Defect, concept

In the previous sections composition variation has been attributed more or less to point defects and extensions of the point defect concept. In this section structures that can be considered to be built from slabs of one or more parent structures are described. They are frequently found in mineral specimens, and the piecemeal way in which early examples were discovered has led to a number of more or less synonymic terms for their description, including intergrowth phases, composite structures, polysynthetic twinned phases, polysomatic phases, and tropochemical cell-twinned phases. In general, they are all considered to be modular structures. 

Philip B. Crosby was an internationally known quality expert. He is best known for popularizing the Zero Defects concept and the four absolutes for quality management that originated in the United States at the Martin Marietta Corporation where Crosby worked during the 1960s. 

In the same way as the electron transfer is mapped by the band diagram, the ion transfer of the ion-ion associates can be represented by an ionic level diagram (see Fig. 18 center, bottom).75,77 Figure 18 indicates that, in particular by comparison with the situation of water, the ionic associates play the role of internal acids and bases. It is even possible to transform the Brpnsted-concept in its ionotropic generalization to solids by using the point defect concept. In the same way as the numbers of H+ and OH" reflect the acidity and basicity in water, the numbers of v Ag and Agj reflect the (ionotropic) acidity and basicity in AgCl. An acidity function based on 2. which is identical... 

The Zero Defects concept is based on the fact that mistakes are caused by two things lack of knowledge and lack of attitude. Lack of knowledge can be measured and attacked by tried and true means. But lack of attention is a state of mind. It is an attitude problem that must be changed by the individual [p. 171]. 

For bulk materials, all techniques based on structure-insensitive properties, as described in this section and elsewhere, yield closely similar data. The crystallinity model is thus a valid defect concept to describe structure-insensitive properties of semicrystalline polymers. It breaks down for three-phase systems, consisting, for example, of a crystalline phase, a mobile amorphous phase, and a rigid-amorphous fraction (see Chap. 6). In addition, one does not expect valid answers for structure-sensitive properties. 

For a summary of the history and development of defect concepts of non-polymeric defects see Nabarro FRN (1967) Theory of Crystal Dislocations. Oxford University Press (Clarendon), London FriedelJ (1964) Dislocations. Pergamon, Oxford [translation of (1956) Les Dislocations. Gauthiers-Villars, Paris] Frank FC(1949) Disc Farad Soc 5 48-54 Frank FC, Read WT, Jr (1950) Phys Rev 70 722-723. 

Further on, the rightfulness of application of the structural defect concept to polymers yielding process description will be considered. As a rule, previously assumed concepts of defects in polymers were primarily used for the description of this process or even exclusively for this purpose [4—11]. Theoretical shear strength of crystals was first calculated by Frenkel, basing on a simple model of two atoms series, displaced in relation to one another by the shear stress (Fig. 4.1a) [3]. According to this model, critical shear stress Tg is expressed as follows [3] ... 

Defects In Polymers Although the point defect concept in polymers is different than in metals and ceramics, vacancies, interstitial atoms, and impurity atoms/ions and groups of atoms/ions as interstitials have been found to exist in crystalline regions. 

The text will have fulfilled its purpose in an ideal marmer, if it not only conveys to the reader the elegance and power of the defect concept, when it not only puts him or her in the position of being able to recognize the common aspects of different properties and processes such as doping and neighbouring phase effects, ionic and electronic conductivity, passivation and corrosion of metals, diffusion and reaction processes, synthesis kinetics and sintering kinetics in solids, electrode reactions and... 

The defect concept Point defects as the main actors... 

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