Exchange interactions in antiferromagnetic salts of iridium II. Magnetic susceptibility measurements

1959 ◽  
Vol 250 (1260) ◽  
pp. 97-109 ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Exchange Interaction ◽  
Ammonium Salt ◽  
Potassium Salt ◽  
Room Temperature ◽  
Exchange Interactions ◽  
Nearest Neighbour ◽  
Paramagnetic Resonance ◽  
Magnetic Susceptibilities ◽  
Isotropic Exchange

Measurements have been made of the magnetic susceptibilities of ammonium and potassium chloroiridates at temperatures between room temperature and 1°K. The results obtained at high temperatures have been analysed into a susceptibility following a Curie-Weiss law together with temperature-independent terms. The values of the isotropic exchange inter­actions between neighbouring iridium ions deduced from the Weiss constant agree well with those calculated from paramagnetic resonance measurements. At lower temperatures the magnetic susceptibilities become almost independent of temperature over a certain range and then fall sharply at the antiferromagnetic transtion points (2.16 °K for the ammonium salt, 3.08°K for the potassium salt). These results are discussed in term s of the exchange interaction between nearest- and next-nearest-neighbour iridium ions.

Exchange interactions in antiferromagnetic salts of iridium. I. Paramagnetic resonance experiments

1959 ◽  
Vol 250 (1260) ◽  
pp. 84-96 ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Theoretical Analysis ◽  
Resonance Spectrum ◽  
Exchange Interactions ◽  
Ammonium Salts ◽  
Nearest Neighbour ◽  
Helium Temperature ◽  
Paramagnetic Resonance ◽  
Anisotropic Part ◽  
Rhombic Symmetry

Paramagnetic resonance methods have been used to investigate Ir-Ir exchange interactions in K 2 IrCl 6 and (NH 4 ) 2 IrCl 6 . Measurements are described of the resonance spectrum from nearest-neighbour pairs of Ir ions in semi-dilute mixed crystals where Pt is substituted for Ir. The results show that the isotropic p art of the Ir-Ir exchange, J / k , is antiferromagnetic and of magnitude 11.5 ± 1°K and 7.5 ± 1°K for the potassium and ammonium salts, respectively. There is also found to be an anisotropic part with rhombic symmetry and with magnitude of order 1 cm -1 . No lines attributable to next-nearest-neighbour pairs were found, and it is suggested that this interaction is small. The results are com pared briefly with the magnetic susceptibility experiments of Cooke et al . (part II) who find that the concentrated salts go antiferromagnetic in the liquid-helium temperature range, and also with the theoretical analysis of the superexchange mechanism given by Judd (part III).

Magnetism, electronic spectra, and structure of transition metal alkoxides. II. The preparation and magnetism of iron(III) alkoxides

1966 ◽  
Vol 19 (3) ◽  
pp. 363 ◽  
Author(s):  
RW Adams ◽  
RL Martin ◽  
G Winter
Keyword(s):  
Room Temperature ◽  
Benzene Solution ◽  
Magnetic Moments ◽  
Exchange Interactions ◽  
Metal Alkoxides ◽  
Antiferromagnetic Exchange ◽  
Crystal Data ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
The Core

The iron(III) alkoxides, Fe(OMe)3, Fe(OEt)3, and Fe(Obun)a have been prepared by a procedure alternative to those previously described in the literature. The trimeric nature of the three compounds in benzene is confirmed by cryoscopy, and preliminary X-ray single crystal data for the ethoxide are consistent with trimeric entities in the solid. The temperature variation of the magnetic susceptibilities for the three compounds follows the Curie-Weiss law between 90 and 300�K but with large values of θ=- 200�K. The unusually low magnetic moments vary markedly with temperature, and at room temperature remain depressed in benzene solution at peer μeff 4.4 B.M. This anomalous behaviour is ascribed to the presence of weak antiferromagnetic exchange interactions within the cluster of iron atoms which forms the core of the trimeric species Fe3(0R)9. The compounds are sensitive both to hydrolysis and to heating. Hydrolysis decreases and pyrolysis increases the magnetic susceptibility. This provides a convenient method for following the progress of both types of reaction.

scholarly journals Magnetic susceptibility and related properties of rare-earth crystals

1939 ◽  
Vol 170 (940) ◽  
pp. 112-129 ◽  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Specific Heat ◽  
Absorption Spectra ◽  
Room Temperature ◽  
Magnetic Susceptibilities ◽  
Temperature Range ◽  
The Mean

