The influence of oxygen pressure on lead oxidation kinetics

Abstract

The dependence of the oxidation rate of lead films on the pressure of oxygen was investigated by ellipsometric and resistance techniques for oxygen pressures between 200 Pa and 100 kPa and in the temperature range 323-423 K. Measurements of the pressure dependence were obtained by studying the change in oxidation rate following an abrupt change in pressure. The results of all experiments indicated a small positive dependence, though significant variations in the values were observed both with extent of oxidation, and between experiments conducted at different temperatures. During the first few minutes of the reaction an unusual trend was noted in the observed kinetics which could be interpreted as being due to absorption of oxygen, by the metal close to the metal-oxide interface, resulting in changes to the metal conductivity and the refractive index, determined by ellipsometry, of the lead substrate.