| 摘要 |
1,090,037. Piezoelectric elements. HITACHI SEISAKUSHO KABUSHIKI KAISHA. March 4, 1965, No. 9251/65. Heading H1E. The polarizing voltage applied to a ferroelectric body is periodically inverted. In the embodiment described, the ferroelectric sample is immersed in oil at a temperature of 100‹ C. and a voltage of 80 kV/cm. applied, the voltage being reversed every 2 minutes or every 5 minutes for a period of 45 minutes. A final application of the voltage for a period of 10 minutes is made after the sample has been cooled to room temperature. A voltage which steadily increases during the period of application may be used. Alternating voltages of sine, triangular, or rectangular waveform, and voltages at mains frequency (50 cycles) may be used. The method may be applied to PZT compositions which may contain Sr, Ba, La, Na and K as additives or substituents. It is also applicable to BaTiO 3 and to (K 0À5 Na 0À5 )NbO 3 . For the latter compositions a voltage of 40 kV. reversed every 5 minutes for a period of 30 minutes at a temperature of 80‹ C. may be used. Where the resistance of the sample is too low at room temperature, poling may be carried out at a lower temperature. |
