Formation of MgZnO alloy under thermodynamic conditions

Mg_xZn_1−xO ceramics with x=0.10, 0.15, 0.20, 0.25 and 0.30 were sintered at T_s=700–1250 °C. Photoluminescence (PL) and PL excitation (PLE) spectra as well as X-ray diffraction patterns were measured at 293 K. Bandgap width was evaluated from the position of PLE peak. Non-monotonous dependence of PLE peak position on T_s was observed for all used x. This effect was concluded to be caused by the formation of cubic phase side by side with hexagonal one and the enhancement of this process with increasing T_s, which resulted in the decrease of Mg content in the hexagonal phase at T_s>1000 °C. Temperature range of 1000–1050 °C was found to be the optimum one for the formation of hexagonal MgZnO alloy at used x. It was shown that x=0.20 was the solubility limit of MgO in hexagonal Mg_xZn_1−xO ceramics