A STUDY OF THE STRUCTURE AND COMPOSITION OF SI-DOPED PBTIO3

It is very useful to grow epitaxial PbTiO3 films on Si substrates for applications in integrated devices. At high growth temperatures, this leads to the formation of an intermediate metastable Pb2-xTi2-ySix+yO6 phase (with a pyrochlore structure) and the consequent partial incorp oration of Si into the PbTiO3 lattice. To understand the effect of Si on the ferroelectric characteristics of the material, it is important to determine the position and state of aggregation of Si in the PbTiO3 lattice. We have attempted to investigate this aspect by a neutron di ffraction study of silicon doped ceramic lead titanate. Our results in dicate that the silicon may exist in the form of a glassy lead silicat e phase dispersed at the grain boundaries. Some of the Si atoms may al so occupy interstitial positions in the lattice.