With the use of both experimental and numerical methods, the conditions required for phosphoran olivine formation as well as its structural features and thermodynamic stability have been studied. Olivine containing up to 35 wt % P₂O₅ was synthesized in evacuated quartz glass ampoules at temperatures of 1373, 1473, and 1573 K using San Carlos olivine or an oxide mixture blended with either magnesium phosphate Mg₃(PO₄)₂ or iron phosphide FeP and studied by scanning electron microscopy/energy-dispersive spectrometry, wavelength-dispersive spectroscopy analysis, X-ray powder diffraction, and Raman spectroscopy. The inhomogeneity of the composition of synthesized phosphoran olivines as well as the results of first-principles calculations unequivocally indicates their metastable crystallization. The absence of the shift of phosphoran olivine X-ray diffraction reflections with respect to phosphoran-free olivine might indicate that the entry of phosphorus in olivine causes only a slight distortion of the structure, which is consistent with the results of first-principles calculations. The position of the Raman bands associated with the most intensive internal vibration modes of [SiO₄]^4– tetrahedra at 824 and 857 cm^–1 and [PO₄]^3– tetrahedra at 981 cm^–1 does not change with respect to phosphoran-free olivine and farringtonite, respectively. Their relative intensities in phosphoran olivine may reflect the Si/P ratio. The phosphoran olivine formation energy is dependent on the distance between [PO₄]^3– tetrahedra in the structure. With the use of first-principles calculations, it has been shown that neither pressure in the range from 0 to 8 GPa nor temperature in the range from 0 to 1500 K favors the equilibrium entry of phosphorus into olivine at concentrations equal to or exceeding 6.3 wt %.

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磷橄榄石形成的实验和从头研究

通过使用实验和数值方法，研究了磷聚糖橄榄石形成所需的条件及其结构特征和热力学稳定性。在 1373、1473和 1573 K 的温度下，使用圣卡洛斯橄榄石或与磷酸镁 Mg ₃ (PO ₄ ) ₂混合的氧化物混合物，在真空石英玻璃安瓿中合成了含有高达 35 wt% P ₂ O _{5 的}橄榄石或磷化铁 FeP，并通过扫描电子显微镜/能量色散光谱、波长色散光谱分析、X 射线粉末衍射和拉曼光谱进行研究。合成磷聚糖橄榄石组成的不均匀性以及第一性原理计算的结果明确表明它们是亚稳态结晶。磷橄榄石 X 射线衍射反射相对于无磷橄榄石没有偏移可能表明磷进入橄榄石仅导致结构的轻微扭曲，这与第一性原理计算的结果一致。与 [SiO ₄ ] ^4–的最强烈的内部振动模式相关的拉曼谱带的位置824 和 857 cm ^{–1 处的}四面体和 981 cm ^–1处的[PO ₄ ] ^3-四面体分别相对于不含磷烷的橄榄石和磷灰石没有变化。它们在磷聚糖橄榄石中的相对强度可能反映了 Si/P 比。磷聚糖橄榄石的形成能取决于结构中[PO ₄ ] ^3-四面体之间的距离。使用第一性原理计算表明，0 到 8 GPa 范围内的压力和 0 到 1500 K 范围内的温度均不利于磷以等于或超过 6.3 wt% 的浓度平衡进入橄榄石%。