Effect of 6 MeV electrons on luminescence properties of Y₂O₃:Tb³⁺ nanophosphors

Y₂O₃:Tb³⁺ nanophosphors were synthesized by solution combustion technique and irradiated with 6 MeV energetic electrons in the fluence range 2-10×10¹³ e^-cm^-2. Powder X-ray diffraction (PXRD) patterns confirm cubic phase of Y₂O₃. The crystallite size was estimated using Scherrer method and was found to be in the order of ~39 nm. SEM micrographs revealed the formation of non-uniform spherical shaped particles for higher electron fluence. Photoluminescence spectra (PL) of pristine and Tb³⁺ doped Y₂O₃ were recorded in the fluence range 2-10×10¹³ e^-cm^-2. PL intensity was found to increase up to 4×10¹³ e^-cm^-2 and thereafter it decreases with further increase in electron fluence. This may be attributed to lattice disorder produced by dense electronic excitation under electron irradiation. The characteristic emission peaks of Tb³⁺ were observed at ~ 484-490 nm (⁵D₄→⁷F₆), 548 nm (⁵D₄→⁷F₅) and 587 nm (⁵D₄→⁷F₄) at excited wavelength 397 nm. Two TL glow peaks were recorded in both pristine and electron irradiated samples indicate that two types of traps were created. The color co-ordinate values (x, y) were located in the green region of the CIE diagram suggests that electron irradiated Y₂O₃:Tb³⁺ phosphor could be used in white LEDs.