Piezo-electricity

V, is measured by striking one end of a bar of the material (by glueing a piezo-electric crystal there and applying a charge-difference to the crystal surfaces) and measuring the time sound takes to reach the other end (by attaching a second piezo-electric crystal there). Most moduli are measured by one of these last two methods. 

The application of interference techniques overcomes the limitations exerted by the large optical wavelengths. With commercial phase-measurement interference microscopes (PMIM), a surface resolution of the order of 0.6 nm can be achieved [33, 34]. In a microscope a laser beam is both reflected from the sample surface and from a semitransparent smooth reference surface (Fig. 3). The interference pattern is recorded on an area detector and modulated via the piezo-electric driven reference surface. The modulated interference pattern is fed into a computer to generate a two-dimensional phase map which is converted into a height level contour map of the sample surface. While the lateral resolution (typically of the... 

Piezo-electric hygrometry employing a quartz crystal with a hygroscopic coating in which moisture is alternately absorbed from a wet-gas and desorbed in a dry-gas stream the dynamics is a function of the gas humidity. 

Gibbs energy for the adsorption of water and the interfacial parameter, 187 Gokstein and the piezo electric method for the determination of the potential of zero charge, 42 Gold... 

Perkins and Andersen, 31 photo emission method (Barker), 41 potentiostatic scrape method, 38 piezo electric method (Gokstein), 42 rapid emergent method (Packham), 38... 

Alpha-quartz has many useful properties which lead to its wide use in industry as a glass, ceramic and molecular sieve. However, undoubtedly its most technically important use occurs by virtue of its piezo-electric properties, which allow it to be used as a frequency regulating device in satellites, computers, and the ubiquitous quartz-watch . Unfortunately, it has been found that quartz crystals are susceptible to damage by radiation, and that this is associated with the presence of defects in the crystal lattice. These defects, particularly aluminum and hydrogen, are grown into the crystal and so far have proved impossible to remove. This problem has been the cause of intensive research, which has led to some information on the possible types of defects involved, but has failed to produce details of their geometries, and the way in which they interact. 

Figure 4.29. Experimental set-up for atomic force microscopy. The sample is mounted on a piezo electric scanner and can be positioned with a precision better than 0.01 nm in thex, y, and z directions. The tip is mounted on a flexible arm, the cantilever. When the tip is attracted or repelled by the sample, the deflection of the cantilever/tip assembly is...

PHB has been claimed to have piezo-electric properties similar to those of natural bone, giving it potential as biodegradable fixative plates that could actually stimulate bone formation and consequently promote the healing of the patient [117]. Furthermore, PHB has been used to produce non-woven patches for pericardium repair following open-heart surgery. 

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... 

The tip is first brought near to the sample via a coarse Z positioner, such as a controlled approach piezo-electric motor. This provides a 10 A step size and so is capable of very precise and controlled movement. As soon as a tunnelling current is detected, the tip is stopped and the fine control system is operated. Thus the lip is mounted on the end of a hollow, cylindrical piezo crystal, a tube scanner (a piezo-electric crystal can be made to deform under the influence of a voltage applied across it). The tube scanner has four strip electrodes on the outside, providing movement in the x and y directions (lateral movement), and one electrode covering the whole of the inside. A... 

Note 4 The flexo-electric effect is the analogue of the piezo-electric effect in solids, where the polarization is induced by a strain that produces a translational deformation of the crystal. The flexo-electric effect in a liquid crystal is caused by a purely orientational deformation. 

Together, this famous couple, Pierre Curie, 1859-1906, and Mme. Marie Sklodowska Curie, 1867-1934, discovered radium and polonium, and founded the beneficent science of radioactivity. Pierre served as professor of physics at the Sorbonne, and collaborated with his brother, Jacques Curie, in the discovery and investigation of piezo-electricity. He introduced the concept of symmetry in physical phenomena and studied magnetic properties as a function of temperature. Marie served as professor of radioactivity at the University of Paris. 

Gabriel Lippmann, 1845-1921. Professor of mathematical physics at the University of Paris. Inventor of the capillary electrometer and of a process of direct color photography. The phenomenon of piezo-electricity in crystals predicted by Professor Lippmann was first demonstrated experimentally by Pierre and Jacques Curie. 

Part II deals, in six chapters, with the principles underlying the progressive stages in the elucidation of internal structure. Chapters VI and VII deal with the principles of structure determination by trial Chapter VIII with the use of physical properties (such as habit, cleavage, and optical, magnetic, pyro- and piezo-electric properties) as auxiliary evidence in structure determination. In Chapter IX are to be found several examples of the derivation of complete structures. Chapter X gives an introductory account of the use of direct and semi-direct methods based on the calculation of electron density distributions and vector distributions from X-ray diffraction data. 

If the combination of X-ray and morphological evidence does not determine the space-group uniquely, additional information may be sought by tests for piezo-electric and pyro-electric properties, and by an optical examination for any evidence of rotation of the plane of polarization. (See Chapter VIII.) The results of such tests may settle the matter, since only certain crystal classes have these properties. Only positive results are decisive the apparent absence of piezo-electric or pyro-electric effects may be due to feeble phenomena. 

As for the physical properties of crystals, some account of crystal morphology and optics has been given in Chapters II and III, where, however, these subjects were developed only as far as was necessary for identification purposes. For structure determination further consideration of both these subjects, as well as others such as the magnetic, pyroelectric, and piezo-electric properties of crystals, is desirable this will be found in Chapter VIII. 

Pyro-electric and piezo-electric tests. When a crystal belonging to one of the non-centrosymmetric classes is heated or cooled, it develops electric charges and becomes positive at one end and negative at the other end of each polar axis. Therefore, if a crystal is found to be pyro electric, it must belong to one of the classes which lack a centre of symmetry. Various qualitative tests for pyro-electric character have been used. The three most suitable for small crystals are the following ... 

Piezo-electricity is the property, possessed by some crystals, of developing electric charges when compressed or extended in particular directions. Conversely, when a potential difference is applied to suitable points on such a crystal, it expands or contracts. Piezo-electric properties can occur in all crystals lacking a centre of symmetry, except those belonging to the cubic class 432 (Wooster, 1938). A test for such properties, suitable for small crystals or even powders, is the following,... 

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