Papers by Keyword: Europium

Abstract: The remediation of palm oil mill effluent (POME) presents a considerable hurdle for Malaysia’s palm oil mill, requiring fulfillment with the environmental regulations before discharge. This work demonstrated a semiconductor-mediated photocatalytic technology to treat POME and synchronously evaluated the biogas generation. X-ray diffraction findings indicated that the fabricated ZnO product possessed wurtzite as a major crystalline phase. Its band gap energy was measured to be 3.27 eV via a UV-vis diffuse reflectance spectroscopy technique. The hierarchical ZnO microsphere morphology assembled by lots of layered nanosheets was observed via field-emission scanning electron microscopy. Under UV irradiation, the as-fabricated ZnO product displayed an enhanced photoactivity in comparison to the commercially available TiO₂ in treating the POME. Moreover, the ZnO/Ce and ZnO/Eu were also fabricated and showed greater photocatalytic efficacy after doping the rare earth ion in ZnO. Remarkably, the evaluation of biogas generation depicted that the ZnO/Ce and ZnO/Eu photocatalysis produced a greater quantity of CH₄ and CO₂ after 360 min irradiation. The work offered an environmentally friendly and efficient photocatalytic technology via ZnO/RE in treating wastewater and synchronously generating renewable energy.

Abstract: Zinc oxide (ZnO) is a widely studied semiconductor material due to its unique physical and chemical properties. It is a promising candidate for various electronics, optoelectronics, and energy harvesting applications. Photoluminescence, the emission of light upon excitation by photons, is crucial in studying europium-doped zinc oxide (ZnO) nanostructures. The incorporation of europium, a lanthanide element, into the ZnO semiconductor matrix has garnered significant attention due to the remarkable optical characteristics of this combination. Various factors, including the crystallographic properties, defect structure, and material morphology, influence the photoluminescence behavior of europium-doped ZnO nanostructures. This paper presents a review of the photoluminescence study of europium-doped ZnO nanostructures.

Abstract: Undoped and Ni-Eu co-doped ZnO thin films were successfully fabricated via spray pyrolysis at 400°C. The impact of co-doping on the structural, morphological, electrical, and optical properties of the thin films was thoroughly investigated. X-ray diffraction (XRD) analysis confirmed the absence of secondary phases and verified the successful incorporation of dopant ions into the ZnO lattice. Morphological examination revealed enhanced crystallization and a more uniform surface following the incorporation of nickel. Spectral studies in the UV-Vis region were conducted to determine the optical band gap of the synthesized ZnO films, indicating a slight decrease in bandgap values and volume and surface energy losses (VELF and SELF) with increasing Ni doping concentration. Photoluminescence spectra exhibited emission peaks in the UV region around 415 nm and broad visible emissions spanning 450-650 nm for all samples. Electrical characterization using Hall Effect measurements confirmed n-type electrical conductivity in all prepared films, as evidenced by the observed negative Hall coefficients. The co-doped ZnO thin films, particularly those incorporating Ni-Eu, show promise for applications in electronic and optoelectronic devices. Additionally, we investigated the photodegradation of green malachite under a UV lamp. Remarkably, the results demonstrated degradation rates of 93% within 2 hours, showcasing promising potential for practical applications.

Abstract: This article reports the study of photoluminescence spectra of Di Strontium Magnesium Silicate (Sr₂MgSi₂O₇) doped with various concentration of Europium (Eu³⁺) prepared using solid-state reaction technique. The doping concentration (s) of Eu3+ were 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 mol% respectively. Excitation spectrum monitored at 620 nm wavelength that exhibited two prominent peaks centered at 256 nm and 277 nm. Peak observed at 277 nm was more intense therefore the emission spectra were monitored at 277. Emission Spectra of all the samples revealed intense peaks centred at 607, 618 and 637 are attributed to ⁵D₀ ⁷F₂ of Europium (III) ions accommodated at various lattice sites having different energies. Overall emission was found in the red colour region which was confirmed using a CIE chromaticity diagram with coordinate (0.4805, 0.3763). Critical distance for energy transfer in the concentration, beyond which concentration quenching occurred in PL spectra, was calculated. In this case, the critical distance was found to be 19.87 Å, therefore the mechanism involved in concentration quenching of Sr₂MgSi₂O₇ doped with 2.0 mol % of Europium (III) must be only multipole-multipole exchange whereas the exchange interaction is ineffective.

Abstract: In this study Barium Lanthanum Aluminate BaLaAlO₄ and BaLaAlO₄:xEu red phosphors were produced at different x at.% Eu concentration (x = 0,1,3,5 and 7 at.% of Eu) by combustion synthesis method and post-annealing. The X-ray diffraction (XRD) patterns shows that all samples present the orthorhombic phase (JCPDS # 44-0164). Scanning electron microscopy (SEM) shows that the grains size diminished and then increases as a function of Eu-doping concentration addition. Photoluminescence spectra of the samples, under UV excitation, show a maximum strong red emission at l_em= 615 nm attributed to the ⁵D₀®⁷F₂ Eu³⁺ ion transition. The Eu-doped BaLaAlO₄ sample that present the highest luminescence intensity was with the x= 1.0 at.% of Eu doping concentration. The quenching in photoluminescence spectra was detected for the Eu doping concentrations of x= 5 and 7 at%, which was ascribed to due to dipole-quadrupole (d-q) interactions. Because the strong red emission of Eu-doped BaLaAlO₄ phosphor it could be used UV activated LEDs.

