Photoacoustic and X-ray photoelectron spectroscopic studies in reduced lead zirconate titanate ceramics

Abstract

Lead zirconate titanate (PZT) is known to become a semiconductor after reduction in a hydrogen atmosphere. An attempt is made here to characterize the reduced, as well as the unreduced, PZT system with the help of photoacoustic (PA) spectroscopy and X-ray photoelectron spectroscopy (XPS) and to obtain useful information regarding its electronic behaviour. The band gap of the unreduced PZT is estimated to be 3.56 eV from PA spectra which is observed to remain unaffected after doping with lanthanum, niobium and strontium. XPS results indicate the presence of metallic lead in PZT after hydrogen reduction whereas other elements remain unaffected. This becomes responsible for the change in its conductivity and also for the increased absorption in the visible range which is reflected in the PA spectra. The electronic structure based on PA spectra is also presented for the reduced and unreduced PZT systems.