Spectroscopic analysis of NIR emitting phosphors based on NaLaMgWO doped with Nd and Er.

While searching for a new host suitable for near infrared (NIR) emission, we explored a new composition NaLaMgWO. The samples were prepared by solid state reaction method. X-ray Diffraction confirms crystallization of NaLaMgWO 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 Nd and Er; 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 Nd and 524 nm for Er. Very weak excitation from host tungstate band was also observed at wavelengths around 317 nm. Nd emitted at 1089 nm and Er 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. NaLaMgWO doped with Nd or Er can be a suitable material for optically pumped lasers in NIR region.