MnO-doped ZnO ceramics have been synthesized through the conventional ceramic processing route. Mn2+ ions have been incorporated into the ZnO lattice within the limits of solid solubility. By using X-band-frequency and high-field electron paramagnetic resonance (EPR), we have resolved some of the main electronic transitions for the S = 5/2, I = 5/2 high-spin system and have determined accurately the EPR spin-Hamiltonian parameters. By combining data from crystallographic X-ray diffraction and EPR with the semi-empirical Newman superposition model, we have found the local configurational position of Mn2+ and have confirmed the symmetry of the lattice. The results presented in this contribution indicate that Mn ions substitute at Zn sites in ZnO. The effect of Mn2+ ions on the intrinsic defects becomes remarkable, thus the vacancy related intrinsic defect signals cannot be visible in the EPR spectrum. MnO doping affects the band gap energy of ZnO system which was confirmed via UV-Vis spectroscopy.

No abstract

The effect of V2O5 and B2O3 additions on sintering behaviour and physical properties of ZnO ceramics was investigated. XRD studies revealed ZnO as main phase with a hexagonal wurtzite-type structure. The V2O5 addition is the reason for an increase in grain size and some grains of oblong shape morphology in the ZnO ceramics. The dual addition of V2O5-B2O3 improved the liquid-assisted sintering of ZnO ceramics and resulted in further increase in grain size with more uniform grain growth. The reduction of sintering temperature to 900?C for ZnO ceramics was observed with the dual addition of V2O5 and B2O3. The room temperature PL spectra of the Z (ZnO), ZV (ZnO with 0.5mol% V2O5) and ZVB (ZnO with 0.5mol% V2O5 and 0.5mol% B2O3) ceramics revealed broad visible emission band because of impurities and defects in ZnO ceramics caused by oxygen vacancies due to vanadium and boron additions, as well as zinc interstitials. This emission band between 450-750 nm includes the entire visible region from blue to red.

No abstract