Oxygen vacancies mediated cooperative magnetism in ZnO nanocrystals: A d0 ferromagnetic case study

Punia, Khushboo; Lal, Ganesh; Barbar, S. K.; Dolia, S. N.; Alvi, P. A.; Dalela, S.; Kumar, Sudhish

doi:10.1016/j.vacuum.2020.109921

Cited by 55 publications

(12 citation statements)

References 79 publications

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“…1 duced in the Ni 0.95 Cr 0.05 nanostructures embedded in the Ag matrix is about 0.036, estimated from the XRD data (Kaushik et al 2013;Punia et al 2021aPunia et al , 2021b, is slightly higher than Ni 0.95 Cr 0.05 NCs (0.026) and Ni 0.95 Cr 0.05 nanogranular thin ilms (0.022). 3 Ni 0.95 Cr 0.05 nanogranular thin ilms: These were deposited by conventional sputtering of Ni 0 .…”

Section: Methodsmentioning

confidence: 87%

Design of various Ni–Cr nanostructures and deducing their magnetic anisotropy

et al. 2021

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Understanding the efects of interparticle interactions is a vital problem because magnetic nanoparticles showcase a variety of magnetic conigurations due to diferent contributions to their total energy. To derive reliable and robust properties from magnetic nanoparticles, it is, thus, necessary to understand the competition between particle anisotropy and interparticle interactions that deine the magnetic state of nanoparticles, where size control plays an important role. Here, we apply the random anisotropy model (RAM) that considers various magnetic interactions to selectively prepared NiCr nanostructures (NiCr dense nanoclusters, nanogranular NiCr thin ilms, and Ag(NiCr) nanocomposites) with diferent interparticle interactions. The estimated single-particle magnetic anisotropy K values (2.82 − 12.3 × 10 4 J/m 3 ) and careful analysis of magnetization behavior for these nanostructures reveal that orbital hybridization, surface segregation, and interface character govern the magnetic interactions among nanoparticles. Our study demonstrates how magnetic behaviors vary in these diferent magnetic systems consisting of superparamagnetic (SPM) and ferromagnetic (FM) contributions speciic to magnetic interactions.

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Section: Methodsmentioning

confidence: 87%

Design of various Ni–Cr nanostructures and deducing their magnetic anisotropy

et al. 2021

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“…The ratio of the two peaks at 632 cm À 1 (denoted as A 632 ) and 463 cm À 1 (denoted as A 463 ) can indicate the relative oxygen vacancy position. [26] The peak fittings of 632 cm À 1 and 463 cm À 1 are shown in Figure 6. When the doping amount of copper was 0.1, the value of A 632 /A 463 was the highest, indicating that there were more oxygen vacancies on the catalyst surface.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Cu‐Promoted Pt/Ce_0.5Zr_0.5O_x Catalyst for Ammonia Production Reaction of Passive SCR from Nitric Oxide and Hydrogen

et al. 2022

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In response to stricter emission regulations, lean-burn engines have attracted more and more attention. However, lean burn engines would inevitably lead to the increase in NO x emissions. The researchers combined Three-Way Catalyst (TWC) and Selective Catalytic Reduction (SCR) to propose "passive SCR", which makes the engine periodically switch between rich and lean burn. During rich combustion, ammonia is produced by the TWC catalyst, stored in the downstream SCR, and reacts with NO x during lean combustion, in which increasing the ammonia yield on the TWC catalyst is the key. In this study, the self-propagating high-temperature synthesis method was used to modify the catalyst by adding copper to improve the ammonia production efficiency. The conversion rate of catalysts with different copper doping ratios from NO to ammonia was measured. Through XRD, BET, H 2 -TPR, TEM, HRTEM, XPS, in-situ DRIFTS, etc., the improvement mechanism of copper doping was analysed. The results showed that Pt 0.01 Cu 0.1 Ce 0.45 Zr 0.45 O x had the highest catalytic activity, the widest reaction temperature window (300-550 °C) with the conversion greater than 96 %. The characterization results showed that appropriate amount of copper doping can adjust the valence distribution, form more oxygen vacancies, and improve the distribution of active species. The in-situ DRIFTS further demonstrated that the conversion from bridged to monodentate and bidentate nitrate may be the key factors on the catalyst surface.

