Magnetic and structural anomalies of NanC60 (n = 2, 3)

Open Physics ◽  
2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Vladimir Kulbachinskii ◽  
Boris Bulychev ◽  
Vladimir Kytin ◽  
Alexey Krechetov ◽  
Valeriy Tarasov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Fold Increase ◽  
Paramagnetic Susceptibility ◽  
Phase Reaction ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Face Centered ◽  
Increasing Temperature ◽  
Electron Paramagnetic

AbstractSodium fullerides NanC60 (n = 2, 3) have been synthesized by a liquid phase reaction and investigated with X-ray diffraction (XRD), nuclear magnetic resonance (NMR), electron paramagnetic resonance, and differential thermal analysis. XRD data indicate that the crystal structure of Na2C60 at 300 K is face centered cubic (FCC). A phase transition from primitive cubic to FCC crystal structure has been observed in this work in Na2C60 fulleride at 290 K. The transition is accompanied by the step-like change of paramagnetic susceptibility. The crystal structure of Na3C60 is more complicated than, and different from, what has been reported in the literature. A nearly seven-fold increase of paramagnetic susceptibility with increasing temperature has been observed in the Na3C60 fulleride at 240–260 K. In the same temperature range, a new line at about 255 ppm appears in the 23Na NMR spectrum, indicating a significant increase of electron density near the Na nucleus. The observed effect can be explained by a metal-insulator transition caused by a structural transition.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

Magnetic Properties and Morphology of the Cobalt Particles Prepared in Different Liquid Solvent

2013 ◽  
Vol 749 ◽  
pp. 192-197
Author(s):  
Xue Min Huang ◽  
Quan Sheng Wang ◽  
Ying Liu ◽  
Xiu Chen Zhao ◽  
Shu Lai Wen
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Ethylene Glycol ◽  
Water System ◽  
Cubic Phase ◽  
Water Mixture ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
The Difference ◽  
Face Centered

The two kinds of flower-like ultrafine cobalt particles were prepared by reducing cobalt chloride (CoCl2·6H2O) with hydrazine hydrate (N2H4·H2O) under ultrasonic and microwave radiation, in which ethanol-water or ethylene glycol-water mixture was used as solvent. The morphology, crystal structure and magnetic properties of the as-prepared particles were characterized by scanning electron microscope (SEM), x-ray diffraction pattern (XRD) and vibrating sample magnetometer (VSM). The results show that the petals of the flower-like cobalt particles prepared in the ethanol-water system were dendritic, while the petals of the flower-like cobalt particles prepared in the ethylene glycol-water system were sword-like. The crystal structure of cobalt particles prepared in the two kinds of systems both consisted of hexagonal close-packed cubic phase and face-centered cubic phase, but the relative content was different. The saturation magnetization of the cobalt particles with dendritic petals and the cobalt particles with sword-like petals was the same approximately, but their coercivity was greatly different (the difference in value about 7184.14Am-1), which might be attributed to the magnetocrystalline anisotropy and shape anisotropy.

A partly disordered 2 × 2 × 2 – superstructure of γ-brass related phase in Mn–Ni–Zn system

2021 ◽  
Vol 236 (3-4) ◽  
pp. 71-80
Author(s):  
Sivaprasad Ghanta ◽  
Anustoop Das ◽  
Rajat Kamboj ◽  
Partha P. Jana
Keyword(s):  
Crystal Structure ◽  
High Symmetry ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Cubic Lattice ◽  
The Face ◽  
Face Centered ◽  
Related Phase

