Defects and Conductivity

The closely related phase La2Cu04 (Section 4.3.3) is similar. In both of these materials there is strong evidence to suggest that the interstitial oxygen atoms are not distributed at random but are partly or completely ordered, depending upon preparation conditions. This has significance for high-temperature superconductors (Section 8.6). 

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Yasuda I and Hikita T. Electrical conductivity and defect structure of calcium-doped lanthanum chromites. 7. Electrochem. Soc. 1993 140 1699-1704. 

Tsoga A, Naoumidis A, and Stover D. Total electrical conductivity and defect structure of Zr02-Ce02-Y203-Gd203 solid solutions. Solid State Ionics 2000 135 403M09. 

Hall effect measurements were used to investigate the electrical properties of the poly-Si films formed by the ALILE process. Due to the incorporated Al, the poly-Si films are always p-type. At room temperature, a hole concentration of 2.6 x 1018 run 3 and a hole mobility of 56.3 cm2 V 1 s 1 were determined [16]. Temperature dependent Hall measurements revealed both valence band conduction and defect band conduction (two-band conduction). For such highly doped material, the presence of a defect band conduction is expected. The Al concentration in the poly-Si films was measured by secondary ion mass spectroscopy (SIMS). An Al concentration of about 3 x 1019 cm 3 was found, which is about a factor of 10 larger than the... 

B. Calfes and J.F. Baumard, Mixed conduction and defect structure of Zr02-Ce02-Y203 solid solutions. /. Electrochem. Soc., 131 (1984) 2407-2413. 

In the case of conducting polymers, the motion of delocalized electrons occurs through conjugated systems however, the electron hopping mechanism is likely to be operative, especially between chains (interchain conduction) and defects. Electrochemical transformation usually leads to a reorganization of the bonds of the polymers prepared by oxidative or less frequently reductive polymerization of ben-zoid or nonbenzoid (mostly amines) and heterocyclic compounds. 

Yang Z, Harvey AS, Infortuna A, Schooirman J, Gauckler LJ (2011) Electrical conductivity and defect chemistry of Ba(x)Sr(l-x)CoyFe(l-y)0(3-delta) perovskites. J Solid State Electr 15 277... 

Figure 4-14 Relative values (calculated values) for conductivity and defect density when a donor and acceptor are added to BaTiOj.

Pol] Poliak, T.M., High Temperature Electrical Conductivity and Defect Chemistry of Iron-Doped Alumina , Thesis, Massachusets Inst. Technology, 81pp. (1976) (Electr. Prop., Experimental, 29)... 

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