Investigation of the Fabrication Parameters Affecting the Cathodoluminescence Property of ZnAl_2O_4:Mn Green Phosphors

摘要

We investigated systematically the effects of fabrication parameters on the luminescent property of ZnAl_2O_4:Mn phosphor, which emits a highly chromatic pure green light. The samples used were synthesized in the air at 1200℃ by a solid phase method using ZnO, α-Al_2O_3, and MnCl_2 or MnCO_3 powders, followed by thermal treatment in a reducing atmosphere at temperatures (T_r) from 800 to 1200℃. We confirmed that the cathodoluminescence (CL) property of the as-synthesized sample strongly depends on the molar ratio of Zn and Al atoms in the source (R_(Zn/Al)- Namely, intense CL was observed only from the samples synthesized from the source with R_(Zn/Al)< 0.5, indicating that the Zn-deficient conditions are favorable for Mn impurities to be incorporated into the Zn site of ZnAl_2O_4. More importantly, it is suggested from the T_r dependence of CL that most of the Mn impurities in the samples synthesized under the Zn-deficient conditions are in the state of the divalent ions even without a reduction treatment.