Electrical and magnetic properties of strontium substituted lanthanum manganate perovskite crystals prepared using fused salt electrolysis

Journal Article · Tue Jun 01 04:00:00 EDT 1999 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1999.8224· OSTI ID:679222

McCarroll, W H ^[1]; Ramanujachary, K V ^[2]; Fawcett, I D; Greenblatt, M ^[3]

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1. Rider Univ., Lawrenceville, NJ (United States). Chemistry Dept.
2. Rowan Univ., Glassboro, NJ (United States). Dept. of Chemistry and Physics
3. Rutgers-the State Univ., Piscataway, NJ (United States). Dept. of Chemistry

Crystals of Sr-doped perovskite lanthanum manganates, containing 7--34 mole percent Sr have been grown by fused salt electrolysis using Cs{sub 2}-MoO{sub 4}-MoO{sub 3} solvents in stabilized zirconia crucibles. The rhombohedral crystals grow with cubic-like habits typically with facial areas 0.25--4 mm{sup 2} on edge with the average facial area decreasing with increasing Sr content. All measured crystals with Sr contents between 11.7 and 33.6 mole percent SR underwent transitions from a paramagnetic-insulator to a ferromagnetic-metallic state with values of {Tc} and T{sub IM} between 325 and > 400 K (for T{sub IM}), the values increasing with Sr content. A magnetoresistance of approximately 45% at 375 K was observed for a crystal of composition Sr{sub 0.336}La{sub 0.661}Mn{sub 0.997}O{sub 3}. The anomalously high {Tc} = 325 K for Sr{sub 0.117}La{sub 0.844}Mn{sub 0.990}O{sub 3} for a sample of such low Sr content is interpreted in terms of a high vacancy level on the A cation site which stabilizes the rhombohedral perovskite structure, which otherwise might have been expected to be orthorhombic type-1. The formation of Sr-doped lanthanum manganate perovskite at the cathode with the orthorhombic type-2 structure is interpreted in terms of an electrostatically assisted air oxidation mechanism. 42 refs., 4 figs., 2 tabs.

• Sponsoring Organization: National Science Foundation, Washington, DC (United States)
• OSTI ID: 679222
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 145; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
LANTHANUM OXIDES
MAGNETIC SUSCEPTIBILITY
MAGNETORESISTANCE
MANGANESE OXIDES
STRONTIUM OXIDES
TEMPERATURE DEPENDENCE
TRANSITION TEMPERATURE