Effect of oriented defect-dipoles on the ferroelectric and piezoelectric properties of CuO-doped (K0.48Na0.52)(0.96)Li0.04Nb0.805Ta0.075Sb0.12O3 ceramics

摘要

The orientation characteristics of the defect dipoles formed by acceptor ions (Cu-Nb(n)') and oxygen vacancies (V-O(center dot center dot)) in CuO-doped (K0.48Na0.52)(0.96)Li0.04Nb0.805Ta0.075Sb0.12O3 piezoceramics were investigated. The ferroelectric and piezoelectric properties of the ceramics were obviously affected by the defect dipoles which are oriented along with the domains when poled under a dc electrical field of 3.5 kV/mm at the temperature near T-C. The poled ceramics with 1.0-3.0 mol% CuO displayed strong asymmetric P-E loops and a large internal bias field (E-i), 3.89-4.57 kV/cm, when polarized at the temperature near T-C. The enhanced piezoelectric coefficient d(33), 186-192 pC/N, was obtained for the ceramics poled near T-C when 0.02 = x = 0.03. The ceramics with oriented defect dipoles showed a relatively good thermal stability of d(33) until 180 degrees C.