GENERALIZED THEORY OF PHASE-TRANSITIONS IN SOLIDS

Systematic analysis of the state of a solid in phase transitions of ty pes I and II is undertaken within the framework of matrix calculus, si nce the initial conditions of thermodynamic equilibrium are formulated , as is known, in quadratic form. This analysis permits the explanatio n of the fundamental equation (partial derivative p/partial derivative V)(T) = 0 or of why c(p) --> infinity on the line of type-II phase tr ansitions and why, in the critical state, c(nu) tends to infinity and the sound velocity to zero. A new method of determining the critical i ndices for singular components of the properties in the region of type -II transitions is thoroughly tested; the values of all the critical i ndices are calculated. Analytical expressions are established for phas e-transition lines of types I and II and also for characteristic curve s starting at the critical or tricritical point. The form of the melti ng line is considered. Overall, this work is a generalization of the e xisting theory of phase transitions: on the one hand, issues that were formerly unclear are explained; on the other, new results and conclus ions are obtained.