Role of Zn-interstitial defect states on d0 ferromagnetism of mechanically milled ZnO nanoparticles

Ghose, Srabantika; Rakshit, T.; Ranganathan, R.; Jana, Debnarayan

doi:10.1039/c5ra13846a

Cited by 41 publications

(16 citation statements)

References 53 publications

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“…Thus shifts in the intensity of the E high 2 and E low 2 modes would be consistent with large shifts in the concentrations of O and Zn vacancies and interstitials. Previously, it has been reported that the A 1 (LO) mode is affected by the presence of defects 32 . Hence, Raman studies confirm that the SHI irradiation treatment introduces disorder into the nanostructures, which certainly includes large concentrations of intrinsic point defects associated with the O and Zn sublattices.…”

Section: Resultsmentioning

confidence: 99%

Robust water repellent ZnO nanorod array by Swift Heavy Ion Irradiation: Effect of Electronic Excitation Induced Local Chemical State Modification

Ranjith

Nivedita

Asokan

et al. 2017

Sci Rep

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Tailoring the surface properties by varying the chemistry and roughness could be of interest for self-cleaning applications. We demonstrate the transformation of hydrophobic ZnO Nano rod (NR) array into superhydrophobic nature by changing the local chemical state and without altering the surface roughness by swift heavy ion (SHI) irradiation. The aligned ZnO NR arrays were irradiated using 150 MeV Ag ions with different fluences from 5E10 to 3E12 ions/cm2. The observed static water contact angles of ZnO NRs samples were 103° ± 3°, 152° ± 4°,161° ± 3°, 164° ± 2°, 167° ± 2°,154 ± 3° and 151° ± 2° for the pristine, ion fluencies of 1E11, 3E11, 5E11, 7E11, 1E12 and 3E12 ions cm−2, respectively. The change in local surface chemistry via formation of surface oxygen related defects due to electronic excitations induced by ion irradiation determine the water dewetting properties. It is found that surface oxygen related defects could be tuned by varying the fluence of the SHIs. Durability tests show that the SHI induced surface oxygen-deficient ZnO NRs have the stable superhydrophobic behavior for more than a year.

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Section: Resultsmentioning

confidence: 99%

Robust water repellent ZnO nanorod array by Swift Heavy Ion Irradiation: Effect of Electronic Excitation Induced Local Chemical State Modification

Ranjith

Nivedita

Asokan

et al. 2017

Sci Rep

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“…Therefore, the intrinsic or extrinsic defects are popularly investigated by researchers via simulations or experiments to depress and enhance the useless and useful defects, respectively. Zn i and V O play role as donors in ZnO material [3][4][5]. Ghose et al [4] proved that Zn i and V O can exist in different charged states.…”

Section: Introductionmentioning

confidence: 99%

“…Zn i and V O play role as donors in ZnO material [3][4][5]. Ghose et al [4] proved that Zn i and V O can exist in different charged states. For example, the yellow emission from photoluminescence spectra is attributed to doubly charged oxygen vacancies (V •• O ) ( • is the Kröger-Vink notation) or the blue luminescence is attributed to Zn i .…”

Section: Introductionmentioning

confidence: 99%

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

Hoang

Phạm

Nguyen

et al. 2021

Journal of Nanomaterials

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In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the c -axis (AB┴), into bond center sites paralleled to the c -axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature.

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“…Up to now, RTFM has been observed in a number of pure low dimensional nanosized metal oxides, such as SnO 2 [4,5], ZnO [6,7], CuO [8,9], MgO [10,11], Al 2 O 3 [5,12], CaO [13], etc. It has been identified that d 0 ferromagnetism is closely related to the existence of defects at the surface regions [14]. These defects may confine the compensating charges in molecular orbitals, forming local magnetic moments, and RTFM may be established only if the defect concentration essentially exceeds that of its equilibrium magnitude [15].…”

Section: Introductionmentioning

confidence: 99%

“…It is now believed that both -the surface non-stoichiometry and the defects of oxide nanostructures play a crucial role in the observance of RTFM, since conventional ideas of magnetism are unable to account for d 0 ferromagnetism [16]. However, the main obstacle to the use such materials for the fabrication of potential devices is the lack of understanding of the role of defects [14]. This somewhat controversial research topic definitely requires further detailed investigations.…”

Section: Introductionmentioning

confidence: 99%

Levitation-jet synthesis of In-O nanoparticles with room-temperature ferromagnetic properties

Morozov

Белоусова

Firth

et al. 2017

Advanced Powder Technology

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Octahedral and roughly spherical In-In 2 O 3 nanoparticles ranging in average particle size from 30 up to 300 nm were prepared by levitation-jet aerosol synthesis through condensation of metal indium vapor in helium gas flow with gaseous oxygen/air injection at ambient and reduced pressure. Scanning electron microscopy (SEM), X-ray diffraction (XRD), BET measurements, UV-vis, FT-IR, Raman, XPS, and vibratingsample magnetometry (VSM) characterized the nanoparticles. Room-temperature ferromagnetism with maximum magnetization of up to 0.17 emu/g was recorded for the nanoparticles. The results indicate a predominant role of the actual microstructure on the nanoparticle properties. It is suggested that the observed ferromagnetic ordering may be related to intrinsic defects at the In/In 2 O 3 interface structure of such a composite material. This suggestion is in good agreement with the results of optical and XPS experiments on the NPs.

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Role of Zn-interstitial defect states on d0 ferromagnetism of mechanically milled ZnO nanoparticles

Abstract: An impurity defect level formed by interstitial zinc at the surfaces of undoped ZnO nanoparticles plays a crucial role for d0 ferromagnetism.

Cited by 41 publications

References 53 publications

Robust water repellent ZnO nanorod array by Swift Heavy Ion Irradiation: Effect of Electronic Excitation Induced Local Chemical State Modification

Robust water repellent ZnO nanorod array by Swift Heavy Ion Irradiation: Effect of Electronic Excitation Induced Local Chemical State Modification

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

Levitation-jet synthesis of In-O nanoparticles with room-temperature ferromagnetic properties

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