In, Nb, and Zr co-doped TiO2 ((In0.5Nb0.5)0.005(Ti1-xZrx)0.995O2) (x = 0–0.80) ceramics were prepared by a solid-state reaction method, and their structures, dielectric properties, and response to DC bias were studied. The solubility limit was found to be near x = 0.10, and the excess added Zr was present in the form of secondary ZrTiO4 phase. The mean grain size increased from 20.2 to 39.5 μm in the x = 0–0.10 range and then decreased to 5.2 μm for x = 0.20. Permittivity at 1 kHz exceeded 104 for the samples in the x = 0–0.20 range and then decreased to 570 for x = 0.40. For x = 0.20, the ceramic sample showed εr ≈ 104 and tanδ ≤ 0.05 (20 Hz–100 kHz), as well as good temperature (−150 to 125 °C) and DC bias (0–875 v/cm) stability. The breakdown electric field increased from 940 v/cm for x = 0 to 5770 v/cm for x = 0.20. The excellent dielectric properties are attributed to the coexistence of smaller grains and the presence of insulating ZrTiO4 in the sample.
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