Influence of Defects on First Order Structural Phase Transitions

Abstract

The influence both of symmetry-breaking ("random local field") defects and of symmetry conserving ("random local transition temperature") ones on first order phase transitions is studied within the Landau theory. It is shown that an explicit account, for the elasticity effects, is important in the case of symmetry-breaking defects: the discontinuity of the order parameter at the transition increases due to the defects when the elasticity effects are taken into account but it decreases when they are neglected. For the symmetry-conserving defects, the account for the elasticity does not change the results qualitatively: the defects always diminish the discontinuity of the order parameter. The phase transition temperature always decreases due to the randomness induced by the two types of defects.