Crystal Structure, Luminescence, and Thermodynamic Properties of Pb10 –xEux(GeO4)2 +x(VO4)4 –x (x = 0.1, 0.2, 0.3) Substituted Apatites

• Published in: Inorganic materials Vol. 57; no. 11; pp. 1158 - 1166
• Main Authors: Denisova, L. T., Molokeev, M. S., Aleksandrovskii, A. S., Kargin, Yu. F., Golubeva, E. O., Denisov, V. M.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2021; Springer Nature B.V
• Subjects: Apatite; Atomic structure; Chemistry; Chemistry and Materials Science; Crystal structure; Europium; Europium compounds; Germanium oxides; Hexagonal cells; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Lead oxides; Luminescence; Materials Science; Mathematical analysis; Parameters; Shape effects; Substitutes; Thermodynamic properties; X-ray diffraction; luminescence; high-temperature heat capacity; apatites; lead europium germanatovanadates; structure
• ISSN: 0020-1685; 1608-3172
• DOI: 10.1134/S0020168521110030

— Pb 10 – x Eu x (GeO 4 ) 2 + x (VO 4 ) 4 – x ( x = 0.1, 0.2, 0.3) Eu-substituted lead germanatovanadates with the apatite structure have been prepared by solid-state reactions, via firing in air in the temperature range 773–1073 K, using oxides (PbO, Eu 2 O 3 , GeO 2 , and V 2 O 5 ) as starting materials. Using X-ray diffraction, we have determined the hexagonal cell parameters (sp. gr. P 6 3 / m ) of the synthesized phases and refined their crystal structure (the atomic position coordinates, isotropic thermal parameters, and principal bond lengths in their structure are presented). We have measured the luminescence spectra of the Pb 10 – x Eu x (GeO 4 ) 2 + x (VO 4 ) 4 – x ( x = 0.1, 0.2, 0.3) apatites and shown that europium concentration has little effect on the shape of the luminescence spectra. Using experimental heat capacity data obtained for polycrystalline samples by differential scanning calorimetry in the temperature range 350–1050 K, we calculated the main thermodynamic functions of the Eu-substituted lead germanatovanadates.