Title : Recent development in NaCa(AG):Sm3+ (where AG = BO3-3, PO4-3 and SO4-2) nanophosphors-applications for solid state lightning
In the present work, we have intended to investigate the photoluminescent (PL) properties of NaCa(AG): Sm3+(AG = BO3-3, PO4-3, SO4-2) nanophosphors synthesized via the solution combustion method. Structural, morphological, and optical properties were carried out using different techniques. From the XRD results, it is confirmed that these materials are formed in the orthorhombic (BO3-3, PO4-3) and monoclinic (SO4-2) structures. Morphological studies were carried out using a high-resolution scanning electron microscopy technique. From these results, it is confirmed that the prepared materials are formed in different particle shapes and sizes. Optical band gap energy values were calculated from the diffuse reflectance measurements, using the Kubelka-Munk function. Variations in the optical band gaps were noticed for the all undoped NaCaBO3, NaCaPO4, NaCaSO4 and doped NaCa(AG):Sm3+(AG = BO3-3, PO4-3, SO4-2) nanophosphors. Photoluminescence excitation spectra were measured by monitoring the emission peak at 614nm wavelength, and this resulted in a high intensity excitation peak at 404nm. Similarly, by using this 404 nm UV excitation wavelength, photoluminescence emission spectra were noticed leading to a high intensity orange-red emission at 608 nm wavelength. From the photoluminescent properties it was noticed that NaCaPO4:Sm3+ showed the highest intensity in orange-red emissions compared to the other materials studied. Using PL data, the Commission International de I’Eclairage (CIE), colour coordinates were noticed and estimated for all studied materials. From the CIE colour diagram, it is confirmed that sodium calcium phosphate has the best colour purity. From the present investigations we found that Sm3+ doped sodium calcium phosphate to be a potential candidate for the enhancement of reddish-orange colour emission for solid state lighting and for colour display applications.