抄録
The displacive phase transition in narrow-gap semiconductors is investigated in the mean-field approximation, developing the Kristoffel-Konsin model to the electronic systems with a finite band width. The application of Landau’s phenomenological theory is made for the purpose to study the property near the critical temperature. For narrow-gap semiconductors, it is shown that the Landau’s expansion coefficients are determined only by the band edge structure, contrary to the critical temperature. The dependence of the critical temperature on the carrier concentration is calculated by an elliptic band model. It is found that two kinds of critical temperatures are present in a certain carrier concentration region. The comparison with the experimental result is made on SnTe.
