Research output: Contribution to journal › Article › peer-review
Phase Relations in CaSiO3 System up to 100 GPa and 2500 K. / Sagatova, D. N.; Shatskiy, A. F.; Sagatov, N. E. et al.
In: Geochemistry International, Vol. 59, No. 8, 08.2021, p. 791-800.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Phase Relations in CaSiO3 System up to 100 GPa and 2500 K
AU - Sagatova, D. N.
AU - Shatskiy, A. F.
AU - Sagatov, N. E.
AU - Litasov, K. D.
N1 - Publisher Copyright: © 2021, Pleiades Publishing, Ltd.
PY - 2021/8
Y1 - 2021/8
N2 - 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.
AB - 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.
KW - breyite
KW - density functional theory
KW - larnite
KW - mantle
KW - perovskite
KW - quasi-harmonic approximation
KW - wollastonite
UR - http://www.scopus.com/inward/record.url?scp=85111166486&partnerID=8YFLogxK
U2 - 10.1134/S0016702921080073
DO - 10.1134/S0016702921080073
M3 - Article
AN - SCOPUS:85111166486
VL - 59
SP - 791
EP - 800
JO - Geochemistry International
JF - Geochemistry International
SN - 0016-7029
IS - 8
ER -
ID: 29292673