Thermodynamic properties of ferromagnesium silicate perovskites from vibrational spectroscopy

IR reflectance and absorbance spectra obtained from polycrystalline and single-crystal perovskites of MgSiO₃ and (Mg_0.9Fe_0.1 )SiO₃ compositions yielded virtually all the expected fundamental modes. Near-IR absorbance spectra indicate that the polycrystals were anhydrous, whereas the single crystal contained about 0.06 wt% H₂O. A Kieffer-type model was used to calculate heat capacity, entropy, and Debye temperature for the orthorhombic perovskite phase. -from Authors