Realizing a Novel Red-Emitting Ca 0.99 MoO 4 :0.01Eu 3+ , Al 3+ Phosphor: Charge Compensation, Molten Salt Synthesis

The red-emitting Ca 0.99 Mo 1 – x Al x O 4 :0.01Eu 3+ phosphors were synthesized by molten-salt synthesis (MSS) process at 700°C for 3 h using NaCl and KCl as the reaction medium. The phase compositions and luminescent properties of the obtained Ca 0.99 Mo 1 – x Al x O 4 :0.01Eu 3+ phosphors were well investigated by X‑ray powder diffraction (XRD), transmission electron microscope (TEM), photoluminescence excitation (PLE), and emission (PL) spectra. The TEM studies revealed that the morphologies of phosphors are sphere-like and cube-like with sizes from 210 to 260 nm. In the PLE spectra, the PLE peaks at 395 and 465 nm well matches with the near ultraviolet (NUV) or blue wavelengths. The strongest PL peak was caused by 5 D 0 → 7 F 2 electric dipole transition in the PL spectra. Additionally, the effect of Al 3+ concentrations on PL properties for Ca 0.99 Mo 1 – x Al x O 4 :0.01Eu 3+ was investigated in detail. The results demonstrated that the PL intensity increases with the increase in Al 3+ concentration till reaching a maximum value at 7 mol %. The PL intensity of the Ca 0.99 Mo 0.93 Al 0.07 O 4 :0.01Eu 3+ is 2.74 times than that of the Ca 0.99 MoO 4 :0.01Eu 3+ . The CIE chromaticity coordinates for Ca 0.99 Mo 1 – x Al x O 4 :0.01Eu 3+ phosphors are located in the red region, and the value of color purity for Ca 0.99 Mo 0.93 Al 0.07 O 4 :0.01Eu 3+ is determined to be about 94.17%. Therefore, the above obtained results suggested that the samples possess potential application value in the field of white light emitting diodes (WLEDs).