Effect of processing conditions on crystallinity and luminescent characteristics of aeschynite-type complex oxide crystals doped with Dy3+ and Eu3+

摘要

Effect of processing conditions on the crystallinity and luminescent characteristics of aeschynite-type Dysup3+/sup- and Eusup3+/sup-doped GdTiNbOsub6/sub formed under hydrothermal conditions from precursor solutions of inorganic salts, i.e. Dy(NOsub3/sub)sub3/sub, EuClsub3/sub, GdClsub3/sub, TiOSOsub4/sub, and NbClsub5/sub was investigated. A processing condition using the hydrolysis of urea promoted the formation of aeschynite with finer crystallite due to an increase in nucleation number. The aeschynite-type solid solution was directly formed under hydrothermal conditions at 240°C because its lattice parameters changed according to the Vegard’s Law. The photoluminescence (PL) emission intensity of aeschynite crystals depended on their crystallinity, which was closely related to their processing conditions. Without subsequent heat treatment in air, the as-prepared aeschynite-type solid solutions substitutionally doped with 5 mol % Dysup3+/sup and 50 mol % Eusup3+/sup showed the maximum and intense PL emissions under direct excitation of dopant ions. In the case of indirect excitation using energy transfer from the host absorption band at 280 nm, the characteristic blue and yellow PL emission intensities involved in the broad host emission of the Dysup3+/sup-doped GdTiNbOsub6/sub were improved dramatically after heating at 1300°C in air.