Electrical and magnetic properties

5 ELECTRICAL AND MAGNETIC PROPERTIES 6.5.1 Didectric constant and dectric dipole moment 

The value of the dielectric constant, e, for phosgene vapour at 15 C and 101.325 kPa, was measured as 1.0067 [420aj. From dielectric measurements on the vapour, the dipole moment, p, of phosgene was found to be (3.933 0.050) x 10 3 C m (1.179 D) [461] earlier measurements of e in the vapour phase gave a value for the dipole moment (re-evaluated with modern constants) of (3.97 0.03) x 10 2o q (1.19 D) [1911]. Quantitative Stark effect measurements on CO Cl, confined to the rotational 0 1, 

Dipole moment derivatives have been determined both experimentally [981 ] and theoretically [290,292,1655,1657,2098], although the agreement between these values is poor. These observations are relevant to infrared band intensities (see Section 7.2). 

The dielectric constant of liquid phosgene, expressed as a function of absolute temperature, is given by Equation (6.11) in the range of +20 to -132 C, and is illustrated in Fig. 6.9 [461]. 

The value of t at 20 C, from Equation (6.11), is therefore 4.712. However, the value of f rises considerably with decrease in temperature, reaching ca. 10.7 at -130 C. Previous measurements [1798] of the dielectric constant, made at 0 and 22 C, are believed to be too low by 8 and 7% respectively [461]. 

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Interest is maintained ia these materials because of the combination of mechanical, corrosion, electric, and magnetic properties. However, it is their ferromagnetic properties that lead to the principal appHcation of glassy metals. The soft magnetic properties and remarkably low coercivity offer tremendous opportunities for this appHcation (see Magnetic materials, bulk Magnetic materials, thin film). 

Any difference in physical properties of the individual solids can be used as the basis for separation. Differences in density size, shape, color, and electrical and magnetic properties are used in successful commercial separation processes. An important factor in determining the techniques that can be prac tically applied is the particle-size range of the mixture. A convenient guide to the application of different solid-solid separation techniques in relation to the particle-size range is presented in Fig. 19-1, which is a modification of an original illustration by Roberts et al. 

The toroidal and helical forms that we consider here are created as such examples these forms have quite interesting geometrical properties that may lead to interesting electrical and magnetic properties, as well as nonlinear optical properties. Although the method of the simulations through which we evaluate the reality of the structure we have imagined is omitted, the construction of toroidal forms and their properties, especially their thermodynamic stability, are discussed in detail. Recent experimental results on toroidal and helically coiled forms are compared with theoretical predictions. 

The sensitive dependence of the electrical and magnetic properties of spinel-type compounds on composition, temperature, and detailed cation arrangement has proved a powerful incentive for the extensive study of these compounds in connection with the solid-state electronics industry. Perhaps the best-known examples are the ferrites, including the extraordinary compound magnetite Fc304 (p. 1080) which has an inverse spinel structure (Fe )t[Fe Fe ]o04. 

We are going to be concerned with electrical and magnetic properties in this text, so I had better put on record the fundamental force laws for stationary charges and steady currents. These are as follows. 

Crystal growth 6.7.4,3 Crystal structure and lattice parameters 6.7.2.4.1 Electrical and magnetic properties 6.7.2.4.1... 

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