Effect of Sr-doping on sinterability, morphology, structure, photocatalytic activity and AC conductivity of ZnO ceramics

The change in morphology, structure, catalytic activity and ac electrical conductivity of the Sr-doped ZnO (Zn1-xSrxO, x = 0, 0.01, 0.02 and 0.03) ceramic powders was investigated after sintering. The sintering of the Sr-doped samples results in faster growth in particle-size and the shape becomes spherical by dissolution of the sharp edges in order to reduce the strain produced by Sr-doping and to reduce the surface energy. The growth in particle-size reduces the photocatalytic activity. Sr-doping reduces the band gap of ZnO by a small value (similar to 0.1 eV). The ac conductivity values decrease with increase in Sr-concentration, but increase with temperature and frequency. This behavior is due to the conduction by small polarons created by Sr-doping. Our results may facilitate a way for the easy fabrication of monolithic ZnO based devices with improved dielectric and semiconducting properties of ZnO ceramics by doping a small amount of Sr.