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Electron Paramagnetic Resonance Study of Copper(II) Fluosilicate Hexahydrate

De, Dilip Kumar and STHANAPATI, J. and GHOSHAL, A. K. and PAL, A. K. (1982) Electron Paramagnetic Resonance Study of Copper(II) Fluosilicate Hexahydrate. JOURNAL OF MAGNETIC RESONANCE, 47. pp. 181-186.

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An electron paramagnetic resonance study was performed on single crystals of copper fluosilicate hexahydrate. EPR signals correspond to three tetragonally distorted pctahedral Cu(II) ions (A site) with g values: g11 = 2.390, gJ. .= 2.093, and ·one regular octahedral Cu(II) ion (B site) with g = 2.093. The spectra are thus quite different from those observed earlier by Bleaney and Ingram in Cu(II):ZnSiF6 • 6H20. Fluosilicate hexahydrates of divalent metals belong to a series of crystals wellsuited for X-ray, magnetic susceptibility and anisotropy, electron paramagnetic resonance, optical, and other studies (J-4). Observations of an isotropic EPR signal at 90 K and above and anisotropic EPR signals at 20 K by Bleaney and Ingram (J) in Cu:ZnSiF6 • 6H20 provided the first experimental evidence of the Jahn-Teller effect. A determination of crystal structures of this series by Ray eta/. (2, 3) has revealed that copper(II) fluosilicate hexahydrate (3), contrary to earlier belief, is not isomorphous with zinc fluosilicate hexahydrate. The structure is still rhombohedral (space group R3) with a cell four times as large as that supposed earlier. The unit cell, which has dimensions a = b = 18.18 A and c = 9.857 A, contains three magnetically nonequivalent tetragonally distorted Cu(II) · 6H20 octahedra (Cu-0(1) = 1.97 A, Cu-0(2) = 1.97 A, Cu-0(3) = 2.367 A) designated as the A sites; and one regular Cu(II) · 6H20 octahedron (Cu-0 = 2.074 A) designated as the B site. It was therefore considered of interest to study EPR in single crystals of copper fluosilicate hexahydrate with the object of unravelling the nature of the ligand fields in a crystal where two types of Cu(II) complexes coexist.

Item Type: Article
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Engineering, Science and Mathematics > School of Physics
Depositing User: Mrs Hannah Akinwumi
Date Deposited: 22 Apr 2015 14:18
Last Modified: 22 Apr 2015 14:18

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