Abstract: The Tb³⁺-doped zinc phthalate (ZnPht:Tb) phosphor was prepared by the solid phase reaction of zinc oxide and phthalic anhydride in the saturated water vapor
at 80～100℃. The crystal structure, emission and excitation spectra were determined. The dependence of the fluorescent spectrum properties on the Tb³⁺
ion concentration was investigated. The energy transfer mechanism from π,π* and n,π* excited states of Pht^2- radical to ⁵D₄ energy level of Tb³⁺
ion was revealed: (1) S₁(π,π*, n,π*)→(⁵H_j,⁵L_j)→⁵D₃→ T₁(π,π*, n,π*)→⁵H₄; (2) S₁(π,π*, n,π*)→ T₁(π,π*, n,π*)→⁵H₄.

Key words: phthalic acid, zinc salt, terbium, phosphor