Anomalous magnetic properties in the solid state of salts of the Bis[2-(2-pyridylamino)-4-(2-pyridyl)thiazole]iron(II) ion

1967 ◽  
Vol 20 (3) ◽  
pp. 479 ◽  
Author(s):  
RN Sylva ◽  
HA Goodwin
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Crystal Lattice ◽  
Temperature Dependence ◽  
Iron Atom ◽  
Thermal Equilibrium ◽  
Magnetic Moments ◽  
Chloride Salt ◽  
Marked Influence ◽  
Free Iron

The magnetism of nine salts containing the bis[2-(2-pyridylamino)-4-(2- pyridyl)thiazole]iron(II) ion has been investigated over the temperature range c. 100-350�K. All salts were obtained hydrated and in some instances the magnetism of the anhydrous salts was also investigated. The magnetism was found to be markedly dependent on the anion of the salt. Two distinct classes of compounds were recognized- those obeying a simple Curie-Weiss law and having magnetic moments corresponding to the expected value for spin-free iron(II); and those whose temperature dependence of magnetism was found to be anomalous. For these compounds the magnetic moments varied from almost spin-paired to almost spin-free values. The anomalous behaviour has been qualitatively interpreted in terms of a thermal equilibrium between the nearly equi-energetic spin-paired and spin-free states of the iron atom. The differences in the behaviour of different salts have been ascribed to differences in crystal lattice forces. The presence of hydrate water in the crystal lattice has been shown in some instances to have a marked influence on the magnetism. Two magnetically isomeric forms of the anhydrous chloride salt have been obtained. It has been shown that there is an association between the magnetism and colour of the compounds.

Magnetic Properties of Ni Nanoparticles Embedded in Amorphous SiO2

2002 ◽  
Vol 746 ◽  
Author(s):  
Fabio C. Fonseca ◽  
Gerardo F. Goya ◽  
Renato F. Jardim ◽  
Reginaldo Muccillo ◽  
Neftalí L. V. Carreño ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Temperature Dependence ◽  
Excellent Agreement ◽  
Magnetic Moments ◽  
Magnetic Hysteresis ◽  
Blocking Temperature ◽  
Spherical Particles ◽  
Average Particle ◽  
Ni Nanoparticles ◽  
Tem Analysis

ABSTRACTA modified sol-gel technique was used to synthesize nanocomposites of Ni:SiO2 which resulted in Ni nanoparticles embedded in a SiO2 amorphous matrix. Transmission electron microscopy TEM analysis were performed to study the structure and morphology of the magnetic powders. The Ni particles were found to have a good dispersion and a controlled particle size distribution, with average particle radius of ∼ 3 nm. A detailed characterization of the magnetic properties was done through magnetization measurements M(T,H) in applied magnetic fields up to ± 7 T and for temperatures ranging from 2 to 300 K. The superparamagnetic (SPM) behavior of these metallic nanoparticles was inferred from the temperature dependence of the magnetization. The blocking temperature TB, as low as 20 K, was found to be dependent on Ni concentration, increasing with increasing Ni content. The SPM behavior above the blocking temperature TB was confirmed by the collapse of M/MS vs. H/T data in universal curves. These curves were fitted to a log-normal weighted Langevin function allowing us to determine the distribution of magnetic moments. Using the fitted magnetic moments and the Ni saturation magnetization, the radii of spherical particles were determined to be close to ∼ 3 nm, in excellent agreement with TEM analysis. Also, magnetic hysteresis loops were found to be symmetric along the field axis with no shift via exchange bias, suggesting that Ni particles are free from an oxide layer. In addition, for the most diluted samples, the magnetic behavior of these Ni nanoparticles is in excellent agreement with the predictions of randomly oriented and noninteracting magnetic particles. This was confirmed by the temperature dependence of the coercivity field that obeys the relation HC(T) = HC0 [1-(T/TB)1/2] below TB with HC0 ∼ 780 Oe.

Magnetic properties of rare earth chromium borates at high temperatures

2021 ◽  
pp. 166-170
Author(s):  
O.K. Kuvandikov ◽  
◽  
N.I. Leonyuk ◽  
V.V. Malsev ◽  
M.M. Kuzmin ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Temperature Dependence ◽  
High Temperatures ◽  
Wide Temperature Range ◽  
Magnetic Moments ◽  
Chemical Formula ◽  
Temperature Range ◽  
Curie Temperatures

Temperature dependence of the magnetic susceptibility has been studied for rare-earth borates NdCr3(BO3)4, SmCr3(BO3)4 and LuCr3(BO3)4 by the Faradey method in the wide temperature range (300-1200 K). The dependence for each phase follows the Curi - Weis law. The Curie temperatures, Neel temperatures and magnetic moments corresponding to the chemical formula of the crystals, have been found.

