Synthesis, Structure, and Properties of Sodium or Potassium-Doped Lanthanum Orthomanganites from NaCl or KCl Flux
✍ Scribed by Ram Niwas Singh; C. Shivakumara; N.Y. Vasanthacharya; S. Subramanian; M.S. Hegde; H. Rajagopal; A. Sequeira
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 495 KB
- Volume
- 137
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Lanthanum and oxygen-deficient La 1؊x؊y A x MnO 3؊ (A ؍ Na or K) ferromagnetic oxide phases have been synthesized from NaCl or KCl flux, starting from La 2 O 3 and MnCO 3 at 900°C. Composition of the final product could be varied by varying initial composition La y MnO 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 4؉ concentration was 27% in the sodium doped manganite, La 0.82 Na 0.13 MnO 2.93 with Curie temperature 325 K, and Mn 4؉ was 25% in the potassium doped La 0.82 K 0.08 MnO 2.89 with T c of 310 K. Structure of these two phases have been refined from neutron diffraction studies. Stoichiometric La 1؊x A x MnO 3 (A ؍ Na or K) have been obtained for the initial composition La y MnO 3 (y ؍ 0.85). Orthorhombic phases obtained were found to be Mn-deficient La 1؊x Na x Mn 1؊x Mn 1؊y O 3 (xK0.02; yK0.05), which were ferromagnetic insulators, even though total Mn 4؉ contents were as high as 29%.