Hitachi Metals, Ltd.

Kentaro Ino

Takeshi Shimada

Toshiki Kida

Itaru Ueda

Takesha Shimada

Provided is a semiconductor ceramic composition that is a lead-free semiconductor ceramic composition in which a portion of Ba in a BaTiO-based oxide is substituted by Bi and A (in which A is at least one kind of Na, Li and K), the semiconductor ceramic composition having a region between a center portion and an outer shell portion within a crystal grain, in which when Bi concentration is measured in a radial direction within the crystal grain, the Bi concentration in the region is higher than both Bi concentration in the center portion and Bi concentration in the outer shell portion.

Semiconductor ceramic composition, method for producing the same, and PTC element

To improve jump characteristic of BaTiO&#x2014;(BiNa)TiOmaterial. There is provided a process for producing a semiconductive porcelain composition in which a part of Ba is substituted with Bi&#x2014;Na, the process including a step of preparing a (BaQ)TiOcalcined powder (in which Q is a semiconductor dopant), a step of preparing a (BiNa)TiOcalcined powder, a step of mixing the (BaQ)TiOcalcined powder and the (BiNa)TiOcalcined powder, a step of molding and sintering the mixed calcined powder, and a step of heat-treating the obtained sintered body at 600&#xb0; C. or lower; and a PCT heater employing the element prepared by the above steps.

Process for producing semiconductive porcelain composition and heater employing semiconductive porcelain composition

An object is to provide a PTC element that can be made thinner, using a Pb-free semiconductor ceramic composition. The object is achieved with a PTC element including at least two metal electrodes and a BaTiOsystem semiconductor ceramic composition arranged between the electrodes, in which, in the semiconductor ceramic composition, a portion of Ba in the BaTiOsystem is substituted by Bi&#x2014;Na and a semiconductorizing element, vacancies are formed on Bi sites by depleting at least a portion of Bi, and oxygen defects are formed on a crystal thereof. Since the PTCR characteristic at the inside of the semiconductor ceramic composition is negligibly weak in comparison with the PTCR characteristic at the interface between the semiconductor ceramic composition and the electrodes, the PTC element can be made thinner.

PTC element and heating-element module

A semiconductive porcelain composition/electrode assembly which is low in room temperature resistivity of 100 &#x3a9;&#xb7;cm or less and is reduced in change with the passage of time due to energization with regard to the semiconductive porcelain composition in which a part of Ba of BaTiOis substituted with Bi&#x2014;Na and which has a P-type semiconductive component at a crystal grain boundary. Also, there is a process for producing a semiconductive porcelain composition/electrode assembly wherein an electrode is joined to a semiconductive porcelain composition in which a part of Ba of BaTiOis substituted with Bi&#x2014;Na and which has a P-type semiconductive component at a crystal grain boundary, the process including joining the electrode to the semiconductive porcelain composition, followed by conducting a heat treatment at a temperature of from 100&#xb0; C. to 600&#xb0; C. for 0.5 hour to 24 hours.

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Osaka, Japan

Kentaro Ino