Preparation and characterization of lithium oxide

Thermal decomposition of Li2CO3 was measured in the temperature range from 814 to 970 K in vacuum by means of a thermo-balance. The rate of this reaction was found to obey the kinetic equation, −ln(1 − α) = kt, and the rate constant, k(s−1), was represented as k = 6.03 × 107exp(−198 kJ mol−1)/RT. The apparent activation energy of the decomposition reaction nearly agrees with the value of the enthalpy of reaction, Li2CO3(s) → Li2O(s) + CO2(g). Secondly using Li2O powder which was prepared by thermal decomposition in the temperature region 923–973 K, pellets of Li2O were sintered in vacuum at the temperature range 1373–1623 K. Sinterability depended strongly on the sintering temperature and the pressure of compact but was almost uninfluenced by the decomposition temperature of Li2CO3. The pellets, which were 94% TD in density, were obtained by sintering at 1473 K for 4 h. Grain growth, however, occurred at the sintering temperature above 1473 K. Adopting the platinum container with double walls in which compacts were charged, the weight loss caused by vaporization during sintering was reduced to one-third compared to the case using the ordinary container at the sintering temperature above 1473 K.