Structural, dielectric, and piezoelectric properties of fine-grained NBT–BT0.11 ceramic derived from gel precursor

(Na1/2Bi1/2)TiO3 doped in situ with 11 mol% BaTiO3 (NBT–BT0.11) powders were synthesized by a sol–gel method, and the electrical properties of the resulting ceramics were investigated. The powders consisting of uniform and fine preliminary particles of about 50 nm were prepared by calcining the gel precursor at 700 °C. (Na1/2Bi1/2)0.89Ba0.11TiO3 ceramics, sintered at temperatures up to 1150 °C have a rhombohedral symmetry, while the ceramic sintered at 1200 °C exhibits a tetragonal crystalline structure. The ceramics show high dielectric constant (ɛr ∼ 5456), dielectric loss of 0.02, depolarization temperature Td ∼ 110 °C and temperature corresponding to the maximum value of dielectric constant Tm ∼ 262 °C. The dielectric constant (ɛ33) and the piezoelectric constant (d33) attain the maximum values of 924 and 13 pC/N, respectively, while the electromechanical coupling factor (kp) value is 0.035. The NBT–BT0.11 ceramics derived from sol–gel present high mechanical quality factor (Qm ∼ 860). The dielectric and piezoelectric properties values of NBT–BT0.11 ceramics derived from sol–gel are smaller than those of samples produced by the conventional solid state reaction method, due to the grains size and oxygen vacancies that generate dipolar defects.