TY - JOUR

T1 - Temperature-Induced Phase Transition in a Feldspar-Related Compound BaZn2As2O8∙H2O

AU - Горелова, Людмила Александровна

AU - Верещагин, Олег Сергеевич

AU - Бочаров, Владимир Николаевич

AU - Панькин, Дмитрий Васильевич

AU - Dordevic, Tamara

N1 - Publisher Copyright: © 2022 by the authors.

PY - 2022/10/6

Y1 - 2022/10/6

N2 - The high-temperature (HT) behavior of BaAs2Zn2O8∙H2O was studied by in situ single-crystal X-ray diffraction (SCXRD) and hot stage Raman spectroscopy (HTRS) up to dehydration and the associated phase transition. During heating, the studied compound undergoes the dehydration process with the formation of BaAs2Zn2O8, which is stable up to at least 525 °C. The evolution of the fourteen main Raman bands was traced during heating. The abrupt shift of all Raman bands in the 70–1100 cm–1 spectral region was detected at 150 °C, whereas in the spectral region 3000–3600 cm–1 all the bands disappeared, which confirms the dehydration process of BaAs2Zn2O8∙H2O. The transition from BaAs2Zn2O8∙H2O to BaAs2Zn2O8 is accompanied by symmetry increasing from P21 to P21/c with the preservation of the framework topology. Depending on the research method, the temperature of the phase transition is 150 °C (HTRS) or 300 °C (HT SCXRD). According to the HT SCXRD data, in the temperature range 25–300 °C the studied compound demonstrates anisotropic thermal expansion (αmax/αmin = 9.4), which is explained by flexible crankshaft chains of TO4 (T = As, Zn) tetrahedra. Additionally, we discussed some crystal-chemical aspects of minerals with both (ZnOn) and (AsOm) polyhedra (n = 4, 5, 6; m = 3, 4) as main structural units.

AB - The high-temperature (HT) behavior of BaAs2Zn2O8∙H2O was studied by in situ single-crystal X-ray diffraction (SCXRD) and hot stage Raman spectroscopy (HTRS) up to dehydration and the associated phase transition. During heating, the studied compound undergoes the dehydration process with the formation of BaAs2Zn2O8, which is stable up to at least 525 °C. The evolution of the fourteen main Raman bands was traced during heating. The abrupt shift of all Raman bands in the 70–1100 cm–1 spectral region was detected at 150 °C, whereas in the spectral region 3000–3600 cm–1 all the bands disappeared, which confirms the dehydration process of BaAs2Zn2O8∙H2O. The transition from BaAs2Zn2O8∙H2O to BaAs2Zn2O8 is accompanied by symmetry increasing from P21 to P21/c with the preservation of the framework topology. Depending on the research method, the temperature of the phase transition is 150 °C (HTRS) or 300 °C (HT SCXRD). According to the HT SCXRD data, in the temperature range 25–300 °C the studied compound demonstrates anisotropic thermal expansion (αmax/αmin = 9.4), which is explained by flexible crankshaft chains of TO4 (T = As, Zn) tetrahedra. Additionally, we discussed some crystal-chemical aspects of minerals with both (ZnOn) and (AsOm) polyhedra (n = 4, 5, 6; m = 3, 4) as main structural units.

KW - feldspar

KW - high-temperature

KW - crystal structure

KW - Raman spectroscopy

KW - phase transition

KW - arsenate

KW - Raman spectroscopy

KW - arsenate

KW - crystal structure

KW - feldspar

KW - high-temperature

KW - phase transition

UR - http://www.scopus.com/inward/record.url?scp=85140848321&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/37b841a9-d210-3600-854c-598c35a63011/

U2 - 10.3390/min12101262

DO - 10.3390/min12101262

M3 - Article

VL - 12

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 10

M1 - 1262

ER -