Enhanced in-plane ferroelectricity in Ba0.7Sr0.3TiO3 thin films grown on MgO(001) single-crystal substrate -: art. no. 212904

Highly oriented Ba0.7Sr0.3TiO3 thin films were grown on MgO (001) single-crystal substrate using pulsed-laser deposition and the in-plane ferroelectric properties of the film were evaluated. X-ray diffraction characterization revealed a good crystallinity and tensile in-plane stress in the film. A well-defined ferroelectric hysteresis loop with P-r=9.5 mu C/cm(2) was observed along the (100) direction, which implied an enhanced in-plane ferroelectricity in the Ba0.7Sr0.3TiO3 thin film in comparison with the Ba0.7Sr0.3TiO3 ceramics. Curie temperature of the film was found to be similar to 88 degrees C, which is nearly 50 degrees C higher than that of the Ba0.7Sr0.3TiO3 ceramics. The butterfly-shaped C-V characteristic curve also evidenced the enhanced in-plane ferroelectric property in the film, and a large dielectric tunability of 69% was found at 1 MHz under a moderate dc bias field. The observation of enhanced ferroelectricity along the in-plane direction in the highly oriented Ba0.7Sr0.3TiO3 thin film was explained in terms of the increased tetragonality (a/c=1.016) induced by the lattice misfit strain. (c) 2005 American Institute of Physics.