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'Pyrite' in keywords
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1990 (1)
1989 (1)
1Author    D. Siebert, R. Miller, S. Fiechter, P. Dulski, A. HartmannRequires cookie*
 Title    An EPR Investigation of Cr 3+ and Ni 2 + in Synthetic Pyrite Crystals  
 Abstract    In many synthetic pyrite single crystals of high quality and purity we could detect Cr 3 + and Ni 2 + by EPR at 78 K as unwanted impurities. The assignment was possible by means of the isotopes Cr 53 and Ni 61 , occurring in natural abundance. The paramagnetic centers exhibit unusual g-values. In case of Ni 2+ a ligand hyperfine interaction could be observed beside the normal hyperfine interaction with the Ni 61 nucleus. For some crystals the Cr 3+ signal intensity could be increased up to ten times by temperature increasement from 78 K to about 100 K. At 78 K the Cr 3+ intensity was quenched by IR irradiation. 
  Reference    Z. Naturforsch. 45a, 1267—1272 (1990); received August 4 1990 
  Published    1990 
  Keywords    Pyrite, EPR, Paramagnetic ions, Conductivity 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-1267.pdf 
 Identifier    ZNA-1990-45a-1267 
 Volume    45 
2Author    D. Siebert, J. Dahlem, S. Fiechter, A. HartmannRequires cookie*
 Abstract    Synthetic pyrite crystals doped with halogen (CI, Br) or manganese (Mn) were investigated by ESR at 78 K with an X-band spectrometer and a TE102 cavity with lOOkc field modulation. The crystals were preferably measured with the directions <100>, <110), and <111) parallel to the static magnetic field H0. The ESR spectrum of Mn-doped crystals showed a sextet which can be explained by a spin-Hamiltonian for an electron spin S = 1/2 in interaction with the nuclear spin / = 5/2 of the Mn nucleus for axial symmetry. Due to the observed spin and due to the orientation of the paramagnetic centers the spectra were assigned to Mn2+ in the low spin state which resides on cation site in the FeS-, lattice. In halogen-doped crystals four pairs of lines can be interpreted by the interaction of the two isotopes of / = 3/2, 79Br, 81 Br and 35C1, 37C1, respectively, with an electron spin S — 1/2. According to the observed symmetry of the ESR signals the paramagnetic centers can be explained as (S-X)2~ radicals (X = CI, Br) which substitute for the (S2)2~ dumb-bells of pyrite. All crystals evoked extremely narrow ESR lines, especially the halogen-doped crystals with linewidths down to 0.03 mT. Excellent agreement between measured and calculated spectra up to the finest details has been obtained. A n E S R In v e s tig a tio n o f S y n th e tic P y r ite C r y s ta ls 
  Reference    Z. Naturforsch. 44a, 59—66 (1989); received November 12 1988 
  Published    1989 
  Keywords    Pyrite, ESR anorganic radicals, hyperfine coupling, spin densities 
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 TEI-XML for    default:Reihe_A/44/ZNA-1989-44a-0059.pdf 
 Identifier    ZNA-1989-44a-0059 
 Volume    44