A MODEL FOR EVALUATING AND PREDICTING HIGH-TEMPERATURE THERMAL-EXPANSION

In this paper, a new set of experimental data, alpha(V)K(T)V, represen ting the partial temperature derivative of the work done by the therma l pressure of the solid, is fitted by ii terms of a modified Einstein model. Experimental data show that alpha(V)K(T)V, not alpha(V)K(T), ap proaches a constant value at high temperature. Based on the observed l inear relationship of isothermal bulk modulus with temperature at high temperature, thermal expansion can be evaluated by fitting alpha(V)K( T)V data. Our previous results have shown that at low temperature or f ur materials with less variable bulk modulus and expansivity, ther-mal expansion data can be simply approximated by an n term Einstein model . More generally and for many materials, alpha(V)K(T)V data resemble a n isochoric specific heat curve. With this method, thermal expansion c an be predicted at high temperatures from low and intermediate tempera ture range data. With accurate thermal expansion data, high temperatur e bulk moduli can also be predicted.