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Weak Ferromagnetism (weak + ferromagnetism)
Selected AbstractsLayered [BaM(C3H2O4)2(H2O)4] (M = Fe or Co) Complexes , Spectroscopic, Magnetic and Thermal StudyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2003Izaskun Gil de Muro Abstract Complexes with formula [BaM(C3H2O4)2(H2O)4], where M = Fe or Co, were synthesised and characterised. These two types of complexes are isostructural and crystallise in the Pccn space group. Their structure consists of two-dimensional networks of octahedral MO6 polyhedra in which the transition metal ions are coordinated by bridging malonate ligands, through the O-C-O atoms. These M-malonate units are extended along the crystallographic [101] plane. Spectroscopic data are consistent with the cations being in a high-spin octahedral symmetry. The two types of compounds exhibit 2D antiferromagnetic interactions as well as weak ferromagnetism below the Néel temperature, as a result of an intralayer misalignment of the spins. Thermal treatment of the metallo-organic precursors gave rise to BaMO3,y oxides at lower temperatures and reaction times than those found in the literature using the ceramic method. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003). [source] Multiferroic Properties of Nanocrystalline PbTiO3 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Min Wang Nanocrystalline PbTiO3 (PTO) powders in a perovskite structure have been synthesized by the sol,gel process using lead acetate, glycerin, and titanium (IV) isopropoxide as precursors. PTO ceramics were obtained by sintering the powders at temperatures ranging from 600° to 1000°C. The structure and morphology of the ceramics have been determined by X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy. The PTO powder calcined at 450°C shows weak ferromagnetism at room temperature. The PTO ceramics sintered at various temperatures exhibit coexistence of ferroelectricity and weak ferromagnetism at room temperature. Enhancement in the magnetic moment and ferroelectricity with a reduction in the grain size of PTO ceramics was observed. This result facilitates the possibilities of new perovskite electromagnetic devices at the nanoscale level. [source] Combustion synthesis and characterization of nano-crystalline LaFeO3 powderPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009Hui Shen Abstract Nano-crystalline LaFeO3 was synthesized by a sol,gel auto-combustion method from a mixed aqueous solution of lanthanum and iron nitride, using citric acid as the fuel. Powder X-ray diffraction and TG/DTA analysis show that the LaFeO3 crystallites can be directly obtained by the sol,gel combustion process, without any other undesired phase. The results of SEM and TEM reveal that the as-burnt samples and powder calcined at 700 °C are agglomerated with particle size in the range of 25,50 nm and 60,80 nm, respecitvely. The M (T) and M (H) curves measurements show the existence of a weak ferromagnetism and the mainly anti-ferromagnetic ordering of the spins in the calcined sample. Compared with the powder calcined at 600 °C and 700 °C, the as-burnt LaFeO3 exhibits much stronger ferromagnetic behavior, with larger magnetization and smaller coercive field. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Observation of weak ferromagnetism in the C14 Laves phase of the (Fe1,xNix)2Nb systemPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2009C. Paduani Abstract In this work we report the observation of weak ferromagnetism in the hexagonal C14 Laves phase (s.g. P63/mmc) of the (Fe1,xNix)2Nb system, which has been reported as nonmagnetic in the literature. A larger unit cell volume is observed as compared to Fe2Nb. From low-temperature magnetization measurements it is found that the Ni substitution for Fe indeed leads to the onset of a weak ferromagnetic ordering in the C14 Laves phase of this pseudobinary system. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] NMR properties of half-Heusler CoVSbPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006H. Nishihara Abstract The complex NMR properties of CoVSb are reported. On the basis of band structure calculations the compound is predicted to be a half metallic ferromagnet but magnetisation measurements suggest that the compound is a weak ferromagnet. In zero applied field at 4.2 K, three spin echo signals have been observed with peak frequencies of 30, 63 and 82 MHz, which are tentatively assigned as signals associated with antimony, vanadium and cobalt atoms. The cobalt atoms are suggested to have moments of about 0.8 ,B. In addition three spin echo signals have been observed in swept applied fields at 4.2 K which include signals from non magnetic cobalt and vanadium sites. Thus weak ferromagnetism in CoVSb is concluded to be complex on a microscopic scale with the moment of 0.18 ,B per formula unit, obtained from static magnetic measurements, being the average moment of magnetic and nonmagnetic sites of cobalt and vanadium atoms. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||