Study on properties of tantalum-doped La₂Ti₂O₇ ferroelectric ceramics

A series of ceramics with a general formula, La₂Ti_2-xTa_xO₇, in which x = 0.05; 0.1; 0.2; and 0.3, were prepared by Spark Plasma Sintering (SPS). Effects of tantalum substitution for titanium on the structure, dielectric, and piezoelectric properties were studied. Results revealed that the structure changed gradually from 4-layer to 3-layer due to the higher valence of Ta. The solid solution limit of tantalum in La₂Ti₂O₇ lattice was in the proximity of x = 0.2. The ferroelectric Curie temperature (Tc) decreased with increasing tantalum doping content. dc resistivity reached a maximum value at x = 0.2 with a value of ~1.0 × 10⁸Ω · cm at 600°C. The influence of texture on the piezoelectric properties of La₂Ti_2-xTa_xO₇ ceramics was also investigated. A maximum d₃₃ value ~2.1 pC/N was obtained at x = 0.2.