Abstract The phases of CaAl2O4 and Ca2Al6O11 were synthesized at 15 GPa and 1600 °C. Microprobe data gave formulae Ca1.003Al1.998O4 and Ca2.05Al5.97O11, on the basis of 4 and 11 oxygen atoms. The crystal structures have been refined by single-crystal X-ray diffraction. Orthorhombic unitcell parameters for CaAl2O4 are a = 8.8569(10) A; b = 2.8561(4) A; c = 10.2521(11) A; V = 259.34(5) A3; Z = 8 (space group Pnma). The Ca2Al6O11 phase was obtained for the first time. It crystallizes with a space group P42/mnm and has lattice parameters a = b = 11.1675(4) A; c = 2.83180(10) A; V = 353.16(2) A3; Z = 2. A Raman spectrum was obtained for a new phase for the first time. Our results suggest that both studied phases are stable under the condition of the transition zone and can be considered as potential aluminum concentrators in the Earth's deep geospheres.

中文翻译：

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新型高压相 CaAl2O4 和 Ca2Al6O11 的合成和晶体结构

摘要 CaAl2O4 和Ca2Al6O11 相在15 GPa 和1600 °C 下合成。基于 4 个和 11 个氧原子，微探针数据给出了化学式 Ca1.003Al1.998O4 和 Ca2.05Al5.97O11。晶体结构已通过单晶 X 射线衍射进行了细化。CaAl2O4 的正交晶胞参数为 a = 8.8569(10) A；b = 2.8561(4) A；c = 10.2521(11) A; V = 259.34(5) A3；Z = 8（空间群 Pnma）。首次获得 Ca2Al6O11 相。它以 P42/mnm 空间群结晶，晶格参数 a = b = 11.1675(4) A；c = 2.83180(10) A; V = 353.16(2) A3；Z = 2。首次获得了新相的拉曼光谱。我们的结果表明，两个研究相在过渡带条件下都是稳定的，可以被认为是地球上潜在的铝浓缩物。