“…Its tanδ value is rather independent of the measured frequency. The highest ε r (2.25 × 10 4 , at 1013 Hz and room temperature) is found for the sample with x = 0.15, which is close to that of (A, B)-doped NiO systems (where A = Li and B = Ti 9,13,18,19 , Cr 20 , V 22 , Fe 24 and Si 10 ), calcium copper titanate perovskite materials 4 and slightly higher than that of (Li, Al)-doped NiO 14 , (Li, Sn)-doped NiO 5 , (K, Ti) doped NiO 31 , (Na, Si)-doped NiO 6 and perovskite oxide materials 50 . Its tanδ value is close to that of other NiO-based ceramics such as (Li, Al) doped NiO prepared via a simple thermal decomposition route 14 , and (Li, Si)-doped NiO prepared using a chemical precipitation method 10 .…”