Crystals, conductance

Figure 4.8 Fraction of amorphous polyethylene as a function of time for crystallizations conducted at indicated temperatures (a) linear time scale and (b) logarithmic scale. Arrows in (b) indicate shifting curves measured at 126 and 130 to 128°C as described in Example 4.4. [Reprinted with permission from R. H. Doremus, B. W. Roberts, and D. Turnbull (Eds.) Growth and Perfection of Crystals, Wiley, New York, 1958.]...

The driving force in polymer synthesis is the search for new polymers with improved properties to replace other materials of construction. Polymers are lightweight and can be processed easily and economically into a wide range of shapes and forms. The major synthetic efforts at present are aimed at polymers with high temperature, liquid crystal, conducting, and nonlinear optical properties [Maier et al., 2001 Sillion, 1999]. There is an interrelationship between these efforts as will become apparent. 

In agreement with this analysis, single-crystal conductivity measurements using the four-probe technique reveals semiconducting behaviour for /r -(TMTTF)2Re04, as shown in Fig. 6.30. In this case aRj — 0.011 cm and Ea — 0.17 eV. 

Fig. 31. Temperature-dependent single crystal conductivity of Ni(pc)I, Ni(tbp)I, and Ni(tatbp)I (Refs. 2, 132, 133)...

Figure la shows the current AIR increase on the dose of the P-irradiation. Saturation time increased from 5 up to 20 min when the radiation intensity is increased. Relaxation time remains constant 1 h in all cases. The linear increase of Cgo single crystal conductivity on intensity is revealed (Fig. lb). 

Dithiotetracene (DTT) has been found as a by-product of some TTT syntheses,and its most likely structure is given in Table V although quinonoid structures may also perhaps be considered." A better synthesis of DTT has been given more recently and the (DTT)(TCNQ) complex has a single crystal conductivity of 3 10 D cm ... 

Difficulty in the synthesis of TTN has retarded conductivity studies, although it seems to be a promising component for organic metals. The single crystal conductivity of (TTN)(TCNQ) at room temperature is 40 D cm , compared with 1 D cm found for (TTT)(TCNQ). ... 

For Ar = phenyl, the single crystal conductivity of the charge-transfer salt is about 0.17 10 H cm , much less than for the (TTF)(TCNQ) complex, a fact which has been ascribed to a different type of crystal packing. ... 

Why do ionic crystals conduct electric current in the liquid phase or when dissolved in water but do not conduct electric current in the solid phase ... 

Plaster and sugar crystals conduct heat differently along the direction of the coordinate axes. Their thermal conductivity is given by the following tensor... 

Phenazine doping of E2P-TCNQ also yields segregated stacks 2 . The bulkier ethyl groups apparently suffice to order the phenazine stack, which by symmetry now consists of a mixed array of P and E2P. The chemical disorder of P(M2P) (TCNQ)2 is therefore suppressed in P(E2P)(TCNQ)2. The TCNQ ionicity is still around q = 0.5. Its four-probe single-crystal conductivity at 300 K is... 

Figure 7.1 Arrhenius plots for ionic conductivity. (1) Li2SO4 [2] (2) Agl [2] (3) LisN [22] (4) Na-p-alumina [23], Plots (1) and (2) produced with polycrystals plots (3) and (4) produced with single crystals conductivity perpendicular to the hexagonal axis.

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