Dielectric zinc compounds

Table 4.1-149 Electro-optical constants of zinc compounds. Under the influence of an electric field, the refractive index changes in accordance to the nonlinearity of the dielectric polarization (Pockels effect). Crystals with hexagonal symmetry have three electro-optical constants rsi, 733, 751 crystals with cubic symmetry have only one electro-optical constant 741...

An ellipsoidal/spherical particles blending system shows much stronger ER effect than one-component system [59]. A contradictory result was obtained in hydroxyl-zinc compounds such as plate shape particle of Zn5(011)s(N03)2 2II2O and rod-like particle of Zn5(011)8(Cll3C00)2 -21120 /silicone oil suspensions. The rod particle suspension showed weak ER cffcct.fOOl, which was attributed to the low dielectric constant of the rod particle suspension. It may be hard to draw such a conclusion as the particle materials are different. 

Inhibitors are used most often to remove or neutralize contaminants, or to form a film with relatively high dielectric strength on the equipment. Oxygen scavengers, such as sodium sulphite, are currently used in both water and oil muds. Calcium or zinc compounds are used to precipitate carbon dioxide or hydrogen sulfide. Alkaline materials are used in drilling fluids for both rhelogical control and... 

Table 1.1. Abundance of the metal in the earths s crust, optical band gap Es (d direct i indirect) [23,24], crystal structure and lattice parameters a and c [23,24], density, thermal conductivity k, thermal expansion coefficient at room temperature a [25-27], piezoelectric stress ea, e3i, eis and strain d33, dn, dig coefficients [28], electromechanical coupling factors IC33, ksi, fcis [29], static e(0) and optical e(oo) dielectric constants [23,30,31] (see also Sect. 3.3, Table 3.3), melting temperature of the compound Tm and of the metal Tm(metal), temperature Tvp at which the metal has a vapor pressure of 10 3 Pa, heat of formation AH per formula unit [32] of zinc oxide in comparison to other TCOs and to silicon...

In this chapter some of the presently known optical properties of zinc oxide are reviewed. In particular, the anisotropic dielectric functions (DFs) of ZnO and related compounds from the far-infrared (FIR) to the vacuum-ultraviolet (VUV) spectral range are studied. Thereupon, many fundamental physical parameters can be derived, such as the optical phonon-mode frequencies and their broadening values, the free-charge-carrier parameters, the static and high-frequency dielectric constants, the dispersion of the indices of refraction within the band-gap region, the fundamental and above-band-gap band-to-band transition energies and their excitonic contributions. 

Later, in 2014 McCann and Organ investigated the role of halide additives in the Negishi reaction catalyzed by 29 involving sp -hybridized zinc reagents. Diarylzinc compounds were found to couple in low dielectric solvents (i.e., THF) with zero salt present whereas arylzinc halides failed to couple in THF alone, requiring the addition of salt. Further, unlike alkyl-alkyl coupling there was no evidence to support the... 

Due to their good donor properties formamide and acetamide dissolve many ionic compounds7 94,96 g ch as alkali halides, various salts of copper, zinc, cadmium, aluminium, tin, lead, nickel, mercury and other acceptor compounds, such as FeCls or SbCls. The high dielectric constants allow considerable dissociation of the compounds ionized in the solutions. 

The adsorption of heavy metal ions can be largely influenced by the presence of organic compounds. Complexation may increase or reduce adsorption of heavy metal ions. A calcium bentonite (Montigel, Sud-Chemie, Bavaria) adsorbs 71% Zn " from 1100 ppm Zn in solution (2 g bentonite/100 ml solution) (Fig. 6). In the presence of diethyl ketone and phenol 89% and 92% of the Zn ions are adsorbed [69]. Zinc ions also promote the adsorption of diethyl ketone (from 5 to 28%) and phenol (from 2 to 6%). Both organic compounds form weak complexes or solvation shells around Ae zinc ions. As the concentration of the organic compounds is very low (1 %), eiu ichment of the zinc ions on the surface due to the decreased dielectric constant is not decisive. 

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