Field dependence of dielectric properties of BST single crystals

(Ba1-xSrx)TiO3 single crystal fibers with x=0.35 and 0.40 were grown, using the laser heated pedestal growth (LHPG) technique, in order to investigate the dielectric properties under de bias for potential tunable capacitor application at room temperature. Temperature dependences of the dielectric constant and loss factor as a function of de-bias field were measured. At room temperature and 5000V/cm, the changes on the dielectric constant were 45% and 20% for x=0.35 (Tc approximate to 20 degrees C) and x=0.40 (Tc approximate to 4 degrees C), respectively. Low dielectric loss (10(-3)-10(-2)) around RT, with and without the bias field, were observed for the composition x=0.40. This composition although, showed distribution of phases generated during the melt growth process and that disturbed, to some extent, the field dependence behavior in the paraelectric phase.