Effect of precursor salt on phase evolution, powder morphology and photoluminescence behaviour of zinc oxide and mixed zinc oxide-zinc borate systems

Abstract

Inorganic phosphor materials consisting of a host (especially oxide and borate based) and activator have performed as a potential candidate in different areas including lighting applications. In this present study, zinc oxide as well as mixed zinc oxide-zinc borate is selected as a host material and rare earth europium is used as an activator for the development of phosphors. The phase evolution of zinc borate along with zinc oxide in a single step wet-chemical synthesis process is a challenge. So, the objective of the present work is to develop a host consists of zinc oxide as well as mixed zinc oxide-zinc borate using borohydride method by selecting two precursor salts and optimizing calcination temperature. In addition, photoluminescence of Eu-doped zinc oxide as well as mixed zinc oxide-zinc borate is also studied. Pure phase of zinc oxide was observed starting from 450 °C to 800 °C, while using zinc chloride. In case of zinc acetate, zinc borate was evolved along with zinc oxide above 600 °C. The particles are agglomerated in nature within the range between 100 nm to 300 nm in both precursor salts. The emission spectra, while using an excitation wavelength of 390 nm (i.e. near visible), shows a clear indication of the transition peaks of Eu3+-ion at 590 nm, 612 nm and 640 nm, which corresponds to 5𝐷0 →7𝐹1 , 5𝐷0 →7𝐹2 and 5𝐷0 →7𝐹3 transition, respectively. Further, samples prepared using acetate precursor was found better luminescence than the samples prepared using chloride precursor.