New thermodynamic data for CoTiO(3), NiTiO(3 )and CoCO(3 )based on low-temperature calorimetric measurements

The low-temperature heat capacities of nickel titanate (NiTiO(3)), cobalt titanate (CoTiO(3)), and cobalt carbonate (CoCO(3)) were measured between 2 and 300 K, and thermochemical functions were derived from the results. Our new data show previously unknown low-temperature lambda-shaped heat capacity anomalies peaking at 37 K for CoTiO(3 )and 26 K for NiTiO(3). From our data we calculate standard molar entropies (298.15 K) for NiTiO(3 )of 90.9 ± 0.7 J mol(-1 )K(-1 )and for CoTiO(3 )of 94.4 ± 0.8 J mol(-1 )K(-1). For CoCO(3), we find only a small broad heat capacity anomaly, peaking at about 31 K. From our data, we suggest a new standard entropy (298.15 K) for CoCO(3 )of 88.9 ± 0.7 J mol(-1 )K(-1).