Preparation of nano-t-Se with different particle sizes and particle size dependence of the melting thermodynamics

Selenium nanomaterials have unique optical, electrical, magnetic and healthcare functions. Selenium nanomaterials with different particle sizes have different properties and performances, and the thermal stability of selenium nanoparticles has a key impact on their properties and performances. In this paper, nano-t-Se was prepared by a precursor-ultrasonic conversion method. Firstly, the effects of reducing agent dosage, ultrasonic frequency and time on the particle sizes of nano-t-Se were studied, and t-Se nanoparticles with different particle sizes were prepared. Then, the melting thermodynamic properties of nano-t-Se with different particle sizes were determined by DSC. The influence of particle sizes on the melting temperature and thermodynamic properties of nano-t-Se was discussed. The experimental results showed that the precursor-ultrasonic conversion method was a reliable method for preparing t-Se nanoparticles with different particle sizes. By controlling the amount of the reducing agent, ultrasonic frequency and time, the controllable preparation of nano-t-Se with the required particle sizes can be realized. It was found that the particle sizes had significant effects on the melting temperature and the thermodynamic properties of nano-t-Se, and the melting temperature, melting enthalpy and melting entropy of nano-t-Se decreased with the decrease of particle sizes, respectively. When the particle sizes of nano-t-Se decreased from 52.1 nm to 17.4 nm, the initial melting temperature decreased from 218.02 °C to 213.82 °C, the melting enthalpy decreased from 5.496 kJ mol−1 to 3.962 kJ mol−1, and the melting entropy decreased from 5.182 J mol−1 K−1 to 4.136 J mol−1 K−1. Besides, it was also found that the initial melting temperature, melting enthalpy and melting entropy of nano-t-Se showed a good linear relationship with the reciprocal of the particle sizes in the experimental particle size range, respectively. The controllable preparation method of nano-t-Se with different particle sizes and the particle size dependence of the melting temperature and the melting thermodynamic properties can provide important guidance for the preparation, research and application of nano-t-Se.