Oxides formed on the (111) surface of lead II. Red PbO or litharge

Abstract

The electron microscopy of oxidized lead films revealed that the oxide consists of a yellow PbO layer in which small (10-17-10-18 cm3) rectangular islands of red PbO are dispersed. The red PbO islands are thicker than the yellow PbO layer and are oriented with their [021] direction approximately perpendicular to the (111) surface of the lead film. Moiré fringe patterns visible in the red PbO islands show that their lattices are bent. The magnitude and sign of this bendings was measured. It was found that the bending enables the red PbO islands to satisfy one epitaxial orientation near their center and two forms of another near their ends. However, the bending does not arise entirely from an attempt to satisfy two epitaxial relationships simultaneously. The bending seems to result promaroly from a gradient in the oxygen concentration. As this gradient is unlikely to be constant it is probable that a true elastic strain is also present. Simple explanations for the sign of the lattice bending and for the shape and orientation of the red PbO grains are proposed. © 1977.