Unusual blue and red luminescence properties of BaO–ZrO₂ nanocrystals

Abstract BaO–ZrO₂ nanocrystals were synthesized using the chemical bath deposition technique and then subjected to post-synthesis annealing between 500 and 900 °C. X-ray diffraction patterns showed the amorphous structure for as-synthesized sample, while annealed samples show either disordered tetragonal phase or a mixture of tetragonal and monoclinic phases at high temperatures. The emission spectrum displays blue emission band for the as-synthesized sample with peak maximum at 434 nm. All annealed samples showed both blue (434 nm) and red (710 nm) emission bands upon excitation at 248 and 360 nm. Samples excited at 310 nm produced only the red emission band centered at 710 nm, which decreased monotonically with increasing temperature and was completely quenched at 900 °C. CIE results show the phosphor is capable of producing blue, red and white light depending on the excitation wavelength chosen and the post-synthesis heat treatment temperature. The synthesized phosphor is cost-effective and can be applied in display and other lighting technologies.