This paper investigates the size effect on the melting temperature of gold particles. Using a scanning electron-diffraction technique, the melting points of small gold particles with diameters down to 20 Å were measured. The results show that the melting temperature decreases as the particle size decreases. Two phenomenological models were used to explain this effect: one assumes a solid particle, a liquid particle of the same mass, and a vapor phase, while the other assumes a liquid layer surrounding the solid particle. The first model uses only physical constants of gold, while the second model requires an assumed liquid layer thickness of about 6 Å. The experimental results agree well with both models. The first model predicts a linear relationship between the relative lowering of the melting temperature and the surface curvature of the particles. The second model, which includes nonlinear terms, is more closely associated with experimental results. The melting temperature of small particles was determined using three criteria: the disappearance of the state of order in the solid, the modification of the rate of evaporation at the melting point, and the modification of the particle shape at the melting point. The study found that the melting temperature of gold particles decreases with decreasing particle size. The results were compared with theoretical predictions and showed good agreement. The melting temperature of small particles was determined using a scanning electron-diffraction technique, and the results were analyzed using a quantitative image analyzer. The size distribution of the particles was obtained from micrographs, and the melting temperature was calculated based on the mass distribution of solid particles. The results were compared with the predictions of two phenomenological models. The first model, which assumes a solid particle, a liquid particle of the same mass, and a vapor phase, was found to agree well with the experimental results. The second model, which assumes a liquid layer surrounding the solid particle, also showed good agreement with the experimental results. The results suggest that the melting temperature of small particles is influenced by the size effect, and the two models provide different explanations for this phenomenon. The study concludes that the melting temperature of small gold particles decreases with decreasing particle size, and the results agree closely with the predictions of the first phenomenological model.This paper investigates the size effect on the melting temperature of gold particles. Using a scanning electron-diffraction technique, the melting points of small gold particles with diameters down to 20 Å were measured. The results show that the melting temperature decreases as the particle size decreases. Two phenomenological models were used to explain this effect: one assumes a solid particle, a liquid particle of the same mass, and a vapor phase, while the other assumes a liquid layer surrounding the solid particle. The first model uses only physical constants of gold, while the second model requires an assumed liquid layer thickness of about 6 Å. The experimental results agree well with both models. The first model predicts a linear relationship between the relative lowering of the melting temperature and the surface curvature of the particles. The second model, which includes nonlinear terms, is more closely associated with experimental results. The melting temperature of small particles was determined using three criteria: the disappearance of the state of order in the solid, the modification of the rate of evaporation at the melting point, and the modification of the particle shape at the melting point. The study found that the melting temperature of gold particles decreases with decreasing particle size. The results were compared with theoretical predictions and showed good agreement. The melting temperature of small particles was determined using a scanning electron-diffraction technique, and the results were analyzed using a quantitative image analyzer. The size distribution of the particles was obtained from micrographs, and the melting temperature was calculated based on the mass distribution of solid particles. The results were compared with the predictions of two phenomenological models. The first model, which assumes a solid particle, a liquid particle of the same mass, and a vapor phase, was found to agree well with the experimental results. The second model, which assumes a liquid layer surrounding the solid particle, also showed good agreement with the experimental results. The results suggest that the melting temperature of small particles is influenced by the size effect, and the two models provide different explanations for this phenomenon. The study concludes that the melting temperature of small gold particles decreases with decreasing particle size, and the results agree closely with the predictions of the first phenomenological model.