Reactionary processes during mechanical treatment of mixtures of ZnO and MnO₂. I. Formation of defects and solid solution

Abstract

Kinetics of defects formation, reaction process and formation of solid solution in powder mixtures of ZnO and MnO₂ induced by prolonged mechanical treatment (MT) have been investigated (X-ray, FTIR, EPR). At MT in zones of deformation-destruction the different defects ( ${\text{V}}_{{\text{Zn}}}^ - :{\text{Zn}}_{\text{i}}^{\text{0}}$ (I), ${\text{V}}_{{\text{Zn}}}^ -$ (II), and ${\text{(V}}_{{\text{Zn}}}^ - {\text{)}}_{\text{2}}^ -$ (III) centers at all) are forming. The defects have various physical and chemical properties, and have different activation energies of annealing, E_act The part of these defects is responsible for the processes of hydration and carbonation of samples. In turn, the formation of defects is accompanied by development of various mechanothermical processes, which increase temperature of the sample, T _MT, with the increasing of duration of MT, t _MT. The increasing of t _MT activates the reactionary processes: promotes a consecutive annealing the «low-temperature» defects having small values of E_act (I, II and III) and also leads to formation of Mn²⁺-doped Zn(OH)₂. With the further increase of t _MT, the process of MT is accompanied by an increasing of temperature of samples up to equilibrium, T _eq and accumulation of “high-temperature” defects in the sample. As a result, in the sample the conditions for intensification of volumetric diffusion processes and formation of Mn²⁺-doped ZnO were created.