| Autor: |
Ogorodova, L. P., Gritsenko, Yu. D., Vigasina, M. F., Vyatkin, S. V., Melchakova, L. V., Ksenofontov, D. A. |
| Předmět: |
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| Zdroj: |
Geochemistry International; Nov2022, Vol. 60 Issue 11, p1114-1121, 8p |
| Abstrakt: |
Brazilianite Na0.91Al3.03(PO4)1.98(OH)4.06 (Galilea, Minas Gerais, Brazil) has been studied by thermal and electron microprobe analysis, powder X-ray diffraction, IR, Raman, and EPR spectroscopy. The EPR method has established that the peculiar feature of the studied sample is the presence of a structural impurity of vanadium. The enthalpy of formation of brazilianite NaAl3(PO4)2(OH)4 from the elements ∆fH0(298.15 K) = −5322.3 ± 5.1 kJ/mol was determined by the method of calorimetry of dissolution in a melt of lead borate 2PbO∙B2O3 on a Setaram (France) Calvet microcalorimeter. The value of the absolute entropy S0(298.15 K) = 303.8 ± 0.9 J/(mol K) was estimated, and the entropy of formation ∆fS0(298.15 K) = − 1407.1 ± 1.1 J/(mol K) and the Gibbs energy of formation from elements ∆fG0(298.15 K) = − 4902.8 ± 5.1 kJ/mol were calculated. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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