Synthesis and optical properties of Eu3+ -substituted glaserite-type orthovanadates CsK2 Y[VO4 ]2.

ABSTRACT

A new Eu3+ -substituted CsK2 Y[VO4 ]2 glaserite-type orthovanadate phosphor was synthesized by the conventional high temperature solid-state reaction method. The phase purity was confirmed by powder X-ray diffraction study and it reveals that all the compositions crystallize in the hexagonal structure. The morphology and elemental composition were measured by FE-SEM with Energy Dispersive Analysis Of X Rays (EDAX). The band gap is determined by diffuse reflectance spectra. The self-activated luminescence of the host and Eu3+ -substituted luminescence behaviours were studied in detail by photoluminescence spectra. The host CsK2 Y[VO4 ]2 shows green emission, whereas the Eu3+ -substituted compositions show red emission. Effect of Eu3+ concentrations on the photoluminescence behaviour were also been studied. The Eu3+ -doped samples show not only several sharp emission lines but also a broad emission band due to presence of the [VO4 ]3- in the host, which clearly indicates that there is incomplete energy transfer from (VO4 ) charge transfer band to Eu3+. The life time of the phosphors also been studied. The Commission Internationale de l'Eclairage (CIE) chromaticity colour coordinates were calculated and it is very much closer to the National Television Standard Committee (NTSC) standards. These investigations evidently reveal that the self-activated and Eu3+ -activated phosphors show a great potential applications as a red phosphor for solid-state lighting includes white light-emitting diodes (wLEDs).