Interface Defects in n-Type 3C-SiC/SiO2: An EPR Study of Oxidized Porous Silicon Carbide Single Crystals

2005 ◽  
Vol 483-485 ◽  
pp. 273-276 ◽  
Author(s):  
Hans Jürgen von Bardeleben ◽  
J.L. Cantin ◽  
L. Ke ◽  
Y. Shishkin ◽  
Robert P. Devaty ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Carbon Atom ◽  
Spin Hamiltonian ◽  
Dangling Bond ◽  
Interface Defects ◽  
X Band ◽  
Interface Defect ◽  
Bond Center ◽  
Oxidized Porous Silicon ◽  
Hamiltonian Parameters

The defects at the 3C-SiC/SiO2 interface have been studied by X-band EPR spectroscopy in oxidized porous 3C-SiC. One interface defect is detected; its spin Hamiltonian parameters, spin S=1/2, C3V symmetry, g//=2.00238 and g⊥=2.00317, central hyperfine interaction (CHF) with one carbon atom and AB//[001]=48G and superhyperfine (SHF) interaction with three equivalent Si neighbour atoms and TB//[001]=12.4G, allow us to attribute the center to a sp3 coordinated carbon dangling bond center, PbC.

EPR Studies of Mn2+-Doped Diammonium Hexaaqua Magnesium(II) Sulfate

2006 ◽  
Vol 61 (12) ◽  
pp. 683-687 ◽  
Author(s):  
Ram Kripal ◽  
Ashutosh Kumar Shukla
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Fine Structure ◽  
Single Crystals ◽  
Room Temperature ◽  
Spin Hamiltonian ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) studies of Mn2+ impurity in single crystals of diammonium hexaaqua magnesium(II) sulfate have been carried out at 9.3 GHz (X-band) at room temperature. The EPR spectra exhibit a group of five fine structure transitions. The spin-Hamiltonian parameters were determined. Mn2+ enters the lattice interstitially. The EPR spectrum of a powder sample supports the data obtained by single crystal studies. - PACS number: 76.30

EPR of VO2+ in ZnCs2(SO4)2 · 6 H2O Single Crystals

1977 ◽  
Vol 32 (9) ◽  
pp. 1068-1069 ◽  
Author(s):  
V. K. Jain ◽  
T. M. Srinivasan
Keyword(s):  
Single Crystals ◽  
Spin Hamiltonian ◽  
X Band ◽  
Hamiltonian Parameters

Abstract The EPR of VO2+ is studied in single crystals of ZnCs2(SO)4)2 · 6 H2O at X-band. The V-0 axis is found to have two orientations. The spin-Hamiltonian parameters at 298 K are determined.

EPR Studies of Tb 4+ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates

1996 ◽  
Vol 51 (8) ◽  
pp. 885-894 ◽  
Author(s):  
S. Hansen ◽  
B. D. Mosel ◽  
W. Müller-Warmuth ◽  
P. E. Fielding
Keyword(s):  
Magnetic Field ◽  
Zero Field ◽  
Scheelite Structure ◽  
Spin Hamiltonian ◽  
Field Limit ◽  
Paramagnetic Resonance ◽  
Zircon Structure ◽  
X Band ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance spectra of tetravalent terbium ions have been observed in host crystals of ZrSiO4 , HfSiO4 , ThSiO4 , ThGeO4 (zircon structure) and ZrGeO4 , HfGeO4 (scheelite structure) at X band and Q band and various temperatures. The spin Hamiltonian parameters have been determined from the rotational diagrams; the zero field splittings turned out to be extremely large, so that complex spectra far from the strong magnetic field limit had to be analyzed. In all the compounds Tb4+ substitutes for the tetragonal metal lattice sites. The incorporation of terbium, the origin of the large second-order parameters and comparisons with the spectra of trivalent gadolinium in similar systems are discussed.

