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

Kinetics of physico-chemical processes during intensive mechanical processing of ZnO–MnO2 powder mixture

“…According to the results of quantitative spectral analysis, the contamination produced by the tungsten carbide jars after 3120 min of milling did not exceed 0.02%. It is worth to point out that almost the same contamination content was observed in the case of 99% ZnOþ 1% MnO 2 samples after 2880 min of intense MP [25]. Therefore, because the kinetics of the physical and chemical processes described in this study are totally different from Kakazey [25], we consider that the low contamination of the tungsten carbide jars and the low content of impurities in the initial reactives did not have a principal influence on this study.…”

“…It is also important to emphasize that the transition from the crystalline ZnO to the nano-quasiamorphous state was not observed when the mechanical processing was made for ZnO samples with small amounts of b-MnO 2 [25]. In that study, no reaction was observed and the minimal crystallite size obtained after t MP ¼ 3120 min was D $ 25 nm [25].…”

“…However, Bartolome et al. [24] and Kakazey et al [25,26] not observed a ferromagnetic state induced in the system by ball milling. The authors of a review article [27] concluded that the combination ofmicroscopic defects and delicate point like defects created upon energy impact in ZnO leads to weak ferromagnetic properties.…”

“…Kakazey et al [29] Contents lists available at ScienceDirect also reported solubility lower than 3%. The formation of the solid solution ZnO:Mn 2 þ during prolonged mechanical processing (MP) of powder mixtures of ZnOþ 1%wt MnO 2 and ZnO þ10%wt MnO 2 were observed by electron paramagnetic resonance spectra by Kakazey et al [25,26]. They also observed that the solubility of Mn 2 þ ions in ZnO particles after intense MP-process was not more than 3%.…”

Microstructural evolution in BaO–Y2O3–Co3O4 mixtures during high-energy milling and its role in the formation of YxBa1−xCoO3−δ and YBaCo4O7

“…From previous studies [14], we have estimated that the equilibrium temperature of samples during milling in regime A reaches nearby 500 • C. Thus, we consider that such temperature was reached in this study and that higher temperature is needed for the initiation of the reaction. Thereby, the mechanically activated powders were thermally treated (TT) at different temperatures above 500 • C.…”