Piezo-ceramic element

To the promising groups of applications envisaged back in 1969 [5], viz. sensors, photocells, solar batteries, electrostatic accumulators, photodiodes xergraphy, etc., can be added important new types of piezo ceramic elements, elastic poly(pyrrole) film (elongation >100%) useful for plasters and tubes, self dopant materials [55], printed circuits, deposition by irradiation [17], laser processing, surface structure modification [139], corrosion protection, and NLO [88]. 

The use of air-bome ultrasound for the excitation and reception of surface or bulk waves introduces a number of problems. The acoustic impedance mismatch which exists at the transducer/air and the air/sample interfaces is the dominant factor to be overcome in this system. Typical values for these three media are about 35 MRayls for a piezo-ceramic (PZT) element and 45 MRayls for steel, compared with just 0.0004 MRayls for air. The transmission coefficient T for energy from a medium 1 into a medium 2 is given by... 

The working electrode, in the form of a rectangle of thin foil, c. 20 pm thick, is glued to a piezo-electric ceramic element of the same lateral dimensions. Both the piezo element and the edge of the working electrode arc then isolated from the electrolyte with inert epoxy cement. The essence of the piezo-electric effect is that if the ceramic element is deformed in any way, a... 

Another laboratory technique that allows the measurement of the shear wave velocity of a soil sample is the bender element testing method. Bender elements consist of two piezo-ceramic plates bonded together in such a way that application of a voltage causes one plate to expand and the other to contract. This generates seismic waves in... 

The positioning of the sample at better than atomic precision is carried out with piezo crystals, which are ceramic electromechanical transducers that distort when a voltage is applied. As the distortion is proportional to the applied voltage, one can displace a sample by means of piezos at any desired precision, provided that the electronics are sufficiently accurate and stable. The rapid development of the scanning probe microscope would not have been possible without the availability of modern, stable electronics. In order to obtain optimum atomic resolution, one usually selects a tubular piezo element with a small scan range (ca. 1 pm) for larger scan ranges, the scanner is a tripod with a separate piezo element for each dimension. 

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