Near ultraviolet excited down conversion Eu and Er co-doped CaAl2O4 color tunable nano-phosphors: Structural, morphological and photolumniscent characteristics

Abstract

Abstract A series of CaAl2O4:Eu3+ (1 mol%) co-doped with Er3+ (0, 1, 2, and 5 mol%) was synthesized by urea assisted combustion method at 600 °C and further calcinations was done at 1000 °C to enhance the crystalline character and luminescence properties. Synthesized samples were characterized structurally and optically using the X-ray diffraction (XRD) and spectrofluorometer respectively. From XRD analysis, monoclinic phase of CaAl2O4 is reported in all the samples indicating that doping of Eu3+ and Er3+ do not change the crystalline structure of calcium aluminate. Both Eu3+ and Eu2+ states were detected in the synthesized materials whose ratio changes with calcination as well as with co-doping of the Er3+ ions. CaAl2O4:Eu3+ (1 mol%) synthesized at 600 °C show high intense peak around 440 nm due to presence of Eu2+ state, whose intensity decrease with co-doping and upon calcination where as at the same time intensity of peak in the red region due to the presence of Eu3+ increases. In the compounds calcined at 1000 °C, electric dipole 5D0 → 7F3 transition of Eu3+ at 657 nm appears as peak with highest intensity. The Er3+ ion acts as sensitizer and enhances the luminescent properties of co-doped samples.