Fabrication of (Ba,Pb)TiO3-based tapes with positive temperature coefficients of resistivity by the oxidation of malleable, metal-bearing precursors (the volume identical metal oxidation process)

The feasibility of producing (Ba,Pb)TiO3-based thermistor tapes by the oxid ation of malleable, metal-bearing precursors has been demonstrated. Intimat e Ba-Pb-Ti-TiO2-bearing powder mixtures, produced by high-energy vibratory milling, were packed within a fugitive metal can and then compacted and for med into tapes of uniform thickness by cold drawing and rolling. The tape-s haped precursors were oxidized and converted into (Ba,Pb)TiO3-based tapes w ith a series of heat treatments at less than or equal to 1120 degrees C. Wi th proper control of thermal treatments and chemical additions (Sb2O3 + MnO 2 dopants), positive-temperature-coefficient-of-resistivity thermistors wer e produced that exhibited significant increases in resistivity commencing a t temperatures greater than or equal to 350 degrees C.