Synthesis, Crystal Structure, Electrical, and Magnetic Properties of the New Layered Cobalt Oxides (Sr, Ca, Ln)3Co2O6±δ (Ln=Sm, Eu, Gd, Tb, Dy, Ho, and Y)

✍ Scribed by K. Yamaura; Q. Huang; R.J. Cava

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 352 KB
• Volume: 146
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8375

✦ Synopsis

New layered Co oxides of nominal formula Sr 2 (Ln 0.8 Ca 0.2 ) Co 2 O 6 (Ln ‫؍‬ Sm, Eu, Gd, Tb, Dy, Ho, and Y) are reported. Single-phase polycrystalline samples were obtained at compositions Sr 2 Y 1؊x Ca x Co 2.5؉ O 6؊ (0.24x40.5; 04 40.24), Sr 2 Y 1؊x Ca x Co 3.4؉ 2 O 6؉ (0.24x40.5; 0.624 40.79), and Sr 2 Dy 0.8 Ca 0.2 Co 2 O 6.09 . Powder X-ray and neutron di4raction, thermogravimetric analysis, magnetic susceptibility, and ac resistivity measurements were used to characterize the samples. The tetragonal unit cell for Sr 2 Y 0.8 Ca 0.2 Co 2 O 6.00 (I4/mmm; a ‫؍‬ 3.82765(6) A s , and c ‫؍‬ 19.5795(3) A s ) is comparable to that of the double layer superconducting copper oxide La 2؊x Sr x CaCu 2 O 6 . A long-range antiferromagnetic (AF) ordered state below about 300 K is found for Sr 2 Y 1؊x Ca x Co 2.5؉ 2 O 6؊ , and a magnetically glassy state below about 40 K for the oxidized AF phases. All materials are electrically insulating.