Photoacoustic spectroscopy of ceramic ZnO doped with Bi2O3

Photoacoustic (PA) spectroscopy is applied to study the heat generation by nonradiative processes of ceramic ZnO containing 1 mol.% Bi2O3 for the different sintering temperatures (700–1100°C) in the wavelength range of 320–800 nm with a modulation frequency of 33 Hz. PA spectroscopy provides optical absorption spectra for opaque samples such as ceramics. PA signal intensities increase above a photon energy of 2.3 eV. It is found that the PA signal intensities plotted semilogarithmically vary linearly below a photon energy of 3.0 eV in the two regions (A: 3.0–2.8 eV; B: 2.6–2.4 eV). The steepness factor of region A, which characterizes the slope of exponential optical absorption, decreases with rising sintering temperature, indicating the increase of segregation of Bi at particle surfaces and grain boundaries. That of region B increases rapidly with rising sintering temperature, indicating the structural ordering by sintering processes. Thus, PA method has a potential for characterizing the electronic states and structural disorder of ceramic materials.