Calorimetric study of high-pressure polymorphs of MnSiO3
Masaki Akaogi, Alexandra Navrotsky
CLAS-NS: Molecular Sciences, School of (SMS)
With increasing pressure, MnSiO3 rhodonite stable at atmospheric pressure transforms to pyroxmangite, then to clinopyroxene and further to tetragonal garnet, which finally decomposes into MnO (rocksalt) plus SiO2 (stishovite). High temperature solution calorimetry of synthetic rhodonite, clinopyroxene and garnet forms of MnSiO3 was used to measure the enthalpies of these transitions. ΔH9740for the rhodonite-clinopyroxene and ΔH2980for the clinopyroxene-garnet transition are 520±490 and 8,270±590 cal/mol, respectively. The published data on the enthalpy of the rhodonite-pyroxmangite transition, phase equilibrium boundaries, compressibility and thermal expansion data are used to calculate entropy changes for the transitions. The enthalpy, entropy and volume changes are very small for all the transitions among rhodonite, pyroxmangite and clinopyroxene. The calculated boundary for the clinopyroxene-garnet transition is consistent with the published experimental results. The pyroxene-garnet transition in several materials, including MnSiO3, is characterized by a relatively small negative entropy change and large volume decrease, resulting in a small positive P - T slope. The disproportionation of MnSiO3 garnet to MnO plus stishovite and of Mn2SiO4 olivine to garnet plus MnO are calculated to occur at about 17-18 and 14-15 GPa, respectively, at 1,000-1,500 K.
Physics and Chemistry of Minerals
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Garnets Engineering & Materials Science
Polymorphism Engineering & Materials Science
garnet Earth & Environmental Sciences
clinopyroxene Earth & Environmental Sciences
Enthalpy Engineering & Materials Science
stishovite Earth & Environmental Sciences
enthalpy Earth & Environmental Sciences
Akaogi, M., & Navrotsky, A. (1985). Calorimetric study of high-pressure polymorphs of MnSiO3. Physics and Chemistry of Minerals, 12(6), 317-323. https://doi.org/10.1007/BF00654341
Calorimetric study of high-pressure polymorphs of MnSiO3. / Akaogi, Masaki; Navrotsky, Alexandra.
In: Physics and Chemistry of Minerals, Vol. 12, No. 6, 11.1985, p. 317-323.
Akaogi, M & Navrotsky, A 1985, 'Calorimetric study of high-pressure polymorphs of MnSiO3', Physics and Chemistry of Minerals, vol. 12, no. 6, pp. 317-323. https://doi.org/10.1007/BF00654341
Akaogi M, Navrotsky A. Calorimetric study of high-pressure polymorphs of MnSiO3. Physics and Chemistry of Minerals. 1985 Nov;12(6):317-323. https://doi.org/10.1007/BF00654341
Akaogi, Masaki ; Navrotsky, Alexandra. / Calorimetric study of high-pressure polymorphs of MnSiO3. In: Physics and Chemistry of Minerals. 1985 ; Vol. 12, No. 6. pp. 317-323.
@article{f8d58470b3fb4b6ca7d509708e70c9b6,
title = "Calorimetric study of high-pressure polymorphs of MnSiO3",
abstract = "With increasing pressure, MnSiO3 rhodonite stable at atmospheric pressure transforms to pyroxmangite, then to clinopyroxene and further to tetragonal garnet, which finally decomposes into MnO (rocksalt) plus SiO2 (stishovite). High temperature solution calorimetry of synthetic rhodonite, clinopyroxene and garnet forms of MnSiO3 was used to measure the enthalpies of these transitions. ΔH9740for the rhodonite-clinopyroxene and ΔH2980for the clinopyroxene-garnet transition are 520±490 and 8,270±590 cal/mol, respectively. The published data on the enthalpy of the rhodonite-pyroxmangite transition, phase equilibrium boundaries, compressibility and thermal expansion data are used to calculate entropy changes for the transitions. The enthalpy, entropy and volume changes are very small for all the transitions among rhodonite, pyroxmangite and clinopyroxene. The calculated boundary for the clinopyroxene-garnet transition is consistent with the published experimental results. The pyroxene-garnet transition in several materials, including MnSiO3, is characterized by a relatively small negative entropy change and large volume decrease, resulting in a small positive P - T slope. The disproportionation of MnSiO3 garnet to MnO plus stishovite and of Mn2SiO4 olivine to garnet plus MnO are calculated to occur at about 17-18 and 14-15 GPa, respectively, at 1,000-1,500 K.",
author = "Masaki Akaogi and Alexandra Navrotsky",
journal = "Physics and Chemistry of Minerals",
publisher = "Springer Verlag",
T1 - Calorimetric study of high-pressure polymorphs of MnSiO3
AU - Akaogi, Masaki
AU - Navrotsky, Alexandra
N2 - With increasing pressure, MnSiO3 rhodonite stable at atmospheric pressure transforms to pyroxmangite, then to clinopyroxene and further to tetragonal garnet, which finally decomposes into MnO (rocksalt) plus SiO2 (stishovite). High temperature solution calorimetry of synthetic rhodonite, clinopyroxene and garnet forms of MnSiO3 was used to measure the enthalpies of these transitions. ΔH9740for the rhodonite-clinopyroxene and ΔH2980for the clinopyroxene-garnet transition are 520±490 and 8,270±590 cal/mol, respectively. The published data on the enthalpy of the rhodonite-pyroxmangite transition, phase equilibrium boundaries, compressibility and thermal expansion data are used to calculate entropy changes for the transitions. The enthalpy, entropy and volume changes are very small for all the transitions among rhodonite, pyroxmangite and clinopyroxene. The calculated boundary for the clinopyroxene-garnet transition is consistent with the published experimental results. The pyroxene-garnet transition in several materials, including MnSiO3, is characterized by a relatively small negative entropy change and large volume decrease, resulting in a small positive P - T slope. The disproportionation of MnSiO3 garnet to MnO plus stishovite and of Mn2SiO4 olivine to garnet plus MnO are calculated to occur at about 17-18 and 14-15 GPa, respectively, at 1,000-1,500 K.
AB - With increasing pressure, MnSiO3 rhodonite stable at atmospheric pressure transforms to pyroxmangite, then to clinopyroxene and further to tetragonal garnet, which finally decomposes into MnO (rocksalt) plus SiO2 (stishovite). High temperature solution calorimetry of synthetic rhodonite, clinopyroxene and garnet forms of MnSiO3 was used to measure the enthalpies of these transitions. ΔH9740for the rhodonite-clinopyroxene and ΔH2980for the clinopyroxene-garnet transition are 520±490 and 8,270±590 cal/mol, respectively. The published data on the enthalpy of the rhodonite-pyroxmangite transition, phase equilibrium boundaries, compressibility and thermal expansion data are used to calculate entropy changes for the transitions. The enthalpy, entropy and volume changes are very small for all the transitions among rhodonite, pyroxmangite and clinopyroxene. The calculated boundary for the clinopyroxene-garnet transition is consistent with the published experimental results. The pyroxene-garnet transition in several materials, including MnSiO3, is characterized by a relatively small negative entropy change and large volume decrease, resulting in a small positive P - T slope. The disproportionation of MnSiO3 garnet to MnO plus stishovite and of Mn2SiO4 olivine to garnet plus MnO are calculated to occur at about 17-18 and 14-15 GPa, respectively, at 1,000-1,500 K.
JO - Physics and Chemistry of Minerals
JF - Physics and Chemistry of Minerals