Synthesis, structure and magnetic properties of Ln1 – xAxMnO3 (Ln = Pr, Nd; A = Na, K) from NaCl or KCl flux
| Autor: | C. Shivakumara, G. N. Subbanna, N.Y. Vasanthacharya, N. P. Lalla, T. Srinivasa, M. S. Hegde |
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| Rok vydání: | 2001 |
| Předmět: |
Transition temperature
Manganate Inorganic chemistry General Chemistry Crystal structure Magnetic susceptibility Condensed Matter::Materials Science Crystallography chemistry.chemical_compound chemistry Ferromagnetism Condensed Matter::Superconductivity Materials Chemistry Condensed Matter::Strongly Correlated Electrons Orthorhombic crystal system Phase diagram Solid solution |
| Zdroj: | Journal of Materials Chemistry. 11:2572-2579 |
| ISSN: | 1364-5501 0959-9428 |
| DOI: | 10.1039/b104725f |
| Popis: | Na- or K-substituted $PrMnO_3$ and $NdMnO_3$ phases have been prepared using neutral NaCl or KCl fluxes at a relatively low temperature of $900^o C$. These flux syntheses not only promote the reaction at low temperatures but also act as a source of the alkali metal in the final product. The structures of these oxides have been refined by the powder X-ray Rietveld method and confirmed by the electron diffraction studies. All these phases crystallize in the orthorhombic structure (space group Pbnm) and are ferromagnetic insulators. Na-doped mixed rare-earth manganites of the formula $(Pr_{1-x}La_x)_{1-y}$ $Na_yMnO_3$ $(0\leq x\leq 0.80; 0.08\leq y\leq 0.15)$ have also been synthesized in NaCl flux; among these mixed rare-earth manganites those crystallizing in rhombohedral structures are ferromagnetic metals (FMM), and those in orthorhombic structures are ferromagnetic insulators (FMI). The phase diagram of average A-site radii vs. ferromagnetic transition temperature, Tc, of the stoichiometric phases has been constructed here and compositions with $ \leq 1.20 \AA$ crystallizing in the orthorhombic structures fall in the ferromagnetic insulating region. Compositions with $ \geq 1.20 \AA$ crystallize in the rhombohedral structures and these are ferromagnetic metals. |
| Databáze: | OpenAIRE |
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