ABSTRACT
Iron-containing oxides are the most important functional substance class and find a tremendous variety of applications. An attractive modern application is their use in biomedical technologies as components in systems for imaging, drug delivery, magnetically mediated hyperthermia, etc. In this paper, we report the results of the experimental investigation of submicron Y3Fe5O12 garnet particles obtained in different sizes by solution combustion synthesis (SCS) using glycine organic fuel to discuss the interdependence of peculiarities of the crystal and magnetic structure and size's influence on its functional magnetothermal performance. A complex study including Mössbauer and Raman spectroscopy accompanied by X-ray diffractometry, SEM, and measurements of field and temperature magnetic properties were performed. The influence of the size effects and perfectness of structure on the particle set magnetization was revealed. The ranges of different mechanisms of magnetothermal effect in the AC magnetic field were determined.
ABSTRACT
Exploring two-dimensional anode materials that can utilize the storage capacity and diffusion mobility of Li ions is at the heart of lithium ion battery (LIB) research. Herein, we report the results of ab initio electronic structure calculations on the storage capacity and diffusion mobility affinities of Li ions adsorbed onto nondefective and defective MXene V2C monolayers. It is found that Li ions strongly chemisorb on the two sides of the V2C surface with a preferential adsorption site at the hollow center of the honeycomb structure. The binding profile and open-circuit voltage calculations reveal that the Li/V2C structure exhibits a specific capacity as high as 472 mA h g-1 at the Li2V2C stoichiometry, a value relatively high compared with those of the typical anode materials including graphite (372 mA h g-1). Furthermore, the diffusion barrier of a Li ion over the V2C surface is identified to be no more than 0.1 eV, which is a few times smaller than that of graphene and graphitic anodes. In addition, during the lithiation and delithiation processes, the change in the lateral lattice is quite small, only about a 2% increase at the full lithiation of Li2V2C, implying a good cycling performance. Importantly, these intriguing findings are very robust against the intrinsic structural and atomic defects including local point vacancies and biaxial compressive and tensile strains. More specifically, the presence of a monovanadium vacancy enhances the binding energy up to 3.1 eV per Li ion, which is about a 30% enhancement compared with the defect-free Li/V2C structure, and reduces the activation barrier by about 2 meV; meanwhile, these binding and diffusion mobility features can be improved even more when the lattice constant of the V2C monolayer is expanded. These results thus suggest that MXene V2C could be a promising anode material with high capacity and high rate capabilities for next generation high-performance LIBs.
ABSTRACT
Herein, using first-principles calculations, we predict spin reorientation from in-plane to out-of-plane magnetization of an individual Fe magnet at the monophosphor vacancy in two-dimensional blue phosphorous (2D blue-P) by a few percent of tensile strain. We further reveal that this magnetization reversal is associated with the spin-state transition of Fe 3d 5 state from low-spin (1 [Formula: see text]) to high-spin state (5 [Formula: see text]), which occurs at the same tensile strain imposed into 2D blue-P, from the Ligand field theory analyses in the unpaired electron counts. The underlying mechanism for both the spin-state transition and spin-reorientation phenomena is the strain induced changes in the spin-orbit coupled adatomic [Formula: see text] and [Formula: see text] states through the strong hybridization with the P-3pâ orbitals. These findings open interesting prospects for exploiting stain engineering of 2D materials to manipulate magnetism and magnetization orientation of single-molecule magnets adsorbed on it.
