Size-dependent melting thermodynamic properties of selenium nanowires in theory and experiment

The melting thermodynamic properties of nanomaterials depend on the particle size and present great differences compared with that of bulk counterparts. However, the current researches on melting thermodynamics are solely confined to nanoparticles, and the size effect on the melting thermodynamics of nanowires remains unclear. Herein, a core-shell model was proposed and the universal equations for size-dependent melting thermodynamic properties were derived to explain the unique melting behaviors of nanowires. Experimentally, Se nanowires with different diameters were prepared by a precursor conversion method, and the melting thermodynamic properties were determined by differential scanning calorimetry. Both theoretical and experimental results demonstrated that the melting temperature, the melting enthalpy and the melting entropy decrease with the decrease in diameter, and all these physical quantities linearly vary with the inverse diameter within the experimental particle size range. Furthermore, using the quantitative size-dependent thermodynamic theory of nanowires, we can explain and predict the melting behaviors in the preparations and applications of other nanowires. A new core-shell melting model of nanowires was proposed to explain the size effect on the melting thermodynamics of nanowires.