Piezoelectric crystal data

BP processing of stripping analysis responses allowed the quantitative determination of heavy metals in the presence of interferences, and selectivity coefficients of berberine-selective electrodes were predicted satisfactorily. o BP networks were used to analyze piezoelectric crystal data to simultaneously determine sulfur dioxide concentration and relative humidity. 2 A BP network was used to model properties of materials. 2 x vo studies described the modeling and recognition of flow injection patterns. " Compared to principal components regression and partial least squares (PLS), BP provided a better method for multicomponent kinetic determinations. BP... 

I2 in CCI4. The contents of the separatory funnel are shaken, and the organic and aqueous layers are allowed to separate. The organic layer, containing the excess I2, is transferred to the surface of a piezoelectric crystal on which a thin layer of Au has been deposited. After allowing the I2 to adsorb to the Au, the CCI4 is removed and the crystal s frequency shift is measured. The following data are reported for a series of thiourea standards. 

Of all the piezoelectric crystals that are available for use as shock-wave transducers, the two that have received the most attention are x-cut quartz and lithium-niobate crystals (Graham and Reed, 1978). They are the most accurately characterized stress-wave transducers available for stresses up to 4 GPa and 1.8 GPa, respectively, and they are widely used within their stress ranges. They are relatively simple, accurate gauges which require a minimum of data analysis to arrive at the observed pressure history. They are used in a thick gauge mode, in which the shock wave coming through the specimen is... 

Acceleration is perhaps the best method of determining the force resulting from machine vibration. Accelerometers use piezoelectric crystals or films to convert mechanical energy into electrical signals and Figure 43.23 is a schematic of such a device. Data acquired with this type of transducer are relative... 

A benefit of the use of accelerometers is that they do not require a calibration program to ensure accuracy. However, they are susceptible to thermal damage. If sufficient heat radiates into the piezoelectric crystal, it can be damaged or destroyed. However, thermal damage is rare since data acquisition time is relatively short (i.e. less than thirty seconds) using temporary mounting techniques. 

Air None (real time) Uncoated piezoelectric crystal detector 0.5 ng No data Kristoff and Guilbault 1983... 

Air None (real time) Coated piezoelectric crystal detector No data No data Milanko et al. 1992... 

Once the manufacturer s data are known, we can estimate K and thus the voltage obtained at the electrodes of the piezoelectric crystal. 

An older general review by Stefan et al. [2] considers mathematical modeling for data processing (including a variety of chemometric methods such as linear and nonlinear partial least squares, fuzzy neural networks, and multivariate analysis of variance), designs for electrochemical sensor arrays as well as applications in environmental, food and clinical analysis. Arrays of potentiometric ion-selective electrodes, piezoelectric crystal sensors, and voltammetric biosensors, as well as the electronic nose gas-phase sensor arrays are reviewed. 

Using data obtained from thermocurrent, piezoelectric and dilatometric measurements, the first and second pyroelectric coefficients were calculated for the Rb5Nb3OFi8 crystal. Fig. 114 presents the results. 

The most common form of silica is low quartz, which by virtue of its piezoelectric and other properties is of considerable commercial importance. A detailed compilation of crystal structure data is available (54). 

Figure 2.4 Strain-field curves for < 001 > oriented 0.91PbZn1/3Nb2/303-0.09PbTi03 single crystals. The sample in (a) was poled at room temperature, where the resulting domain state is unstable (due to induction of tetragonal material associated with the curved morphotropic phase boundary), yielding substantial hysteresis. In (b) the crystal was poled at low temperatures to keep it in the rhombohedral phase. When measured at room temperature, the piezoelectric response is much more linear and non-hysteretic, due to the improved stability of the ferroelectric domain state. Data courtesy of S. E. Park.

Fig. 2.5. Temperature-dependent mobility of ZnO single crystals measured with the current flowing parallel (a) or perpendicular (b) to the c-axis of the crystals. The theoretical mobilities for the different scattering processes (optical, acoustical, and piezoelectric as well as ionized impurity scattering) as calculated by Wagner and Helbig [34,35] are shown as differently dashed lines. The calculated combined mobility curves (solid lines) fit the experimental data quite well for temperatures above about 20-50 K. The carrier concentrations at 300 K were about Ad — Na = 2.25 x 1016 cm 3 and Na = 2.75 x 1016 cm 3 (compensation ratio Aa/Ad = 0.55)...

Direct measurements of spout voidage have been made by Soviet workers, using the piezoelectric technique mentioned in Section IV,B. Simultaneously with particle-velocity measurements, they recorded the frequency with which the solid particles collided with the piezo-crystal from the number of peaks observed on the oscilloscope per unit time. The local voidage at the probe tip was calculated from these data using the equation... 

Most cascade impactors do not give data in real time. The collection surfaces must be removed from the device and subjected to chemical or gravimetric analysis. However, one impactor does give data in real time. The Model PC-2 Air Particle Analyzer (California Measurements, Inc., Sierra Madre, CA) achieves a real-time measurement by using piezoelectric quartz crystal microbalance (QCM) mass sensors to electronically weigh particles at each impactor stage [62,63], The device has 10 stages and separates the aerosol into... 

The quartz disk is used as the bottom plate of a cell culture vessel and is moimted in a temperature controlled crystal holder (37 °C). The surface electrodes on either side of the quartz are connected to an impedance analyzer (Solatron Instruments, SI-1260) operating in continuous wave mode. The frequency-dependent complex impedance Z(J) returned by the impedance analyzer is expressed as magnitude of impedance Z (f) and phase shift between voltage and current (f). The raw data is analyzed by the well-known Butterworth-Van Dyke (BVD) equivalent circuit with the liunped impedance elements Co, Rq, iq, Cq and Zl. Rq, Lq and Cq represent the piezoelectric properties of the unperturbed resonator itself, whereas Co summarizes its dielectric properties and all parasitic contributions arising from contacts and wiring. The load material in contact with the resonator surface is represented by the complex impedance Zl. As long as the resonator is not loaded too... 

A number of technology developments can be identified that promise to advance the applications of QCM and related piezoelectric resonance techniques. These involve modifications in the QCM device, the crystal, as well as in the systems under study and their methods of analysis. Some of these approaches have already begun to be studied and implemented. The specific areas of these improvements include increasing mass sensitivity, hybrid devices and novel resonance techniques, enabling determination of the kinetics of processes, use of cells as information-rich sensing elements, and applying data mining techniques to provide accurate analyses and outputs from complex sensor inputs in future devices. We briefly discuss each of these below. 

Landolt-Bomstein Numerical Data and Functional Relationships in Science and Technology, III/ll, Elastic, Piezoelectric, Pyroelectric, Piezooptic, Electrooptic Constants, and Nonlinear Dielectric Susceptibilities of Crystals, Springer-Verlag, Berlin, 1979. 

Landolt-Bomstein Numerictil Data tmd Functional Relationships in Science and Technology, New Series. Gn IB Crystal tmd Solid State Physics. Vol. 11. Revised and Extended Edition of Volumes 111/1 and 111/2. — Elastic, Piezoelectric, Pyroelectric, Electrooptic Consttmts, and Nonlinear Susceptibility of CrysUils, 854 p. Springer, Berlin/Heidelberg/New York (1979)... 

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