The effect of doping donor ions in the dielectric properties of (In0.5B0.5)0.1Ti0.9O2 (BV, Nb, Ta) ceramics

With the rapid development of integrated circuits, TiO2-based colossal dielectric constant ceramics have been widely studied as a critical alternative material in MLCC (Multilayer Ceramic Capacitors). However, the preparation technique is primarily based on the traditional solid-phase reaction method. In this work, (In0.5V0.5)0.1Ti0.9O2, (In0.5Nb0.5)0.1Ti0.9O2, and (In0.5Ta0.5)0.1Ti0.9O2 (abbreviated as: IVTO, INTO, and ITTO) ceramics were prepared by a sol-gel method. In comparison, Nb5+ (r = 0.64 Å) and Ta5+ (r = 0.65 Å) have close ionic radii, which are more susceptible to Ti4+ (r = 0.745 Å) sites substitution than V5+ of a small ionic radius (r = 0.54 Å), effectively facilitating the carrier concentration. Meanwhile, the Ta5+ have another advantage in refining the ceramic grain size to further improve grain boundary resistance. The ITTO ceramics show a colossal dielectric constant of 9.3 × 104, low dielectric loss of 0.07 (1 kHz, room temperature), and stable temperature application range for X9F (−55 °C–200 °C，Δεr/ε25 °C ≤ ±7.5 %). The dielectric mechanism is related to the internal barrier layer capacitance (IBLC) effect. Thus, this work as a novel strategy provides an effective mean for further development of future colossal dielectric constant materials.