A.C.Impedance Analysis on b-axis Oriented Ba_(1-x)Sr)xTi_2O_5 Prepared by an Arc-Melting Method

摘要

Dielectric properties of SrO substituted BaTi2O5,Ba_(1-x)Sr_xTi_2O_5 prepared by arc melting were investigated.Due to the thermal instability of BaTi2O5 at high temperatures,the decomposition of BaTi2O5 was accompanied with solid solution of SrO in BaTi2O5.Lattice parameters of Ba_(1-x)Sr_xO_5 decreased with increasing SrO,and the solubility limit of SrO in Ba_(1-x)Sr_xTi2O5 was about x=0.12.A small amount of second phases of BaTiO3 and Ba6Ti_(17)O_(40) were identified at x < 0.12 by scanning electron microscopy.Ba_(1-x)Sr_xTi_2O_5 showed a strong b-axis orientation.The Curie temperature (T_c) of Ba_(1-x)Sr_xTi_2O_5 changed in the range between 703 and 750 K depending on SrO content.The dielectric permittivity of Ba_(1-x)Sr_xTi_2O_5 at the T_c was attained to 2700 by substituting SrO of x=0.03.The electrical conductivities of Ba_(1-x)Sr_xTi_2O_5 were lower than that of non-substituted BaTi2O5.Ba_(1-x)Sr_xTi_2O_5 containing the second phases showed distorted Cole-Cole semicircles which were deconvoluted into two semicircles based on a Maxwell-Wagner model corresponding to a ferroelectric bulk matrix and parae-lectric second phases.