Ferromagnetic Properties of Spark-Processed Photoluminescing Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
J. Hack ◽  
M. H. Ludwig ◽  
W. Geerts ◽  
R. E. Hummel
Keyword(s):  
Magnetic Properties ◽  
High Purity ◽  
Paramagnetic Centers ◽  
Bulk Silicon ◽  
High Concentration ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Ultra High Purity ◽  
Ferromagnetic Ordering ◽  
First Time

AbstractMagnetic properties of photoluminescing spark-processed silicon (sp-Si) have been investigated for the first time. Contrary to the diamagnetic signal known for bulk silicon, sp-Si displays a paramagnetic resonance as well as a ferromagnetic hysterisis loop. The paramagnetic resonance was studied using an EPR system and showed a high concentration of at least two distinct paramagnetic centers. One center can be eliminated by annealing in Ultra-High Purity nitrogen for 30 minutes at 600 °C. Measurements utilizing a SQUID magnetometer revealed that sp-Si displays ferromagnetic ordering with a saturization magnetization occuring at low fields. This is attributed to the high density of paramagnetic centers. Temperature dependent measurements were performed to establish possible links between magnetic properties and the luminescence of sp-Si.

Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

2002 ◽  
Vol 17 (11) ◽  
pp. 2960-2965 ◽  
Author(s):  
E. Arushanov ◽  
L. Ivanenko ◽  
D. Eckert ◽  
G. Behr ◽  
U. K. Rößler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
External Field ◽  
Single Crystals ◽  
Spin Glasses ◽  
Paramagnetic Centers ◽  
Temperature Dependent ◽  
Paramagnetic Curie Temperature ◽  
Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

scholarly journals Magnetic properties of the natural and isotope-modified diamond and silicon carbide

2018 ◽  
Vol 185 ◽  
pp. 04007 ◽  
Author(s):  
A.N. Taldenkov ◽  
A.V. Inyushkin ◽  
E.A. Chistotina ◽  
V.G. Ralchenko ◽  
A.P. Bolshakov ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Magnetic Properties ◽  
Isotopic Composition ◽  
Single Crystals ◽  
High Purity ◽  
Diamagnetic Susceptibility ◽  
Synthetic Diamond ◽  
Paramagnetic Centers ◽  
Natural Isotopic Composition ◽  
Ferromagnetic Component

The magnetic properties of single crystals of synthetic diamond and crystals of silicon carbide were studied. High-purity samples of diamonds synthesized with HPHT and CVD technologies were used. The crystals of silicon carbide were grown by sublimation and industrial technology. Along with samples with a natural isotopic composition, monoisotopic crystals of diamond (99.96% 12C and 99.96% 13C) and silicon carbide (99.993% of 28Si) were studied. On the basis of the data obtained, the diamagnetic susceptibility was determined and the concentration of paramagnetic centers and the content of the ferromagnetic component were evaluated. The results are discussed.

scholarly journals On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

2020 ◽  
Vol 56 (8) ◽  
pp. 4967-4978
Author(s):  
R. Böttcher ◽  
H. T. Langhammer ◽  
T. Walther ◽  
S. Kücker ◽  
S. G. Ebbinghaus
Keyword(s):  
Magnetic Properties ◽  
Barium Titanate ◽  
Paramagnetic Susceptibility ◽  
Oxygen Octahedra ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Forbidden Transition ◽  
The Face ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic

AbstractSystematic measurements of the magnetic moment of hexagonal 6H-BaTiO3 + 0.04 BaO + x NiO (0.005 ≤ x ≤ 0.02) ceramics were performed to study the influence of Ni ions on the magnetic properties. By temperature-dependent measurements of the paramagnetic susceptibility at 90 kOe, the Ni2+ ion was identified as the majority defect in air-sintered Ni-doped hexagonal barium titanate. Q-band EPR investigations of a 2.0 mol% Ni-doped single crystal revealed three different Ni centers located at Ti sites: first, Ni3+ ions at Ti sites in intact oxygen octahedra, second, Ni3+ associated with an oxygen vacancy and third, the presence of Ni2+ centers leading to a forbidden transition. The Ni3+—VO associate characterized by a vacancy in the face-sharing oxygen plane of the oxygen octahedra can be ruled out. The crystal field parameters of the Ni2+ defect were estimated by a combined fitting of the paramagnetic susceptibility and the EPR fine structure parameter D to $$B_{0}^{4}$$ B 0 4 ≈ −17,300 cm−1, $$\left| {B_{0}^{2} } \right|$$ B 0 2 ≈ 2500 cm−1 and $$B_{3}^{4}$$ B 3 4 ≈ 19,000 cm−1.

Synthesis, structure and magnetic properties of ultra-high purity CrO 2 prepared under high O 2 -gas pressure

2017 ◽  
Vol 67 ◽  
pp. 72-75 ◽  
Author(s):  
X.L. Wang ◽  
P.Z. Si ◽  
H.L. Ge ◽  
K.P. Shinde ◽  
K.C. Chung ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
High Purity ◽  
Gas Pressure ◽  
Ultra High Purity

Magnetic properties of some Fe–S six-membered ring compounds

2002 ◽  
Vol 80 (12) ◽  
pp. 1646-1649 ◽  
Author(s):  
Ping Liu ◽  
Jia Cheng Liu ◽  
Jian Wang ◽  
Jian Kai Cheng ◽  
Wen Jie Li ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Behavior ◽  
Cluster Compounds ◽  
Spin Interaction ◽  
Fe Model ◽  
Temperature Dependent ◽  
Magnetic Exchange ◽  
Ring Compounds ◽  
First Time ◽  
Active Centres

