Enhanced dielectric and piezoelectric properties of Bi5Ti3FeO15 ceramics by manganese doping

Lightly manganese-modified, Aurivillius-type, Bi₅Ti₃FeO₁₅ (BTF) ceramics were synthesized by substituting a small amount of manganese ions onto the Ti⁴⁺ sites using conventional solid-state reaction. The resultant manganese-modified BTF ceramics (BTF-Mn) exhibit better dielectric and piezoelectric properties by comparison with the control BTF. With only 4 mol% manganese substitution, the piezoelectric properties of the BTF-Mn ceramics are optimal, exhibiting a high piezoelectric coefficient (d₃₃~23 pC/N), and a low dielectric loss tanδ (~0.3% at 1 kHz). The temperature-dependent dielectric spectra reveal that the BTF-Mn ceramics possess a high Curie temperature of 765 °C. Such BTF-Mn ceramics also exhibit nearly temperature-independent dielectric properties up to 400 °C, suggesting that the manganese-modified BTF ceramics are promising materials for high temperature piezoelectric applications.