Structural and electrical studies of sol-gel synthesized nanocrystalline hexagonal yttrium iron manganite ceramics.

Hexagonal yttrium manganites, YMnO3, are interesting materials for their multiferroic behavior. Substituting suitable cations either at the Y-site or Mn-site offers great opportunities to produce a variety of manganites and tune their properties. Nanocrystalline yttrium iron manganites with the compositional formula YFeMnO3, = 0.0, 0.10, 0.15, 0.20 and 0.25, were synthesized by sol-gel autocombustion method. The prepared samples were heated at 1100C for 1 h. Another set of samples with compositional formula YFeMnO3, = 0.0, 0.10, 0.15, 0.20 and 0.25, were also synthesized by the same method and heated at 1100C for 1 h. Various characterizations were done on these manganite systems synthesized by substituting iron at different sites. X-ray diffraction (XRD) technique studied the structure of the samples and analysis of XRD patterns confirmed the formation of hexagonal phase in the samples. Structural parameters such as lattice constants, crystallite size, theoretical density, etc. were determined using the XRD data. The unit cell dimensions have been found to agree with the standard data and the Debye-Scherrer crystallite size obtained from XRD data ranges from 42 nm to 77 nm. The room temperature frequency variations of electrical properties such as dielectric constant, dielectric loss and AC conductivity were measured in the range of 100 Hz-2 MHz and the variations showed a dispersive behavior for all the samples. The various measurements and the results obtained were studied and discussed in the paper. [ABSTRACT FROM AUTHOR]