# Phase Relations in CaSiO3 System up to 100 GPa and 2500 K

D. N. Sagatova, A. F. Shatskiy, N. E. Sagatov, K. D. Litasov

Результат исследования: Научные публикации в периодических изданияхстатьярецензирование

1 Цитирования (Scopus)

## Аннотация

Phase relations in one of the key petrological systems, CaSiO3, have been comprehensively investigated for the first time in the pressure range 0–100 GPa and temperatures 0–2500 K within the density functional theory using the method of lattice dynamics in the quasi-harmonic approximation. The results showed that at atmospheric pressure and 0 K CaSiO3 is stable in the wollastonite structure, which above 1250 K transforms to the high-temperature pseudowollastonite modification. Above a pressure of 4 GPa, CaSiO3 is stable in the breyite structure. The phase equilibrium curve has a negative slope of dP/dT = –0.6 MPa/K. At 8 GPa, CaSiO3 decomposes into an assemblage of Ca2SiO4-larnite and titanite-structured CaSi2O5. The phase equilibrium curve has a positive slope of dP/dT = 1.35 MPa/K. At a pressure of 13 GPa, Ca2SiO4-larnite reacts with CaSi2O5, forming a phase with a perovskite-like structure – CaSiO3-perovskite. The pressure of this phase transition is practically independent of temperature. In the low-temperature region, Ca-perovskite is stable in the tetragonal modification CaSiO3-I4/mcm. Above 340 K at 13 GPa, Ca-perovskite is stable in the cubic modification CaSiO3-$$Pm\bar {3}m.$$ The phase transition temperature increases to 755 K with pressure increase to 100 GPa. The thermodynamic parameters were also calculated for the first time for wollastonite, pseudowollastonite, and titanite-structured CaSi2O5.

Язык оригинала английский 791-800 10 Geochemistry International 59 8 https://doi.org/10.1134/S0016702921080073 Опубликовано - авг. 2021

## Предметные области OECD FOS+WOS

• 1.05 НАУКИ О ЗЕМЛЕ И СМЕЖНЫЕ ЭКОЛОГИЧЕСКИЕ НАУКИ
• 1.05.GC ГЕОХИМИЯ И ГЕОФИЗИКА

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