Mild hydrothermal formation and comparative coprecipitation route for EuTiNbO6 fine phosphor

Aeschynite-type EuTiNbO6 fine phosphor with sufficient luminescence intensity was directly formed as homogeneous cuboid particles with high crystallinity in the range of 1-2 μm from precursor solution mixtures of EuCl3, TiOSO4, and NbCl5 under weakly basic conditions via hydrothermal treatment at 240 °C for 5 h. The as-prepared aeschynite phase stably existed after heating at 1000-1400 °C for 1 h in air. Under excitation at wavelengths of 395 nm, among all samples before and after heating in air, the as-prepared EuTiNbO6 fine crystals before heating emitted luminescence with the highest intensity in the red spectral region with strong red and weak orange light corresponding to 5D0→7F2 and 5D0→7F1 transitions of Eu3+, respectively. The amorphous coprecipitation powder crystallized into euxenite-type phase at 700-1000 °C and transformed into aeschynite-type phase at 1000-1200 °C. High-temperature heating at 1400 °C was essential for the coprecipitation powder to obtain almost a single phase of aeschynite-type EuTiNbO6 and sufficient emission intensity.