A tunable blue to blue-white SrGa2O4 phosphor was prepared with a solid-state reaction method by varying the composition concentration of source materials. The decomposition temperature and weight loss of Ga2O3 and SrCO3 were evaluated by thermogravimetric analysis. The deficiency of Ga in SrGa2O4 phosphor can be compensated by increasing the molar ratio of Ga2O3 / SrCO3. Photoluminescence measurements show that Ga is the luminescence center of strontium gallate phosphor. When the molar ratio of Ga2O3 / SrCO3 is 1, the emission wavelength of SrGa2O4 phosphor is similar to 402 nm, which is referred to the T-4(1) --> (4)A(2) transition of electrons in Ga d orbits. Crystallization of SrGa4O7 was observed as the phosphor was prepared at a higher molar ratio of Ga2O3 / SrCO3. The ligand field and the electron transferring mechanism in Ga will be modulated by the development of SrGa4O7. Thus, the emission wavelength of phosphor is altered from 402 to 430 nm where the electron is transferred from T-4(2A) exciting state to (4)A(2) ground state while the emission spectrum is broadened. (C) 2004 The Electrochemical Society.