A study on cathodoluminescent properties of carbon nanotube-ZnGa₂O₄

Abstract

Cathodoluminescent properties of carbon nanotube(CNT)-ZnGa₂O₄ : Mn^(2+) phosphor composites were investigated. Different concentrations of CNT were coated in ZnGa₂O₄ : Mn^(2+) phosphors particle surface. X-ray diffraction (XRD) patterns showed a single phase, CNT did not affect the phosphor structure. The existence of CNTs on the phosphor particles were confirmed by obtained Raman spectra. As increase of CNTs in the ZnGa₂O₄ : Mn^(2+) phosphor, its photoluminescent intensity was continuously decreased whereas its cathodoluminescent intensity was increased. The CNT-ZnGa₂O₄ : Mn^(2+) phosphor composites emission peaking at about 505 nm. The optimal concentration of CNTs in the CNT-ZnGa₂O₄ : Mn^(2+) phosphor composite was 0.9 wt.%. It can be explained in terms of two competing factors :（1) Increased conductivity of ZnGa₂O₄ : Mn^(2+) phosphor resulting in the decrease of charging effect on the phosphor particle surface, and (2) decreased transparency from the CNTs' black-color absorption of lights.