Photoluminescence of titanium-doped zinc spinel blue-emitting nanophosphors

Structure and Photoluminescence Properties of Sm3+ Ion-Doped YInGe₂O₇ Phosphor

A new phosphor, Sm³⁺ ion-doped YInGe₂O₇, was synthesized using a planetary ball mill solid state reaction. The XRD patterns show that all of the peaks can be attributed to the monoclinic YInGe₂O₇ crystal structure when the Sm³⁺ ion concentration is increased up to 20 mol %. Under an excitation wavelength of 404 nm, the Sm³⁺ intra-4f transition appears in the emission spectrum including two stronger emission peaks located at 560–570 nm and 598 nm correspond to the ⁴G_5/2 → ⁶H_5/2 and ⁴G_5/2 → ⁶H_7/2 transitions, respectively, and another weak emission peak located at 645 nm is due to the ⁴G_5/2 → ⁶H_9/2 transition. The decay time decreases from 4.5 to 0.8 ms as Sm³⁺ ion concentrations increase from 1 to 20 mol %, and the decay mechanism of the ⁴G_5/2 → ⁶H_7/2 transition is a single decay component between Sm³⁺ ions only. The concentration quenching effect occurs when the Sm³⁺ ion concentration is higher than 3 mol %. The CIE color coordinate of Y_0.97Sm_0.03InGe₂O₇ phosphor is at x = 0.457 and y = 0.407, which is located in the orange-yellow light region.

Photoluminescence properties of LiTi2 - x Eux (PO4 )3 phosphor

A solid-state reaction route-based LiTi_2 - x Eu_x (PO₄ )₃ was phosphor synthesized for the first time to evaluate its luminescence performance by excitation, emission and lifetime (τ) measurements. The LiTi_2 - x Eu_x (PO₄ )₃ phosphor was excited at λ_exci.  = 397 nm to give an intense orange-red (597 nm) emission attributed to the ⁵ D₀  → ⁷ F₁ magnetic dipole (ΔJ = ±1) transition and red (616 nm) emission (⁵ D₀  → ⁷ F₂ ), which is an electric dipole (ΔJ = ±2) transition of the Eu³⁺ ion. Beside this, excitation and emission spectra of host LiTi₂ (PO₄ )₃ powder were also reported. The effect of Eu³⁺ concentration on luminescence characteristics was explained from emission and lifetime profiles. Concentration quenching in the LiTi_2 - x Eu_x (PO₄ )₃ phosphor was studied from the Dexter's model. Dipole-quadrupole interaction is found to be responsible for energy transfer among Eu³⁺ ions in the host lattice. The LiTi_2 - x Eu_x (PO₄ )₃ phosphor displayed a reddish-orange colour realized from a CIE chromaticity diagram. We therefore suggest that this new phosphor could be used as an optical material of technological importance in the field of display devices. Copyright © 2016 John Wiley & Sons, Ltd.