Photoluminescence of new Tb3+-intercalated octosilicates depending on phase transition caused by annealing

A new Tb³⁺-intercalated layered octosilicate (Tb-Oct) was prepared through protonation, exfoliation and intercalation processing. Photoluminescence of the Tb-Oct silicates dependant of phase transition has been investigated in detail. The emissions attributed to ⁵D₄-⁷F_J (J = 3, 4, 5, 6) transition of Tb³⁺were observed from the emission spectra of the as-prepared Tb-Oct silicates. After the as-prepared Tb-Oct silicates thermal treatment at 200 °C, all diffraction peaks disappeared, suggesting the collapse of layered structure. With the increase in the annealing temperature from 200 to 1000 °C, no diffraction peaks appeared in all the annealed samples. Photoluminescence spectra show that the green emission ascribed to ⁵D₄-⁷F₅ transition of Tb³⁺ markedly increased as the sample was annealed at 800 °C. However, this green emission disappeared while the sample was annealed at 400, 600, and 1000 °C, which may relate to actual surroundings of Tb³⁺ ions. That is, the amorphous phase formed at 800 °C is more favorable for the green emission of Tb³⁺.