Abstract The T phase in the Mn–Ni–Zn system was obtained as a product of high-temperature solid-state syntheses from the loaded composition of MnxNi2−xZn11 (x = 0.2–1.5)/MnxNi15.38−xZn84.62 (x = 1.54–11.54). The crystal structure of the T phase has been explored by means of X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The structures were solved in the face-centered cubic space group F 4 ‾ 3 m $F‾{4}3m$ (216) and contain 409–410 atoms/unit cell. The lattice constants were found to be a = 18.1727(2) and 18.1954(1) Å for crystals C1 and C2, respectively. The crystal structure denoted the T phase is a (2aγ)3-superstructure of the ordinary cubic γ-brass-type phase. The phase is isostructural to (Fe, Ni)Zn6.5. A “cluster” description has been used to visualize the crystal structure of the title phase. The structures have been constructed by the five distinct clusters and they are situated about the high symmetry sites of the face-centered cubic lattice. The T phase is stabilized at a valance electron concentration of 1.78, which is slightly higher than those expected for typical γ-brass Hume‐Rothery compounds.

scholarly journals Исследование Sr-допированных ферроманганитов иттербия методами ЭПР и мессбауэровской спектроскопии

2018 ◽  
Vol 60 (5) ◽  
pp. 933
Author(s):  
И.И. Нигьматуллина ◽  
В.В. Парфенов ◽  
Р.М. Еремина ◽  
Т.П. Гаврилова ◽  
И.В. Яцык
Keyword(s):  
Crystal Structure ◽  
Electron Paramagnetic Resonance ◽  
Phase Separation ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Magnetic Microstructure ◽  
X Ray ◽  
Nuclear Gamma Resonance ◽  
Electron Paramagnetic

AbstractIn this paper, we have studied the crystal structure of strontium-substituted manganite and ytterbium ferromanganites Yb_0.82Sr_0.18Mn_1 – x Fe_ x O_3 ( x = 0–0.2) by using X-ray diffraction analysis. Magnetic microstructure has been studied by electron paramagnetic resonance and nuclear gamma-resonance (Mössbauer) spectroscopy. We have observed phase separation in the ceramics for antiferromagnetic, superparamagnetic, and ferromagnetic phases.

The guanidinium t-diaqua-bis(oxalato)chromate(III) dihydrate complex: synthesis, crystal structure, EPR spectroscopy and magnetic properties

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Idelle Nono Kamga ◽  
Augustin Nkwento Nana ◽  
Bridget Ndoye Ndosiri ◽  
Frédéric Capet ◽  
Michel Foulon ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Dimensional Network ◽  
Ft Ir ◽  
Water Ligands ◽  
Electron Paramagnetic ◽  
Oxygen Atoms

Abstract A new salt (CH6N3)[t-Cr(C2O4)2(H2O)2]·2H2O (1) (CH6N3 + = guanidinium cation) has been synthesized and characterized by single-crystal X-ray diffraction, FT-IR and UV–Vis spectroscopies, elemental and thermogravimetric analyses. In the crystal structure of 1, the chromate(III) ion lies on an inversion center in the form of an elongated octahedron. The coordination sphere consists of four oxygen atoms of two chelating oxalato ligands in the equatorial plane and two axial oxygen atoms of water ligands. The structural feature of focal interest in the structure of 1 is the formation of pillars of [Cr(C2O4)2(H2O)2]− complex anions and CH6N3 + guanidinium cations, with the next-neighbor cations rotated by an angle of 60° relative to each other. O–H···O and N–H···O hydrogen bonds play an important role in the construction of the three-dimensional network. The electron paramagnetic resonance (EPR) and magnetic properties of 1 have also been investigated.

scholarly journals Synthesis and crystal structure of La21Cr8−2aAlbGe7−bC12[a= 0.22 (2) andb= 0.758 (19)]

2016 ◽  
Vol 72 (11) ◽  
pp. 1565-1568
Author(s):  
Jaskarun Pabla ◽  
Yuri Janssen ◽  
Jack W. Simonson
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Structure Type ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Cubic Crystal ◽  
Synthesis And Crystal Structure ◽  
Geometrically Frustrated ◽  
The Face ◽  
Face Centered