The Fe3S3 cluster is an important component located in the active centres of some iron–sulfur proteins. The magnetic properties of three Fe3S3 compounds have been studied for the first time by fitting the temperature-dependent magnetic susceptibilities. The calculated g factors and J couplings reproduce the magnetic behavior of such compounds very well. There is an antiferromagnetic spin interaction between pairs of magnetic centers in the Fe3S3 cluster compounds. The magnetic exchange of Fe-S-Fe model magnetic molecules is discussed.Key words: Fe3S3 compounds, magnetic, antiferromagnetic.

scholarly journals Magnetic Properties of Bacterial Magnetosomes Produced by Magnetospirillum caucaseum SO-1

2021 ◽  
Vol 9 (9) ◽  
pp. 1854
Author(s):  
Kamil G. Gareev ◽  
Denis S. Grouzdev ◽  
Peter V. Kharitonskii ◽  
Demid A. Kirilenko ◽  
Andrei Kosterov ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Two Phase ◽  
Paramagnetic Resonance ◽  
Modified Method ◽  
Iron Oxide Magnetic Nanoparticles ◽  
A Minor ◽  
First Time ◽  
Electron Paramagnetic

In this study, the magnetic properties of magnetosomes isolated from lyophilized magnetotactic bacteria Magnetospirillum caucaseum SO-1 were assessed for the first time. The shape and size of magnetosomes and cell fragments were studied by electron microscopy and dynamic light scattering techniques. Phase and elemental composition were analyzed by X-ray and electron diffraction and Raman spectroscopy. Magnetic properties were studied using vibrating sample magnetometry and electron paramagnetic resonance spectroscopy. Theoretical analysis of the magnetic properties was carried out using the model of clusters of magnetostatically interacting two-phase particles and a modified method of moments for a system of dipole–dipole-interacting uniaxial particles. Magnetic properties were controlled mostly by random aggregates of magnetosomes, with a minor contribution from preserved magnetosome chains. Results confirmed the high chemical stability and homogeneity of bacterial magnetosomes in comparison to synthetic iron oxide magnetic nanoparticles.

scholarly journals Electron paramagnetic resonance (EPR) study of DOPA–melanin complexes with kanamycin and copper(II) ions

2011 ◽  
Vol 25 (3-4) ◽  
pp. 197-205 ◽  
Author(s):  
Lidia Najder-Kozdrowska ◽  
Barbara Pilawa ◽  
Ewa Buszman ◽  
Dorota Wrzesniok ◽  
Andrzej B. Więckowski
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Epr Spectroscopy ◽  
Paramagnetic Centers ◽  
High Concentration ◽  
Paramagnetic Resonance ◽  
Fitting Method ◽  
Epr Parameters ◽  
Dopa Melanin ◽  
Electron Paramagnetic ◽  
Paramagnetic Centres

This work comprises the study of DOPA–melanin complexes with kanamycin and copper(II) ions made by electron paramagnetic resonance EPR spectroscopy. The high concentration of paramagnetic centers in melanin makes the use of EPR spectroscopy possible. The unpaired electron localized on the oxygen atom in indol-5,6-quinone groups is the paramagnetic centers in this polymer. The aim of this work was the analysis of EPR parameters of recorded spectra. For researches were prepared melanin complexes which differed in complexing order of drug and Cu(II) ions, and in concentration of CuCl2solutions used during synthesis. The introduction of drugs and metal ions into melanin causes changes in EPR parameters of recorded spectra. Kanamycin causes the increase and copper(II) ions the decrease of concentrations of paramagnetic centres in melanin. Shape of EPR signal of DOPA–melanin was analyzed by fitting method. Results indicate that EPR line of DOPA–melanin is superposition of Gaussian and Lorentzian function.

Deep Levels and Compensation in High Purity Semi-Insulating 4H-SiC

2006 ◽  
Vol 911 ◽  
Author(s):  
William C Mitchel ◽  
W. D. Mitchell ◽  
H. E. Smith ◽  
W. E. Carlos ◽  
E. R. Glaser
Keyword(s):  
High Purity ◽  
Secondary Ion Mass Spectrometry ◽  
Activation Energies ◽  
Deep Levels ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Carbon Vacancy ◽  
Near Ir ◽  
Electron Paramagnetic ◽  
Secondary Ion

AbstractA study of temperature dependent Hall effect (TDH), electron paramagnetic resonance (EPR), photoluminescence (PL) and secondary ion mass spectrometry (SIMS) measurements has been made on high purity semi-insulating (HPSI) 4H-SiC crystals grown by the physical vapor transport technique. Thermal activation energies from TDH varied from a low of 0.55 eV to a high of 1.5 eV. All samples studied showed n-type conduction with the Fermi level in the upper half of the band gap. Carrier concentration measurements indicated the deep levels had to be present in concentrations in the low 1015 cm-3 range. Several defects were detected by EPR including the carbon vacancy and the carbon-silicon divacancy. PL measurements in the near IR showed the presence of the UD-1, UD-2 and UD-3 emission lines that have been found in HPSI material. No correlation between the relative intensities of the PL lines and the TDH activation energies was seen. SIMS measurements on nitrogen, boron and other common impurities indicate nitrogen and boron concentrations higher than those of individual deep levels as determined by TDH or of intrinsic defects as determined by EPR such as the carbon vacancy or the divacancy. It is determined that several different defects with concentrations greater than or equal to 1x1015 cm-3 are required to compensate the residual nitrogen and boron.

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