Versatile properties of CaGd2ZnO5:Eu3+ nanophosphor: its compatibility for lighting and optical display applications
Abstract
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.