Synthesis, characterization and formation mechanism of Gd₂O₂S:Pr³⁺,Ce³⁺ phosphors by sealed triple-crucible method

Abstract

Ln(NO 3) 3 • 6H 2 O (Ln = Gd, Pr and Ce), urea, sodium sulfite (Na 2 SO 3) and carbon powder were used as the starting materials. The precursor was synthesized with Ln(NO 3) 3 • 6H 2 O (Ln = Gd, Pr and Ce) solutions and urea at 95 °C for 4 h, and then the Gd 2 O 2 S:Pr 3+ ,Ce 3+ phosphors were prepared by calcined the precursor (in inner crucible), Na 2 SO 3 (in middle crucible) and carbon powder (in outer crucible) at 1000 °C for 2 h in a sealed environment. The X-ray powder diffraction (XRD) results confirm that the as-synthesized Gd 2 O 2 S phase has high purity and without the presence of any impurities. The field emission scanning electron microscopy (FE-SEM) inspection shows the morphology of Gd 2 O 2 S:Pr 3+ ,Ce 3+ is hexagonal in shape and about 1 μm in size. The photoluminescence (PL) spectra under 301 nm ultraviolet (UV) light excitation shows a strong green emission at 513 nm. The quenching concentration occurs at Pr 3+ ions concentration of 0.2% and its corresponding Commission Internationle de L'Eclairage (CIE) coordinates is (0.0273, 0.7921). The decay lifetimes are τ 1 = 0.248 μs and τ 2 = 1.824 μs for the Gd 2 O 2 S:0.2%Pr 3+ ,Ce 3+ phosphor. The Gd 2 O 2 S:0.2%Pr 3+ ,Ce 3+ phosphor film has excellent performance in the light utilization and the charge-transfer capability under 270 nm UV light radiation.

Near‐Infrared Luminescent Materials Incorporating Rare Earth/Transition Metal Ions: From Materials to Applications

“…[ 21 ] also reported that the introduction of an appropriate amount of flux H 3 BO 3 was helpful to the enhancement of the fluorescence intensities of CaAl2O 4 : Eu 2+ , and Nd 3+ ; moreover, Sang et al. [ 22 ] showed a high‐temperature solid‐phase method using Ln(NO 3 ) 3 ‐6H 2 O (Ln = Gd, Pr, Ce), urea, sodium sulfite (Na 2 SO 4 ) and carbon powder as raw materials, and improved the traditional high‐temperature solid‐phase method by introducing the precipitation method to prepare the precursor, and then synthesized Gd 2 O 2 S: Pr 3+ , Ce 3+ phosphors by the sealed three‐crucible method, which not only prevented the carbon contamination but also improved the luminescence performance of the phosphors.…”

“…[19] For the high-temperature solid-phase method, temperature, pressure, charge compensator, and flux are important indicators that affect the luminescence properties of the materials. For example, Yang et al [20] found that the luminescence intensity of Sr 2 CeO 4 : Eu 3+ was enhanced with the increase of calcination temperature in the range of 900-1100 °C; Teng et al [21] also reported that the introduction of an appropriate amount of flux H 3 BO 3 was helpful to the enhancement of the fluorescence intensities of CaAl2O 4 : Eu 2+ , and Nd 3+ ; moreover, Sang et al [22] showed a high-temperature solid-phase method using Ln(NO 3 ) 3 -6H 2 O (Ln = Gd, Pr, Ce), urea, sodium sulfite (Na 2 SO 4 ) and carbon powder as raw materials, and improved the traditional hightemperature solid-phase method by introducing the precipitation method to prepare the precursor, and then synthesized Gd 2 O 2 S: Pr 3+ , Ce 3+ phosphors by the sealed three-crucible method, which not only prevented the carbon contamination but also improved the luminescence performance of the phosphors.…”