Synthesis, up/down-conversion luminescence and cathodoluminescence properties of CaLa2ZnO5:Er3+/Yb3+ nanocrystalline phosphors

Abstract

RE3+ (Er3+/Yb3+) ions co-activated CaLa2ZnO5 (CLZO) nanocrystalline phosphors were synthesized by a citrate sol–gel method. The crystallinity and phase formation of CLZO host lattice and CLZO: Er3+/Yb3+ phosphors were analyzed by X-ray diffraction patterns. The morphological studies were carried out by means of field-emission scanning electron microscope and field-emission transmission electron microscope images. The up-conversion (UC) luminescence properties of Er3+ ions doped CLZO phosphors were examined under the excitation at 980nm, which exhibited the green and red emissions. To enhance the emission intensity of CLZO:Er3+ phosphors, Yb3+ ions were co-doped with Er3+ ions. With increasing the pump power, the green emission intensities were enhanced as compared to the red emission intensities due to the energy transfer process from Yb3+ to Er3+ ions. A potential energy transfer mechanism was investigated to understand the enhancement of UC emission intensities. Additionally, photoluminescence properties were studied at 380nm of excitation wavelength for the CLZO:1Er3+ and CLZO:1Er3+/3Yb3+ phosphors. Cathodoluminescence (CL) properties were studied as a function of filament current and accelerating voltage for the optimized CLZO:1Er3+/3Yb3+ phosphor. The CL spectra exhibited almost similar spectral behavior to the observed UC spectra except the intensity variation. Also, the Commission International De I׳Eclairage chromaticity coordinates were calculated.