TY - JOUR

T1 - Evolution of syngenite, K2Ca(SO4)2·H2O over a wide range of temperatures and pressures

AU - Байкина, Анна Сергеевна

AU - Задоя, Анастасия Игоревна

AU - Борисов, Артем Сергеевич

AU - Alabarse, Frederico

AU - Holzheid , Astrid

AU - Уголков, Валерий

AU - Сийдра, Олег Иоханнесович

PY - 2025/5/19

Y1 - 2025/5/19

N2 - The crystal chemistry of syngenite K2Ca(SO4)2·H2O and its lattice dynamics under low and high temperatures and high pressure were studied. The research facilities used include in situ temperature variable single-crystal (SCXRD) and powder X-ray diffraction (PXRD), in situ PXRD under high pressure (HP), thermal analysis (DSC and TGA), and Raman spectroscopy. For the first time, a detailed study of syngenite in the range of negative temperatures down to −180 °C was performed. It indicates the absence of phase transitions in the range from −180 °C to 240 °C. The largest expansion of the structure is observed along the α11, which is consistent with the layered architecture. The minor thermal expansion along the α22 is observed in the plane of the [Ca(SO4)2]2− layer, formed by the bassanite-type chains. The study of powder samples at HP up to 20 GPa was carried out using synchrotron radiation and a diamond anvil cell. The phase transition is registered at 10 GPa. After the decompression, the syngenite post-phase becomes partially amorphized.

AB - The crystal chemistry of syngenite K2Ca(SO4)2·H2O and its lattice dynamics under low and high temperatures and high pressure were studied. The research facilities used include in situ temperature variable single-crystal (SCXRD) and powder X-ray diffraction (PXRD), in situ PXRD under high pressure (HP), thermal analysis (DSC and TGA), and Raman spectroscopy. For the first time, a detailed study of syngenite in the range of negative temperatures down to −180 °C was performed. It indicates the absence of phase transitions in the range from −180 °C to 240 °C. The largest expansion of the structure is observed along the α11, which is consistent with the layered architecture. The minor thermal expansion along the α22 is observed in the plane of the [Ca(SO4)2]2− layer, formed by the bassanite-type chains. The study of powder samples at HP up to 20 GPa was carried out using synchrotron radiation and a diamond anvil cell. The phase transition is registered at 10 GPa. After the decompression, the syngenite post-phase becomes partially amorphized.

KW - baric compression tensor

KW - synchrotron X-ray diffraction

KW - syngenite

KW - thermal expansion tensor

UR - https://www.mdpi.com/2073-4352/15/4/334

UR - https://www.mendeley.com/catalogue/bab85693-74fe-3028-893f-e33f0eda65b1/

U2 - 10.3390/cryst15040334

DO - 10.3390/cryst15040334

M3 - Article

VL - 15

JO - Crystals

JF - Crystals

SN - 2073-4352

IS - 4

M1 - 334

ER -