Heat capacity and thermodynamic functions of hollandite-type K0.17TiO1.9·0.061H2O

Abstract The heat capacity of K 0.17 TiO 1.9 ·0.061H 2 O has been measured by the use of a Quantum Design Physical Property Measurement System (PPMS) in the temperature range from 1.9 K to 302 K. An upturn below 3 K and weak bump at 7 K are observed and ascribed to Schottky anomaly and boson peak, respectively. The experimental data for K 0.17 TiO 1.9 ·0.061H 2 O are fitted to a joint contributions of lattice vacancy, lattice vibration, Schottky anomaly and boson peak in the low temperature range ( T T T  > 63 K). The standard molar heat capacity, molar entropy, and molar enthalpy for K 0.17 TiO 1.9 ·0.061H 2 O at T  = 298.15 K are determined to be (64.2 ± 0.7) J·K −1 ·mol −1 , (65.7 ± 0.7) J·K −1 ·mol −1 , and (10.5 ± 0.1) kJ·mol −1 , respectively, leading to a Gibbs energy of −(9.05 ± 0.09) kJ·mol −1 .