Cathodoluminescence emission of REE (Dy, Pr and Eu) doped LaAlO₃ phosphors

Luminescence emission from rare earth (REE) ions doped materials are being of interest since can be employed as scintillators, catalysts, battery and magnetic materials, etc. We herein report on the preliminary results obtained from the cathodoluminescence (CL) properties of undoped LaAlO₃ (LAO) and LaAlO₃: REE³⁺ (REE=Dy³⁺, Pr³⁺ and Eu³⁺) samples synthesized by a sol-gel process based on the Pechini's method with a spray-drying technique. The samples, previously characterized by means of Environmental Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis Spectrometry, display CL spectra with well-defined peaks that could specifically be associated with the LAO structure (in the range of 300–450 nm) and point defects (from 450 to 800 nm) spectral regions. The observed wavebands are as follows: (i) 480 and 570 from the Dy-doped LAO correspond respectively to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transitions, (ii) 490–638 from the Pr-doped LAO is linked to ³P₀→³H₄, ¹D₂→³H₄ transitions and (iii) 590 and 620 where the dopant Eu³⁺ gives rise to ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transitions and (iv) a UV-blue broad band is associated with NBHOC in undoped LAO. Such emissions are due to the presence of the 4f electrons of rare earth ions that are shielded by the outer 5s and 5p electrons, the intra-4f emission spectra of REE that induce sharp and narrow wavebands.