Abstract

Pb_{10 – x}Pr_x(GeO₄)_{2 + x}(VO₄)_{4 – x} (x = 0, 1, 2, 3) apatites have been prepared by solid-state reactions via sequential firing of appropriate oxide mixtures (PbO, Pr₂O₃, GeO₂, and V₂O₅) in air in the temperature range 773–1073 K. Their unit-cell parameters have been determined as functions of temperature by high-temperature X-ray diffraction measurements, and the linear and volume expansion coefficients of Pb₇Pr₃(GeO₄)₅(VO₄) have been calculated. The heat capacity of the synthesized Pb_{10 – x}Pr_x(GeO₄)_{2 + x}(VO₄)_{4 – x} (x = 0, 1, 2, 3) compounds with the apatite structure has been determined by differential scanning calorimetry in the temperature range 350–1050 K. The c_p(T) curves of the samples with x = 1, 2, and 3 have been shown to have extrema (in particular, peaks at 701, 917, and 1018 K for the x = 3 sample) due to phase transitions. The experimental C_p(T) heat capacity data have been used to evaluate the thermodynamic functions of the synthesized apatites.

中文翻译：

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Pb 10 – x Pr x（GeO 4）2 + x（VO 4）4 – x（x = 0、1、2、3）磷灰石的热容在350–1050 K范围内

摘要

铅_{10 - X}镨_X（GEO ₄）_{2 + X}（VO ₄）_{4 - X}（X = 0，1，2，3）磷灰石已制备通过经由适当的氧化物的混合物顺序点火（固态反应的PbO， Pr ₂ O ₃，GeO ₂和V ₂ O ₅）在773–1073 K的温度范围内的空气中。通过高温X射线衍射测量确定了它们的晶胞参数与温度的函数关系，并且线性和Pb ₇ Pr ₃（GeO ₄）的体积膨胀系数已经计算出₅（VO ₄）。通过差示扫描量热法测定了合成的磷灰石结构的Pb _{10- x} Pr _x（GeO ₄）_{2 + x}（VO ₄）_{4 -x}（x = 0、1、2、3）化合物的热容。的温度范围内350-1050 K的ç _p（Ť）与所述样品的曲线X = 1，2，和3中已经示出为具有极值（特别地，峰在701，917，和1018 K为X = 3个样本）。实验C _p（T）热容量数据已用于评估合成磷灰石的热力学功能。