Abstract
From electrical resistivity and Hall coefficient measurements below 3 K on slightly reduced, semiconductive rutile single crystals with oxygen deficiencies between 3.7×/ and 5.5×/, it is concluded that the electrical conduction takes place by means of a defect-level permutation conduction mechanism involving Ti interstitial donors. In the range of 3.7×/≤≤2×/ the electrical resistivity decreases with increasing , while in the range of 2×/≤≤5.5×/ it increases with increasing . Values of between 8×/ and 2×/ correspond to the so-called intermediate concentration range of the impurity (defect) conduction, but the transition to metallic-type conduction does not occur because of a change in the defect structures, i.e., the formation of planar defects and the clustering of Ti interstitial donors at higher oxygen deficiencies.
- Received 12 October 1993
DOI:https://doi.org/10.1103/PhysRevB.49.7251
©1994 American Physical Society