Growth and structural characterization of lanthanum doped lead titanate fiber

Lanthanum doped lead titanate Pb1-x La-x Ti1-x/4 O-3 fibers (x =0, 5 and 15 at%) were grown by sol-gel technique and characterized For their phase for mation behavior and crystal structure. The precursor sol was concentrated u pon heating at 100 degrees C to make it spinnable and used for fiber drawin g, For heat treatment, a two-step heating schedule was designed on the basi s of DSC analysis of the as drawn fibers. X-ray diffraction analysis showed that the tetragonality of the Lead Titanate (PT) fibers reduces with La do ping and the structure is changed to pseudocubic from tetragonal. MicroRama n Spectroscopy confirms these observations of change in crystal structure a nd distortion in the material due to La doping. Dense and elongated grains of about 1 mu m diameter were observed at the surface and at the cross sect ion of PT fibers. La doped fibers show a porous fracture surface and also t he grain size reduces dramatically with the addition of La. Strain energy i s believed to play a major role in the observed changes in the microstructu re.