Hyper-Rapid thermal defect annealing during grinding of ZnO powders

Abstract

Effect of rapid thermal annealing on electrical and optical properties of Ga doped ZnO thin films prepared at room temperature

Origin and evolution of paramagnetic states in mixtures of ZnO and carbon nanoparticles during intensive mechanical treatment

“…All these processes lead to a consistent temperature increment in the sample, T S . The signal II disappears after thermal treatment at T II * 453 K; signal I disappears after thermal treatment at T I * 493 K; and signal III disappears after thermal treatment at T III * 533 K (Kakazey et al 2002). Thus, sequential disappearance of EPR signals from II, I, and III centers during increasing of MP times indicates that T S exceeds the annealing temperature of the corresponding defect.…”

“…Therefore, these changes in the amplitude of signals I, II, and III reflect the occurrence of two types of the thermal processes during MP: ultrafast thermal processes and slow thermal processes. The ultrafast thermal processes involve particle destruction, defects formation, heat generation, defects annealing, and ultrafast heating and cooling in the destruction zone (*1700 K, Kakazey et al 2002). The efficiency of the annealing is determined by the duration of thermal impulse (s T ) and by the temperature of the defect centers annealing.…”

“…Many of the EPR properties of ZnO and carbon materials are known (Schallenberger and Hausmann 1976;Galland and Herve 1974;Geisler and Simmons 1964;Ischenko et al 2005;Vlasenko 2010; Kaftelen et al 2012;Hoffmann and Hahn 1974;Halliburton et al 2005;Vanheusden et al 1997;Beuneu et al 1999;Barklie 2001;Arcon et al 2006;Kakazey et al 2001Kakazey et al , 2002Kakazey et al , 2008Abragam and Bleaney 2012). In this study, the microstructural evolution and reaction processes in the mixture of ZnO ?…”

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

“…Signals from V À Zn : Zn 0 i centers (I) and from V À Zn centers (II), which are usually observed during the destruction of pure ZnO or ZnO with small amount of MnO 2 (see Fig. 6 for samples of 99% ZnOþ1% b-MnO 2 and 90% ZnOþ10% b-MnO 2 [25,26,[38][39][40][41]) were not observed in samples of 50% ZnOþ50% b-MnO 2 (Fig. 6).…”

“…The differences in the EPR spectra of specimens with different amount of MnO 2 (Fig. 6) are caused by the mechanothermal processes developed in an individual ZnO particle and by the formation of specific defects during grinding [40]. The maximum temperature reached during milling is inversely proportional to the thermal conductivity of the environment.…”