Study on properties of tantalum-doped La_2Ti_2O_7 ferroelectric ceramics

摘要

A series of ceramics with a general formula, La_2Ti_(2-x)Ta_xO_7, 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 La_2Ti_2O_7 lattice was in the proximity of x = 0.2. The ferroelectric Curie temperature (T_c) decreased with increasing tantalum doping content, dc resistivity reached a maximum value at x = 0.2 with a value of ～ 1.0 × 10~8Ω· cm at 600℃. The influence of texture on the piezoelectric properties of La_2Ti_(2_x)Ta_xO_7 ceramics was also investigated. A maximum d_(33) value ～2.1 pC/N was obtained at x = 0.2.