Melting Point of the Small Crystallization Structure

We consider the melting process of a plasma crystal in a smoky plasma under conditions of the quasi-regular packing approximation of identical spherical charged condensed particles (grains). We theoretically investigate the influence of the grain size on the melting point of small crystal-like structures, formed by agglomerates of metal oxide particles or spatial-ordered particle structures. The dependence of the melting temperature of the plasma crystal is obtained using the Lindemann criterion in dependence on the grains' charges and their concentration. The experimental dependence of the frequency of electroacoustic vibrations of alumina particles on their charges in the smoky plasma was used to determine the root-mean-square deviation of the particles with respect to their equilibrium positions in a crystal. An expression is obtained that determines the dependence of the melting point of small crystal-like structures on the fractal dimension and the number of grains in the cluster. It is shown that the melting point of small crystal structures increases sharply in the region of low grain concentrations and asymptotically approaches the melting point of a massive crystal with increasing concentration. The results lead to suggestion that in the smoky plasma containing grains of three size fractions, the simultaneous existence is possible for three aggregate states of the condensed phase.