Investigations on electronically conducting oxide systems (X)

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Abstract
This paper deals with the preparation and characterization of single-domain crystals of BaNbxVTixIIITi1-2xIVO3 (x = 3 × 10-4 to 3.1 × 10-2). x = 0.01 yields the Curie temperature of 55°C. The characteristic platelet-like appearance of BaTiO3a single crystals grown from a basic BaCl2 flux is maintained up to x = 5 × 10-3. The anisotropy of the specific conductivity is about half an order of magnitude at room temperature and decreases at rising temperatures. The largely analogous dependence of the lattice constants on temperature makes the conclusion possible that the mobility of the polarons is essentially determined by the changes in distance between the Ti-atoms. The absorption spectrum was taken between 400 and 26,000 cm-1. Besides the absorption at 4000 cm-1 characteristic of polaron states it has a band of weak intensity at 16,000 cm-1 which is due to d-d electron transitions in Ti(III)-cations. Altogether, the consideration of the crystal field results in the establishment of a term scheme which permits the uniform description of electrical and spectral properties of crystals.