Exploration of the Crystal Structure and Thermal and Spectroscopic Properties of Monoclinic Praseodymium Sulfate Pr<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>
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
Affiliations
Yuriy G. Denisenko
Department of Inorganic and Physical Chemistry, Tyumen State University, 625003 Tyumen, Russia
Victor V. Atuchin
Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, 630090 Novosibirsk, Russia
Maxim S. Molokeev
Laboratory of Crystal Physics, Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
Alexander E. Sedykh
Institute of Inorganic and Analytical Chemistry, Justus-Liebig-University Giessen, 35392 Giessen, Germany
Nikolay A. Khritokhin
Department of Inorganic and Physical Chemistry, Tyumen State University, 625003 Tyumen, Russia
Aleksandr S. Aleksandrovsky
Laboratory of Coherent Optics, Kirensky Institute of Physics Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
Aleksandr S. Oreshonkov
Laboratory of Molecular Spectroscopy, Kirensky Institute of Physics Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
Nikolai P. Shestakov
Laboratory of Molecular Spectroscopy, Kirensky Institute of Physics Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
Sergey V. Adichtchev
Institute of Automation and Electrometry, Russian Academy of Sciences, 630090 Novosibirsk, Russia
Alexey M. Pugachev
Institute of Automation and Electrometry, Russian Academy of Sciences, 630090 Novosibirsk, Russia
Elena I. Sal’nikova
Department of Inorganic and Physical Chemistry, Tyumen State University, 625003 Tyumen, Russia
Oleg V. Andreev
Department of Inorganic and Physical Chemistry, Tyumen State University, 625003 Tyumen, Russia
Illaria A. Razumkova
Department of Inorganic and Physical Chemistry, Tyumen State University, 625003 Tyumen, Russia
Klaus Müller-Buschbaum
Institute of Inorganic and Analytical Chemistry, Justus-Liebig-University Giessen, 35392 Giessen, Germany
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.
