Spectrophotometric analysis of a high-temperature phase transition in lead tetroxide Pb3O4

We have investigated the influence of a phase transition in polycrystalline layers of lead tetroxide Pb₃O₄ on their diffuse reflection spectra in the wavelength range of 380–700 nm. We have determined differences in the character of the spectral dependences of the reflection coefficient and surface morphology that are related to the formation of a new high-temperature phase. We have determined values of the optical band gap from analysis of the diffuse reflection spectra of this metal oxide semiconductor compound under normal conditions and after its transition from the tetragonal to an orthorhombic modification.