An UV-C/B emitting Xe excimer discharge lamp comprising BaZrSi3O9 – A lamp performance and phosphor degradation analysis

Abstract This work concerns a highly efficient UV-C emitting phosphor, viz. BaZrSi 3 O 9 , which photoluminescence is suitable for a number of photochemical processes, e.g. for air, surface, or water disinfection as well as oxidative purification processes of water. The latter imply direct photolysis as well as photooxidation involving auxiliary components like H 2 O 2 . The material was investigated with respect to its application as a conversion layer in Xe excimer discharge lamps (λ Em = 172 nm). To this end, substitution of Zr 4+ by Hf 4+ was performed aiming at an optimization of the preparative process and the resulting VUV conversion efficiency. As-prepared powder samples were consecutively employed in state-of-the-art dielectric barrier Xe excimer discharge lamps and their performance was compared to YPO 4 :Bi 3+ as a UV-C emitting commercially available reference material (Phillips GmbH). Even the non-optimized BaZr 0.8 Hf 0.2 Si 3 O 9 succeeded the standard in terms of long term stability of its luminous flux. Detailed analysis of the material was secured by crystallographic as well as extensive optical and spectroscopic measurements. The latter was supplemented by EPR studies in order to further examine the underlying aging mechanism which governs the phosphor decay during Xe excimer lamp operation.