Influence of Size on Melting Thermodynamics of Nanoparticles: Mechanism, Factors, Range, and Degree

Abstract

AbstractParticle size plays a crucial role in melting process of nanoparticles, but the mechanism, factors, range, and degree of the size effect are still unclear. Here, the precise equations of the integral melting enthalpy and entropy with radius of nanoparticles are deduced, without any adjustable parameters, and the influencing mechanism and the factors are discussed. Experimentally, the melting of spherical nano‐Au with different radii (0.9–37.4 nm) is taken as a system to research the melting behavior of nanoparticles. Combining the results of theory and experiments, the influencing regularities, range, and degree are discussed. The results indicate that there are significant effects of particle size on the temperature, integral enthalpy, and integral entropy of melting, which decrease with the radius decreasing. These effects can be attributed to specific surface area, surface tension, and its temperature coefficient. When the radius exceeds 10 nm, specific surface area is the decisive factor, there exists the linear relationships of temperature, integral enthalpy, and integral entropy of melting with the reciprocal of radius. However, when the radius is less than 10 nm, the effects of surface tension and its temperature coefficient gradually hold the main position, the linear relations do not exist.