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.

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

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.

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.

Investigation of the Spin Hamiltonian Parameters and the Local Structure of Two Ni3+ Centers in KTaO3

2004 ◽  
Vol 59 (4-5) ◽  
pp. 203-208 ◽  
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong ◽  
Wang-He Wei
Keyword(s):  
Covalent Bonding ◽  
Interstitial Oxygen ◽  
Nearest Neighbour ◽  
Spin Hamiltonian ◽  
Electron Paramagnetic Resonance Data ◽  
Paramagnetic Resonance ◽  
Local Structures ◽  
Resonance Data ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

The spin Hamiltonian anisotropic g factors g∥ and g⊥ and the local structures of the Ni3+ centers I and II in KTaO3 are theoretically investigated by using the perturbation formulas of the spin Hamiltonian parameters for 3d7 ions in tetragonally distorted octahedrons and dodecahedrons. By analyzing the electron paramagnetic resonance data of the studied systems, the centers I and II can be attributed to Ni3+ ions occupying octahedral Ta5+ (associated with a nearest-neighbour oxygen vacancy VO along the C4 axis) and the dodecahedral K+ (associated with a nearest-neighbour interstitial oxygen OI along the C4 axis) sites, respectively. Based on these studies, it is found that at the center I the impurity Ni3+ is displaced away from VO by ΔZI ≈ −0.31(2) Å along the C4 axis. At the center II a large off-center displacement, ΔZII ≈ 1.12(2) Å , towards the OI along the C4 axis is obtained, due to Ni3+-OI covalent bonding.

Epr of Mn2+ in Ni(CH3COO)2 4H2O and K2 Ni(SO4)2 6H2O

1980 ◽  
Vol 3 ◽  
Author(s):  
Sushil K. Misra ◽  
M. Jalochowski
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Properties ◽  
Transition Temperature ◽  
Single Crystals ◽  
Liquid Helium ◽  
Liquid Nitrogen ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

ABSTRACTThe technique of electron paramagnetic resonance has been applied to study the magnetic properties of nickel acetate and nickel potassium tutton salt single crystals, using Mn2+ ion as probe. From the values of spin Hamiltonian parameters and linewidths at room, liquid nitrogen and liquid helium temperatures it is concluded that these crystals do not become magnetically ordered as the temperature is lowered to 3.2K, and thus the transition temperature, below which the crystal would order either ferromagnetically, or antiferromagnetically, for these crystals, should be below 3.2K.

EPR AND OPTICAL STUDIES OF VANADYL IONS IN ALKALI LEAD BOROTELLURITE GLASSES

2005 ◽  
Vol 19 (13n14) ◽  
pp. 643-653 ◽  
Author(s):  
R. P. SREEKANTH CHAKRADHAR ◽  
G. SIVARAMAIAH ◽  
J. LAKSHMANA RAO ◽  
N. O. GOPAL
Keyword(s):  
Optical Absorption ◽  
Molecular Ions ◽  
Tetragonal Symmetry ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Fermi Contact Interaction ◽  
Fermi Contact ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic ◽  
Boltzmann Law

Electron Paramagnetic Resonance (EPR) and optical absorption spectra of VO 2+ ions in different alkali lead borotellurite glasses have been studied. The spin-Hamiltonian parameters (g and A), bonding parameter [Formula: see text] and Fermi contact interaction parameter k have been calculated. The values of spin-Hamiltonian parameters confirm that the vanadyl ions are present in the glasses as VO 2+ molecular ions in an octahedral site with a tetragonal compression. The number of spins (N) participating in resonance is calculated as a function of temperature (123–393 K) for 9 mol% of VO 2+ ions in lithium lead borotellurite glass sample. It is observed that N obeys the Boltzmann law. From EPR data, the paramagnetic susceptibility (χ) is calculated at various temperatures and the Curie constant has been evaluated from 1/χ–T graph. The optical absorption spectrum exhibits two bands characteristic of VO 2+ ions in tetragonal symmetry. The band gap (E opt ) and the Urbach energies (ΔE) have been determined from the ultraviolet absorption edges and are found to be dependant on the size of the alkali ion. The theoretical values of optical basicity (Λ th ) of these glasses have also been evaluated.

EPR Studies of Cr3+ and Fe3+ in Host Crystals with Langbeinite Structure

1996 ◽  
Vol 51 (10-11) ◽  
pp. 1123-1133
Author(s):  
J. Kastner ◽  
B. D. Mosel ◽  
W. Müller-Warmuth
Keyword(s):  
Charge Compensation ◽  
Qualitative Description ◽  
Ligand Field ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Local Relaxation ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance (EPR) spectra of trivalent chromium and iron ions have been investigated in host crystals of double sulfates with langbeinite structure, A2B2(SO4)3 , with A = NH4+, Rb+, Tl+ and B = Cd2+, Mg2+. In most cases, single crystals could be grown, and the spin Hamiltonian parameters have been determined from the rotational diagrams. Powder spectra were analyzed and simulated as well. Three centres of axial symmetry with different zero field splittings have been observed for Cr3+, and two for Fe3+. The trivalent impurity ions have been shown to occupy divalent lattice sites substitutionally, but the environments are different depending on the structure and the mechanism of charge compensation. A qualitative description of the incorporation of dopants has been possible on this basis, taking into account the local relaxation and the ligand field stabilization effects. Temperature dependent single crystal and powder measurements have provided information on the zero field splitting and phase transitions.

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