HIGH-TEMPERATURE ENTHALPY-INCREMENT MEASUREMENTS AND DERIVED HEAT-CAPACITY OF LITHIUM ORTHOSILICATE (LI4SIO4) AT TEMPERATURES FROM 300-K TO 1000-K

The enthalpy increments of lithium orthosilicate (Li4SiO4) have been measured by drop calorimetry at temperatures from 300 K to 1000 K. In the enthalpy-against-temperature curve, a few humps were observed above 800 K. In order to derive corresponding heat-capacity values precisely from the enthalpies, a new analytical procedure (modified-QLLR method) was used. Three heat-capacity anomalies, which correspond to the humps in the enthalpy curve, were found at temperatures of about 885 K, 930 K, and 985 K. © 1992 Academic Press Limited All rights reserved.