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Structural and Magnetic Properties of Fe Impurities in YBa sub 2 Cu sub 3 O/sub 7-delta/.

DE88009961

Publication Date	1988
Personal Author	Dunlap, B. D.; Jorgensen, J. D.; Kwok, W. K.; Kimball, C. W.; Matykiewicz, J. L.
Page Count	6
Abstract	Samples having the general composition YBa sub 2 (Cu/sub 1/minus/x/Fe/sub x/) sub 3 O/sub 7/minus/delta/ have been investigated using x-ray and neutron diffraction, Moessbauer spectroscopy and bulk property measurements. X-ray and neutron data show that samples having x greater than or equal to 0.04 are tetragonal. Neutron diffraction shows that this structure is very similar to that found for undoped YBa sub 2 Cu sub 3 O/sub 7/minus/delta/ when the oxygen concentration is low, although in the present case, the total oxygen content is found to be greater than or equal to7 for all concentrations. Contrary to the common statement that Fe substitutes onto the Cu sites, it is found from neutron diffraction that the Cu1 site is not occupied, and that Fe appears to have a substantial substitution for Ba. Both Moessbauer spectroscopy and heat capacity measurements show the presence of magnetic transitions at temperatures well below the superconducting transition temperature, with evidence for a large variation in magnetic transition temperatures. 16 refs., 4 figs.,. (ERA citation 13:034357)
Keywords	Barium Oxides Copper Oxides Iron Oxides Yttrium Oxides Doped Materials Impurities Iron 57 Iron Additions Magnetism Moessbauer Effect Specific Heat Superconductivity Superconductors High temperature superconductors Yttrium barium cuprates ERDA/360204 ERDA/656100 Barium yttrium cuprates Magnetic impurities Crystal structure
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	46D - Solid State Physics
Corporate Authors	Argonne National Lab., IL.; Illinois Inst. of Tech., Chicago.; Department of Energy, Washington, DC.; Northern Illinois Univ., Dekalb.
Supplemental Notes	Portions of this document are illegible in microfiche products. International conference on high temperature superconductors and materials and mechanisms of superconductivity, Interlaken, Switzerland, 29 Feb 1988.
Document Type	Conference Proceedings
NTIS Issue Number	198822
Contract Number	W-31109-ENG-38

Structural and Magnetic Properties of Fe Impurities in YBa sub 2 Cu sub 3 O/sub 7-delta/.

Structural and Magnetic Properties of Fe Impurities in YBa sub 2 Cu sub 3 O/sub 7-delta/.
DE88009961

Publication Date	1988
Personal Author	Dunlap, B. D.; Jorgensen, J. D.; Kwok, W. K.; Kimball, C. W.; Matykiewicz, J. L.
Page Count	6
Abstract	Samples having the general composition YBa sub 2 (Cu/sub 1/minus/x/Fe/sub x/) sub 3 O/sub 7/minus/delta/ have been investigated using x-ray and neutron diffraction, Moessbauer spectroscopy and bulk property measurements. X-ray and neutron data show that samples having x greater than or equal to 0.04 are tetragonal. Neutron diffraction shows that this structure is very similar to that found for undoped YBa sub 2 Cu sub 3 O/sub 7/minus/delta/ when the oxygen concentration is low, although in the present case, the total oxygen content is found to be greater than or equal to7 for all concentrations. Contrary to the common statement that Fe substitutes onto the Cu sites, it is found from neutron diffraction that the Cu1 site is not occupied, and that Fe appears to have a substantial substitution for Ba. Both Moessbauer spectroscopy and heat capacity measurements show the presence of magnetic transitions at temperatures well below the superconducting transition temperature, with evidence for a large variation in magnetic transition temperatures. 16 refs., 4 figs.,. (ERA citation 13:034357)
Keywords	Barium Oxides Copper Oxides Iron Oxides Yttrium Oxides Doped Materials Impurities Iron 57 Iron Additions Magnetism Moessbauer Effect Specific Heat Superconductivity Superconductors High temperature superconductors Yttrium barium cuprates ERDA/360204 ERDA/656100 Barium yttrium cuprates Magnetic impurities Crystal structure
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	46D - Solid State Physics
Corporate Authors	Argonne National Lab., IL.; Illinois Inst. of Tech., Chicago.; Department of Energy, Washington, DC.; Northern Illinois Univ., Dekalb.
Supplemental Notes	Portions of this document are illegible in microfiche products. International conference on high temperature superconductors and materials and mechanisms of superconductivity, Interlaken, Switzerland, 29 Feb 1988.
Document Type	Conference Proceedings
NTIS Issue Number	198822
Contract Number	W-31109-ENG-38