Novel SrGa[sub 2]O[sub 4] Phosphor for Tunable Blue-White Luminescence

Abstract

A tunable blue to blue-white SrGa 2 O 4 phosphor was prepared with a solid-state reaction method by varying the composition concentration of source materials. The decomposition temperature and weight loss of Ga 2 O 3 and SrCO 3 were evaluated by thermogravimetric analysis. The deficiency of Ga in SrGa 2 O 4 phosphor can be compensated by increasing the molar ratio of Ga 2 O 3 /SrCO 3 . Photoluminescence measurements show that Ga is the luminescence center of strontium gallate phosphor. When the molar ratio of Ga 2 O 3 /SrCO 3 is 1, the emission wavelength of SrGa 2 O 4 phosphor is ϳ402 nm, which is referred to the 4 T 1 → 4 A 2 transition of electrons in Ga d orbits. Crystallization of SrGa 4 O 7 was observed as the phosphor was prepared at a higher molar ratio of Ga 2 O 3 /SrCO 3 . The ligand field and the electron transferring mechanism in Ga will be modulated by the development of SrGa 4 O 7 . Thus, the emission wavelength of phosphor is altered from 402 to 430 nm where the electron is transferred from 4 T 2A exciting state to 4 A 2 ground state while the emission spectrum is broadened.

Synthesis and Luminescent Properties of Ce³⁺-Activated SrGa₂O₄ and Sr(Ga-Al)₂O₄

“…This crystalline system involves four independent constants, a, b, c, and£. Thus XRD pattern is considerably complex and may contain more than a hundred lines [6]. The XRD patterns of samples sintered at different temperatures were shown in Fig.…”

“…The electron in Ga ligand field could be transferred from the excited energy levels of 4 T 2B , 4 T 1 , 4 T 2A , and 2 E B to the ground state of 4 A 2 to release energy and emit light in region of UV and a further emission located at 520nm is ascribed to 2 E A → 4 A 2 as shown in Fig. 3 (a) [6]. When doped with Ce 3+ as the activator and co-doped with Li + as the charge compensator, a bright blue-green emission was observed.…”