High-temperature heat capacity of YBiGeO5 and GdBiGeO5 in the range 373–1000 K

Evaluation of thermodynamic properties of alkaline borogermanates and germanosilicates using the regression analysis method

“…A comparison of the heat capacity [18] of pure silicon oxides (44.42 J•K -1 •mol -1 ), boron (62.98 J•K -1 •mol -1 ) and germanium (51.95 J•K -1 •mol -1 ) with the corresponding coefficients in equations (12)(13)(14) shows good convergence between them. The heat capacities of pure lithium (54.25 J•K -1 •mol -1 ) and sodium (68.56 J•K -1 •mol -1 ) oxides are also quite close to the obtained coefficients.…”

“…An analysis of Eqs. (6)(7)(8)(9)(10)(11)(12)(13)(14) shows that the coefficients for the same alkali metal oxides differ for silicates, borates and germanates (Figures 2-3). It should be noted that the values of the coefficient bj depend not only on the type of alkali metal oxide, but also on the class of the compound.…”

“…The correlation coefficient, indicating the correctness of the calculation method, was > 0.99 for Eqs. (6)(7)(8)(9)(10)(11)(12)(13)(14). Standard error (SE) characterises the overall accuracy of the resulting equations.…”

“…Nevertheless, there is currently little thermodynamic data on germanates. However, several studies on the high temperature heat capacity of rare earth germanates are extant [13][14][15]. These compounds are very promising in practical terms due to their luminescent properties.…”