Crystallization evolution and ferroelectric behavior of Bi_3.25La_0.75Ti₃O₁₂-based thin films prepared by rf-magnetron sputtering

Ta-doped Bi_3.25La_0.75Ti₃O₁₂ (BLTT) ferroelectric thin films were prepared via rf-magnetron sputtering with subsequent annealing treatments. The crystallization evolution and ferroelectric behavior of BLTT thin films were studied using in situ high temperature X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM) and piezoresponse force microscopy (PFM). With the increase of annealing temperatures, the thin films exhibited a preferred 〈117〉 crystalline orientation first and then weakly crystallizations to c-axis were obtained at high temperatures. SEM analysis reveals that the grain growth might be performed by melting and combining of particles in surface layer of original grains. PFM phase images reveal that less domain switching could be induced for BLTT films with larger grains.