Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a fast and facile sonochemical method

Neto, N. F. Andrade; Dias, Beatriz Pinheiro; Tranquilin, R. L.; Longo, E.; Li, M.; Bomio, M. R. D.; Motta, F. V.

doi:10.1016/j.jallcom.2019.153617

Cited by 34 publications

(13 citation statements)

References 43 publications

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“…41−43 Because of the increased disordering in the lattice by U 6+ and Mg 2+ , their local environments gradually converge, with the U−O and OUO bands under increasing influence from the presence of divalent cations. The downshift in the Raman peaks has also been observed in other systems from chargecoupled substitution, such as Li + −Zn 2+ in Co 0.4 Zn 0.6 Fe 2 O 4 (Fd3̅ m) 41 and Ag + −Zn 2+ in CaWO 4 , 44 The uranyl-type ion (UO 2 2+ ) was also confirmed by spectroscopic methods, as evidenced by PL of the UO bonds. Figure 7 shows the emission spectra of La 2 (U x Mg x Zr 1−2x ) 2 O 7 from λ ex = 230 nm excitations with the schematic of the energy-level diagram for the uranylcontaining systems.…”

Section: Resultssupporting

confidence: 56%

“…Such a downshift can be caused by the low electronic state element occupying a high electronic state. − Because of the increased disordering in the lattice by U 6+ and Mg 2+ , their local environments gradually converge, with the U–O and OUO bands under increasing influence from the presence of divalent cations. The downshift in the Raman peaks has also been observed in other systems from charge-coupled substitution, such as Li + –Zn 2+ in Co 0.4 Zn 0.6 Fe 2 O 4 ( Fd 3̅ m ) and Ag + –Zn 2+ in CaWO 4 , while being absent in the single U-doped RE 2 Hf 2 O 7 , again suggesting its close connection to the local structural modification from coupled low-valence cations. When x increased to 0.3, La 2 (U x Mg x Zr 1–2 x ) 2 O 7 crystallized in defect fluorite, where Mg 2+ and U 6+ both occupy the same eight-coordinated crystallographic site and tend to be randomly distributed, which results in diminishing intensity of octahedra-related Raman modes.…”

Section: Results and Discussionmentioning

confidence: 54%

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Uranium-Incorporated Pyrochlore La₂(U_xMg_xZr_1–2x)₂O₇ Nuclear Waste Form: Structure and Phase Stability

et al. 2020

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As efficient and stable nuclear waste forms, singlephase uranium (U 6+ )-incorporated La 2 Zr 2 O 7 nanoparticles were designed and synthesized in an air atmosphere. To obtain a high U loading, divalent magnesium (Mg 2+ ) was introduced to balance the extra charge from the substitution of tetravalent zirconium (Zr 4+ ) by U 6+ with a minimized impact to the lattice. There is a compositiondriven phase transition from order pyrochlore to defect fluorite as the U concentration increases from 10 to 30 mol %, demonstrating both good solubility and stability of the La 2 Zr 2 O 7 host for U and potentially for other actinides. La 2 (U x Mg x Zr 1−2x ) 2 O 7 (x = 0−0.3) nanoparticles showed good dispersity and crystallinity with an average particle size of ∼48 nm. Furthermore, X-ray photoelectron spectroscopy, Raman spectroscopy, and emission spectroscopy revealed that U was stabilized in the hexavalent state in the form of a UO 2 2+ ion. Spectroscopic methods also demonstrated that our samples caused a scintillating response with an orange emission (597 nm) by 230 nm excitation. In addition, density functional theory simulations were employed to investigate the atomic structures and electronic properties of the U-incorporated pyrochlores. The calculated bond lengths, atomic charges, and charge density confirm the existence of UO 2 2+ ions. Supported by both experimental and computational results, a novel geometrical structure was proposed to explain the Mg 2+ −U 6+ substitution. This work demonstrated the successful development of U-incorporated La 2 Zr 2 O 7 nanoparticles and provided an efficient way to immobilize U in these ceramic waste matrixes.

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Section: Resultssupporting

confidence: 56%

Section: Results and Discussionmentioning

confidence: 54%

Uranium-Incorporated Pyrochlore La₂(U_xMg_xZr_1–2x)₂O₇ Nuclear Waste Form: Structure and Phase Stability

et al. 2020

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“…Also, doping with cations of different valences and/or ionic rays tend to generate more defects in the host material lattice, favoring a reduction in the size of the crystallite. 21,22 Figure 2 shows the HRTEM micrographs obtained by HRTEM. According to micrographs, the doping doesn't promote change in the particle size, being all samples close to 12.4 (± 5) nm.…”