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“…Doping ZnO with appropriate ions with varying sizes is great approach way to vary its properties for certain device applications. [ 7–9 ] According to Chaudhary et al., WO 3 ‐ZnO@rGO nanocomposites can be used for relevant photocatalytic applications and wastewater purification. [ 10 ] Additionally, Yousaf et al.…”

Section: Introductionmentioning

confidence: 99%

“…Doping ZnO with appropriate ions with varying sizes is great approach way to vary its properties for certain device applications. [7][8][9] According to Chaudhary et al, WO 3 -ZnO@rGO nanocomposites can be used for relevant photocatalytic applications and wastewater purification. [10] Additionally, Yousaf et al have reported that the ZnO-NiO/rGO nanohybrid shows exceptional photocatalytic performance and is a reliable contender in the field of catalysis.…”

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confidence: 99%

Exploring the Defects and Vacancies with Photoluminescence and XANES Studies of Gd³⁺‐Substituted ZnO Nanoparticles

Sahu

Kumar

Vats

et al. 2022

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of ZnO has not yet been completely realized and explored despite two decades of rigorous research. It has a wide range of uses in photocatalysts, UV lasers, solar cells, photodiodes, sensors, optoelectronics, spintronic devices, and more. [1][2][3][4][5][6] Depending on the application, essential modifications have been made over time to increase the stability of ZnO nanostructures. High quantum confinement effect plays a significant role in the configuration of the electronic structure at the nanoscale. Also, factors such as doping, defects, and crystallinity affect various properties of the nanostructures. Doping ZnO with appropriate ions with varying sizes is great approach way to vary its properties for certain device applications. [7][8][9] According to Chaudhary et al., WO 3 -ZnO@rGO nanocomposites can be used for relevant photocatalytic applications and wastewater purification. [10] Additionally, Yousaf et al. have reported that the ZnO-NiO/rGO nanohybrid shows exceptional photocatalytic performance and is a reliable contender in the field of catalysis. [11] Transition metal (TM) and rare earth (RE)-doped metal oxides have been studied extensively under this regime. For optoelectronics and spintronic applications, ZnO doped with rare-earth ions is Undoped ZnO and Zn 1−x Gd x O nanoparticles are made using a sono-chemical co-precipitation approach. X-ray diffraction and transmission electron microscopy investigations verified the formation of a wurtzite structure with spherical geometry. All the samples are found to be nanocrystalline by transmission electron microscopy, with crystallite diameters ranging from 14 to 22 nm. The optical constants are calculated via diffuse reflectance spectroscopy. The Urbach energy and photoluminescence spectrum both showed that all doped nanoparticle samples contained defects and disorder due to vacancies. The band structure finding suggest that the forbidden gap of ZnO may change due to the conduction band shift, Burstein-Moss shift, and shrinkage effect. The near band emission in the ultraviolet region and deep level emission of the photoluminescence spectrum are both strong and decreased with increasing Gd 3+ concentration. Studies using X-ray absorption near edge spectroscopy revealed that the host nano-lattice Zn sites are substituted with Gd 3+ cations to preserve the symmetry with minor distortion. Investigations into charge transfer through the oxygen bands (Gd-O-Zn) are made using O K-edge spectra. The defect emission bands identified through Gd doping indicated that these emissions may be changed for ZnO samples, which could be advantageous for applications in phosphors and light-emitting devices.

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Oxygen vacancies mediated cooperative magnetism in ZnO nanocrystals: A d0 ferromagnetic case study

Cited by 55 publications

References 79 publications

Design of various Ni–Cr nanostructures and deducing their magnetic anisotropy

Design of various Ni–Cr nanostructures and deducing their magnetic anisotropy

Cu‐Promoted Pt/Ce_0.5Zr_0.5O_x Catalyst for Ammonia Production Reaction of Passive SCR from Nitric Oxide and Hydrogen

Exploring the Defects and Vacancies with Photoluminescence and XANES Studies of Gd³⁺‐Substituted ZnO Nanoparticles

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Oxygen vacancies mediated cooperative magnetism in ZnO nanocrystals: A d0 ferromagnetic case study

Cited by 55 publications

References 79 publications

Design of various Ni–Cr nanostructures and deducing their magnetic anisotropy

Design of various Ni–Cr nanostructures and deducing their magnetic anisotropy

Cu‐Promoted Pt/Ce0.5Zr0.5Ox Catalyst for Ammonia Production Reaction of Passive SCR from Nitric Oxide and Hydrogen

Exploring the Defects and Vacancies with Photoluminescence and XANES Studies of Gd3+‐Substituted ZnO Nanoparticles

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Product

Resources

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Cu‐Promoted Pt/Ce_0.5Zr_0.5O_x Catalyst for Ammonia Production Reaction of Passive SCR from Nitric Oxide and Hydrogen

Exploring the Defects and Vacancies with Photoluminescence and XANES Studies of Gd³⁺‐Substituted ZnO Nanoparticles