Exploration of the Crystal Structure and Thermal and Spectroscopic Properties of Monoclinic Praseodymium Sulfate Pr2(SO4)3

Autor: Yuriy G. Denisenko, Victor V. Atuchin, Maxim S. Molokeev, Alexander E. Sedykh, Nikolay A. Khritokhin, Aleksandr S. Aleksandrovsky, Aleksandr S. Oreshonkov, Nikolai P. Shestakov, Sergey V. Adichtchev, Alexey M. Pugachev, Elena I. Sal’nikova, Oleg V. Andreev, Illaria A. Razumkova, Klaus Müller-Buschbaum
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Molecules, Vol 27, Iss 13, p 3966 (2022)
Druh dokumentu: article
ISSN: 27133966
1420-3049
DOI: 10.3390/molecules27133966
Popis: Praseodymium sulfate was obtained by the precipitation method and the crystal structure was determined by Rietveld analysis. Pr2(SO4)3 is crystallized in the monoclinic structure, space group C2/c, with cell parameters a = 21.6052 (4), b = 6.7237 (1) and c = 6.9777 (1) Å, β = 107.9148 (7)°, Z = 4, V = 964.48 (3) Å3 (T = 150 °C). The thermal expansion of Pr2(SO4)3 is strongly anisotropic. As was obtained by XRD measurements, all cell parameters are increased on heating. However, due to a strong increase of the monoclinic angle β, there is a direction of negative thermal expansion. In the argon atmosphere, Pr2(SO4)3 is stable in the temperature range of T = 30–870 °C. The kinetics of the thermal decomposition process of praseodymium sulfate octahydrate Pr2(SO4)3·8H2O was studied as well. The vibrational properties of Pr2(SO4)3 were examined by Raman and Fourier-transform infrared absorption spectroscopy methods. The band gap structure of Pr2(SO4)3 was evaluated by ab initio calculations, and it was found that the valence band top is dominated by the p electrons of oxygen ions, while the conduction band bottom is formed by the d electrons of Pr3+ ions. The exact position of ZPL is determined via PL and PLE spectra at 77 K to be at 481 nm, and that enabled a correct assignment of luminescent bands. The maximum luminescent band in Pr2(SO4)3 belongs to the 3P0 → 3F2 transition at 640 nm.
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