Versatile properties of CaGd₂ZnO₅:Eu³⁺ nanophosphor: Its compatibility for lighting and optical display applications

Red color-emitting CaGd₂ZnO₅:Eu³⁺ (CGZO:Eu³⁺) nanophosphors were synthesized by a facile sol-gel process. The structural and luminescent properties of these phosphors were investigated as a function of annealing temperature and Eu³⁺ ion concentration. The orthorhombic phase was confirmed at different annealing temperatures, showing an irregular morphology within the nanoscale range. Photoluminescence (PL) excitation spectra of CGZO:Eu³⁺ showed host absorption band (HAB), charge transfer band (CTB), and intense f-f transitions of Eu³⁺ in the violet and blue wavelength regions. The CTB intensity increased and the HAB intensity decreased with increasing annealing temperature or Eu³⁺ ion concentration. The CGZO:Eu³⁺ exhibited a strong absorption in the blue region as compared to the CTB and had a superior property compared to available commercial phosphors. This feature facilitates the fabrication of high color rendering index white light-emitting diodes for display systems. In PL spectra, an intense red emission was observed due to the hypersensitive ⁵D₀→⁷F₂ transition with good asymmetry ratio and chromaticity coordinates. Optimized annealing temperature and concentration of Eu³⁺ ions were observed for CGZO host lattice based on the 466 nm excitation wavelength. The cathodoluminescent properties were also similar to the PL results.