Journal article

Thermochemistry, Structure, and Optical Properties of a New β-La2(SO4)3 Polymorphic Modification


Authors listBasova, Sofia A.; Molokeev, Maxim S.; Oreshonkov, Aleksandr S.; Zhernakov, Maksim A.; Khritokhin, Nikolay A.; Aleksandrovsky, Aleksandr S.; Krylov, Alexander S.; Sal'nikova, Elena I.; Azarapin, Nikita O.; Shelpakova, Natalia A.; Mueller-Buschbaum, Klaus; Denisenko, Yuriy G.

Publication year2023

JournalInorganics

Volume number11

Issue number11

eISSN2304-6740

Open access statusGold

DOI Linkhttps://doi.org/10.3390/inorganics11110434

PublisherMDPI


Abstract
A new polymorphic modification of lanthanum sulfate was obtained by thermal dehydration of the respective nonahydrate. According to powder X-ray diffraction, it was established that beta-La-2(SO4)(3) crystallized in the C2/c space group of the monoclinic system with the KTh2(PO4)(3) structure type (a = 17.6923(9), b = 6.9102(4), c = 8.3990(5) angstrom, beta = 100.321(3)(degrees), and V = 1010.22(9) angstrom(3)). Temperature dependency studies of the unit cell parameters indicated almost zero expansion along the a direction in the temperature range of 300-450 K. Presumably, this occurred due to stretching of the [LaO9](n) chains along the c direction, which occurred without a significant alteration in the layer thickness over the a direction. A systematic study of the formation and destruction processes of the lanthanum sulfates under heating was carried out. In particular, the decisive impact of the chemical composition and formation energy of compounds on the thermodynamic and kinetic parameters of the processes was established. DFT calculations showed beta-La-2(SO4)(3) to be a dielectric material with a bandgap of more than 6.4 eV. The processing of beta-La-2(SO4)(3) with the Kubelka-Munk function exhibited low values below 6.4 eV, which indicated a fundamental absorption edge above this energy that was consistent with LDA calculations. The Raman and infrared measurements of beta-La-2(SO4)(3) were in accordance with the calculated spectra, indicating that the obtained crystal parameters represented a reliable structure.



Citation Styles

Harvard Citation styleBasova, S., Molokeev, M., Oreshonkov, A., Zhernakov, M., Khritokhin, N., Aleksandrovsky, A., et al. (2023) Thermochemistry, Structure, and Optical Properties of a New β-La2(SO4)3 Polymorphic Modification, Inorganics, 11(11), Article 434. https://doi.org/10.3390/inorganics11110434

APA Citation styleBasova, S., Molokeev, M., Oreshonkov, A., Zhernakov, M., Khritokhin, N., Aleksandrovsky, A., Krylov, A., Sal'nikova, E., Azarapin, N., Shelpakova, N., Mueller-Buschbaum, K., & Denisenko, Y. (2023). Thermochemistry, Structure, and Optical Properties of a New β-La2(SO4)3 Polymorphic Modification. Inorganics. 11(11), Article 434. https://doi.org/10.3390/inorganics11110434



Keywords


crystal chemistryDielectricsTHERMAL-DECOMPOSITION

Last updated on 2025-10-06 at 12:00