Section: Resultsmentioning

confidence: 99%

“…showed that as the W 6+ cation is added in high concentrations in the Ag 2 MoO 4 structure, the formation of Ag 2 WO 4 starts and, as the amount of W 6+ increases, this becomes the most stable phase in growth. Also, doping with cations of different valences and/or ionic rays tend to generate more defects in the host material lattice, favoring a reduction in the size of the crystallite 21,22 …”

Section: Resultsmentioning

confidence: 99%

Antimicrobial and electrical properties of ce‐ and ni‐doped zns nanoparticles obtained by a sonochemical method

Neto

Oliveira

Corrêa

et al. 2021

Int J Applied Ceramic Tech

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In this work, cerium-and nickel-codoped ZnS nanoparticles were obtained by a sonochemical method for 20 min. The nanoparticles were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and microscopy electronic transmission (MET). The electrical properties are estimated through I-V curves and the antimicrobial activity was analyzed against E. coli (gram-negative) and S. aureus (gram-positive) bacteria using the diffusion disk methodology. The diffractograms indicate the obtaining of cubic structure ZnS for the pure sample, whereas the doped samples present the cubic and hexagonal structures of the ZnS. The bandgap reduced from 3.60 to 3.52 eV, for pure and codoped samples. I-V curves indicate an increase in resistivity with doping, being more evident for samples containing cerium. Antimicrobial activity increased as doping occurred, where the codoped sample showed the best results. Even for the low amount of dopant (1 mol%), the antimicrobial activity can be increased by about 50% for the codoped sample, compared to the pure ZnS. Thus, it is known that the doping of ZnS with cerium and nickel provides the stabilization of the hexagonal metastable phase, which acts to restrict electronic mobility and, consequently, improves the antimicrobial response of the material.

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“…The addition of isopropyl alcohol (•OH radical scavenger) determines a significant decrease in the photocatalysis efficiency, evidencing the critical role of the hydroxyl radical in methylene blue degradation, possibly via Mechanism (4), where MBH denotes the methylene blue dye in its non-oxidized form and MB• the smaller molecular compounds, which could be formed during the initial stages of photodegradation [49,50]. Superoxide radicals seem to play a marginal role in the visible-light-aided degradation of MB since no significant decrease in the photocatalysis efficiency was registered by the addition of the ascorbic acid scavenger [51,52].…”

Section: 𝑙𝑛 𝑘 ⋅ 𝑡mentioning

confidence: 99%

Visible Domain Photocatalysis Performance of Ti-Si Thermal-Sprayed Coatings

et al. 2021

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Cost and performance-effective materials used in advanced oxidation processes such as photocatalysis have obtained widespread attention in recent years. In this study, thermal spraying was used as a one-step method to obtain thick visible-light-active photocatalyst coatings on two types of substrates, namely, plain carbon steel and copper. A mixed metallic titanium–silicon powder bearing 10% wt. Si was used as feedstock. The optical bandgaps of the coatings were close to 1.000 eV, allowing good photodecoloration efficiencies (>89%) and mineralization efficiencies (>67%) for methylene blue dye from aqueous solutions under visible light irradiation. The photodegradation process could be successfully modelled by the Langmuir–Hinshelwood pseudo-first-order kinetic model, with reaction rate constants k between 0.16 and 1.06 h−1.

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Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a fast and facile sonochemical method

Cited by 34 publications

References 43 publications

Uranium-Incorporated Pyrochlore La₂(U_xMg_xZr_1–2x)₂O₇ Nuclear Waste Form: Structure and Phase Stability

Uranium-Incorporated Pyrochlore La₂(U_xMg_xZr_1–2x)₂O₇ Nuclear Waste Form: Structure and Phase Stability

Antimicrobial and electrical properties of ce‐ and ni‐doped zns nanoparticles obtained by a sonochemical method

Visible Domain Photocatalysis Performance of Ti-Si Thermal-Sprayed Coatings

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Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a fast and facile sonochemical method

Cited by 34 publications

References 43 publications

Uranium-Incorporated Pyrochlore La2(UxMgxZr1–2x)2O7 Nuclear Waste Form: Structure and Phase Stability

Uranium-Incorporated Pyrochlore La2(UxMgxZr1–2x)2O7 Nuclear Waste Form: Structure and Phase Stability

Antimicrobial and electrical properties of ce‐ and ni‐doped zns nanoparticles obtained by a sonochemical method

Visible Domain Photocatalysis Performance of Ti-Si Thermal-Sprayed Coatings

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Product

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Uranium-Incorporated Pyrochlore La₂(U_xMg_xZr_1–2x)₂O₇ Nuclear Waste Form: Structure and Phase Stability

Uranium-Incorporated Pyrochlore La₂(U_xMg_xZr_1–2x)₂O₇ Nuclear Waste Form: Structure and Phase Stability