Synthesis, Crystal Structure, and Magnetic Properties of La4Co3O10+δ(0.00≤δ≤0.30)

✍ Scribed by Ole Henrik Hansteen; Helmer Fjellvåg

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 445 KB
• Volume: 141
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.7958

✦ Synopsis

The effects of nonstoichiometry on the crystal structure, thermal expansion, structural phase transitions, and magnetic properties of La 4 Co 3 O 10؉ , 0.004 40.30, have been investigated between 2 and 1000 K. Rietveld analysis of high resolution powder X-ray diffraction data reveals the crystal structure of La 4 Co 3 O 10؉ (Ruddlesden-Popper type phase; La n؉1 Co n O 3n؉1 with n‫)3؍‬ to be slightly monoclinically distorted, space group C2/m. The monoclinic distortion increases and the unit cell volume decreases slightly on increasing nonstoichiometry, . A structural phase transition, monoclinic to tetragonal, possibly via an intermediate orthorhombic state, occurs at 840 K. Magnetic susceptibility data indicate long-range antiferromagnetic ordering below T N +13 K. Above 20 K there are three temperature regimes with nearly Curie-Weiss paramagnetic behaviour for the magnetic susceptibility: 20-80 K, 100-450 K, 650-985 K. This indicates a temperature-induced change from a lower, possibly via an intermediate, to a higher spin configuration for Co III comparable to that described for LaCoO 3 . Fielddependent magnetic susceptibility is observed for > 0.00 for T(100 K.