Oxygen excess in the '114' cobaltite hexagonal structure: The ferrimagnet CaBaCo{sub 4}O{sub 7.50}

Journal Article · Thu Sep 15 04:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.07.039· OSTI ID:21580255

Pralong, V ^[1]; Caignaert, V; Sarkar, T; Lebedev, O I; Duffort, V; Raveau, B ^[1]

---

1. Laboratoire CRISMAT, UMR 6508 CNRS ENSICAEN, 6 bd Marechal Juin, 14050 Caen (France)

The study of the oxidation of the '114' orthorhombic cobaltite CaBaCo{sub 4}O{sub 7}, using first electrochemistry and then soft chemistry based on oxidation by NaClO, has allowed a new phase, CaBaCo{sub 4}O{sub 7.50}, to be prepared topotactically. The structural study of this phase shows that its hexagonal structure, closely related to that of orthorhombic CaBaCo{sub 4}O{sub 7}, is curiously similar to that of the members of the LnBaCo{sub 4}O{sub 7} series, in spite of its excess oxygen. Its magnetic study shows that this phase, like CaBaCo{sub 4}O{sub 7}, is ferrimagnetic with the same T{sub C} (60 K), but differently exhibits an unusual magnetic hysteresis. This exceptional behavior of CaBaCo{sub 4}O{sub 7} with respect to oxidation as well as the magnetic properties of CaBaCo{sub 4}O{sub 7.50} is interpreted in terms of the presence of defects due to oxidation. - Graphical Abstract: The study of the oxidation of the '114' orthorhombic cobaltite CaBaCo{sub 4}O{sub 7}, using first electrochemistry and then soft chemistry based on oxidation by NaClO, has allowed a new phase, CaBaCo{sub 4}O{sub 7.50}, to be prepared topotactically. The structural study of this phase shows that its hexagonal structure, closely related to that of orthorhombic CaBaCo{sub 4}O{sub 7}, is curiously similar to that of the members of the LnBaCo{sub 4}O{sub 7} series, in spite of its oxygen excess. Its magnetic study shows that this phase, like CaBaCo{sub 4}O{sub 7}, is ferrimagnetic. Highlights: > Topotactic oxidation by means of electrochemistry and soft chemistry of the '114' orthorhombic cobaltite CaBaCo{sub 4}O{sub 7}. > This new phase, CaBaCo{sub 4}O{sub 7.5} shows an hexagonal structure, is closely related to that of orthorhombic mother phase CaBaCo{sub 4}O{sub 7}. > CaBaCo{sub 4}O{sub 7.5} is ferrimagnetic and exhibits an unusual magnetic hysteresis, due to defect pinning centers.

• OSTI ID: 21580255
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 9 Vol. 184; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL REACTIONS
CHEMISTRY
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DEFECTS
ELECTROCHEMISTRY
ELEMENTS
FERRIMAGNETISM
HYSTERESIS
MAGNETIC PROPERTIES
MAGNETISM
NONMETALS
ORTHORHOMBIC LATTICES
OXIDATION
OXYGEN
PHYSICAL PROPERTIES