Synthesis and luminescence properties of CaMoO₄:Sm³⁺ phosphors for orange photonic materials

The series of CaMoO₄ samples with different melting temperature (600, 700, 800 and 900°C) were synthesized in this work to investigate their phase structures by X-ray diffraction (XRD). The XRD result confirmed that the crystalline structures of the phosphors were obtained at 800°C (tetragonal structure with I41/a space group). Then, the series of Ca_1-xMoO₄:Sm_x (where x = 0.005, 0.010, 0.015, 0.020, 0.025 and 0.030) were prepared by solid-state reaction method to study their luminescence properties. The absorption spectra, recorded in UV, Vis and NIR regions, showed peaks at 405, 465, 952, 1096, 1252, 1405, 1513, 1573 and 1629 nm. The excitation spectra, observed with 644 nm emission wavelength, showed the excitation peaks at 364, 377, 405, 419, 440, 481, 530 and 562 nm. The highest peak located at 405 nm corresponding to the ⁶H_5/2→⁶P_3/2 transition. The emission spectra, excited with 405 nm excitation wavelength, showed the emission peaks at 563, 605 and 644 nm, assigned as ⁴G_5/2→⁶H_5/2, ⁶H_7/2 and ⁶H_9/2 transitions, respectively. The concentration quenching of Sm³⁺ in the Ca_1-xMoO₄:Smx phosphor occurred when x = 0.010. The emitted light of the phosphors, analyzed in the framework of the CIE 1931 color space, were shown in orange region.