Photopyroelectric Spectrum of MNO2 Doped Bi2O3 - TiO2 - ZnO Ceramic Combination.

Photopyroelectric spectroscopy is used to study the energy band-gap of the ceramic (ZnO + 0.25 Bi₂O₃ +0.25 TiO₂ + x MnO₂), x = 0 - 1.3 mol%, sintered at isothermal temperature 1190 and 1270°C for 2 hours in air. The wavelength of incident light, modulated at 9 Hz, is kept in the range of 300 to 800 nm and the photopyroelectric spectrum with reference to the doping level is discussed. The energy band-gap is estimated from the plot (phv)²vs hv and is 2.80 eV for the samples without MnO₂ at both sintering temperatures. It decreases to 2.08 eV with a further increase of MnO₂. The phase constitution is determined by XRD analysis. Microstructure and compositional analysis of the selected areas are analyzed using SEM and EDX. The maximum relative density, 91.4 %, and the grain size, 47 μm, were observed in this ceramics combination. [ABSTRACT FROM AUTHOR]