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Structural chemistry and magnetic properties of Y2CoGe4O12

DOI: 10.1016/j.jssc.2015.04.033 DOI Help

Authors: Xiao-Qiang Liu (Zhejiang University) , Peter Battle (Oxford University) , Joe Ridout (Oxford University) , Diming Xu (Oxford University) , Silvia Ramos (University of Kent)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Solid State Chemistry , VOL 228 , PAGES 183 - 188

State: Published (Approved)
Published: August 2015
Diamond Proposal Number(s): 8169

Abstract: Polycrystalline Y2CoGe4O12 has been prepared by standard ceramic methods. The crystal structure (space group P4/nbm; a=9.8465(2), c=4.92986(9) Å) consists of metal-rich layers separated from each other by Ge4O12 groups comprised of four corner-sharing GeO4 tetrahedra. Two cation sites lie within the layers; an eight-coordinate site occupied by yttrium and a six-coordinate site occupied by a 1:1 disordered distribution of yttrium and cobalt. Neutron diffraction revealed two-fold disorder on the oxide sublattice; this has been elucidated using Co K-edge EXAFS spectroscopy. The availability of two sites allows each oxide ion to accommodate the coordination preferences of its single Co/Y neighbour; the GeO4 tetrahedra distort to absorb any consequent strain. The octahedron of anions around each Co2+ cation shows a pseudo-tetragonal distortion with a strain (Co–O)eq–(Co–O)ax/(Co–O)eq=−0.173. This results in an unusually large effective magnetic moment of 6.05 µB per Co2+ cation.

Journal Keywords: Mixed-Metal Germanate; Neutron Diffraction; EXAFS; Structure Determination

Subject Areas: Chemistry, Materials, Physics

Instruments: B18-Core EXAFS

Added On: 05/08/2015 09:56

Discipline Tags:

Physics Physical Chemistry Chemistry Magnetism Materials Science Inorganic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)