Synthesis, Structure, and Physical Properties of Cobalt Perovskites: Sr

Journal Article · Thu Feb 15 04:00:00 EST 2001 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.2000.9041· OSTI ID:783957

Primo-Martin, Vicent; Jansen, Martin

The perovskites Sr{sub 3}CoSb{sub 2}O{sub 9}, Sr{sub 2}CoSbO{sub 6}, and Sr{sub 2}CoSbO{sub 5.63} have been synthesized in polycrystalline form by solid state reactions from acetate precursors as obtained by freeze-drying. The crystal structure of insulating Sr{sub 3}CoSb{sub 2}O{sub 9} has been refined from X-ray data by the Rietveld method and was found to be orthorhombic (Immm) with a=5.6411(1) {angstrom}, b=5.6610(1) {angstrom}, c=7.9829(2) {angstrom}. From the molar susceptibility curves an effective magnetic moment {micro}{sub eff}=5.39 {micro}B and a spin-glass transition at ca. 6 K are deduced. The semiconducting perovskite Sr{sub 2}CoSbO{sub 6} was synthesized by applying an elevated O{sub 2} pressure (3 kbar), and Co exclusively in the oxidation state +3 was attained. The Rietveld refinement of this compound has revealed a rhombohedral cell (Rm) with a=5.5992(2) {angstrom} and c=13.6609(2) {angstrom} and partial order (77%) of the B cations. An effective magnetic moment per formula unit of {micro}eff=3.83 {micro}B and a spin-glass transition at ca. 47 K were observed. A semiconducting and oxygen-deficient perovskite, Sr{sub 2}CoSbO{sub 5.63}, was obtained by annealing Sr{sub 2}CoSbO{sub 6} at 950 C in Ar. The Rietveld refinement proved it to be a double-cubic perovskite (Fmm) with a=7.9658(1) {angstrom}, and a higher order of Co and Sb at the B sites (84%) was found, due to the formation of Co{sup 2+}. From the magnetic susceptibility data an effective moment of 4.85 {micro}B and a spin-glass transition at ca.17 K were deduced.

• Research Organization: Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (DE)
• Sponsoring Organization: None (US)
• OSTI ID: 783957
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 157; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACETATES
ANNEALING
ANTIMONY OXIDES
CATIONS
CHEMICAL PREPARATION
COBALT
COBALT IONS
COBALT OXIDES
CRYSTAL PHASE TRANSFORMATIONS
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
EXPERIMENTAL DATA
HIGH SPIN STATES
LATTICE PARAMETERS
LYOPHILIZATION
MAGNETIC DIPOLE MOMENTS
MAGNETIC MOMENTS
MAGNETIC SUSCEPTIBILITY
ORTHORHOMBIC LATTICES
PEROVSKITE
PEROVSKITES
PHYSICAL PROPERTIES
POLYCRYSTALS
SEMICONDUCTOR MATERIALS
SPACE GROUPS
SPIN GLASS STATE
STRONTIUM OXIDES
SYNTHESIS
TRIGONAL LATTICES
VALENCE