CaWO4:Smx(x=0, 0.5, 1.0, 1.5, 2.0mol%) white phosphors with different concentrations of Sm3+ ions weresynthesized using the hydrothermal method. The crystal structure, surface, and optical properties of the CaWO4:Smphosphors were investigated using X-ray diffraction(XRD), field-emission scanning electron microscopy(FE-SEM),photoluminescence(PL) and photoluminescence excitation(PLE). From the XRD results, the crystal structure of theCaWO4:Sm phosphors was found to be tetragonal. The CaWO4:Sm phosphors became more cohesive with increasing Sm3+-ion concentration. The photoluminescence excitation(PLE) peak of the phosphors, at around 250nm, was ascribed to thetransition from the 1A1 ground-state to the high-vibration level of 1T2 in the WO42− complex. The maximum emissionspectra of the phosphors were observed when the Sm3+ concentration was 0.5mol%. The luminescence intensity of theCaWO4 phosphors was decreased for Sm3+ concentrations greater than 0.5mol%.

Red phosphors Ca1-1.5xWO4:Eux3+ were synthesized with different concentrations of Eu3+ ions by using a solid-statereaction method. The crystal structure of the red phosphors was found to be a tetragonal system. X-ray diffraction (XRD) resultsshowed the (112) main diffraction peak centered at 2θ=28.71o, and the size of crystalline particles exhibited an overalldecreasing tendency according to the concentration of Eu3+ ions. The excitation spectra of all the phosphors were composedof a broad band centered at 275nm in the range of 230-310nm due to O2−→W6+ and a narrow band having a peak at 307nmcaused by O2−→Eu3+. Also, the excitation spectrum presents several strong lines in the range of 305-420nm, which areassigned to the 4f-4f transitions of the Eu3+ ion. In the case of the emission spectrum, all the phosphor powders, irrespectiveof Eu3+ ion concentration, indicated an orange emission peak at 594nm and a strong red emission spectrum centered at 615nm,with two weak lines at 648 and 700nm. The highest red emission intensity occurred at x=0.10mol of Eu3+ ion concentrationwith an asymmetry ratio of 12.5. Especially, the presence of Eu3+ in the Ca1-1.5xWO4:Eux3+ shows very effective use of excitationenergy in the range of 305-420nm, and finally yields a strong emission of red light.