Warm white light generation from a single phase Dy³⁺ doped Mg₂Al₄Si₅O₁₈ phosphor for white UV-LEDs

Abstract

A series of Mg2-xAl4Si5O18:xDy(3+) (0 ≤x≤ 0.18) samples were synthesized, for the first time, by a solid state method both in a reducing atmosphere and in air. XRD, diffuse reflectance spectra, excitation spectra, emission spectra, decay times and thermal quenching were used to investigate the structure, photoluminescence, energy transfer and thermal properties. The results show that Mg2Al4Si5O18:Dy(3+) can efficiently absorb UV light and emit violet-blue light in the range of 400 to 500 nm from oxygen vacancies in the host as well as blue light (∼480 nm) and yellow light (∼576 nm) from the f-f transitions of Dy(3+). The emission intensities of the samples obtained under a reducing atmosphere are far superior to those of the samples obtained in air due to an efficient energy transition from oxygen vacancies in the host to Dy(3+). An analysis of the thermal quenching shows that the phosphor Mg2Al4Si5O18:Dy(3+) has excellent thermal properties. The emission intensities of typical samples synthesized in a reducing atmosphere and in air at 250 °C are 70% and 81% of their initial intensities at 20 °C, respectively. In addition, the emission colors of all of the samples are located in the white light region and the optimal chromaticity coordinates and Correlated Color Temperature are (x = 0.34, y = 0.33) and 5129 K, respectively. Therefore, these white Mg2Al4Si5O18:Dy(3+) phosphors could serve as promising candidates for white-light UV-LEDs.

A white-light emitting phosphor LuNbO4:Dy3+ with tunable emission color manipulated by energy transfer from NbO43− groups to Dy3+

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Photoluminescence properties of novel white phosphor of Dy3+-doped LaBSiO5 glass

“…The emission intensities of 4 F 9/2 -6 H 15/2 and 4 F 9/2 -6 H 13/2 transitions increase rapidly with the increasing of Dy 3 þ concentration, reaching a maximum value at 1%, and then decrease quickly with further increasing the Dy 3 þ ions concentration due to the concentration quenching. In general, a concentration quenching effect is caused by a non-radiative energy transfer process between the neighboring Dy 3 þ ions when the Dy 3 þ concentration reaches at a critical value [19]. The critical distance R c of Dy 3 þ ions is an important parameter for evaluating the photoluminescence properties and could be calculated using the critical concentration of the activator ion as follows [20]:…”

Dy3+ and Eu3+ complexes co-doped flexible composite nanofibers to achieve tunable fluorescent color

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