EFFECT OF SR2+ SUBSTITUTION ON DIELECTRIC PROPERTIES AND PTCR BEHAVIOR OF BATIO(3)

Ba1-xSrxTiO3 ceramics have been widely used as electronic materials. However, conflicting results for the effect of Sr2+ for the maximum value of the relative dielectric constant at the Curie point of Ba1-xSrxTiO3 ceramics have been reported. Several researchers have studied the possibility of using Ba1-xSrxTiO3 ceramics as positive temperature coefficient resistivity (PTCR) material but complete information has not been fulfilled. The purposes of this study were to the ascertain the effect of Sr2+ substitution on some dielectric and electrical properties of BaTiO3 and to further investigate the possibility of utilizing Ba1-xSrxTiO3 ceramics as PTCR materials. In this study an X-ray diffractometer and scanning microscope were used to study phases and microstructures of Ba1-xSrxTiO3 . In addition, the capacitance and resistance of Ba1-xSrxTiO3 were measured and their relative permittivity and resistivity were calculated and analyzed. Results indicated that Sr2+ substitutions cause the unit cell of Ba1-xSrxTiO3 to shrink and change from a tetragonal to a cubic symmetry. Moreover, Sr2+ substitution shifts the Curie point of Ba1-xSrxTiO3 to a lower temperature. Lastly, pure Ba1-xSrxTiO3 does not display good PTCR characteristics for commercial PTCR material.