra, i.e., octahedra with oxygen as a central ion, forming an antiperovskite-type structure. At high pressures, the octahedra are nearly ideal and slightly rotated. The high-pressure phase is tetragonal (I4/mcm). Upon pressure release, there is a phase transition with a symmetry lowering to an orthorhombic phase (Pnma), where the octahedra tilt and deform slightly.

中文翻译：

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具有四面体配位 sp3 杂化碳和 OSr6 八面体的 Sr3[CO4]O 反钙钛矿

我们已合成了原碳酸酯的Sr ₃ [CO ₄ ] O在20和30通过GPA加热至≈3000（300）K.之后，我们用回收[CO的原碳酸酯的激光加热金刚石压腔₄ ] ^4-基团的环境条件。单晶衍射显示[CO ₄ ] ^4-基团的存在，即sp ^{3 -}杂化碳四面体由共价结合的氧原子配位。[CO ₄ ] ^4–四面体位于由角共享 OSr ₆形成的笼子中八面体，即以氧为中心离子的八面体，形成反钙钛矿型结构。在高压下，八面体几乎是理想的并且略微旋转。高压相是四方相（I 4/ mcm）。在压力释放时，存在对称性降低到正交相 ( Pnma )的相变，其中八面体略微倾斜和变形。