Enhanced dielectric and piezoelectric properties of Mn doped (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-SrTiO3 thin films

Lead free 0.95(0.8Bi0.5Na0.5TiO3-0.2Bi0.5K0.5)TiO3-0.05SrTiO3 (BNT-BKT-ST) + x mol% (x = 0-1.0) Mn thin films were deposited on Pt (1 1 1)/Ti/SiO2/Si substrates by a sol-gel processing technique. The effects of Mn content on the structural, ferroelectric, piezoelectric and dielectric properties of the BNT-BKT-ST thin films were investigated in detail. The BNT-BKT-ST thin films doped with different Mn content exhibit pseudo-cubic perovskite structure and doped with 0.5 mol% Mn exhibits the largest grain size and the best dielectric properties. Reduced leakage current and improved piezoelectric constant (d33) were observed in the Mn doped BNT-BKT-ST thin films. The maximum d33 value of BNT-BKT-ST thin films doped with 0.5 mol% Mn is approximately 93 pm/V, which is comparable to that of polycrystalline PZT thin films. The results indicated that Mn doped BNT-BKT-ST thin films would be of great interest for lead-free piezoelectric devices.