Single crystals of a new multinary chromium carbide, La21Cr8−2aAlbGe7−bC12(henicosalanthanum octachromium aluminium hexagermanium dodecacarbide), were grown from an La-rich self flux and were characterized by single-crystal X-ray diffraction. The face-centered cubic crystal structure is composed of isolated and geometrically frustrated regular Cr tetrahedra that are co-centered within regular C octahedra. These mutually separated Cr4−aC6clusters are distributed throughout a three-dimensional framework of Al, Ge, and La. The title compound is isotypic with La21−δMn8X7C12andR21Fe8X7C12(R= La, Ce, Pr;X= Al, Bi, Ge, Sn, Sb, Te) and represents the first example of a Cr-based compound with this structure-type.

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

scholarly journals Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2123
Author(s):  
Maria Râpă ◽  
Maria Stefan ◽  
Paula Popa ◽  
Dana Toloman ◽  
Cristian Leostean ◽  
...  
Keyword(s):  
Food Packaging ◽  
Spin Trapping ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Hno3 Solution ◽  
X Ray ◽  
Trapping Method ◽  
Ft Ir ◽  
Doped Zno ◽  
Electron Paramagnetic

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

Microstructure Characterization of Ag Nanoparticles Prepared by Hydrothermal Method

2012 ◽  
Vol 476-478 ◽  
pp. 1138-1141
Author(s):  
Zhi Qiang Wei ◽  
Qiang Wei ◽  
Li Gang Liu ◽  
Hua Yang ◽  
Xiao Juan Wu
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Hydrothermal Method ◽  
Ag Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered

Ag nanoparticles were successfully synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively. The samples by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) to determine the chemical composition, particle size, crystal structure and morphology. The experiment results indicate that the crystal structure of the samples is face centered cubic (FCC) structure as same as the bulk materials, The specific surface area is 24 m2/g, the particle size distribution ranging from10 to 50 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results.

Crystal structure of magnesium chromium vanadate Mg2CrV3O11, a member of the A2BV3O11 vanadate family

2007 ◽  
Vol 22 (3) ◽  
pp. 246-252 ◽  
Author(s):  
A. Worsztynowicz ◽  
S. M. Kaczmarek ◽  
W. Paszkowicz ◽  
R. Minikayev
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Ion Pairs ◽  
Exchange Constant ◽  
Type I ◽  
Type Ii ◽  
Paramagnetic Resonance ◽  
Interatomic Distances ◽  
Electron Paramagnetic ◽  
Full Occupancy

The crystal structure of recently discovered chromium (III) dimagnesium trivanadate (V) Mg2CrV3O11 was refined using the Rietveld method. The crystal system of Mg2CrV3O11 is triclinic with space group P1− (Mg1.7Zn0.3GaV3O11 type) and lattice parameters a=6.4057(1) Å, b=6.8111(1) Å, c=10.0640(2) Å, α=97.523(1)°, β=103.351(1)°, γ=101.750(1)°, and Z=2. The characteristic feature of compounds in the A2BV3O11 (A=Mg, Zn and B=Ga, Fe, Cr) family is a strong tendency to share the octahedral M(1) and M(2) sites by both divalent A and trivalent B atoms, and the bipyramidal M(3) sites occupied by divalent A ions. In the present refinement, the only constraint assuming full occupancy of the M(1), M(2), and M(3) sites leads to the following Cr/(Cr+Mg) ratios: 0.70(2) at M(1), 0.24(2) at M(2), and 0.03(2) at M(3). These occupancies are discussed and compared to those of isotypic compounds. The values of interatomic distances are found to be comparable with those reported by R. D. Shannon in 1976. Electron paramagnetic resonance has been also analyzed. Two absorption lines with g≈2.0 (type I) and g≈1.98 (type II) have been recorded in the EPR spectra, and attributed to V4+ ions and Cr3+–Cr3+ ion pairs, respectively. The exchange constant J between Cr3+ ions has been calculated.

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