Forming Gas Annealing of the Carbon PbC Center in Oxidized Porous 3C- and 4H-SiC: An EPR Study

2006 ◽  
Vol 527-529 ◽  
pp. 1015-1018 ◽  
Author(s):  
J.L. Cantin ◽  
Hans Jürgen von Bardeleben
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Dissociation Energy ◽  
Vacuum Annealing ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Paramagnetic Resonance ◽  
Interface Defect ◽  
Bond Center ◽  
Electron Paramagnetic

Previous Electron Paramagnetic Resonance (EPR) studies identified the carbon dangling bond center as the main paramagnetic interface defect in 3C, 4H, 6H-SiC/SiO2. We demonstrate that this defect, called PbC center, can be passivated by forming gas annealing at 400°C. We have measured the PbC density at annealed 4H- and 3C-SiC/SiO2 interfaces and attributed its reduction to the transformation of the dangling bonds into EPR inactive C-H bonds. We have also studied the reverse phenomenon occurring during vacuum annealing at temperatures ranging from 600°C up to 1000°C and have determined a dissociation energy of ≈4.3 eV for the 3C and 4H polytypes.

Host Spin-Lattice Relaxation Narrowing in Pr2Co3(NO3)12 · 24 H2O: Mn2+ \ Gd3+ Single Crystals

1980 ◽  
Vol 35 (12) ◽  
pp. 1308-1312 ◽  
Author(s):  
Vimal Kumar Jain
Keyword(s):  
Single Crystals ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Single Type ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Spin Lattice ◽  
X Band ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance of Mn2+ and Gd3+ in single crystals of Pr2Co3(NO3)12 · 24 H2O has been studied at X-band at 305 and 77 K. Mn2+ substitutes at two types of Co2+ sites whereas Gd3 substitutes at the single type of Pr3+ site in the lattice. The spin-Hamiltonian parameters have been evaluated. Observation of resolved Mn2+ and Gd3+ spectra at 305 K and their broadening on lowering the temperature are discussed in terms of host spin-lattice relaxation narrowing.

THE SPIN HAMILTONIAN PARAMETERS CALCULATION OF 14N AND 15N IN NATURAL TYPE I DIAMOND

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4740-4748 ◽  
Author(s):  
CHITTRA KEDKAEW ◽  
PICHET LIMSUWAN ◽  
KANPHOT THONGCHAM ◽  
SIWAPORN MEEJOO
Keyword(s):  
Natural Diamond ◽  
Microwave Frequency ◽  
Esr Spectra ◽  
Type I ◽  
Spin Hamiltonian ◽  
X Band ◽  
Natural Type ◽  
Hamiltonian Parameters ◽  
Parameters Calculation ◽  
Resonance Magnetic Field

The main purpose of this work is to present the ESR spectra and calculate the spin Hamiltonian parameters of 14 N and 15 N impurities in natural diamond. The ESR spectra of diamond crystal were measured on ESR spectrometer operating at X-band microwave frequency. The results of ESR spectra show that the diamond has a P1 center. This center gives rise to three strong resonance absorption peaks at θ = 90°, φ = 0° due to hyperfine interaction between electron spin and nuclear spin of 14 N . The ESR spectra of 15 N impurity consist of two satellites at the same rotation angle (φ). The effects of isolated substitution nitrogen on carbon atom produced a symmetric distortion from Td to C3V symmetry. According to this symmetry, the resonance magnetic field positions of ESR spectra for the rotation angles of 0°, 90° and 180° are almost overlap. The g-factor values and spin Hamiltonian parameters of 14 N and 15 N are: g = 2.0019, A⊥ = 29.73, A‖ = 40.24 and g = 2.0019, A⊥ = −39.90, A‖ = −57.05, respectively.