The magnetic properties of the Tris(2-methyl-1,10-phenanthroline)iron(II) ion

1968 ◽  
Vol 21 (1) ◽  
pp. 83 ◽  
Author(s):  
HA Goodwin ◽  
RN Sylva
Keyword(s):  
Magnetic Properties ◽  
Thermal Equilibrium ◽  
Magnetic Moments ◽  
Anomalous Behaviour ◽  
Ligand Field ◽  
Temperature Dependent ◽  
Methyl Group ◽  
Temperature Range ◽  
Effective Strength

The magnetism of the salts [Fe mephen3]X2 (X = I-, ClO4-, BF4-, PF6-; mephen = 2-methyl- 1,l0-phenanthroline) has been investigated over the temperature range c. 100-300�K. The compounds exhibit anomalous behaviour, and this has been qualitatively interpreted as being the result of the presence of nearly equi-energetic ground terms 1A1 and 5T2 of the complexed iron(11) ion, a thermal equilibrium between these terms causing the magnetic moments to be markedly temperature dependent. This behaviour is apparently the result of the sterie hindrance to the coordination of an iron(11) ion induced by the presence of the methyl group in the ligand and the consequent lowering of the effective strength of the ligand field. The colour of the salts varies with temperature, and this has been discussed in terms of π-bonding between the iron(11) ion and the ligand.

On the magnetic properties of some haemoglobin complexes

1956 ◽  
Vol 235 (1200) ◽  
pp. 23-36 ◽  
Keyword(s):  
Magnetic Properties ◽  
Iron Atom ◽  
Thermal Equilibrium ◽  
Oxygen Molecule ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Theoretical Scheme ◽  
Inorganic Complexes

Most haemoglobin compounds fall satisfactorily into Pauling’s classification of ‘ionic’ and ‘covalent’ complexes. A few, however, have surprising magnetic properties. In this paper interpretations of these properties are offered which enable all the compounds to be fitted into a theoretical scheme of the type which is adequate for an approximate understanding of simple inorganic complexes. In particular, it is suggested that: the oxygen molecule in oxyhaemoglobin is not at right angles to the haem but probably parallel to it; all ferrihaemoglobin derivatives have a spin of either S = ½ or S = 5/2 at each iron atom or, in the case of ferrihaemoglobin hydroxide, are a thermal equilibrium of the two; ferrihaemoglobin derivatives with S = 5/2 have usually or always a large zero-field splitting, the lowest states being characterized by S ᴟ = ± ½ perpendicular to the haem.

scholarly journals H/D isotope effect and magnetic properties of cyanide-bridged Nd(III)-Fe(III) complex

2011 ◽  
Vol 1 (1) ◽  
pp. 425-428
Author(s):  
T. Akitsu ◽  
Y. Kimoto ◽  
Y. Yamada ◽  
K. Nomura
Keyword(s):  
Magnetic Properties ◽  
Hydrogen Bonds ◽  
Crystal Lattice ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Mössbauer Spectra ◽  
Isotope Effects ◽  
Intermolecular Hydrogen Bonds ◽  
Coordination Environment ◽  
Mossbauer Spectra

AbstractWe have prepared four H/D isotope forms of Nd(DMF)4(H2O)3Fe(CN)6·H2O (DMF = N,N-dimethylformamide) by using D2O or DMF-d1. Temperature dependence of magnetization exhibits H/D isotope effects resulting from intermolecular hydrogen bonds. Temperature dependence of Fe 2p3/2 and 2p1/2 XAS and 57Fe Mössbauer spectra suggested that the influence of coordination environment could be distiguished from the influence of crystal lattice based on preliminary crystallographic results.

ELECTRIC AND MAGNETIC PROPERTIES OF NEW APPROXIMATE HALF-METAL Fe3F4

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3412-3417 ◽  
Author(s):  
J. LIU ◽  
X. Q. WANG ◽  
B. Q. HU ◽  
A. P. LIU ◽  
H. N. DONG ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Fermi Level ◽  
Crystal Lattice ◽  
Spin Polarization ◽  
Spinel Structure ◽  
Magnetic Moments ◽  
Spin Correlation ◽  
The Other ◽  
Half Metal ◽  
Energy Distance

Fe 3 F 4 with the spinel structure was designed, and its electric and magnetic properties were calculated in system based on density function theories. And then they were compared with those of Fe 3 O 4. From our calculation, Fe 3 F 4 is a kind of new stable approximate half-metal material because its spin-polarization at fermi level is about 95%, which is near to 100%. The steady constant of crystal lattice is 0.643 nm. The energy distance between the top of the up-spin valence band and the fermi level is about 2.05 eV, which is much larger than 0.6 eV of Fe 3 O 4. In the other hand, the resistivity of Fe 3 F 4 is lower than that of Fe 3 O 4. The molecular magnetic moments 10.68μB of Fe 3 F 4 are evidently higher than 4.0μB of Fe 3 O 4. This shows that there is stronger spin-correlation scattering on transmitted carriers in Fe 3 F 4 than in Fe 3 O 4 so that Fe 3 F 4 may have higher magnetoresistance than Fe 3 O 4. Extremely localization of 3d-electrons caused by hybrid orbits of F2p and Fe3d orbits is the mechanism of the distribution of electronic charges and magnetic moments of Fe 3 F 4.

scholarly journals Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 378
Author(s):  
Li Zhao ◽  
Zhiwei Hu ◽  
Hanjie Guo ◽  
Christoph Geibel ◽  
Hong-Ji Lin ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Growth ◽  
Physical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Magnetic Moments ◽  
Single Crystal Growth ◽  
The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

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