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  direction in the [1 (1) over bar 0] direction of projection. Elliptical grain growth keeps  as increasing the annealing time at 800 degrees C. Transmission electron microscopy and selected-area electron diffraction pattern indicate that the origin of -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  direction. (C) 1999 American Institute of Physics. [S0003-6951(99)00320-4].