Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

Singh, Subhash C.; Kotnala, R. K.; Gopal, Ram

doi:10.1063/1.4928312

Cited by 15 publications

(8 citation statements)

References 36 publications

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“…LAL of elemental Ti resulted in particle oxidation and the formation of TiO and Ti 2 O 3 in addition to TiO 2 with a significantly reduced bandgap . Such LAL-synthesized defect-rich TiO x crystals show the room-temperature ferromagnetism of TiO 2 NPs . Although precise adjustment of the oxidation degree during LAL remains difficult, the oxygen affinities of many metallic materials (e.g., Cu, Zn, and Sn) provide opportunities to conveniently obtain (sub)oxides (e.g., CuO x , , ZnO x , , and SnO x , ) by LAL of pure metal targets in oxygen-containing solutions.…”

Section: Material Process Liquid and Laser Parametersmentioning

confidence: 99%

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

2017

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Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials, thereby enabling the fabrication of bioconjugates and heterogeneous catalysts. Accurate size control of LSPC-synthesized materials ranging from quantum dots to submicrometer spheres and recent upscaling advancement toward the multiple-gram scale are helpful for extending the applicability of LSPC-synthesized nanomaterials to various fields. By discussing key reports on both the fundamentals and the applications related to laser ablation, fragmentation, and melting in liquids, this Article presents a timely and critical review of this emerging topic.

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Section: Material Process Liquid and Laser Parametersmentioning

confidence: 99%

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

2017

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“…Motaung et al 16 reported that V c O and zinc vacancies (V Zn ) are the main defects and that their relative concentration decreases with an increase in particle size, resulting in a decreased ferromagnetism (FM). Singh et al 17 observed size dependent ferromagnetism, where the degree of ferromagnetism in titanium dioxide increases with an increase in the particle size, while it is reversed for zinc oxide. They explained that the origin of ferromagnetism was a consequence of exchange interactions between localized electron spin moments originating from point defects.…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetic behavior of non-stoichiometric ZnS microspheres with a nanoplate-netted surface

et al. 2017

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Undoped ZnS microspheres with a size of 4-5 mm were produced using a hydrothermal method with different ratios of Zn and S precursors. Structural and morphological measurements show that the sphalerite ZnS microspheres have a cavity surface self-assembled with nanoplates with a thickness of 20-30 nm. Experimentally measured magnetic hysteresis curves for the undoped ZnS microspheres clearly indicate ferromagnetic behavior at room temperature with a saturation magnetization M s ¼ 3.66 and 1.566 memu g À1 for an atomic ratio of Zn to S equal to 0.966 and 1.32, respectively. The calculations based on density functional theory within the generalized gradient approximation + Hubbard U (GGA + U) approach demonstrated that the ZnS (111) surface with Zn vacancies produces a ferromagnetic state with a magnetic moment per unit cell of 2.0 m B ; the defective ZnS (111) surface with mixed Zn and S vacancies has a reduced magnetic moment of 1.12 m B because of the structural reconstruction, while the defective ZnS (111) surface with only S vacancies is non-magnetic. The observed weak ferromagnetism for the ZnS microspheres can be ascribed to the Zn vacancies and the cavity surface; the latter results in a large number of unsaturated bonds for the S and Zn atoms at the interfacial and surface regions. These studies will be helpful for understanding the d 0 ferromagnetism. Fig. 3 The XPS spectra of samples #1 and #2 (a). The Zn 2p3/2 spectra with Gaussian fitting of samples #1 (b) and #3 (c). The S 2p3/2 spectra with Gaussian fitting of samples #1 (d) and #3 (e).This journal is

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“…Tarasenka et al investigated structural defects and magnetic properties of laser-made gadolinium silicide nanoparticles . Singh and co-workers laser-synthesized TiO 2 and ZnO nanoparticles that exhibited intrinsic room temperature ferromagnetism; they attributed the observed ferromagnetism to predominant defect centers, which were single ionized oxygen and neutral zinc vacancies in ZnO and oxygen and neutral or ionized titanium vacancies in TiO 2 . Surface chemistry and defects and concomitant photoluminescent properties of millisecond pulsed laser in liquid generated ZnO nanostructures were strongly affected by laser conditions, as reported by Kulinich et al Liu and Liang et al laser-synthesized nonstoichiometric metal oxides (TiO 2– x or SnO 2– x ) with abundant surface oxygen defects .…”

Section: Introductionmentioning

confidence: 77%

Pulsed Laser in Liquids Made Nanomaterials for Catalysis

et al. 2021

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Catalysis is essential to modern life and has a huge economic impact. The development of new catalysts critically depends on synthetic methods that enable the preparation of tailored nanomaterials. Pulsed laser in liquids synthesis can produce uniform, multicomponent, nonequilibrium nanomaterials with independently and precisely controlled properties, such as size, composition, morphology, defect density, and atomistic structure within the nanoparticle and at its surface. We cover the fundamentals, unique advantages, challenges, and experimental solutions of this powerful technique and review the state-of-the-art of laser-made electrocatalysts for water oxidation, oxygen reduction, hydrogen evolution, nitrogen reduction, carbon dioxide reduction, and organic oxidations, followed by laser-made nanomaterials for light-driven catalytic processes and heterogeneous catalysis of thermochemical processes. We also highlight laser-synthesized nanomaterials for which proposed catalytic applications exist. This review provides a practical guide to how the catalysis community can capitalize on pulsed laser in liquids synthesis to advance catalyst development, by leveraging the synergies of two fields of intensive research.

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Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

Cited by 15 publications

References 36 publications

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Ferromagnetic behavior of non-stoichiometric ZnS microspheres with a nanoplate-netted surface

Pulsed Laser in Liquids Made Nanomaterials for Catalysis

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