The thermal behaviour of fedorite from the Murun massif, Russia, has been investigated by means of electron probe microanalysis (EPMA), differential thermal analysis (DTA), thermogravimetry (TG), in situ high-temperature single-crystal X-ray diffraction (HT-SCXRD), ex situ high-temperature Fourier-transform infrared spectroscopy (HT-FTIR). The empirical chemical formula of the sample of fedorite studied is: (Na1.56K0.72Sr0.12)Σ2.40(Ca4.42Na2.54Mn0.02Fe0.01Mg0.01)Σ7.00(Si15.98Al0.02)Σ16.00(F1.92Cl0.09)Σ2.01(O37.93OH0.07)Σ38.00⋅2.8H2O. The TG curve provides a total mass decrease of ~5.5%, associated with dehydration and defluorination processes from 25 to 1050°C. Fedorite crystallises in space group P forumla and has: a = 9.6458(2), b = 9.6521(2), c = 12.6202(4) Å, α = 102.458(2), β = 96.2250(10), γ = 119.9020(10)° and cell volume, V = 961.69(5) Å3. The HT-SCXRD was carried out in air in the 25–600°C range. Overall, a continuous expansion of the unit-cell volume was observed although the c cell dimension slightly decreases in the explored temperature range. Structure refinements indicated that the mineral undergoes a dehydration process with the loss of most of the interlayer H2O from 25 to 300°C. The HT-FTIR spectra confirmed that fedorite progressively dehydrates until 700°C.
High temperature behavior of fedorite, Na2.5(Ca4.5Na2.5)[Si16O38]F2⋅2.8 H2O, from Murun Alkaline Complex (Russia)
Maria Lacalamita;Ernesto Mesto
;Emanuela Schingaro
2023-01-01
Abstract
The thermal behaviour of fedorite from the Murun massif, Russia, has been investigated by means of electron probe microanalysis (EPMA), differential thermal analysis (DTA), thermogravimetry (TG), in situ high-temperature single-crystal X-ray diffraction (HT-SCXRD), ex situ high-temperature Fourier-transform infrared spectroscopy (HT-FTIR). The empirical chemical formula of the sample of fedorite studied is: (Na1.56K0.72Sr0.12)Σ2.40(Ca4.42Na2.54Mn0.02Fe0.01Mg0.01)Σ7.00(Si15.98Al0.02)Σ16.00(F1.92Cl0.09)Σ2.01(O37.93OH0.07)Σ38.00⋅2.8H2O. The TG curve provides a total mass decrease of ~5.5%, associated with dehydration and defluorination processes from 25 to 1050°C. Fedorite crystallises in space group P forumla and has: a = 9.6458(2), b = 9.6521(2), c = 12.6202(4) Å, α = 102.458(2), β = 96.2250(10), γ = 119.9020(10)° and cell volume, V = 961.69(5) Å3. The HT-SCXRD was carried out in air in the 25–600°C range. Overall, a continuous expansion of the unit-cell volume was observed although the c cell dimension slightly decreases in the explored temperature range. Structure refinements indicated that the mineral undergoes a dehydration process with the loss of most of the interlayer H2O from 25 to 300°C. The HT-FTIR spectra confirmed that fedorite progressively dehydrates until 700°C.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
