Dielectric response, non-Ohmic behaviors and humidity-sensing characteristics: Tin doping in sodium yttrium copper titanate ceramics

Abstract

The impact of tin (Sn4+) doping on sodium yttrium copper titanate (Na0.5Y0.5Cu3Ti4O12) ceramics, prepared using a conventional mixed-oxide route, was thoroughly investigated in terms of microstructure, dielectric properties, electrical response, non-linear behaviors, and humidity-sensing characteristics. All sintered ceramics showed a dense micro-structure and a pure Na0.5Y0.5Cu3Ti4O12 phase without any secondary phases. The doped Na0.5Y0.5Cu3Ti4−xSnxO12 ceramics, with x = 0.05, demonstrated excellent dielectric properties, including a low dielectric loss tangent (∼0.032) and a giant dielectric permittivity (∼1.8 × 104) across a wide temperature range. Sn4+ doping improved the non-linear behaviors at 25 °C in Na0.5Y0.5Cu3Ti4O12, with a reduced dielectric loss tangent corresponding to an enhanced grain boundary (GB) response. The colossal dielectric response is attributed to the internal barrier layer capacitor model, which relates to the Schottky barrier height (ΦB) at the GBs. Notably, the ΦB values for the Na0.5Y0.5Cu3Ti4O12 ceramic increased with Sn4+ ion doping. Additionally, an in-depth study of the humidity-sensing properties of the Sn4+-doped Na0.5Y0.5Cu3Ti4O12 material revealed that the capacitance at 1 kHz increased with increasing relative humidity levels, from 30 % to 90 %, suggesting potential applications in humidity-sensing technologies.