Conductors, classification

When we study a solid that does not have the characteristic lustrous appearance of a metal, we find that the conductivity is extremely low. This includes the solids we have called ionic solids sodium chloride, sodium nitrate, silver nitrate, and silver chloride. It includes, as well, the molecular crystals, such as ice. This solid, shown in Figure 5-3, is made up of molecules (such as exist in the gas phase) regularly packed in an orderly array. These poor conductors differ widely from the metals in almost every property. Thus electrical conductivity furnishes the key to one of the most fundamental classification schemes for substances. 

The electronic conductivity of metal oxides varies from values typical for insulators up to those for semiconductors and metals. Simple classification of solid electronic conductors is possible in terms of the band model, i.e. according to the relative positions of the Fermi level and the conduction/valence bands (see Section 2.4.1). 

Interpreting Data Metals are usually malleable and good conductors of electricity. They are generally lustrous and silver or white in color. Many react with acids. Write the word metal beneath the Classification heading in the data table for those element samples that display the general characteristics of metals. 

Table 3 Redkin s Classification in Good Ionic Conductors and Nonconductors as a Function of the Position of the Metal in the Periodic System... 

A detailed discussion of charge transfer in quasi-one-dimensional organic conductors can be found in Refs. 114 and 142. According to the classification of Ref. 114, three methods can be used to evaluate the charge transfer ... 

Of course, more complicated situations may exist, such as n m stoichiometries or ternary salts. See, for example, Graja [142] for a classification of molecular conductors on the basis of conductivity, crystal packing, and charge transfer. See also Pouget [114] for a discussion of charge transfer and instabilities in a number of materials. 

Because of the way Figure 2.6 reveals the various couplings and decouplings that can be encountered in ionic liquid media, we have used it as a basis for ionic liquid classification. We divide ionic liquids into ideal, subionic (or poor ionic) liquids, and superionic liquids. The subionic liquids may still be good conductors at ambient pressure because their fluidities are high, but the conductivity is much lower than if all the moving particles were cations or anions. 

Classifying the elements There are three main classifications for the elements—metals, nonmetals, and metalloids. Metals are elements that are generally shiny when smooth and clean, solid at room temperature, and good conductors of heat and electricity. Most metals also are malleable and ductile, meaning that they can be pounded into thin sheets and drawn into wires, respectively. Figure 6-6 shows several applications that make use of the physical properties of metals. 

Figure 6.19. Classification of FIC glassy conductors as tight and loose , based on plots of o(d.c.) vs. TgIT). Corresponding variation of log(r<,) is also indicated on the right hand side (Schematic after Angell, 1998)...

As it is impossible to analyze all types of electrolyte tvithin the limitations of this chapter, the reader is directed towards many comprehensive reviews where the known solid electrolytes are classified according to their technological functions [38], the nature of their transition to a highly conducting state [13], the constituent chemical species [39], or their crystal structures [40]. Other recent surveys have been devoted to systems with 3-D ionic migration [41] and to the electrolytes with a certain type ofmobile species (e.g., oxygen anions [42]). Information on these groups of ionic conductors can be found in Chapters 7-9. Irrespective of classifications and microscopic mechanisms, the partial ionic conductivity (G,) of a solid can be expressed as... 

The aim of this chapter is to provide a brief introduction into the vast field of solid alkali cation and proton conductors, considering also their Ag+- and Tl + -conducting analogues. More detailed information and an extensive bibliography can be found elsewhere [1-21]. The analysis of the relationships between transport properties, crystal structure and composition ofthese materials requires, initially, a formulation of the major classification principles and criteria. 

As intensive studies on the ECPs have been carried out for almost 30 years, a vast knowledge of the methods of preparation and the physico-chemical properties of these materials has accumulated [5-17]. The electrochemistry ofthe ECPs has been systematically and repeatedly reviewed, covering many different and important topics such as electrosynthesis, the elucidation of mechanisms and kinetics of the doping processes in ECPs, the establishment and utilization of structure-property relationships, as well as a great variety of their applications as novel electrochemical systems, and so forth [18-23]. In this chapter, a classification is proposed for electroactive polymers and ion-insertion inorganic hosts, emphasizing the unique feature of ECPs as mixed electronic-ionic conductors. The analysis of thermodynamic and kinetic properties of ECP electrodes presented here is based on a combined consideration of the potential-dependent differential capacitance of the electrode, chemical diffusion coefficients, and the partial conductivities of related electronic and ionic charge carriers. 

Scheme 11.1 Classification of conductive/ electroactive solids and films, (a) Molecular charge-transfer (CT) complexes and jt-conjugated linear oligomers (b) Mixed electronic-ionic conductors inorganic jt-conjugated polymers and polymer-like...

Classification of the Elements.—Berzelius was the first to divide all the elements into two great classes, to which he gave the names metals and metalloids. The metals, being such substances as are opaque, possess what is known as metallic lustre, are good conductors of heat and electricity, and are electro-positive the metalloids, on the other hand, such as are gaseous, or, if solid, do not possess metallic lustre, have a comparatively low power of conducting heat and electricity, and are electro-negative. 

The most fundamental classification of the chemical elements is into metals and nonmetals. Metals typically have the following physical proper-fies a lustrous appearance, the ability to change shape without breaking (they can be pulled into a wire or pounded into a thin sheet), and excellent conductivity of heaf and elecfricity. Nonmetals fypically do nof have these physical properties, although there are some exceptions. (For example, solid iodine is lustrous the graphite form of carbon is an excellent conductor of elecfricity and the diamond form of carbon is an excellent conductor of heaf.) However, it is the chemical differences between metals and nonmetals that interest us the most ... 

---