Tetranuclear supramolecular structures containing phthalocyanine cores

2007 ◽  
Vol 11 (07) ◽  
pp. 531-536 ◽  
Author(s):  
Ibrahim Özçesmeci ◽  
Sadik Güner ◽  
Ali Ihsan Okur ◽  
Ahmet Gül
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Energy Levels ◽  
Water Soluble ◽  
Orbital Energy ◽  
Characteristic Line ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

A metal-free phthalocyanine with four pyridyl donor groups, bound through ethylthio ester bridges on the periphery, have been prepared. The pyridine donors were quaternized with iodomethane to a water-soluble tetracationic phthalocyanine. The tetranuclear supramolecular phthalocyanine was prepared by the coordination of peripheral pyridine donors with VO(acac)2. The paramagnetic tetranuclear structure was studied in powder and solution forms by the electron paramagnetic resonance (EPR) technique. Electron paramagnetic resonance studies, together with the other spectral data confirmed the presence of identical pyridine-coordinated VO(acac)2 paramagnetic centers attached to the peripheral positions of the phthalocyanine core. The X-band EPR signals recorded from powder and solution forms of supramolecules have a characteristic line shape that proves the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors were calculated as g ∥ < g ⊥ < g e = 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically fitted Spin Hamiltonian parameters.

EPR Study of VO2+ and Cr3+ in Li2SO4 · H2O Single Crystal

1997 ◽  
Vol 52 (11) ◽  
pp. 765-770 ◽  
Author(s):  
F. Çelik ◽  
F. Köksal ◽  
İ. Kartal ◽  
H. Gümüş
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Room Temperature ◽  
Charge Compensation ◽  
Spin Hamiltonian ◽  
Temperature Analysis ◽  
X Band ◽  
Superhyperfine Interaction ◽  
Hamiltonian Parameters ◽  
The Magnetic Field

Abstract A single crystal X-band EPR study of VO2+ and Cr3+ in Li2SO4 • H2O was carried out at room temperature. Analysis of the spectra indicates that VO2+ substitutes for Li+ and that there are two magnetically inequivalent Li+ sites. The charge compensation occurs by removal of a neighboring Li+ . The principal values of the g and A tensors of the spin Hamiltonian for the two sites were determined. Superhyperfine interaction of the 3d1 electron of VO2+ with the neighboring water protons in the unit cell was observed and found to be between 0 and 0.5 mT, depending on the orientation of the magnetic field. Two magnetically different sites were also observed for Cr3+ , and the results were explained by a rhombic spin Hamiltonian. The Hamiltonian parameters g, D, and E were determined. It is concluded that VO2+ and Cr3+ enter into the Li+ places and the charge is compensated by a Li+ vacancy in the VO2+ case and proton vacancies in the Cr3+ case.

scholarly journals Oxovanadium(IV) complexes of bromo-and methoxy substituted N1,N4-diarylidene-S-methylthiosemicarbazones

2006 ◽  
Vol 4 (1) ◽  
pp. 149-159 ◽  
Author(s):  
Tülay. Demirci ◽  
Yüksel Köseoğlu ◽  
Sadik Güner ◽  
Bahri Ülküseven
Keyword(s):  
Epr Spectroscopy ◽  
Magnetic Measurements ◽  
Energy Levels ◽  
Orbital Energy ◽  
Spin Hamiltonian ◽  
X Band ◽  
Solid Compounds ◽  
Hamiltonian Parameters ◽  
Vanadium Ions ◽  
Template Reaction

AbstractFour new oxovanadium(IV) compounds were prepared by template reaction of salicyl-, 5-bromosalicyl-and 3-methoxysalicyl-aldehyde S-methylthiosemicarbazones with 2-hydroxy-, 5-bromo-2-hydroxy-and 3-methoxy-2-hydroxy-benzaldehyde in various combinations. The compounds were isolated as stable solid compounds with general formula [VO(L)] and characterized by elemental analysis, conductivity and magnetic measurements, electronic, IR and EPR spectroscopy. The X-band EPR signals recorded from powder forms of all samples have a single asymmetric line shape and theoretical fit studies proved the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors take values of g‖ < g⊥ < ge = 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically well fitted Spin Hamiltonian parameters. The EPR spectra recorded from solution forms almost have isotropic character.

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