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 formation behavior and crystal structure. The precursor sol was concentrated upon heating at 100 degrees C to make it spinnable and used for fiber drawing, For heat treatment, a two-step heating schedule was designed on the basis 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 doping and the structure is changed to pseudocubic from tetragonal. MicroRaman Spectroscopy confirms these observations of change in crystal structure and 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 section of PT fibers. La doped fibers show a porous fracture surface and also the grain size reduces dramatically with the addition of La. Strain energy is believed to play a major role in the observed changes in the microstructure.