Occupation site of Pr and luminescent properties in Pr-doped perovskite-type lithium ion-conducting oxides, A0.6Li0.3Ti0.5Ta0.5O3: Pr (A = Ca and Sr)

We investigated the lattice parameters and luminescent properties of Pr-doped perovskite-type lithium ion conductors with the nominal composition, A0.6 − 3x / 2PrxLi0.3Ti0.5Ta0.5O3 (A = Ca and Sr, 0 ≤ x ≤ 0.05). Ca0.6Li0.3Ti0.5Ta0.5O3: Pr showed the intense red emission corresponding to the f–f transition of Pr3+ (1D2 → 3H4) on the ultraviolet photo excitation with the energy corresponding to the band gap of host. In contrast, Sr0.6Li0.3Ti0.5Ta0.5O3: Pr exhibited blue-green and red emission on the excitation with blue light corresponding to the f–f transition of Pr3+ (3H4 → 3P2). It was found that these differences in luminescent properties primarily originate from the occupation site of Pr in these perovskite-type oxides.