Dysprosium-Doped Glass-Ceramics From the System Na₂O-Al₂O₃-SiO₂-B₂O₃-Dy₂O₃

Glasses from the system Na₂O-Al₂O₃-SiO₂-B₂O₃-Dy₂O₃ are prepared with three different concentrations of the Dy³⁺ ion-0.5, 1, and 2 at%. Glass-ceramics are obtained after thermal treatment of the parent glass at 580°С and 630°С during 2, 5, and 24 h. The crystallizing phases, the crystallinity degree, and the nano crystalline size are determined. The crystallizing phases after thermal treatment are NaAlSiO₄ in two different modifications and Na₃B₃O₆. XRD analyses show the presence of third unknown phase in some samples. Emission and excitation spectra of the glass-ceramics show the characteristic peaks of Dy³⁺ (⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_11/2 at 483, 575, and 668 nm, respectively). The yellow peak is dominating in all samples. The spectra show different intensity depending on the Dy³⁺ concentration, temperature, and time of the thermal treatment. This result suggests that the emission color can be controlled by these three factors.