Intrinsic- and Rare Earth Ion-Activated Luminescence in NbAlO 4 with Wide Structure Channels.

Compounds with ordered and interconnected channels have versatile multifunctional applications in technological fields. In this work, we report the intrinsic- and Eu 3+ -activated luminescence in NbAlO 4 with a wide channel structure. NbAlO 4 is an n-type semiconductor with an indirect allowed transition and a band-gap energy of 3.26 eV. The conduction band and valence band are composed of Nb 3d and O 2p states, respectively. Unlike the common niobate oxide Nb 2 O 5 , NbAlO 4 exhibits efficient self-activated luminescence with good thermal stability even at room temperature. The AlO 4 tetrahedron effectively blocks the transfer/dispersion of excitation energy between NbO 6 chains in NbAlO 4 , allowing for effective self-activated luminescence from NbO 6 activation centers. Moreover, Eu 3+ -doped NbAlO 4 displayed a bright red luminescence of 5 D 0 → 7 F 2 transition at 610 nm. The site-selective excitation and luminescence of Eu 3+ ions in a spectroscopic probe were utilized to investigate the doping mechanism. It is evidenced that Eu 3+ is doped in the structure channel in NbAlO 4 lattices, not in the normal cation sites of Nb 5+ or Al 3+ . The experimental findings are valuable in developing new luminescent materials and improving the understanding of the material's channel structure.