Comparison of microstructure and ferroelectric properties of alkoxy-derived MBi4Ti4O15 (M: Ca or Sr) thin films

CaBi4Ti4O15 (CBTi144) and SrBi4Ti4O15 (SBTi144) thin films were prepared on Pt-passivated silicon substrate using complex metal alkoxide solutions. The CBTi144 thin films crystallized to a single phase of perovskite at 650 degreesC via a mixture of perovskite and pyrochlore phases. The 650 degreesC-annealed CBTi144 thin films consisted of uniform and isotropic grains and had a closely packed columnar structure. In contrast, the SBTi144 thin films crystallized to the perovskite phase at relatively lower temperature and consisted of smaller and non-uniform grains. The dielectric constants and loss factors of the 650 degreesC-annealed CBTi144 and SBTi144 thin films were 300 and 0.03, and 330 and 0.04, respectively, at 100 kHz. The remanent polarizations and coercive electric fields were 6.0 muC/cm(2) and 79 kV/cm, and 2.9 muC/cm(2) and 55 kV/cm, respectively, at 9 V. The dielectric and ferroelectric, properties depended on both the cation size in the A site and the microstructure.