The thesis attempts to investigate novel phosphors for the application in white light-emitting diode. Ce3+-, Eu2+- activated or Ce3+ and Mn2+ co-activated hosts with compositions of LiScSiO4, LiScSi2O6, NaScSi2O6, LiY9(SiO4)6O2, NaY9(SiO4)6O2, LiLa9(SiO4)6O2 and NaLa9(SiO4)6O2 were successfully synthesized by solid state method under reducing conditions, and characterized by X-ray powder diffraction, fluorescence, chromaticity and reflectance. The research is divided into four parts. The first part investigates Ce3+-activated phosphors of LiScSiO4, LiScSi2O6, NaScSi2O6, LiY9(SiO4)6O2 and NaY9(SiO4)6O2. The excitation spectral range of these phosphors range from 330 nm to 365 nm and the blue emissions range from 390 nm to 445nm region. With the unique features of the inherent d-f transition of Ce3+, the covalency effect and crystal field effect of host have great impact on the splitting of Ce3+ energy levels, and thus is tunable. The second part deals with the mechanism of energy transfer between Ce3+ and Mn2+ in Ce3+/Mn2+ co-activated NaY9(SiO4)6O2 and LiY9(SiO4)6O2, in which Ce3+ acts as a sensitizer and Mn2+ as an activator, and the PL intensity of Mn2+ can be extremely increased through energy transfer. Based on the analysis on the experimental results, the energy transfer mechanism has been determined to be a dipole-quadrupole type in NaY9(SiO4)6O2: Ce3+, Mn2+, and a dipole-dipole type in LiY9(SiO4)6O2: Ce3+, Mn2+, respectively. Furthermore, the extra doping of Tb3+ could enhance the contribution of green, and finally white light-emitting phosphors are formed. Eu2+-activated phosphors including NaScSi2O6:Eu2+, LiLa9(SiO4)6O2: Eu2+ and NaLa9(SiO4)6O2: Eu2+are described in the third part. Owing to d-f transition of Eu2+, the excitation and emission are both broad band. The excitation wavelength ranges from 346 nm to 378 nm in this series and the emission bands were found to situate in the yellow-green emitting region. NaScSi2O6: Ce3+, Eu2+ was expected to produce white light by coactivating Ce3+ and Eu2+, but found failed. Even though the luminescence and quantum efficiency of LiLa9(SiO4)6O2: Eu2+ and NaLa9(SiO4)6O2: Eu2+ are not superior, they has the advantage of excitation with longer wavelength. Finally, the investigation on thermal quenching of all phosphors reveals that the luminescence intensity of phosphors quenches dramatically as temperature rises, since the phonon energy will increase while the temperature rises, leading to smaller activation energy.