Elliptical grain growth in the solid-phase crystallization of amorphous SrBi2Ta2O9 thin films

During the crystallization process of amorphous SrBi2Ta2O9 (SBT) thin films at 800 degrees C in a dry O-2 ambient, we have found elliptical nuclei in the initial nucleation state. These elliptical grains are preferentially oriented to [110] direction in the [1 (1) over bar 0] direction of projection. Elliptical grain growth keeps [110] as increasing the annealing time at 800 degrees C. Transmission electron microscopy and selected-area electron diffraction pattern indicate that the origin of [110]-oriented crystallization is due to the highest ionic packing (001) SBT plane which includes TaO6 octahedra and the nearest bonding direction of TaO6 octahedra in SBT plane is the [110] direction. (C) 1999 American Institute of Physics. [S0003-6951(99)00320-4].