Přednášející: Falak Sher ( Dept. of Chem., Lahore University of Management Sciences (LUMS), Lahore, Pakistan)
Místo: Přednáškový sál Fyzikálního ústavu AV ČR Na Slovance
Jazyk: anglicky
Pořadatelé:
Oddělení dielektrik
Abstrakt: Transition metal oxides show a variety of crystal structures and physical properties. The fascinating magnetic, electrical, optical and catalytic properties of these metal oxides are central to technological advances in memory devices, electronics/spintronics, sensors, nanomaterials, superconductivity etc. Chemical doping of these oxides with cations of different size and charge is widely used to obtain new and exotic phases, and for fine tuning of physical properties. Optimization of synthesis methods after careful analysis of powder X-ray diffraction patterns and finding correlations between crystal structures and physical properties are major research thrust areas in this field. In this talk, I will mostly discuss the multiferroic properties of Bi1−xLaxMnO3 (x = 0.0, 0.1, and 0.2) samples prepared under 3−6 GPa pressure. Rietveld refinement of powder neutron diffraction data show that BiMnO3 and Bi0.9La0.1MnO3 adopt a monoclinic C2/c perovskite superstructure whereas Bi0.8La0.2MnO3 has orthorhombic Pnma symmetry. Both structural analysis and Curie−Weiss fits to magnetic susceptibility data show that high spin d4 Mn3+ is present with no significant Bi deficiency or Mn4+ content apparent. La substitution suppresses the magnetic Curie temperature of the monoclinic phase from 105 K for x = 0 to 94 K at x = 0.1, but the x = 0.2 material shows antiferromagnetic order similar to that of LaMnO3.
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