CERAMIC COMPOSITION FOR LEAD-FREE PTC(POSITIVE TEMPERATURE COEFFICIENT OF RESISTANCE) THERMISTOR AND THE PTC CERAMIC THERMISTOR PREPARED USING THE SAME

WIPO Patent Application WO/2010/044534

A1

The present invention relates to a ceramic composition for a lead-free PTC thermistor which does not contain a lead (Pb) component and has a low specific resistance value at room temperature and a Curie temperature (Tc) of 130℃ or more. The ceramic composition for a lead free PTC thermistor according to the present invention comprises any one selected from formulas 1-4. [Formula 1] Ba1-x(Bi0.5 Na0.5)xTiO3 + y mol% M1Ow [Formula 2] Ba1-x(Bi0.5Na0.5)xTiO3 + y mol% M12Ow + z wt% M2O2 [Formula 3] Ba1-x(Bi0.5K0.5)xTiO3 + y mol% M1Ow [Formula 4] Ba1-x(Bi0.5K0.5)xTiO3 + y mol% M1Ow + z wt% M2O2 (In formulas 1-4, 0.01≤x≤0.05, 0.00＜y≤0.40, 0.00＜z≤0.40; M1 is one or more elements selected from the group consisting of Nb, Sb, La, Y; M2 is Mn; and w is 3 when M1 is a trivalent element and is 5 when M1 is a pentavalent element.) In addition, the invention comprises a ceramic composition for a PTC thermistor of the following formula 5 in which Na0.5K0.5NbO3(NKN) is formed as a solid solution of BaTiO3(BT). [Formula 5] (1-x)BT-xNKN (0