2024/03/17 by Lai Wei, Lili Zhang, Wei, Lai +3
Chemistry · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #Statistical Mechanics (cond-mat.stat-mech) #thermodynamics and calorimetric analyses
paper · pdf · doi:10.48550/arxiv.2404.12393
openalex publication_date 2024/03/17 · openalex created_date 2024/04/23 · openalex updated_date 2026/07/28
For relaxor-ferroelectrics and relaxor-ferromagnets, Ehrenfest classification of phase transitions based on the discontinuity of entropy or specific heat etc. with temperature (T) gives no transition that contradicts the measured order parameter, i.e. spontaneous polarization and magnetization, at low temperatures, while Landau classification based on the minimum derivative of the order parameter to T raises the question about the relationships between the phase transition and the specific heat peak above and near the transition temperature. Here, based on the free energy of the thermodynamic limit systems with T when the external field tends to 0, thermal equilibrium phase transitions are reclassified into three categories, i.e. 1) First-order phase transition, 2) Second-order phase transition, and 3) Diffuse phase transition, naturally giving the the relation of the phase transition to the specific heat peak. Deep analyses indicate that the classification of this paper is based on both the long-range and short-range correlation orders of the systems, while the Ehrenfest's or Landau's independently on the short-range or long-range order, respectively.