Classical Nucleation Theory-Based Multiscale Analysis of Strontium Nitrate Aqueous Crystallization: Thermodynamic-Kinetic Coupling Model and Nucleation Regulation

Abstract

This study investigates the crystallization behavior of Sr(NO3)2 in aqueous solution by integrating classical nucleation theory and the Apelblat equation. We experimentally characterize the metastable zone width as a function of saturation temperature, cooling rate, and stirring rate. Based on classical nucleation theory, we establish a quantitative thermodynamic-kinetic coupling model that directly relates the solubility temperature coefficient to metastable zone width. Phase-specific coupling models are further developed for the low-temperature β-phase and high-temperature α-phase regions, respectively, with high determination coefficients. Two distinct solubility regimes are identified: β-phase solubility increases significantly with T0 in the low-temperature range (278.15–298.15 K), while α-phase solubility growth slows in the high-temperature range (303.15–363.15 K), with a phase transition critical point at 301.54 K. Fitting metastable zone width data to the classical 3D nucleation model reveals that the nucleation rate constant A increases and the solid–liquid interfacial energy parameter B decreases with rising T0, indicating enhanced nucleation driving force and reduced energy barriers collectively narrow the metastable zone width. These findings fill the long-standing data gap in the nucleation kinetic parameters of Sr(NO3)2 aqueous crystallization across the peritectic transition region, and provide theoretical guidance for optimizing cooling rate and temperature staging regulation in the directional growth of Sr(NO3)2 crystals.