1. High-Temperature Heat Capacity of Pb9R(GeO4)3(VO4)3 (R = La, Pr, Nd, Sm) Apatites.
- Author
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Denisova, L. T., Golubeva, E. O., Denisov, V. M., Belousova, N. V., and Chumilina, L. G.
- Abstract
The apatite-like Pb
9 Pr(GeO4 )3 (VO4 )3 and Pb9 Sm(GeO4 )3 (VO4 )3 compounds were prepared by solid-phase synthesis using oxides as starting chemicals: PbO, Pr2 O3 (Sm2 O3 ), GeO2 , and V2 O5 . The successive annealing was carried out at 773–1073 K in the air. The effect of rare-earth elements on the structure of the Pb9 R(GeO4 )3 (VO4 )3 (R = La, Pr, Nd, Sm) apatites and basic thermodynamic functions was investigated. The temperature dependence (350–1050 K) of the heat capacity of the Pr(Sm)-containing apatites has been determined by differential scanning calorimetry. It has been established that the Cp = f(T) curve for the Pb9 Pr(GeO4 )3 (VO4 )3 compound has an extremum associated with a polymorphic transformation in the region of 978 K. [ABSTRACT FROM AUTHOR]- Published
- 2020
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