Browse
Submit Data
Databases
API
Help

Dataset Information

16 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Magnetic and electronic properties of magnetite across the high pressure anomaly.

ABSTRACT: The magnetite Fe₃O₄, being anciently known magnetic material to human kind and remaining in leading positions for development of advanced technologies presently, demonstrates a number of puzzling physical phenomena, being at focus of extensive research for more than century. Recently the pressure-induced anomalous behavior of physical properties of magnetite in vicinity of the structural phase transition, occurring at P ~ 25-30 GPa, has attracted particular attention, and its nature remains unclear. Here we study the magnetic and electronic properties of magnetite across high pressure anomaly and in the pressure-induced phase by means of ⁵⁷Fe synchrotron Moessbauer spectroscopy and neutron diffraction. The hyperfine interaction parameters behavior was systematically analysed over pressure 0-40 GPa and temperature 10-290 K ranges. In the high pressure phase the ferrimagnetic order formation below T_NP ~ 420 K was observed and spin arrangement symmetry was deduced. The structural, magnetic and electronic phase diagram of magnetite in the discussed pressure range is established.

SUBMITTER: Kozlenko DP

PROVIDER: S-EPMC6418096 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

First-principles calculations of structural, electronic, magnetic and elastic properties of Mo2FeB2 under high pressure.

Project description:The structural, electronic, magnetic and elastic properties of Mo2FeB2 under high pressure have been investigated with first-principles calculations. Furthermore, the thermal dynamic properties of Mo2FeB2 were also studied with the quasi-harmonic Debye model. The volume of Mo2FeB2 decreases with the increase in pressure. Using the analysis of the density of the states, atom population and Mulliken overlap population, it is observed that as the pressure increases, the B-B bonds are strengthened and the B-Mo covalency decreases. Moreover, for all pressures, Mo2FeB2 is detected in the anti-ferromagnetic phase and the magnetic moments decrease with the increase in pressure. The calculated bulk modulus, shear modulus, Young's modulus, Poisson's ratio and universal anisotropy index all increase with the increase in pressure. From thermal expansion coefficient analysis, it is found that Mo2FeB2 shows good volume invariance under high pressure and temperature. The examination of the dependence of heat capacity on the temperature and pressure shows that heat capacity is more sensitive to temperature than to pressure.

| S-EPMC6083659 | biostudies-literature

Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites.

Project description:This work describes the thermal stability and magnetic properties of polyvinylidene fluoride (PVDF)/magnetite nanocomposites fabricated using the solution mixing technique. The image of transmission electron microscopy for PVDF/magnetite nanocomposites reveals that the 13 nm magnetite nanoparticles are well distributed in PVDF matrix. The electroactive β-phase and piezoelectric responses of PVDF/magnetite nanocomposites are increased as the loading of magnetite nanoparticles increases. The piezoelectric responses of PVDF/magnetite films are extensively increased about five times in magnitude with applied strength of electrical field at 35 MV/m. The magnetic properties of PVDF/magnetite nanocomposites exhibit supermagnetism with saturation magnetization in the range of 1.6 × 10-3-3.1 × 10-3 emu/g, which increases as the amount of magnetite nanoparticles increases. The incorporation of 2 wt % magnetite nanoparticles into the PVDF matrix improves the thermal stability about 25 °C as compared to that of PVDF. The effect of magnetite particles on the isothermal degradation behavior of PVDF is also investigated.

| S-EPMC5455665 | biostudies-other

Phase transition and electronic properties of Co-As binary compounds at high pressure.

Project description:New stable stoichiometries in the Co-As system are investigated up to 100 GPa by the CALYPSO structure prediction method. In particular, we found three novel stable compounds of Co2As-Pnma, CoAs2-Pnnm, and CoAs3-C2/m at high pressure. According to the theoretical electronic band structures, the structures of Co2As-Pnma, CoAs2-Pnnm, and CoAs3-C2/m have metallic characters, and a pressure-induced electronic topological transition was found in CoAs3-C2/m, which is not shown in other stoichiometries of the Co-As system. The calculated results of the electron localization function show that there are polar covalent bond interactions between Co atoms and As atoms in CoAs2-Pnnm and CoAs3-C2/m. The present results can be helpful for understanding diverse structures and properties of Co-As binary compounds under high pressure.

| S-EPMC9210071 | biostudies-literature

Ultrasmall, Water-Soluble Magnetite Nanoparticles with High Relaxivity for Magnetic Resonance Imaging.

