THE HEAT-CAPACITY (2-300 K TEMPERATURE-RA NGE) AND THE ENTROPY OF CHROMIUM-BEARING GARNETS

The temperature dependence of heat capacity within 2-300 K temperature range of three chromium-bearing garnets was determined by the use of adiabatic calorimeter. The samples were taken from the garnet lerzolit ic nodules in the Udachnaya-Vostochnaya kimberlitic pipe in Yakutia. I t was found that the entropy value of the antiferromagnetic phase tran sition in the presence of Cr and other conditions being equal is marke dly decreased. Besides the presence of Cr is a factor of substantial c hange of the entropy term into energy interaction parameters with Mg p articipation. Mixing entropy value of garnets is negligible.