The investigations on photoluminescence and cathodoluminescence reveal that phosphor ${\text{Ca}}_6{\text{Gd}}_{1.5}{\text{Tb}}_{0.5}{\text{Na}}_2{\left({\text{PO}}_4\right)}_6{\text{F}}_2$ (CGPF-Tb) shows an intense green emission. Under the same conditions, the relative luminance of this phosphor is about 62%, 127%, and 71% of that of commercial phosphor ${\text{Zn}}_2{\text{SiO}}_4:\text{Mn}$ (ZSM) under 147 and 172 nm vacuum ultraviolet (VUV) light, and $2.5\text{\hspace{0.17em} kV}/100\mu \text{A \hspace{0.17em}}{\text{cm}}^{-2}$ cathode ray excitation, respectively. A shorter luminescence decay time $\left({\tau }_{1/10}\sim 6.1\text{\hspace{0.17em} ms}\right)$ makes it more suitable for displays application than ZSM. Hence CGPF-Tb is a promising candidate as a green-emitting component for applications in plasma display panels and field emission displays.