Kutty, TRN and Ravi, V (1991) Improved current limiters based on mixed-phase $BaTiO_3$ ceramic semiconductors. In: Journal of Materials Science: Materials in Electronics, 2 (2). pp. 79-88.
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Very stable and highly reproducible current-limiting characteristics have been observed for polycrystalline ceramics prepared from sintering mixtures of coarse-grained, donor-doped $BaTiO_3$ (tetragonal) as the major phase and ultrafine, undoped cubic perovskite such as $BaSn0_3$, $BaZr0_3$, $SrTi0_3$ or $BaTiO_3$ (cubic) as the minor phase. The initial linear current-voltage (I-V) relationship becomes current-limiting with increase in applied potential and the consequent onset of thermal equilibrium. The strong current maximum of the I-V curve of donor-doped $BaTi0_3$ can be eliminated when the ceramics are constituted of mixed phases. The voltage drop at the insulating grain boundaries minimizes the temperature gradient between the interior and the surface, and subdues the thermal runaway. The magnitude of the limiting current, and hence the power-handling capacity, can be varied with the controlled addition of grain boundary layer modifiers and by optimizing the processing parameters. The dielectric constant versus temperature or voltage variation in power dissipation with ambient temperature and resistivity-temperature relations point to the necessity of the mixed phase character for the current-limiting property.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Springer.|
|Department/Centre:||Division of Chemical Sciences > Materials Research Centre|
|Date Deposited:||27 Jun 2007|
|Last Modified:||17 Jan 2012 06:46|
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