Abstract
Band gap energy (E-g) of doped ZnO ceramic with 1MnO, 0.8 Co3O4, xBi(2)O(3) + yTiO(2) where x = y = 0.6, 1 mol%. Different sintering times 1-4 hours have been studied in 300 to 800 nm wavelength range using a technique Photopyroelectric spectroscopy (PPES). The Graph is plotted between (rho hu)(2) and hu. E-g is assessed from the plot which is about 2.03, 2.07 eV for the samples sintered for 2 hours at low and high doping levels, respectively. The increase in steepness factor (sigma(A), in A-region and sigma B, in B-region) is related to sintering time at low and high doping level. Barrier height (phi(B)) is 0.96, 0.89 eV for lower and higher doping level at 4 hour sintering time, respectively. The dielectric constant varied with the increases of sintering time. The dissipation factor Tans is decreased with the increase of sintering time. The X-ray diffractometry analysis shows that the crystal structure of ZnO doped with different MnO mol% remains to be of hexagonal type at all sintering times. Furthermore, it was observed that few feeble peaks are found related to the new phase Bi2MnTiO4, Zn2TiO4, MnTi4O4 and Bi4Ti3O12 at higher sintering time at both doping levels. The grain size ranges increased with the increase of sintering time and relative density decreased. Sintering time of the sample increases the density is decreased from (90.6, 88. to 88, 86 %) at lower and higher doping levels, respectively.