Effect of A-site Excess on the Piezoelectric Properties of (K_0.48Na_0.52)_1+x(Nb_0.55Ta_0.45)O₃Thin Films

Abstract

Lead-free polycrystalline (K 0.48 Na 0.52 ) 1+x (Nb 0.55 Ta 0.45 )O 3 (x = 0, 0.01, 0.02 and 0.03) thin films have been grown on Pt(111)/Ti/SiO 2 /Si substrates using KrF excimer laser ablation to investigate the effects of A-site ion excess. The film at x = 0.01 exhibited good ferroelectric hysteresis loop with a remnant polarization 2P r of 30 μC/cm 2 and coercive field 2E c of 61 kV/cm. The piezoelectric coefficient d 33,f of the KNNT film with x = 0.01 was found to amount to 79 pm/V. These improved ferroelectric and piezoelectric properties were attributed to the excess of A-site Na and K ions.