Spectroscopic analysis of NIR emitting phosphors based on NaLaMgWO₆ doped with Nd³⁺ and Er³

While searching for a new host suitable for near infrared (NIR) emission, we explored a new composition NaLaMgWO₆. The samples were prepared by solid state reaction method. X-ray Diffraction confirms crystallization of NaLaMgWO₆ in monoclinic system. Composition and phase homogeneity were established by Energy Dispersive Spectra. Presence of La in the host permits doping with the trivalent lanthanides Nd³⁺ and Er³⁺; the known NIR emitters. By virtue of a large number of energy levels, excitation could be achieved by light of various wavelengths from near ultraviolet through visible. Among these 589 nm was most effective for Nd³⁺ and 524 nm for Er³⁺. Very weak excitation from host tungstate band was also observed at wavelengths around 317 nm. Nd³⁺ emitted at 1089 nm and Er³⁺ at 1540 nm. PL intensity was restricted by concentration quenching due to dipole-dipole interaction. The critical distance for Nd-Nd energy transfer was 22.57 Å, while for Er-Er it was 28.44 Å. NaLaMgWO₆ doped with Nd³⁺ or Er³⁺ can be a suitable material for optically pumped lasers in NIR region.