Electronic conductivity dependence upon composition

The previous sections imply that in the case of nonstoichiometric oxides that favor electronic compensation of composition change a relationship exists between the variation in partial pressure and the electronic conductivity. The form that this relationship takes depends upon the way in which the oxide accommodates composition variation. 

The properties are very sensitive to composition and the charge carriers are apparently positive. Other studies have shown poly(acenaph-thalene) to be only slightly photo-conductive while the nitrated polymer exhibits a photocurrent dependent upon the degree of nitration (100). Since the number of mobile n electrons is the same as in poly (vinyl naphthalene), the authors conclude that some form of stereoregularity is required for enhanced conductivity. Complexes of poly(vinyl anthracene) with halogen molecules show enhanced conductivity and reduced activation energy which is thought to be typical of an electronic semiconductor (101). 

Recent work (Lupinski et al., 1967 Hadek et al., 1971 Barlow et al., 1976) has shown that the maximum conductivity depends critically upon the precise composition of the complex salts and is essentially controlled by the neutral impurity molecules. Just as radical anion salts are based on strong electron acceptors such as TCNQ, radical cation salts based on strong electron donors such as TTF are also known. A listing of the more important radical ion salts is included in Table 3. As a rule these salts give rise to an intense esr signal with their spin concentrations reaching 1 to 1.5 spins per DA pair. 

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