Инд. авторы:	Sagatova D.N, Shatskiy A.F., Sagatov N.E., Litasov K.D.
Заглавие:	Phase Relations in CaSiO3 System up to 100 GPa and 2500 K
Библ. ссылка:	Sagatova D.N, Shatskiy A.F., Sagatov N.E., Litasov K.D. Phase Relations in CaSiO3 System up to 100 GPa and 2500 K // Geochemistry International. - 2021. - Vol.59. - Iss. 8. - P.791-800. - ISSN 0016-7029. - EISSN 1531-8397.
Внешние системы:	DOI: 10.1134/S0016702921080073; WoS: 000680906400005;
Реферат:	eng: 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-Pm3m. 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.
Ключевые слова:	STABILITY; PEROVSKITE; LARNITE BETA-CA2SIO4; AB-INITIO; LOWER MANTLE; CRYSTAL-STRUCTURE; wollastonite; V-T EQUATION; EQUATION-OF-STATE; quasi-harmonic approximation; density functional theory; mantle; larnite; perovskite; breyite; HIGH-PRESSURE; TRANSITION;
Издано:	2021
Физ. характеристика:	с.791-800