Role of the chemical substitution on the luminescence properties of solid solutions Ca(1−x)Cd(x)WO4 (0≤x≤1)

Taoufyq, A.; Mauroy, Valérie; Guinneton, F.; Bakiz, B.; Villain, S.; Hallaoui, A.; Benlhachemi, A.; Nolibe, G.; Lyoussi, A.; Gavarri, J.R.

doi:10.1016/j.materresbull.2015.04.006

Cited by 15 publications

(10 citation statements)

References 37 publications

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“…During the last few years, researchers have developed many semiconductors based on oxides [20][21][22][23], hydroxides [24,25], tungstates [26][27][28], molybdates [29] and phosphates [30][31][32][33][34][35][36][37][38] for the decontamination of wastewater. A good photocatalyst should be simple to prepare, nontoxic, cheap and highly effective in utilizing light for the illumination of organic pollutants [39].…”

Section: Introductionmentioning

confidence: 99%

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

et al. 2021

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Polycrystalline bismuth phosphate BiPO4 was synthesized by solid-state reaction at different temperatures varying from 500 to 900 °C. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and Raman spectroscopy. The low-temperature phase of BiPO4 has monoclinic structure with a space group P21/n, and was transformed into the monoclinic phase P21/m with a slight distortion of monoclinic lattice when it was heated above 500 °C. The effect of the transformation on the structure, morphology and photocatalytic properties was examined. The photocatalytic activity of each sample, in presence of Rhodamine B (RhB) in aqueous solution, was carried out and analyzed under UV light irradiation. Photoexperiments showed that the material prepared at 500 °C is the best catalyst with degradation efficiency of the order of 96% after 12 min of reaction time under UV light irradiation. This high photocatalytic efficiency could be due to their structural and morphological changes. The photocatalytic degradation mechanism of RhB in the presence of the best photocatalyst BiP-500 °C is proposed. The stability of the catalyst was also examined by carrying out four successive tests of the degradation in the presence of BiP-500 °C. Total organic carbon (TOC) was used to further estimate the rate of mineralization in the presence of BiP-500 °C (83% TOC removal). Photoluminescence experiments performed under UV-laser light irradiation revealed emissions in the green-orange range, with optimal intensities for the mix systems observed at 550 °C.

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Section: Introductionmentioning

confidence: 99%

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

et al. 2021

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“…In this context, the synthesis and characterization of solid solutions involving metal tungstates such as Sr 1– x Pb x WO 4 , Ca 1– x Sr x WO 4 , Ba 1– x Sr x WO 4 , and Sr 1– x Ba x WO 4 have been performed. The photoluminescence (PL) properties of Ca x Sr 1– x WO 4 and Ca 1– x Cd x WO 4 have been analyzed, while the structures, optical properties, and magnetism have been studied for Zn 1– x Ni x WO 4 , Mn 1– x Cu x WO 4 , Cd 1– x Zn x WO 4 , Ni 1– x Co x WO 4 , Zn 1– x Cu x WO 4 , and Zn 1– x Co x WO 4 …”

Section: Introductionmentioning

confidence: 99%

α-Ag_2–2xZn_xWO₄ (0 ≤ x ≤ 0.25) Solid Solutions: Structure, Morphology, and Optical Properties

et al. 2017

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A theoretical study was elaborated to support the experimental results of the Zn-doped α-AgWO. Theses α-AgZnWO (0 ≤ x ≤ 0.25) solid solutions were obtained by coprecipitation method. X-ray diffraction data indicated that all α-AgZnWO (0 ≤ x ≤ 0.25) microcrystals presented an orthorhombic structure. The experimental values of the micro-Raman frequencies were in reasonable agreement with both previously reported and calculated results. Microscopy images showed that the replacement of Ag by Zn promoted a reduction in the average crystal size and modifications in the morphology, from rod-like with hexagonal shape to roll-like with a curved surface. A theoretical methodology based on the surfaces calculations and Wulff constructions was applied to study the particle shapes transformations and the surface energy variations in α-AgZnWO (0 ≤ x ≤ 0.25) system. The decrease in the band gap value (from 3.18 to 3.08 eV) and the red shift in photoluminescence with the Zn addition were associated with intermediary energy levels between the valence and conduction bands. First-principles calculations with density functional theory associated with B3LYP hybrid functional were conducted. The calculated band structures revealed an indirect band gap for the α-AgZnWO models. The electronic properties of α-AgWO and α-AgZnWO microcrystals were linked to distortion effects and oxygen vacancies (V) present in the clusters, respectively. Finally, photoluminescence properties of α-AgWO and α-AgZnWO microcrystals were explained by means of distortional effects and oxygen vacancies (V) in [AgO] (y = 2, 4, 6, and 7) and [WO] clusters, respectively, causing a red shift. Calculations revealed that the substitution for Ag with Zn occurred randomly in the α-AgWO lattice, and it was more favorable on the Ag4 site, where the local coordination of Ag cations was four.