This paper has arisen from attempts to correlate the results of experiments on magnetic susceptibilities, specific heat and absorption spectra of rareearth crystals. No theory has yet been advanced which is capable of giving simultaneous quantitative numerical agreement on all these properties, nor indeed does it seem possible to develop such a theory. For reasons which we shall explain, it seems more likely that some of the data are wrong, or at least, that they have been wrongly interpreted. Many measurements have been made of the magnetic properties of hydrated rare-earth crystals. Accurate values of the mean molecular susceptibility, X , have been obtained over a temperature range from a few degrees absolute to room temperature, and the anisotropy of the susceptibility at room temperature has also been measured

Magnetic susceptibility measurements on type A myoglobin crystals

1961 ◽  
Vol 262 (1309) ◽  
pp. 287-290 ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Room Temperature ◽  
Type A ◽  
Electron Resonance ◽  
Magnetic Susceptibilities ◽  
The Difference

Measurements have been made of the difference between the magnetic susceptibilities in the directions of the a and b crystal axes in type A acid-met myoglobin crystals, at temperatures between room temperature and 90°K. Below about 150°K a measurable anisotropy has been found. This has been interpreted in terms of a splitting between the ground doublet and the first excited doublet of less than 15 cm -1 , compared with the earlier estimate from electron resonance work of the order of 10 cm -1 or greater.

Magnetic susceptibility of Tri-Coordinated copper(II) complexes

1957 ◽  
Vol 10 (4) ◽  
pp. 386 ◽  
Author(s):  
M Kishita ◽  
Y Muto ◽  
M Kubo
Keyword(s):  
Magnetic Susceptibility ◽  
Chemical Analysis ◽  
Copper Atom ◽  
Room Temperature ◽  
Copper Complexes ◽  
Magnetic Moments ◽  
The Other ◽  
Acetate Monohydrate ◽  
Magnetic Susceptibilities ◽  
Cupric Acetate

The magnetic susceptibilities of salicylal-o-hydroxybenzylamine Cu(II), salicylal-o-hydroxyanil Cu(II), acetylacetone-mono-(0-hydroxyanil) Cu(II), and benzoylacetone- mono-(0-hydroxyanil) Cu(II), as well as their pyridinates, have been measured by the Gouy method at room temperature. The effective magnetic moments calculated from the . data of the pyridine-free complexes per one copper atom are smaller than the theoretical moment, 1.73 B.M., for one odd electron. Although it has been presumed from the method of synthesis, the chemical analysis of the complexes, and the tridentate nature of the ligand molecules that the copper atoms of the chelates have the unusual coordination number 3, the subnormal magnetic moments suggest the presence of dimeric molecules, in which two copper atoms are very close to each other as in cupric acetate monohydrate. On the other hand, the pyridinates have normal magnetic moments expected for tetra-coordinated copper complexes.

Temperature Dependent Line-Shape of the Silicon Dangling Bond EPR-Resonance in Polycrystalline Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
N. H. Nickel ◽  
E. A. Schiff
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Dangling Bond ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Motional Narrowing ◽  
G Value ◽  
Electron Paramagnetic

AbstractThe temperature dependence of the silicon dangling-bond resonance in polycrystalline (poly-Si) and amorphous silicon (a-Si:H) was measured. At room temperature, electron paramagnetic resonance (EPR) measurements reveal an isotropie g-value of 2.0055 and a line width of 6.5 and 6.1 G for Si dangling-bonds in a-Si:H and poly-Si, respectively. In both materials spin density and g-value are independent of temperature. While in a-Si:H the width of the resonance did not change with temperature, poly-Si exhibits a remarkable T dependence of ΔHpp. In unpassivated poly-Si a pronounced decrease of ΔHpp is observed for temperatures above 300 K. At 384 K ΔHpp reaches a minimum of 5.1 G, then increases to 6.1 G at 460 K, and eventually decreases to 4.6 G at 530 K. In hydrogenated poly-Si ΔHpp decreases monotonically above 425 K. The decrease of ΔHpp is attributed to electron hopping causing motional narrowing. An average hopping distance of 15 and 17.5 Å was estimated for unhydrogenated and H passivated poly-Si, respectively.

scholarly journals EPR Spectra of Sintered Cd1−xCrxTe Powdered Crystals with Various Cr Content

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3449
Author(s):  
Ireneusz Stefaniuk ◽  
Werner Obermayr ◽  
Volodymyr D. Popovych ◽  
Bogumił Cieniek ◽  
Iwona Rogalska
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Integral Intensity ◽  
Resonance Field ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Simple Method ◽  
Paramagnetic Curie Temperature ◽  
Cr Content ◽  
Electron Paramagnetic

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1−xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie–Weiss law and the paramagnetic Curie temperature was obtained.

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