One-dimensional conductive materials

One-dimensional Metals Physics and Materials Science, by S. Roth, VCH, Weinheim, 1995. This book considers not only polymers but also other essentially one-dimensional conducting materials in a rather unconventional style. 

J. C. Scott, in Semiconductors and Semimetals, Vol. 27, Highly Conducting Quasi-One-Dimensional Crystalline Materials (E. Conwell, ed.), Academic Press, New York, 1988, p. 385. 

The basis of the solution of complex heat conduction problems, which go beyond the simple case of steady-state, one-dimensional conduction first mentioned in section 1.1.2, is the differential equation for the temperature field in a quiescent medium. It is known as the equation of conduction of heat or the heat conduction equation. In the following section we will explain how it is derived taking into account the temperature dependence of the material properties and the influence of heat sources. The assumption of constant material properties leads to linear partial differential equations, which will be obtained for different geometries. After an extensive discussion of the boundary conditions, which have to be set and fulfilled in order to solve the heat conduction equation, we will investigate the possibilities for solving the equation with material properties that change with temperature. In the last section we will turn our attention to dimensional analysis or similarity theory, which leads to the definition of the dimensionless numbers relevant for heat conduction. 

Similar to (SN)T in their one-dimensional conductivity properties are the slacked columnar complexes typified by [Pt(CN)4 ". These square planar ions adopt a closely spaced parallel arrangement, allowing for considerable interaction among the <1.2 orbitals of the platinum atoms. These orbitals are normally filled with electrons, so in order to gel a conduction band some oxidation (removal of electrons) must take place. This may be readily accomplished by adding a little elemental chlorine or bromine to the pure tetracyanoplatinate salt to get stoichiometries such as K2[Pt(CN)4]Br0, in which the platinum has an average oxidation stale of -t-2.3. The oxidation may also be accomplished electrolytically. as in the preparation of Rb,[Pt(CN)4l(FHF)04 (Fig. 16.8), which has a short Pt—Pt separation. The Pt—Pt distance is only 280 pm. almost as short as that found in platinum metal itself (277 pm) and in oxidized platinum pop complexes (270 to 278 pm see Chapter I5). 12 Gold-bronze materials of this type were discovered as early as 1842, though they have been little understood until recent times. The complexes behave not only as one-dimensional conductors, but... 

EQUATION FOR ONE-DIMENSIONAL CONDUCTION. Figure 10.5 represents a section through a large slab of material of thickness 2s, initially all at a uniform temperature T . At the start of heating both surface temperatures are quickly increased to and subsequently held at temperature 7. The temperature pattern shown in Fig. 10.5 reflects conditions after a relatively short time tj- has elapsed since the start of heating. 

Finally, soHd-state physicists make use of molecular crystals when they wish to understand certain aspects of soUd-state physics better theoretically and experimentally. Weak intermolecular bonding forces, electrical conductivity with a very narrow handwidth, large anisotropies in their electrical, optical and magnetic properties, one-dimensional conductivity. Unear excitons, and linear magnetic ordering states are best studied in these material classes. 

This concept of polarons and, in particular, excitonic polarons has been used to explain observed features of the one-dimensional conducting organic materials based on 7,7,8,8-tetracyano-p-quinodimethane, TCNQ (85). It indicates that a way to reduce the Coulomb repulsion between electrons in the chain is to surround each chain by a highly polarizable medium. However, a limit may be reached beyond which, if the surrounding medium were made more polari zable, the effects due to band narrowing would outweigh the benefits of reduced Coulomb repulsion (85). 

The chemical and physical properties of inorganic complexes which exhibit a columnar structure are discussed below. Section II. A discusses highly conducting one-dimensional inorganic materials which may be described in terms of a partially occupied electron energy band. Section II.B describes those complexes which exhibit a columnar structure and generally low conductivity. Several less well characterized materials which may exhibit columnar structure are introduced in Section II. C. Section II. D selectively surveys inorganic polymers, with emphasis on poly(sulfurnitride). 

For PSA implanted with 50 keV ions, the film resistivity increases rapidly after implantation and is characterized by a rate of change (dRIdt) that decreases in time. The dRIdt is highly dependent on the initial composition of the polymer and the implantation conditions. Empirically, resistance stability improves as the thickness of the film decreases and as the energy of the implant ion and its dose increase. This suggests that the most unstable region of the material is that of the one-dimensional conduction networks toward the mean range of the ions. 

Carbon nanotubes are one-dimensional carbon materials with high aspect ratio (greater than 1000) and excellent mechanical, electrical, and thermal properties when compared to other carbon materials, such as graphite and fuUerene. CNT is one of the most promising filler for nanocomposites and have generated great interests in the polymer industry due the technical applications in electrical conductivity, thermal conductivity, and improvements in mechanical properties (Choi et al. 2014). 

As has been recognized, the closepacked aromatic macrocycles are capable of transporting charge and energy along the stacking axis due to interactions between single macrocycles (one-dimensional conduction) [81,91]. With the increased tractability of liquid crystalline materials, these one-dimensional systems could... 

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