Oxidation kinetics of lead selenide

The oxidation of lead selenide structures prepared in the form of powdered samples is investigated. The powders are produced from a lead selenide batch heat treated under dynamic vacuum and ground in an agate mortar. The mean grain size is equal to 0.5-3.0 mum. The thermodynamic analysis of the possibility of the main chemical reactions proceeding during the oxidation of lead selenide in an oxygen atmosphere is performed. The bulk and surface structural (and phase) compositions of the powdered samples upon oxidation in dry air at a temperature of 823 K for oxidation times of 5-240 min are studied using X-ray diffractometry. The analysis of the X-ray diffraction patterns shows that the PbSeO3 phase is formed on the grain surface of all PbSe powders, whereas no phase transformations are observed inside the grains. The charge state of Se atoms in PbSe crystallites oxidized to different states is determined from the chemical shifts of the K X-ray emission lines. The oxidation kinetics of lead selenide is examined at a temperature of 823 K. It is demonstrated that the kinetic dependences of the oxidation of lead selenide that are determined by two independent methods (chemical shift, X-ray diffractometry) are in satisfactory agreement with each other.