Heat capacity and entropy of Ni2SiO4-olivine from 5 to 1000 K and heat capacity of Co2SiO4 from 360 to 1000 K

The heat capacity of Ni2SiOa-olivine has been measured between 5 and 387 K by cryogenic adiabatic-shield calorimetry and between 360 and 1000 K by ditrerential scanning calorimetry. There is a \-type transition in Ni2SiOa-olivine at 29.15+0.05 K. At 298.15 K the molar heat capacity and entropy of Ni2SiOa-olivine are 723.2+0.2 and 128.110.2 J/ (mol ' K), respectively. Between 300 and 1300 K the heat capacity can be represented by the equation C1 : 289.73 - 0.024015T + 73I0451f - 2779.01Tt/2 to within -+0.57o. From our heat capacity measurements, combined with results from molten salt calorimetry, thermal decomposition of Ni2SiOa-olivine into its constituent oxides, and equilibrium studies, both by CO reduction and solid state electrochemical cell measurements for the reaction