Annealing effects on the structure and properties of Mn-doped (K0.48Na0.52)NbO3 lead-free piezoceramics

The Mn-doped (K0.48Na0.52)NbO3 (KNN) ceramics were annealed in air at 600-800 A degrees C for 16 h and the effects of annealing on the structure as well as the ferroelectric and piezoelectric properties were investigated. The 3 mol% Mn-doped ceramics sintered at 1030-1080 A degrees C were found to be melted after being annealed at 800 A degrees C, and the melting temperature decreased with the increase of Mn content. The T (C) and T (O-T) of the ceramics with x ae<currency> 0.04 shifted significantly to higher temperature after annealing. The annealed ceramics doped with 1-4 mol% Mn possessed a large internal bias field (E (i)) of 5.08-6.6 kV/cm, and larger d (33) and Q (m). The d (33) of the 1 mol% Mn-doped ceramics increased from 109 to 124 pC/N after annealed at 600 A degrees C, and the largest Q (m), 145, was obtained when the 2 mol% Mn-doped ceramics were annealed at 700 A degrees C.