**Acknowledgements**

This work is based on the research supported by Department of Physics, University of the Free State, Bloemfontein, South Africa. The PL system used in this study is supported both technically and financially by rental poll programme of the national laser centre (NCL). The author states that some part related to this work is published in RSC Journal. The author has permission from the publisher Journal RSC advances to use parts of his previously published work titled "Effect of fuel content on luminescence and antibacterial properties of zinc oxide nanocrystalline powders synthesized by the combustion method."
