Piezoresistivity in PTCR Barium Titanate Ceramics: I, Experimental Findings |
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Authors: | Joseph S Capurso Walter A Schulze |
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Affiliation: | Transelco Division, Ferro Corporation, Penn Yan, New York 14527;New York State College of Ceramics at Alfred University, Alfred, New York 14802 |
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Abstract: | Positive temperature coefficient of resistance (PTCR) barium titanate is the active material in a ceramic sensor which employs piezoresistivity to detect changes in applied stress. High-purity, chemically prepared barium titanate is donor-doped with 0.30 at.% lanthanum, and <0.10 at.% of a transition-metal counterdopant may be added to enhance the PTCR effect. Tape-cast sheets of undoped and PTCR BaTiO3 are laminated to produce a three-layer "trilaminate"—a sintered structure which has two semiconducting PTCR layers separated by an insulating layer. The trilaminate is stressed in a four-point bend configuration (placing one semiconducting layer completely in tension, the other in compression), and the resistivities for both stress states are measured concurrently as functions of applied stress and temperature. Results are presented for various semiconducting layer compositions and sintering conditions. |
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