Room temperature structure vibrational and dielectric properties of Ho modified YMnO3

Abstract

The structural, vibrational, and dielectric properties of bulk Ho-doped Y1−xHoxMnO3 (x = 0, 0.03, 0.05) solids prepared by standard solid-state reaction route were investigated. X-ray diffraction (XRD) patterns confirmed the hexagonal P63cm structure of Y1−xHoxMnO3 (x = 0.0, 0.03, 0.05) ceramics. Rietveld refinements of XRD data revealed that the doping ions led to unit cell contraction in three directions due to nearly equal ionic radii of Ho3+ ion (0.901 Å) substituted at the Y-site ion. The grain size of Ho-doped solids varied from 5 to 10 μm. For pristine h-YMnO3, the experimentally observed Raman scattering lines at around 151, 305, 460, and 682 cm−1 are of A1 symmetry, those at 410 cm−1 are of E1 symmetry, and the lines at 139 and 219 cm−1 are of E2 symmetry. Another interesting observation is the existence of an A1 line at 682 cm−1 and an E1 line at about 410 cm−1 which are much stronger than the remaining lines of A1 and E1 symmetries, respectively. The high value of dielectric constant and dielectric loss tangent at low frequency is explained by space charge polarization and the saturation in the high-frequency region is due to the electric dipoles not being in pace with the frequency of the applied electric field.