Photoluminescence properties of Eu³⁺-activated CaMoO₄ phosphors for WLEDs applications and its Judd–Ofelt analysis

A series of scheelite-type Eu³⁺-activated CaMoO₄ phosphors were synthesized by the nitrate–citrate gel combustion method. All the compounds crystallized in the tetragonal structure with space group I4 ₁ /a (No. 88). FESEM results reveal the spherical-like morphology. The CaMoO₄ phosphor exhibited broad emission centered at 500 nm under the excitation of 298 nm wavelength, while Eu³⁺-activated CaMoO₄ shows an intense characteristic red emission peak at 615 nm at different excitation wavelengths, due to ⁵D₀ → ⁷F₂ transition of Eu³⁺ ions. The intensities of transitions between different J levels depend on the symmetry of the local environment of Eu³⁺ ions and were estimated using the Judd–Ofelt analysis. The high asymmetric ratio revealed that Eu³⁺ occupies sites with a low symmetry and without an inversion center. The CIE chromaticity co-ordinates (x, y) were calculated from emission spectra, and the values were close to the NTSC standard. Therefore, the present phosphor is highly useful for LEDs applications.