The Physical Chemistry of Energy-saturated Media

Effect of heating rate on oxidation process of fine-dispersed ZnS:Mn obtained by SHS

“…Powdered ZnS:Mn was obtained by self-propagating high temperature synthesis (SHS) at temperatures that ensure interaction between zinc and sulfur [7][8][9]. Doping with the manganese impurity was carried out from MnCl during synthesis.…”

A study of the reactivity of copper nanopowders in their reaction with glacial acetic acid

“…The relative contributions of these processes can be affected by varying such dispersion conditions as temperature (change in the flowability limit, transition from the plastic to the brittle state at low temperature), medium, and grinding in the presence of surfactants making lower the surface energy and mechanical strength of particles [2,10]. As surfactants can act both inorganic and organic polar compounds: organic acids, alcohols, amines, and high-molecular-weight compounds containing acid, alcoholic, amine, and other fragments.…”

“…Two parameters were used to evaluate the reactivity: heat effect of the reaction and the maximum rate of heat release.Compared with compact substances, highly dispersed materials have an excess energy, and, therefore, they are frequently named energy-saturated systems or media [1,2]. With the high energy content of dispersed particles, which is due, in particular, to the contribution of the surface energy, is associated a very important specific feature of ultradispersed media, i.e., their high reactivity.…”

“…The grinding is commonly done with planetary, ball, and vibration mills. However, ordinary grinding is comparatively rarely used to obtain ultradispersed powders because of the existence of a certain limit of grindability [2,9]. The grinding limit is an individual characteristic of a substance, which is commonly determined experimentally.…”

The factors influencing luminescent properties of ZnS:Mn obtained by the method of one-stage synthesis

“…It is shown in this paper that at physical-chemical analysis of ultradisperse systems it is necessary to take into consideration a dispersion degree of substance. On the basis of this approach, it is explained in [9] interrelation between the dispersion degree of material and temperature, which causes fusion, polymorphic transmutations and sintering; and the influence of dispersion on the diffusion constant in separate crystal grains and on chemical activity of the obtained substance. The authors [9] assert that regardless of the method of producing a disperse system, its redundant energy is defined either by surface energy, or by formation of metastable solutions.…”