Synthesis and photoluminescence properties of novel yellow-emitting Ba₂Gd_5−xDy_xB₅O₁₇ phosphors

Single phase yellow-emitting Dy³⁺ ions doped Ba₂Gd₅B₅O₁₇ phosphors were synthesized by solid-state reaction technique at high temperature. The phase identification and photoluminescence properties of as-prepared phosphors were characterized by X-ray diffraction patterns, excitation and emission spectra, decay curves and temperature-dependent luminescence spectral measurements. Under 276 and 354 nm near-UV excitations, the studied phosphors exhibited two intense emission bands in blue (486 nm) and yellow (575 nm) regions due to the magnetic dipole (⁴F_9/2→⁶H_15/2) and electric dipole (⁴F_9/2→⁶H_13/2) transitions, respectively. The optimal doping concentration of Dy³⁺ ions was found to be x = 0.07 for Ba₂Gd_5−xDy_xB₅O₁₇ phosphors. Under 354 nm excitation, the color coordinates (x, y) of Ba₂Gd_4.93Dy_0.07B₅O₁₇ phosphor were located in the yellow region of Commission International de I-Eclairage 1931 diagram and hence it can be used as a potential yellow component in the fabrication of white light-emitting diodes. Furthermore, the decay curves were fitted to double-exponential function to find the excited state lifetimes of Dy³⁺ ions. Besides, the temperature-dependent luminescence measurements were made to explore the thermal stability and activation energy of the concentration-optimized Ba₂Gd_4.93Dy_0.07B₅O₁₇ phosphor. The results obtained from the present investigation were discussed in detail and compared with the similar reported literatures.