Project description:Ultrasmall (3, 4, 5, and 6 nm), water-soluble Fe3O4 magnetic nanoparticles were synthesized in diethylene glycol (DEG) via a facile one-pot reaction. Hydrodynamic size and relaxation time measurements did not show particle aggregation when Fe3O4 nanoparticles were dispersed in phosphate buffered saline, fetal bovine serum, or calf bovine serum for 1 week. Furthermore, the new Fe3O4 nanoparticles tolerated high salt concentrations (?1 M NaCl) and a wide pH range from 5 to 11. Surface modification of the nanoparticles with poly(ethylene glycol) bis(carboxymethyl) ether (HOOC-PEG-COOH, 600 g/mol) was accomplished through a ligand-exchange reaction. The effects of PEG modification on magnetization and relaxivity of the Fe3O4 nanoparticles were investigated, and the results indicate that the increase in transverse relaxivity after PEG modification may be due to the increased volume of slowly diffusing water surrounding each nanoparticle. In vitro experiments showed that the DEG- and PEG-coated Fe3O4 nanoparticles have little effect on NIH/3T3 cell viability.

| S-EPMC4076104 | biostudies-literature

High-Pressure Single-Crystal Structures of 3D Lead-Halide Hybrid Perovskites and Pressure Effects on their Electronic and Optical Properties.

Project description:We report the first high-pressure single-crystal structures of hybrid perovskites. The crystalline semiconductors (MA)PbX3 (MA = CH3NH3 (+), X = Br(-) or I(-)) afford us the rare opportunity of understanding how compression modulates their structures and thereby their optoelectronic properties. Using atomic coordinates obtained from high-pressure single-crystal X-ray diffraction we track the perovskites' precise structural evolution upon compression. These structural changes correlate well with pressure-dependent single-crystal photoluminescence (PL) spectra and high-pressure bandgaps derived from density functional theory. We further observe dramatic piezochromism where the solids become lighter in color and then transition to opaque black with compression. Indeed, electronic conductivity measurements of (MA)PbI3 obtained within a diamond-anvil cell show that the material's resistivity decreases by 3 orders of magnitude between 0 and 51 GPa. The activation energy for conduction at 51 GPa is only 13.2(3) meV, suggesting that the perovskite is approaching a metallic state. Furthermore, the pressure response of mixed-halide perovskites shows new luminescent states that emerge at elevated pressures. We recently reported that the perovskites (MA)Pb(Br x I1-x )3 (0.2 < x < 1) reversibly form light-induced trap states, which pin their PL to a low energy. This may explain the low voltages obtained from solar cells employing these absorbers. Our high-pressure PL data indicate that compression can mitigate this PL redshift and may afford higher steady-state voltages from these absorbers. These studies show that pressure can significantly alter the transport and thermodynamic properties of these technologically important semiconductors.

| S-EPMC4850512 | biostudies-literature

Electronic and magnetic properties of Co doped MoS2 monolayer.

Project description:First principle calculations are employed to calculate the electronic and magnetic properties of Co doped MoS2 by considering a variety of defects including all the possible defect complexes. The results indicate that pristine MoS2 is nonmagnetic. The materials with the existence of S vacancy or Mo vacancy alone are non-magnetic either. Further calculation demonstrates that Co substitution at Mo site leads to spin polarized state. Two substitutional CoMo defects tend to cluster and result in the non-magnetic behaviour. However, the existence of Mo vacancies leads to uniform distribution of Co dopants and it is energy favourable with ferromagnetic coupling, resulting in an intrinsic diluted magnetic semiconductor.

| S-EPMC4823719 | biostudies-literature

Magnetic, Electronic, and Mechanical Properties of Bulk ε-Fe2N Synthesized at High Pressures.

