New Red-Emitting Phosphor La2Zr3(MoO4)9:Eu3+ and the Influence of Host Absorption on its Luminescence Efficiency

This work investigates the optical properties of Eu3+-activated La2Zr3(MoO4)9. A series of solid solutions with Eu3+ concentrations in the range of 0–100 % were prepared by conventional high temperature solid-state synthesis. An unusual change in the lattice parameters was observed. The phosphor exhibits a broad absorption band in the UV spectral region, and measurements on the non-doped material at 100 K were conducted to elucidate the nature of the absorption band. As demonstrated, Mo6+ charge transfer absorption negatively influences the luminescence efficiency of the phosphor. The temperature-dependent emission spectra revealed that the emission intensity exhibits a bi-sigmoidal temperature dependence. This behaviour results from competing absorption via Mo6+ charge transfer processes, which strongly decrease the efficiency of the phosphor. For application purposes, it is therefore advisable to choose materials that do not exhibit host absorption in the spectral range where excitation is expected.