Two types of Tb- and Na-substituted green phosphors Ca(1-1.5x)WO4: and Ca(1-2x)WO4: weresynthesized with various x values, using a solid-state reaction. The former phosphors contained both substitutional and vacancypoint defects, while the later had only substitutional defects. X-ray diffraction results showed that the main diffraction peak,(112), was centered at 2θ=28.72o and indicated that there was no basic structural deformation caused by substitutions orvacancies. The photoluminescence emission and photoluminescence excitation spectra revealed the optical properties of trivalentterbium ions, Tb3+. Typical transitions, 5D3→7F6, 7F5, 7F4 and 5D4→7F6, 7F5, 7F4, 7F3, and cross relaxations were observed.Subtle differences in the photoluminescence of green phosphors were observed as a result of the point defects. The FT-IRspectra indicated that some of the ungerade vibrational modes had shifted positions and changed shapes, spreading out overa wide range of frequencies. This change can be attributed to the different masses of Tb3+ and Na+ ions and VCa" vacanciescompared to Ca2+ ions. The gerade normal modes of the Raman spectra exhibited subtle differences resulting from point defectsin Ca(1-1.5x)TbxWO4 and Ca(1-2x)TbxNaxWO4.

Red-orange phosphors Gd1-xPO4:Eux3+ (x=0, 0.05, 0.10, 0.15, 0.20) were synthesized with changing theconcentration of Eu3+ ions using a solid-state reaction method. The crystal structures, surface morphology, and optical propertiesof the ceramic phosphors were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), andphotoluminescence (PL) spectrophotometry. The XRD results were in accordance with JCPDS (32-0386), and the crystalstructures of all the red-orange phosphors were found to be a monoclinic system. The SEM results showed that the size ofgrains increases and then decreases as the concentration of Eu3+ ionincreases. As for the PL properties, all of the ceramicphosphors, irrespective of Eu3+ ion concentration, had orange and red emissions peaks at 594nm and 613nm, respectively. Themaximum excitation and emission spectra were observed at 0.10mol of Eu3+ ion concentration, just like the grain size. Anorange color stronger than the red means that 5D0→7F1 (magnetic dipole transition) is dominant over the 5D0→7F2 (electricdipole transition), and Eu3+ is located at the center of the inversion symmetry. These properties contrasted with those of a redphosphor Y1-xPO4:Eux3+, which has a tetragonal system. Therefore, we confirm that the crystal structure of the host materialhas a major effect on the resulting color.