Structural and morphological transformations of BaTiO$_3$ nanocrystals in thin layers of borate oxide glasses

The influence of thin layers (2–15 $\mu$m) of some oxide glass melts on BaTiO$_3$ nanocrystallites has been investigated using X-ray diffractometry and scanning electron microscopy. It has been shown that lead borate and sodium borate glass melts bring about the dissolution of BaTiO$_3$ nanocrystallites and the subsequent crystallization in glasses of lead titanate PbTiO$_3$ and sodium titanate Na$_2$TiO$_3$, respectively. It has been found that thin layers of melts of these glasses have a strong orientation effect on crystallites of the PbTiO$_3$ and Na$_2$TiO$_3$ compounds newly synthesized from barium titanate. The orientation effect exerted by these glass layers results in the formation of a pronounced texture of the perovskite crystallites with the texture axes oriented along the [100] and [001] directions parallel to the surface normal of the substrate for lead titanate and the orientation of the $(21\bar1)$ planes of the film surface for the sodium titanium oxide.