Effects of oxygen ambient on dielectric and ferroelectric properties of lead free Lix(K0.5Na0.5)(1−x)NbO3 thin films derived from chemical solution deposition

We have fabricated lead free Lix(K0.5Na0.5)(1−x)NbO3 (LKNN) thin films by polyvinylpyrrolidone modified chemical solution deposition, and studied the effects of oxygen ambient on dielectric and ferroelectric properties. The obtained LKNN thin films exhibit significantly improved dielectric properties and saturated ferroelectric hysteresis loop. For LKNN (x = 0.06) thin film, it showed dielectric constant of 471 and dielectric loss of tan δ < 0.05 at 1 kHz, and a remnant polarization 2Pr = 14 μC/cm2 and a coercive field Ec = 90 kV/cm, respectively. It was shown that the mutual effects of both oxygen ambient and small Li doping play a key role to suppress the volatilization of K and Na ions during thermal processing, which lead to smaller leakage current and thus excellent dielectric and ferroelectric properties.

► Lead-free Lix(K0.5Na0.5)(1−x)NbO3 (LKNN) thin films were fabricated by chemical solution deposition.
► The interplay of oxygen and Li doping play a key role to suppress the volatilization of K and Na ions.
► Significantly enhanced dielectric constants and small dielectric loss.
► Saturated ferroelectric hysteresis loops.