The photoluminescence properties of f–f emission-type phosphors are strongly dependent on the electronic structure of the host materials. This study investigated in detail the relationship between the bandgap energy and the photoluminescence properties of Pr3+. CaTa2/3Mg1/3O3–CaTaO2N solid solutions, Ca3Ta3-xMgxO6+3xN3-3x (0.00 ≦ x ≦ 1.00), were chosen as the host material for the approach used herein. The bandgap energy level (Eg) for the Ca3Ta3-xMgxO6+3xN3-3x solid solutions was systematically changed from 2.7 to 5.1 eV by controlling the Mg/Ta and O/N ratios. The photoluminescence excitation and emission controls were systematically performed by engineering Eg for the samples. In the excitation spectra, the maximum photoluminescence excitation wavelength shifted to a shorter wavelength according to the Eg expansion. In the emission spectra, the red emission assigned to the 1D2–3H4 levels of Pr3+ in the samples with x = 0.25–0.50 could be excited at near-UV light regions (350 nm) when the Eg in the host materials was adjusted to approximately 3.0 eV. Conversely, several emissions, including a green emission belonging to the 3P0–3H4 levels of Pr3+, were observed when the Eg of the samples with x = 0.75–0.95 became larger than 3.0 eV. The results indicate that the photoluminescence properties of the f–f emission-type phosphors are attributed to the Eg in the host materials.

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