TY - JOUR

T1 - High-temperature behavior of the UV-luminescent sodalite-type natural compound Na8(Al6Si6O24)(HS)2: Comparative study by in situ single-crystal X-ray diffraction and Raman spectroscopy

AU - Shchipalkina, Nadezhda V.

AU - Vereshchagin, Oleg S.

AU - Chukanov, Nikita V.

AU - Gorelova, Liudmila A.

AU - Bocharov, Vladimir N.

AU - Pekov, Igor V.

PY - 2023/7/1

Y1 - 2023/7/1

N2 - The in situ single-crystal X-ray diffraction and Raman spectroscopy were performed for a sapozhnikovite Na8(Al6Si6O24)(HS)2, a rare mineral with sodalite-type crystal structure. The crystal chemical analysis and calculation of thermal expansion coefficients based on the refinement of Na8(Al6Si6O24)(HS)2 crystal structures in the temperature range of 300–1273 K show that this sodalite-type compound undergoes: (1) reversible phase transition P 3n ↔ Pm n at 1223 K, (2) drastic increase of linear expansion coefficient at 1173 K, (3) non-elastic behavior of sapozhnikovite framework after cooling. The temperature dependencies of the unit-cell parameters were divided into two parts and described by quadratic a = 8.911(12) – 0.000018(33)T + 0.000000138(22)T2 (from 300 to 1173 K) and linear a = 7.765(13) + 0.001130(11)T (from 1173 to 1273 K) polynomial functions. Raman spectroscopy data reveal the partial transformations of the extra-framework HS− anion by follows reactions: 6HS–→ S3•– + 3H2S (gas) and 2HS– – 2e → S22− + 2H+. These transformations may cause the observed discontinuity in the thermal expansion curve for sapozhnikovite at 1173 K with drastic increase of linear expansion coefficient and not fully elastic behavior of framework after removal of temperature exposure. After the heat treatment experiments (300–1273 K) the HS− anion restores in the β-cage of sapozhnikovite crystal structure. In the synthetic analogue of sapozhnikovite the heat treatment leads to the irreversible transformation according to the reactions: 2HS– + 2.5O2 (gas) → SO42− + 0.25S4 + H2O (gas) and 2HS– + 3.5O2 (gas) → SO42− + SO2 (gas) + H2O (gas). The orange luminescence of Na8(Al6Si6O24)(HS)2 is stable up to the 1073 K.

AB - The in situ single-crystal X-ray diffraction and Raman spectroscopy were performed for a sapozhnikovite Na8(Al6Si6O24)(HS)2, a rare mineral with sodalite-type crystal structure. The crystal chemical analysis and calculation of thermal expansion coefficients based on the refinement of Na8(Al6Si6O24)(HS)2 crystal structures in the temperature range of 300–1273 K show that this sodalite-type compound undergoes: (1) reversible phase transition P 3n ↔ Pm n at 1223 K, (2) drastic increase of linear expansion coefficient at 1173 K, (3) non-elastic behavior of sapozhnikovite framework after cooling. The temperature dependencies of the unit-cell parameters were divided into two parts and described by quadratic a = 8.911(12) – 0.000018(33)T + 0.000000138(22)T2 (from 300 to 1173 K) and linear a = 7.765(13) + 0.001130(11)T (from 1173 to 1273 K) polynomial functions. Raman spectroscopy data reveal the partial transformations of the extra-framework HS− anion by follows reactions: 6HS–→ S3•– + 3H2S (gas) and 2HS– – 2e → S22− + 2H+. These transformations may cause the observed discontinuity in the thermal expansion curve for sapozhnikovite at 1173 K with drastic increase of linear expansion coefficient and not fully elastic behavior of framework after removal of temperature exposure. After the heat treatment experiments (300–1273 K) the HS− anion restores in the β-cage of sapozhnikovite crystal structure. In the synthetic analogue of sapozhnikovite the heat treatment leads to the irreversible transformation according to the reactions: 2HS– + 2.5O2 (gas) → SO42− + 0.25S4 + H2O (gas) and 2HS– + 3.5O2 (gas) → SO42− + SO2 (gas) + H2O (gas). The orange luminescence of Na8(Al6Si6O24)(HS)2 is stable up to the 1073 K.

KW - High temperature single-crystal diffraction

KW - Hydrosulfide anion

KW - Luminescence

KW - Sodalite type compounds

KW - Thermal expansion

KW - Thermal transformations

KW - Thermo-Raman spectroscopy

UR - https://www.mendeley.com/catalogue/75cbd8d5-e7d9-3f6f-9573-b577123e2d26/

U2 - 10.1016/j.jssc.2023.124067

DO - 10.1016/j.jssc.2023.124067

M3 - Article

VL - 323

JO - Journal of Solid State Chemistry

JF - Journal of Solid State Chemistry

SN - 0022-4596

M1 - 124067

ER -