Partial molar heat capacity of B₂O₃ in borosilicate melt

Abstract

Drop calorimetry measurements were carried out between 575 and 1300 ̊C for SiO2-B2O3-Al2O3-CaO-Na2O melts. Partial molar heat capacity of B2O3 (CpB2O3) in borosilicate melts was determined by combining measured heat capacity and previously reported values of partial molar Cp for other oxides. In the Na2O bearing borosilicate melts, the CpB2O3 decreases with increasing temperature, and the decrease in CpB2O3 is enhanced by an addition of CaO or Al2O3. Large temperature dependence of the heat capacity for radioactive waste melt can be explained by the temperature and compositional variations of the CpB2O3.