Cold conductor based on barium titanate ceramic - contg. niobium and manganese, giving extremely high temp. coefft. of resistance

摘要

A cold conductor (PTC thermistor) is produced from 1 mole BaTiO3, 0.08-0.15 mole % Nb2O3 and 0.05-0.10 mole % MnO2 or Mn(NO3)2, opt. with the addn. of 0.5-3.0 mole % SiO2 and/or 0.5-2 mole % TiO2. The Ba and Ti can be partly replaced by other elements, i.e. Ba by max. 35 atom-% Sr and/or max. 25 atom-% Pb and Ti by max. 20 atom-% Sn. The cold conductor is produced by mixing the constituents, calcining, crushing, reducing the powder, pressing to pellets or discs, tempering for 0.5-5 h in air at 1250-1400 degrees C and then cooling at 200 degrees C/h, pref. at 50-200 degrees C/h, to a temp. of 400 degrees C or below. This ceramic cold conductor has low specific electric resistance in the conductivity range and extremely high coefft. of specific resistance with low voltage dependence.