Enthalpy, heat capacity and enthalpy of transformation of Li2TiO3

The enthalpy of beta- and gamma -Li2TiO3 (Li/Ti = 1.88) was measured between 397 and 1650 K; by isothermal drop calorimetry. The smoothed enthalpy curve between 298 and 1700 K results in H degrees (T)-H degrees (298 K)= -49181 + 131.876T + 0.011097T(2) + 2651112T(-1) J/mol (298-1410 K) and H degrees (T) - H degrees (298 K) = +49729 + 50.517T + 0.031679T(2) - 20143786T(-1) J/mol (1410-1700 K). The heat capacity was derived by differentiation of the enthalpy curve. The value extrapolated to 298 K is C-p.298 = (108.6 +/- 2.5) J/K mol. The enthalpy of the monoclinic-cubic transformation of Li2TiO3 was determined by anisothermal calorimetry and gives Delta H-tr = (9200 +/- 300) J/mol at about 1410 K. (C) 2001 Elsevier Science B.V. All rights reserved.