A novel strategy for controllable emissions from Eu3+ or Sm3+ ions co-doped SrY2O4:Tb3+ phosphors

Abstract

Trivalent rare-earth (RE) ions (Eu³⁺, Tb³⁺ and Sm³⁺) activated multicolor emitting SrY₂O₄ phosphors were synthesized by a sol–gel process. The structural and morphological studies were performed by the measurements of X-ray diffraction profiles and scanning electron microscope (SEM) images. The pure phase of SrY₂O₄ appeared after annealing at 1300 °C and the doping of RE ions did not show any effect on the structural properties. From the SEM images, the closely packed particles were observed due to the roughness of each particle tip. The photoluminescence (PL) analysis of individual RE ions activated SrY₂O₄ phosphors exhibits excellent emission properties in their respective regions. The Eu³⁺ co-activated SrY₂O₄:Tb³⁺ phosphor creates different emissions by controlling the energy transfer from Tb³⁺ to Eu³⁺ ions. Based on the excitation wavelengths, multiple (green, orange and white) emissions were obtained by Sm³⁺ ions co-activated with SrY₂O₄:Tb³⁺ phosphors. The decay measurements were carried out for analyzing the energy transfer efficiency and the possible ways of energy transfer from donor to acceptor. The cathodoluminescence properties of these phosphors show similar behavior as PL properties except the energy transfer process. The obtained results indicated that the energy transfer process was quite opposite to the PL properties. The calculated CIE chromaticity coordinates of RE ions activated SrY₂O₄ phosphors confirmed the red, green, orange and white emissions.