An investigation on the luminescence and structural properties of erbium doped cadmiumniobate phosphors

Abstract

Columbite-type niobates with MNb2O6 general formula having interesting optical,dielectric and microwave dielectric properties have been intensively studied recently.There are lack of study on the luminescent properties of columbite metal niobates.In the present study ,rare earth doped CdNb2O6 compounds with columbite structure ,were produced by molten salt method and synthesized by using starting materials of metal nitrates and niobium oxide and salt systems such as , Li2SO4-Na2SO4 by 1:1 molar ratios. The Morphological properties of the powders as determined from X-ray diffraction and Scanning Electron Microscopy. The mechanism of this behavior has been studied by measuring the spectral characteristics of the photoluminescence and photoluminescence excitation spectra on the crystalline.CdNb2O6 doped with 0.5, 1, 3, 6% Er+3 compounds indicated CdNb2O6 phase (JCPDS file No., 38-1428) .The samples exhibited a single phase and all of the peaks were found to be CdNb2O6 phase at high temperature of over 900°C. The SEM pictures and The EDS of the material are the rod-like particles that seem to be distributed homogeneously.Therefore, the particle size increased along with the sintering temperature. The luminescence properties of columbite compounds were investigated at low (200-800 nm) and high (900-1100 nm) wavelengths.However Er+3:CdNb2O6 compound increased the luminescence intensity.The emission intensity of CdNb2O6 with increasing rare earth dopant Er2O3 concentration due to transfer of excitation energy absorbed by rare earth dopants to the NbO6 groups.Photoluminescence analysis performed between (900-1100nm) showed that ,luminescence intensity of CdNb increased by increasing the dopant ratio but ,concentration quenching was observed for CdNb2O6 above 1%mol dopant concentration