Voltage Coefficient

Composite Devices. Composites made of active-phase PZT and polymer-matrix phase are used for the hydrophone and medical imaging devices (see Composite materials, polymer-matrix Imaging technology). A usehil figure of merit for hydrophone materials is the product of hydrostatic strain coefficient dj and hydrostatic voltage coefficient gj where gj is related to the dj coefficient by (74)... 

Figure 4-7 Voltage Coefficient for Different Sizes of 50V Capacitors from Epcos...

The temperature voltage coefficient has several names temperature coefficient, voltage coefficient or temperature coefficient of voltage. Table 7.3 contains a few values of (d (emf)/dT). 

Worked Example 7.7 The temperature voltage coefficient for a simple alkaline torch battery is —6.0 x 10 4 VK-1. What is the entropy change associated with battery discharge The number of electrons transferred in the cell reaction n = 2. 

Figure 7.5 Graph of cell emf against temperature for the Clark cell Hg HgS04, ZnS04(sat d) Zn. We call the gradient of this graph the temperature voltage coefficient ...

Table 7.3 Temperature voltage coefficients for various cells and half cells...

SAQ 7.6 The emf of a lithium watch battery is exactly 3.000 V at 298 K, but the value decreases to 2.985 V at 270 K. Calculate the temperature voltage coefficient and hence the change in entropy AS(ceii) during cell discharge. (Take n = 1.)... 

Occasionally, the temperature voltage coefficient is not expressed as a simple number, but as apower series in T (we generally call it a virial series, or expansion). For example, Equation (7.19) cites such a series for the cell Pt(S) H2(g) HBr(aq) AgBr(s) Ag(s) ... 

Stability The SSCE has the smallest temperature voltage coefficient of any common reference electrode... 

Voltage coefficient In thermodynamics, the quantity demf/dT) (see Section 3.2.1). 

Composite ferroics. Ingenious experiments have been performed with composites made from a ferroic and another material (Newnham Cross, 1981 Lynn et al, 1981 Rittenmeyer et al, 1982 Safari et al, 1982). For example, in a piezoelectric like PZT, the piezoelectric voltage coefficient g can be defined for a given direction (say Z = 33) thus, 33 = where d and k stand for piezoelectric coefficient... 

Resistivity. Machined cylinders (3/4 x 3/4 inch) were desiccated for several days after being coated on both ends with conducting silver paint. Measurements were made with a Terra-ohmeter at both 100 8t 400 volts over which range the samples appeared to have no significant voltage coefficient Dielectric Constant. This property can be detd by measuring the capacitance of a... 

For low frequency electromechanical applications in which the acoustic wavelength is much larger than the scale of component phases, some of the ceramic-polymer composites have piezoelectric voltage coefficients orders of magnitude larger than solid PZT. Such materials have obvious applications in hydrophones and other listening devices. 

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