Electrical properties of rutile-type In(Al) 0.025Nb 0.025Ti 0.95O2 ceramics

We determined a series of electrical quantities on rutile-type In 0.025Nb 0.025Ti 0.95O2 (INT005) and Al 0.025Nb 0.025Ti 0.95O2 (ANT005) ceramics in an attempt to analyse in particular the premises for formation of high dielectric constant 𝜖(ω) (ω is angular frequency = 2 πf) and low dielectric dissipation factor tan δ over broad temperature and frequency ranges, observed recently on compositions of rutile-type In x/2Nb x/2Ti 1−xO2 (0 ≤ × ≤ 0.1) (INT) ceramics. The values of these quantities are thought to be determined by a mechanism termed electron-pinned defect dipole clusters. The detailed conditions for formation of this special kind of clusters, including the presence of oxygen vacancies and Ti 3+ cations, are evidently unknown yet. We used a changed processing method of sample preparation in air relative to that applied in the literature. The observed different experimental results might supply information on the different microstructure of the oxides. For both oxides prepared in air, 𝜖(ω) is rather low with values 104 at RT, supply evidence of a critical dependence on sample processing conditions. We suspect important factors may be the concentration of oxygen vacancies and possibly non random distribution of cations. We varied our preparation conditions, using also less oxidizing atmosphere of CO 2, that resulted for INT005 in enhanced σDC(500 K) ~10 −3 Ω−1cm−1 and Arrhenius behaviour with E A ~0.6 eV and also low 𝜖(ω) at RT; similar values were observed for ANT005.