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“…We usually attribute the fast and slow recombination emissions to the electrons released from shallow electron traps with self-trapped holes and to that from deeper electron traps. Moreover, the role of the chemical substitution on the luminescence properties under X-ray excitation of Ca (1– x ) Cd ( x ) WO 4 (0 < x < 1) are investigated, and it shows that the emission (2.4–2.5 eV) is sensitive to the substitution of calcium by cadmium . The origin and the influence factor for decay time need to be discussed.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the role of the chemical substitution on the luminescence properties under X-ray excitation of Ca (1−x) Cd (x) WO 4 (0 < x < 1) are investigated, and it shows that the emission (2.4−2.5 eV) is sensitive to the substitution of calcium by cadmium. 12 The origin and the influence factor for decay time need to be discussed. All these results pose a challenge to the nature of the emission of tungstates and are help for improving their scintillating features.…”

Section: ■ Introductionmentioning

confidence: 99%

Radiative/Nonradiative Recombination Affected by Defects and Electron–Phone Coupling in CdWO₄ Nanorods

Zhang

Guo

et al. 2016

J. Phys. Chem. C

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Tungstates are important photoluminescence (PL) materials owing to their unique luminescence center. However, radiative or nonradiative recombination affected by defects and electron-phone coupling have not been well understood. In this paper, we have synthesized CdWO 4 nanorods and studied its temperature-dependent PL spectrum from 20 to 300 K. Theoretical calculations demonstrate that Cd vacancy (V Cd ) and O vacancies) induce extra levels in the band gap, by which the V Cd , V O 0 , and V O 1+ defects mainly contribute to the absorption in 0−4 eV region, while V O 2+ causes the emission bands peaked at 490 nm in PL spectrum. Because of the broken symmetry of octahedron two possible types of lowest unoccupied molecular orbital (LUMO) appear and the transitions from the each LUMO to the highest occupied molecular orbital (HOMO) contribute to the emission at about 410 and 436 nm. The emission intensity of the peaks decreases with an increase in temperature due to the thermal quenching by nonradiative recombination. This work insights into the understanding of physical nature of emission and presents a detailed analysis of the electron transition behaviors in the wolframite-type monoclinic CdWO 4 , which can be used not only to explain the photoluminescence mechanism of CdWO 4 , but also for the structure design to obtain better emission properties in tungstates.

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Role of the chemical substitution on the luminescence properties of solid solutions Ca(1−x)Cd(x)WO4 (0≤x≤1)

Cited by 15 publications

References 37 publications

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

α-Ag_2–2xZn_xWO₄ (0 ≤ x ≤ 0.25) Solid Solutions: Structure, Morphology, and Optical Properties

Radiative/Nonradiative Recombination Affected by Defects and Electron–Phone Coupling in CdWO₄ Nanorods

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Role of the chemical substitution on the luminescence properties of solid solutions Ca(1−x)Cd(x)WO4 (0≤x≤1)

Cited by 15 publications

References 37 publications

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

α-Ag2–2xZnxWO4 (0 ≤ x ≤ 0.25) Solid Solutions: Structure, Morphology, and Optical Properties

Radiative/Nonradiative Recombination Affected by Defects and Electron–Phone Coupling in CdWO4 Nanorods

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α-Ag_2–2xZn_xWO₄ (0 ≤ x ≤ 0.25) Solid Solutions: Structure, Morphology, and Optical Properties

Radiative/Nonradiative Recombination Affected by Defects and Electron–Phone Coupling in CdWO₄ Nanorods