Electrical Properties of Nd-Doped BaTiO₃PTC Ceramics Prepared by Hydrothermal Synthesis

Abstract

Nd-doped BaTiO3 nanopowders with ca. 200 nm in average diameter were prepared by hydrothermal synthesis at 200 and 240 °C for 24 h. Neodymium (III) nitrate hexahydrate (Nd(NO3)3·6H2O) as a donor dopant was added to the powder mixtures of barium hydroxide (Ba(OH)2) and titanium dioxide (TiO2) ranging from 0.25 to 0.45 mol%. A green compact of the powder mixtures obtained was heated at 1340 °C for 2 h with/without three steps of ramp heating processes. Sintered without these steps, 0.35 mol% Nd-doped BaTiO3 with the resistivity of 124 ohm·cm at R. T. indicated insufficient PTCR effect; resistance change of 3 × 102 in the vicinity of Curie temperature. On the other hand, a pellet of 0.35 mol% Nd-doped BaTiO3 sintered via the step-heating process exhibited the large resistance change of 7.5 × 103.