EPR and luminescence properties of LiGa5O8:Mn green emitting phosphor

Green emitting LiGa5O8:Mn powder phosphor has been prepared in a short time by solution combustion method. Powder X-ray diffraction pattern indicated a dominant phase of LiGa5O8 with another secondary LiGaO2 phase. Morphology aspects were studied by using field emission scanning electron microscopy. Upon UV light excitation (296 nm), the phosphor exhibits a strong green luminescence (510 nm), which corresponds to the 4T1→6A1 transition of Mn2+ ions in an environment close to tetrahedral symmetry. EPR spectrum exhibits resonance signals characteristic of Mn2+ ions. It is observed that the spin-Hamiltonian parameters g and A do not vary with temperature. The magnitude of the hyperfine splitting constant (A) in the present study indicates that there exists a moderately covalent bonding between Mn2+ ions and the surrounding ligands. The zero-field splitting parameter (D), spin concentration (N) and paramagnetic susceptibility (χ) have also been evaluated.