Color Tuning from Greenish-Yellow to Orange-Red in Thermal-Stable KBaY(MoO₄)₃:Dy³⁺, Eu³⁺ Phosphors via Energy Transfer for UV W-LEDs

Abstract

In this report, a series of tunable-emitting KBaY(MoO 4 ) 3 :Dy 3+ , Eu 3+ (KBYMO:Dy 3+ , Eu 3+ ) phosphors were synthesized via a Pechini-type sol−gel reaction approach. XRD and Rietveld refinement results confirm the pure phase of as-prepared materials. Upon 351 nm excitation, the optimal sample KBYMO:0.05Dy 3+ shows its two main characteristic emission bands around 488 and 573 nm, which correspond to Dy 3+ transitions 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 , respectively, in addition to a weak band around 660 nm originating from Dy 3+ 4 F 9/2 → 6 H 11/2 transition. In the excitation spectrum monitored at 573 nm, it is worth noting that there are two excitation peaks at 365 and 453 nm, matching with commercial LED chips. With the addition of Eu 3+ into KBYMO:0.05Dy 3+ , the energy transfer from Dy 3+ to Eu 3+ is elucidated, resulting in the tunable emission color from greenish-yellow to orange-red with increasing Eu 3+ content upon a 365 nm UV lamp excitation, which can be proved by analyzing the profiles of the excitation and emission spectra of Dy 3+ , Eu 3+ codoped KBYMO and the decay times of Dy 3+ . The energy-transfer mechanism is determined to be a quadrupole−quadrupole interaction according to Dexter theory and Reisfield's approximation. Moreover, the temperaturedependent luminescence property of representative KBYMO:0.05Dy 3+ , 0.10Eu 3+ is evaluated, which presents an emission intensity maintenance of 82.8% at 423 K relative to room temperature 298 K, showing its good performance. These results indicate that the as-prepared KBYMO:Dy 3+ , Eu 3+ phosphors may be a candidate component applied in UV w-LEDs.

Ratiometric Optical Thermometry in Lanthanide-Doped Molybdate Phosphors via Construction of Diverse Charge-Transfer Bands

“…Since then, more and more scholars have conducted research on rare earth ion-doped KBaRE­(MoO 4 ) 3 (RE = Gd and Y) phosphors. Wang et al synthesized the KBaRE­(MoO 4 ) 3 (RE = Gd and Y)-doped Nd 3+ phosphor with a high-temperature solid-phase method and measured its crystal parameters, showing that its spatial group is the C 2/ c monoclinic system, proving that other ions can be introduced into this host without significant changes in the ionic radius of the matrix material. , Subsequently, on the basis of this theory, Kai Li proposed a series of KBaY­(MoO 4 ) 3 :Tb 3+ ,Eu 3+ ,Sm 3+ /Dy 3+ ,Eu 3+ phosphors, and their applications in white light-emitting diode (WLED) were explored, , but few people have systematically studied the possibility of this phosphor in FIR temperature measurement, so based on this research, we successfully synthesized KBaY­(MoO 4 ) 3 :Tb 3+ ,Eu 3+ phosphors, in which the temperature-insensitive rare earth ion Eu 3+ is used as a reference signal and Tb 3+ , which has poor thermal quenching capacity, is used as a temperature sensor signal. Using its different thermal response signals, a practical dual-emission strategy was constructed and the sensitivity of temperature measurement is successfully improved.…”

A Study on the Anti-thermal Dy3+/Eu3+ Co-doped BaLa4Si3O13 Red Phosphors for White-Light-Emitting Diodes and Optical Thermometry Applications

“…The monitored and excitation wavelength is set at 575 and 350 nm, respectively. All the decay curves can be well fitted by a single-exponential decay function: where I ( t ) is the emission intensity at time t , I 0 is the initial emission intensity, and τ is the decay time. The fitted decay times are 0.51, 0.46, 0.41, 0.33, 0.27, and 0.18 ms for the 1, 3, 5, 7, 9, and 11 mol % Dy 3+ doped BaLa 4 Si 3 O 13 phosphors, respectively.…”

Effect of Bi2+ ions on the photoluminescence properties of BaTiO3:Dy3+ perovskite phosphors for LEDs application

“…2. The (Ba 1-x Bi 0.01 )TiO 3 :xDy 3+ shows thick absorption band in UV-Vis region due to host absorption and also accounts for the charge transfer band between Dy 3+ ions and O 2ions [14]. The charge transfer phenomenon is effected as the consequence of O-2p electron transition to 4f orbital of Dy 3+ ion the empty shell [15].…”