Abstract: The luminescence properties Dy³⁺, Eu³⁺ and Sm³⁺ doped magnesium sodium borate glasses were investigated. The glasses samples containing the composition 30MgO-70Na2B4O7.10H2O-xRE₂O₃ (where RE = Dy³⁺, Eu³⁺, and Sm³⁺, x = 0.1, 0.5, and 1.0 mol %) are prepared by the conventional melt quenching technique. The optical properties have been evaluated using Ultraviolet-Visible Spectroscopy and Photoluminescence Spectroscopy. The X-ray Diffraction pattern was studied to confirm the amorphous nature of the prepared glass. The absorption spectra yield the most intense absorption bands and transition energy levels for Dy³⁺, Eu³⁺, and Sm³⁺ located at 347 nm (⁶H_15/2 → ⁶P_7/2), 393 nm (⁷F₀ → ⁵L₆), and 403 nm (⁶H_5/2 →⁶P_5/2) respectively. The emission spectra demonstrate the highest emission intensity centered at 463 nm (⁴F_9/2 → ⁶F_11/2 + ⁶H_9/2), 612 nm (⁵D₀ → ⁷F_J), and 599 nm (⁴G_5/2 → ⁶H_7/2) for Dy³⁺, Eu³⁺, and Sm³⁺ respectively. Dy³⁺ emits combination of blue, yellow, and red light, Eu³⁺ emits red light and Sm³⁺ emits orange to red light. The higher the content of Dy³⁺, Eu³⁺, and Sm³⁺, the higher the spectral or peak intensity for both absorption and emission. The findings could be useful for development of laser, light emitting diode (LED), and color displays applications. KEY WORDS: Luminescence, Borax glass, Magnesium, Dysprosium, Europium, Samarium.

Abstract: This paper reports a tunable luminescence of europium (Eu ³⁺) doped zirconia (ZrO₂) nanoparticles as a function of hydrothermal temperature, europium concentrations, time and pH value. The nano-sized Eu doped ZrO₂ (Eu:ZrO₂) particle was synthesized by hydrothermal method at the temperature of 200 °C and time up to 48 h. The nano-sized Eu:ZrO₂ particles have a diameter of about 10 nm. The luminescent properties of nano-sized Eu:ZrO₂ particle was enhanced in the sample when high temperature, high Eu ³⁺ concentration and prolonging hydrothermal time were used at pH 7. These results suggest the use of Eu:ZrO₂ nanoparticles followed by thermal annealing in tuning the luminescence of Eu:ZrO₂ nanoparticles which have potential applications as phosphors in solid state lighting.

Abstract: In this paper, a direct co-precipitation method was used to prepare antimony-doped calcium fluoride nanopowders (NPs). The effects of reaction concentration, reaction medium and lanthanum doping on the properties of calcium fluoride NPs were investigated via a control variable method and the best preparation conditions was identified. The structural analysis of the powder materials prepared in this work were carried out by XRD, SEM, ICP and other test methods. By analyzing the experimental data, we found that the best performance of Eu-doped CaF₂ NPs can be acquired under the reaction concentration of 1 mol/L in aqueous solution. In the same time, the NPs possess a high degree of dispersion with an average diameter of 22 nm, which is beneficial to the preparation of transparent Eu³⁺: CaF₂ ceramics with excellent up-conversion luminescence. The results show that the grain size, the crystallinity of the NPs and the amount of Eu infiltration have a decreasing tendency with the increasing reaction concentration, while the degree of agglomeration of the NPs can be enhanced by increasing the reaction concentration.

Abstract: The influence of the europium concentration on the physical and thermal properties of manganese nanoparticles (Mn₃O₄ NPs) ) embedded borotellurite glass are studied. Glasses with composition (59-x)TeO₂-30B₂O₃-10MgO-xEu₂O₃-1Mn₃O₄ (where x = 0.5, 1.0 and 1.5 mol%) are prepared by melt-quenching method and characterized using XRD and Differential Thermal Analysis (DTA). The XRD pattern confirms the amorphous nature of all samples.The physical properties such as density (ρ) and molar volume (V_m) are calculated. The thermal properties of borotellurite glasses show that the glass with 1.0 mol % of Eu₂O₃ possess the highest stability.

Abstract: Ultra-long, single crystal, Eu-doped α-Si₃N₄ nanowires were prepared by a simple approach involving nitriding Eu-doped cryomilled nanocrystalline Si powder in NH₃ flow at 1350 °C for 4 h. Phases, chemical composition and microcosmic feature of cryomilled powders and as-prepared nanowires were tested by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), respectively. The results suggested that Eu was successfully introduced into Si lattice after the cryomilling process and then entered into the lattice of α-Si₃N₄ during the nitridation process. The as-synthesized Eu-doped α-Si₃N₄ nanowires had highly uniform dimension with 20~30 nm in diameter and ~100 μm in length. The room temperature photoluminescence (PL) spectrum of as-synthesized nanowires showed a broad band emission center at 570 nm which was attributed to the transition from 4f⁶5d to 4f⁷ in Eu²⁺. The transition from Eu³⁺ to Eu²⁺ during nitridation process was tested by X-ray photoelectron spectroscopy (XPS).