Abstract
The effects of the sintering time on the electrical properties and the positive temperature coefficient of resistance (PTCR) effect of Ba1.006(Ti1-xNbx)O3 (BTN) ceramics were investigated, which were sintered at 1190 oC for 0.5-6 hours in a reducing atmosphere and then re-oxidized at 800 oC for 1 hour. The results indicated that the sintering time affected the electrical properties and the PTCR effect of the multilayer BTN samples, whose room-temperature resistance decreased with an increase of the sintering time at same sintering temperature of 1190 oC. However, the resistance jump first increased and then reduced as a function of the sintering time. Furthermore, The BTN ceramics exhibited a pronounced PTCR effect, with a resistance jump greater by 3.6 orders of magnitude, along with a low RT resistance of 0.14 Ω at a reoxidated temperature of 800 oC after sintering at 1190 oC for 2 h in a reducing atmosphere. In addition, the activation energy of samples obtained at different sintering times had also been investigated.
Highlights
It is well-known that barium titanate can undergo phase transition from tetragonal to cubic structures 1
positive temperature coefficient of resistance (PTCR) thermistors are usually used in low-voltage integrated circuits as overcurrent-protection elements
The RT resistance of ceramics has been reduced by sintering these materials with a reduction/re-oxidation method, which led to a laminated chip-type structure 7,8
Summary
It is well-known that barium titanate can undergo phase transition from tetragonal to cubic structures 1. Replacing of A or B sites in BaTiO3 (ABO3) with trivalent donors or pentavalent impurities, respectively increases the positive temperature coefficient of resistance (PTCR) effect of this material 2,3, as reported by Heywang 4,5 and Jonker 6. According to a proposed model, the PTCR effect of positive temperature coefficient (PTC) ceramics can be considered a grain-boundary effect. PTCR thermistors are usually used in low-voltage integrated circuits as overcurrent-protection elements. Elements with ever-decreasing room-temperature (RT) resistance are required. The RT resistance of ceramics can be hardly reduced with traditional preparation methods. In this sense, the RT resistance of ceramics has been reduced by sintering these materials with a reduction/re-oxidation method, which led to a laminated chip-type structure 7,8
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
