Hydrothermal synthesis of lanthanide（hydr）oxide micro/nanorods in presence of tetrabutylammonium hydroxide

Uniform and well-defined lanthanide hydroxide and oxide micro/nanorods Ln（OH）_3（Ln=La, Pr, Sm, Eu, Gd, Er） and Gd（OH）_3：Eu^（3＋）, Gd_2O_3：Eu^（3＋） were successfully synthesized through a green and facile hydrothermal method. Tetrabutylammonium hydroxide（TBAH） and lanthanide nitrides were used as the hydrothermal precursors without the addition of any templates/surfactants. The products were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, high-resolution transmission electron microscopy（HRTEM） and photoluminescence（PL） spectra. The result demonstrated that lanthanide hydroxide micro/nanorods with 20–80 nm in diameter and 50–450 in length were obtained. The size of the Ln（OH）_3（Ln=La, Pr, Sm, Eu, Gd, Er） rods increased with the increase of the atomic number. The size of the Gd（OH）_3：Eu^（3＋） rods decreased with the increase of p H value by modulating the amount of the TBAH solution. The as-formed product via the hydrothermal process, Gd（OH）_3：Eu^（3＋）, could be transformed to Gd_2O_3：Eu^（3＋） with the same morphology and a slight shrinking in size after a post annealing process. It is a facial method to synthesize photoluminescent nanomaterial of Gd_2O_3：Eu^（3＋）. The Gd_2O_3：Eu^（3＋） microrods exhibited strong red emission corresponding to ^5D）0→^7F_2 transition（610 nm） of Eu^（3＋） under UV light excitation（257 nm）.