Low-voltage cathodoluminescence properties of green-emitting ZnAl ₂O₄:Mn²⁺ nanophosphors for field emission display

A low-cost ZnAl₂O₄:Mn²⁺ green nanophosphor for field emission display (FED) was successfully synthesized by the coprecipitation method and a two-step firing, firstly calcining at 1200 °C for 2 h in air and then annealing at 900 °C for 3 h in flowing NH ₃ gas. The effects of the preparation process and the Mn²⁺ concentration on optical properties of ZnAl₂O₄:Mn ²⁺ were investigated. The phase composition, particle morphology, photoluminescence (PL) spectra of the ZnAl₂O₄:Mn ²⁺ phosphor as well as low-voltage field emission properties of the FED device prepared by using the synthesized ZnAl₂O ₄:Mn²⁺ phosphor were examined. Similar to ZnGa ₂O₄:Mn²⁺, Mn²⁺-doped ZnAl ₂O₄ showed two green emission bands centered at 508 and 517 nm, respectively, which originate from ⁴T₁( ⁴G)→⁶A₁(⁶S) transitions of Mn²⁺ on T_d and O_h sites. The PL intensity reached the maximum at 0.5 at.% Mn²⁺. Under the low-voltage excitation, the FED device exhibited bright green emission, high voltage brightness saturation, and high color purity.