Electrical Properties of Yb{2-x}VxO{3+x} Nanomaterials Obtained Mechanochemically from Yb2O3 and V2O5 Oxides

Abstract

Electrical   measurements   were   carried   out   on   nanocrystals Yb_2-xV_xO_3+x (YbVO) (where x = 0.10, 0.15, 0.20, 0.30, and 0.40) obtained in the high-energy ball milling process, which crystallite size increased from 23.3 to 42.4 nm with increasing vanadium content. Electrical conductivity and thermoelectric power studies showed insulating properties in the extrinsic region (77–300 K) and n-type semiconductivity in the intrinsic one (350–400 K) with an activation energy of 1.3 eV. Broadband dielectric spectroscopy studies showed  a  low  relative dielectric permittivity  (ε_r < 16) and loss tangent  (tan(δ) < 0.05) weakly dependent on temperature and frequency with the exception of a wide maximum between 200 and 300 K, suggesting an antiferroelectric-paraelectric phase transition. The most interesting result is the observation of a strong increase in the thermoelectric power factor with an increase in unit cell volume and nanograin size in a highly thermally activated Arrhenius region.