Noninteger Valence in Ce‐Based Compounds

Herein, a simple thermodynamic approach using the Helmholtz free energy is proposed to estimate the noninteger valence in Ce‐based compounds at the γ→α phase transition. The idea of an electron phase transition within Anderson–Kondo model is used as a microscopic mechanism and applied to Ce–X (X = Y, Al–Sc) within 0–16 at% of X. In the suggested approach, valence of Ce–X compounds depends on volume collapse and the temperatures of start and finish of phase transition as well as external pressure, which can induce γ→α phase transition, and increases with rising the amount of impurity.