Investigation of red-emitting CaMoO: Eu phosphor by partitioning of substitutional PO ions via solid-state reaction method.

To investigate the impact of PO anionic groups, the trivalent europium ion-doped calcium molybdate (CaMoO-PO:xEu, where x = 0.5, 1.0, 1.5, 2.0, and 2.5 mol%) phosphors were synthesized using the solid-state reaction method. The detailed study of the phosphor materials was carried out by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), optical diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The XRD results indicate that the substitution of PO anion and Eu dopant ion did not affect the crystal structures of the CaMoO phosphors. Ultraviolet-visible (UV-vis) absorption analysis revealed the change of absorption edge of both un-doped and Eu-doped CaMoO-PO phosphors. Under the 394 nm UV-excitation, the recorded PL spectra showed an intense peak at 615 nm corresponding to the Eu: D → F transition. The results of the Commission Internationale de l'Eclairage (CIE) diagram reported that the color of the emissions lies in the red color zone and there is no change in the CIE coordinates of the overall emission for Eu-doped CaMoO-PO as Eu concentration changes. Thus, these observations led to finding the best red components for white light-emitting diode applications.