Study On The BaTiO₃-based High-temperature PTC

The PTCR thermistors based on BaTiO₃ semiconducting ceramic materials become the third application aspects behind capacitors and piezoelectrical ceramics in ferroelectrical ceramic applications and be used widely in communication, household electrical appliances, automobiles sand spaceflights. The article counter the main problems of preparing the BaTiO₃-based high-temperature PTC ceramic, we have studied from two aspects of craft and prescription emphatically separately. On the craft, Have explained the raw materials physical and chemical property are producing the important function on the product of high-temperature PTC ceramic material, matching each other of raw materials will influence the high-temperature PTC ceramic performance quality directly. Through experimental analysis the matching between BaTiO3 and PbTiO₃ raw materials during preparing high-temperature PTC, and it is difficult to produce steadily. In addition, through the experiment, we has proved the match between raw materials BaCO₃ and TiO₂ can also influence the performance of high-temperature PTC ceramic. The experiment proved if the raw materials of BaCO₃ and TiO₂ are undifferentiated from the physical characteristics, the PTC ceramic produced out is of good performance, and steady. In the research of prescription, through the experiments we knew the influence from the Nb₂O₅ or Y₂O₃ single donor doped on high-temperature PTC ceramic, and got the curve graph drawing the resistivity and mixing quantity. In order to restrain lead volatilize and mix the rang of donors to neutralization the harmful acceptor impurity in raw materials, adopt the prescription design of Nb₂O₅ and Y₂O₃ double donors-doped. From the result, we know that regulation proportion of Nb , Y double donors, can make high-temperature PTC ceramics semiconducting, the pottery demonstrates good electric performance. Draw in the experiment, one Mole of marks which acts as Nb is in 0. 08-0. 10,Y in 0. 12-0.14,can produce the good performance high-temperature PTC pottery . According to the above craft and prescription design, apply to the high-temperature ceramics which the Tc=160℃, to that all products test results are: Resistance value is adjustable in 100-1000Ω, α≥30%, voltage V≥850v,β≥105.