Project description:We sintered bulk trigonal ε-Fe2N (space group: P312) with the high-pressure and high-temperature method. Structural refinements by the Rietveld method result in a trigonal unit cell with parameters of a = 4.7767(1) Å and c = 4.4179(3) Å. ε-Fe2N is ferromagnetic with a Curie temperature of ∼250 K, a saturation magnetization (M s) value of up to 1.2 μB/formula units (f.u.), and comparatively low coercive field. The Vickers hardness was measured, and the results showed that the asymptotic hardness of bulk ε-Fe2N is about 6.5 GPa with a load of 1000 g. Thermogravimetric (TG) analysis shows that ε-Fe2N is thermally stable below 670 K. ε-Fe2N exhibits good metal conductivity, and the electron transport measurements show that the resistivity of it is 172 μΩ cm at room temperature. The theoretical calculations suggest that the conducting states are mainly derive from Fe-3d states.

| S-EPMC8154168 | biostudies-literature

Effects of magnetite nanoparticles and static magnetic field on neural differentiation of pluripotent stem cells

Project description:Neural proliferation and differentiation fates of pluripotent stem cells are influenced by external natural forces. Despite the presence of biogenic magnetite nanoparticles in the central nervous system and constant exposure to Earth’s magnetic fields and other sources, there has been scant knowledge regarding the role of electromagnetic stimuli in neurogenesis. Moreover, the emerging application of electrical and magnetic stimulation to treat neurological disorders emphasizes the relevance of understanding the impact and mechanisms behind these stimuli. Here, the effects of magnetic nanoparticles (MNPs) contained in polymeric coatings and the static external magnetic field (EMF, 0.4 Tesla) were investigated on neural induction of murine embryonic stem cells (mESCs) and human induced pluripotent stem cells (hiPSCs) into induced dopaminergic neurons (iDA).

2021-12-17 | GSE190686 | GEO

Diverse Electronic and Magnetic Properties of Chlorination-Related Graphene Nanoribbons.

Project description:The dramatic changes in electronic and magnetic properties are investigated using the first-principles calculations for halogen(X: Cl, Br, I, At)-adsorbed graphene nanoribbons. The rich and unique features are clearly revealed in the atoms-dominated electronic band structures, spin arrangement/magnetic moment, spatial charge distribution, and orbital- and spin-projected density of states. Halogen adsorptions can create the non-magnetic, ferromagnetic or anti-ferromagnetic metals, being mainly determined by concentrations and edge structures. The number of holes per unit cell increases with the adatom concentrations. Furthermore, magnetism becomes nonmagnetic when the adatom concentration is beyond 60% adsorption. There are many low-lying spin-dependent van Hove singularities. The diversified properties are attributed to the significant X-C bonds, the strong X-X bonds, and the adatom- and edge-carbon-induced spin states.

| S-EPMC6294761 | biostudies-literature

Aza-Triangulene: On-Surface Synthesis and Electronic and Magnetic Properties.

Project description:Nitrogen heteroatom doping into a triangulene molecule allows tuning its magnetic state. However, the synthesis of the nitrogen-doped triangulene (aza-triangulene) has been challenging. Herein, we report the successful synthesis of aza-triangulene on the Au(111) and Ag(111) surfaces, along with their characterizations by scanning tunneling microscopy and spectroscopy in combination with density functional theory (DFT) calculations. Aza-triangulenes were obtained by reducing ketone-substituted precursors. Exposure to atomic hydrogen followed by thermal annealing and, when necessary, manipulations with the scanning probe afforded the target product. We demonstrate that on Au(111), aza-triangulene donates an electron to the substrate and exhibits an open-shell triplet ground state. This is derived from the different Kondo resonances of the final aza-triangulene product and a series of intermediates on Au(111). Experimentally mapped molecular orbitals match with DFT-calculated counterparts for a positively charged aza-triangulene. In contrast, aza-triangulene on Ag(111) receives an extra electron from the substrate and displays a closed-shell character. Our study reveals the electronic properties of aza-triangulene on different metal surfaces and offers an approach for the fabrication of new hydrocarbon structures, including reactive open-shell molecules.

| S-EPMC8931755 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data