Infrared, visible and upconversion emission of CaAl12O19 powders doped with Er3+, Yb3+ and Mg2+ ions

CaAl₁₂O₁₉ powders doped with Er³⁺, Yb³⁺, and Mg²⁺ ions have been prepared by a low-temperature combustion synthesis technique. Formation and chemical compositions were analysed by powder X-ray diffraction and energy-dispersive spectroscopy. The visible luminescence spectra of the doped phosphor upon excitation with ∼378 nm radiation from a Xenon lamp have been studied. A broad band emission in the range of 1400–1700 nm with a peak around 1.5 μm and FWHM of about ∼80 nm responsible for the eye-safe telecommunication window has been observed upon direct excitation with a NIR laser into the ⁴I_11/2 level of Er³⁺. The effect of co-doping with Yb³⁺ and Mg²⁺ ions in the CaAl₁₂O₁₉:Er³⁺ matrix on the photoluminescence intensity corresponding to the ²H_11/2,⁴S_3/2→⁴I_15/2, ⁴F_9/2→⁴I_15/2 and ⁴I_13/2→⁴I_15/2 transitions of Er³⁺ is elaborated and discussed in detail.