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| | | Below the so called Curie temperature Tc (see Table 1) the ionic lattice structure in the PZT crystallites becomes distorted and asymmetric (with an axis of polarity) and, additionally, exhibits spontaneous polarization. One result is that the discrete PZT crystallites become piezoelectric. However, the statistical distribution of the grain orientations in the ceramic will cause the macroscopic behavior to be non-piezoelectric. An additional property, the ferroelectric nature of the PZT material, will help to solve this problem. When an intense electric field is applied to the ceramic, the different lattice orientations of the individual ceramic grains can be permanently altered. As a result of this ''poling process'' the ceramic is accorded a net orientation of its internal, spontaneous polarization in the direction of the poling field and | | shows an overall piezoelectric effect. For some PZT ceramics, it is necessary to perform the poling process at elevated temperatures. Table 1 shows the specifications of different PI Ceramic PZT materials. The types PIC 151 and PIC 255 are the PI Ceramic standard industrial actuator materials which are used for the PICATM-Stack and PICATM-Power actuators. These materials show the highest piezoelectric deformation constants, d33, d31 and d15 (see Table 1) and, consequently, the largest induced strain values at comparable fields. These compositions incorporate all our long-term experience in piezo-electronic actuator development, manufacturing and application. | | |
| | | PIC 151 is a modified lead zirconate titanate (PZT) ceramic with high permittivity, coupling factor and charge constant. It is thus well-suited for PICATM-Stack actuators and bender applications. Due to the high coupling factor and the low mechanical quality factor it is also recommended for low fregquency and pulsed ultrasonic applictions. PIC 255 is a modified lead zirconate titanate (PZT) with a high curie temperature, coupling factor and charge constant. The material is optimized for actuator application under dynamic or high-temperature working conditions. Because of its high coercive field, PIC 255 can be used for bipolar-driving-mode applications as well as for PICATM-Shear actuators. Due to its high coupling efficiency, low mechanical quality factor and low temperature coefficient, it is also well suited low-power ultrasonic transducers, non-resonant boardband devices, sensors for load and sound transducers and is preferred for vacuum applications. PIC 252 is a low-sintering modification of PIC 255, especially used for multilayer actuators. It is recommended for dynamic and/or high-temperature operating conditions due to its high curie temperature and low permittivity. This material will replace the currently used ceramic type in the near future. | | |
| | | PIC 151 | | |
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| | | PIC 255 | | |
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| | | PIC 252 | | |
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| | | Table 1: PI Ceramic Standard PZT Materials [in extracts] | | |
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| | | PIC 255 7.8 350 1750 1650 20 0.62 0.35 0.69 80 2000 1420 2000 -180 400 500 -11.3 25 16.1 20.7 13.4 4 | | |
| | | Parameter Density Curie Temperature Relative Dielectric Permittivity Dielectric Dissipation Factor Electromechanical Coupling Factor | | Unit P Tc £11T/£0 tana kp kt k33 Qm Np Ni N3 Nt d3i d33 di5 931 933 s11 s33 c3 TCË33 I/II. | | PIC 151 7.8 250 2400 1980 20 0.62 0.53 0.38 0.69 100 1950 1500 1750 1950 -210 500 -11.5 22 15.0 19.0 10.0 6 | | PIC 155 7.8 345 1450 1400 20 0.62 0.48 0.35 0.69 80 1960 1500 1780 1990 -165 360 -12.9 27 15.6 19.7 11.1 6 | | | PIC 181 7.8 330 1200 1500 5 0.56 0.46 0.32 0.66 2000 2270 1640 2010 2110 -120 265 475 -11.2 25 11.8 14.2 16.6 3 | | PIC 241 7.8 270 1500 1550 5 0.55 0.46 0.32 0.64 1200 2190 1590 1550 2140 -130 290 265 -9.8 21 12.6 14.3 13.8 3 | | PIC 300 7.8 370 1050 950 3 0.48 0.43 0.25 0.46 1400 2350 1700 1700 2100 -80 155 155 -9.5 16 11.1 11.8 16.4 2 | | |
| | | g/cm3 °C | | |
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| | | 10-3 | | |
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| | | Mechanical Quality Factor Frequency Constant | | |
| | | Hzm Hzm Hzm Hzm pm/V pm/V pm/V 10-3 Vm/N 10-3 Vm/N 10-12 m2/N 10-12 m2/N 1010 N/m2 10-7K | | |
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| | | Piezoelectric Deformation (Charge) Coefficient Piezoelectric Voltage Coefficient Elastic Compliance Coefficient Elastic Stiffness Coefficient Temperature Coefficient This data was measured according to EN50324 | | |
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