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Synthesis, crystal structure, electrical, and magnetic properties of the new layered cobalt oxides (Sr, Ca, Ln){sub 3}Co{sub 2}O{sub 6{+-}{delta}} (Ln = Sm, Eu, Gd, Tb, Dy, Ho, and Y)

Journal Article · · Journal of Solid State Chemistry
;  [1];  [2]
  1. Princeton Univ., NJ (United States)
  2. National Inst. of Standards and Technology, Gaithersburg, MD (United States). NIST Center for Neutron Research
New layered Co oxides of nominal formula Sr{sub 2}(Ln{sub 0.8}Ca{sub 0.2})Co{sub 2}O{sub 6} (Ln = Sm, Eu, Gd, Tb, Dy, Ho, and Y) are reported. Single-phase polycrystalline samples were obtained at compositions Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Co{sub 2}{sup 2.5+}O{sub 6{minus}{delta}} (0.2 {le} x {le} 0.5; 0 {le} {delta} {le} 0.24), Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Co{sub 2}{sup 3.4+}O{sub 6+{delta}{prime}} (0.2 {le} x {le} 0.5; 0.62 {le} {delta}{prime} {le} 0.79), and Sr{sub 2}Dy{sub 0.8}Ca{sub 0.2}Co{sub 2}O{sub 6.09}. Powder X-ray and neutron diffraction, thermogravimetric analysis, magnetic susceptibility, and ac resistivity measurements were used to characterize the samples. The tetragonal unit cell for Sr{sub 2}Y{sub 0.8}Ca{sub 0.2}Co{sub 2}O{sub 6.00} (I4/mmm; a = 3.82765(6) {angstrom}, and c = 19.5795(3) {angstrom}) is comparable to that of the double layer superconducting copper oxide La{sub 2{minus}x}Sr{sub x}CaCu{sub 2}O{sub 6}. A long-range antiferromagnetic (AF) ordered state below about 300 K is found for Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Co{sub x}{sup 2.5+}O{sub 6{minus}{delta}}, and a magnetically glassy state below about 40 K for the oxidized AF phases. All materials are electrically insulating.
OSTI ID:
679270
Journal Information:
Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 146; ISSN 0022-4596; ISSN JSSCBI
Country of Publication:
United States
Language:
English