Preferential grain growth in the solid-phase crystallization of amorphous SrB2TaO9 thin films prepared by metal-organic decomposition

We studied the crystallization process of amorphous SrBi2Ta2O9 (SBT) thin f ilms by transmission electron microscopy. The amorphous SET films were prep ared by the metal-organic decomposition method and were heat-treated at 800 degrees C in a dry O-2 ambient. Through a (001) projection, a circular gra in was formed showing no preferential orientation of SET grain. On the othe r hand, through a (110) projection, an elliptical nucleus oriented to anoth er (110) direction was formed. Grain with another orientation also offered evidence of 110-preferred growth. The (110)-preferred growth can be explain ed by the fact that the highest ionic packing plane is the (001) plane incl uding TaO6 octahedra and the nearest bonding direction of the TaO6 octahedr a in an SET structure is the (110) direction.