Synthesis, structure, and properties of sodium or potassium-doped lanthanum orthomanganites from NaCl or KCl flux

Journal Article · Wed Apr 01 04:00:00 EST 1998 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1997.7653· OSTI ID:642147

Singh, R N; Shivakumara, C; Vasanthacharya, N Y; Subramanian, S; Hegde, M S ^[1]; Rajagopal, H; Sequeira, A ^[2]

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1. Indian Inst. of Science, Bangalore (India)
2. Bhabha Atomic Research Center, Trombay (India). Solid State Physics Div.

Lanthanum and oxygen-deficient La{sub 1{minus}x{minus}y}A{sub x}MnO{sub 3{minus}{delta}} (A = Na or K) ferromagnetic oxide phases have been synthesized from NaCl or KCl flux, starting from La{sub 2}O{sub 3} and MnCO{sub 3} at 900 C. Composition of the final product could be varied by varying initial composition La{sub y}MnO{sub 3} (0.7 < y < 1). Final composition of these oxides was obtained from chemical analysis of elements present. As the lanthanum content increased, Na or K content decreased and the structure changed from rhombohedral to orthorhombic symmetry. Mn{sup 4+} concentration was 27% in the sodium doped manganite, La{sub 0.82}Na{sub 0.13}MnO{sub 21.93} with Curie temperature 325 K, and Mn{sup 4+} was 25% in the potassium doped La{sub 0.82}K{sub 0.08}MnO{sub 2.89} with {Tc} of 310 K. Structure of these two phases have been refined from neutron diffraction studies. Stoichiometric La{sub 1{minus}x}A{sub x}MnO{sub 3} (A = Na or K) have been obtained for the initial composition La{sub y}MnO{sub 3} (y = 0.85). Orthorhombic phases obtained were found to be Mn-deficient La{sub 1{minus}x}Na{sub x}Mn{sub 1{minus}x}Mn{sub 1{minus}y}O{sub 3} (x {approx_equal} 0.02; y {approx_equal} 0.05), which were ferromagnetic insulators, even though total Mn{sup 4+} contents were as high as 29%.

• OSTI ID: 642147
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 137; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
LANTHANUM OXIDES
MANGANESE OXIDES
NEUTRON DIFFRACTION
PHYSICAL PROPERTIES
POTASSIUM OXIDES
SODIUM OXIDES
SYNTHESIS
X-RAY DIFFRACTION