Microstructural and electrical properties related to the growth conditions of xBaTiO3/(1-x)Fe2CoO4 composite fibers prepared by LHPG technique

Reference	Presenter	Authors (Institution)	Abstract
08-115	Aloadir Lucas Santos de Oliveira	Milton, F.P.(Universidade Federal de São Carlos); Oliveira, A.L.(Universidade Federal de São Carlos); Viana, D.S.(Universidade Federal de São Carlos); Zabotto, F.L.(Universidade Federal de São Carlos); Andreeta, M.R.(Federal University of São Carlos); Garcia, D.(Universidade Federal de São Carlos);	In this work, fibers of the ${\mathrm{xBaTiO}}_3/(1-\mathrm{x}){\mathrm{Fe}}_2{\mathrm{CoO}}_4$ magnetoelectric system (x = 0.7, 0.8 and 0.9) were grown using the Laser-Heated Pedestal Growth (LHPG) technique. Growth conditions such as pulling rate and seed type were changed to investigate their influence on the microstructure and electrical properties of the resulting material. Phase identification, structural and microstructural analyses were performed through room temperature X-ray diffraction and scanning electronic microscopy. Crystal twinning and lamellar structure patterns were observed in the microstructure formed by ${\mathrm{BaTiO}}_3$ and ${\mathrm{Fe}}_2{\mathrm{CoO}}_4$ phases, being strongly dependent upon the growth condition and composition. As expected, the number of large crystal twins diminishes as the composition becomes near-eutectic (x=0.7). Also, the concentration of the paraelectric hexagonal ${\mathrm{BaTiO}}_3$ relative to the desirable tetragonal perovskite phase was highly influenced by the seed type, being reduced by the use of a single crystal ${\mathrm{SrTiO}}_3$ seed. Moreover, the connectivity between phases as well the crystallographic texture of the sample showed to be strongly dependent of the sample cut direction in relation to the growth axis. All these results revealed the high level of material microstructure complexity that can be achieved by the LHPG processing of such composites and justified the different ferroelectric and dielectric responses characterized as a function of frequency and temperature for each cut direction and growth condition.
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