Investigations on green-emitting, Mn²⁺: BaAl₁₂O₁₉ phosphors obtained by solution combustion process

Manganese-doped BaAl₁₂O₁₉ green phosphor was prepared using a self-propagating (combustion) synthesis. Powder X-ray diffraction and scanning electron microscopy were used to characterize the as-prepared combustion product. A room temperature photoluminescence study shows an emission line at 513 nm corresponding to a transition from the upper ⁴T₁ → ⁶A₁ ground state of Mn²⁺ ions. The electron paramagnetic resonance (EPR) spectrum exhibits six line hyperfine structure at g = 1.981. From the EPR spectrum, the spin-Hamiltonian parameters have been evaluated. The g value indicates that the site symmetry around Mn²⁺ ions is distorted tetrahedral. The number of spins (N) participating in the resonance for g = 1.981 is measured as a function of temperature. The paramagnetic susceptibility (χ) is calculated from the EPR data at various temperatures. From the plot 1/χ versus T, the Curie constant (C) and Curie paramagnetic temperature (θ_p) have been evaluated and discussed.