アーク溶解法により作製したb軸配向Ba_<1-x>Sr_xTi_2O_5の交流インピーダンス解析(<特集>希土類系物質の精密合成,形態制御および機能物性)

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Dielectric properties of SrO substituted BaTi_2O_5, Ba_<1-x>Sr_xTi_2O_5 prepared by arc melting were investigated. Due to the thermal instability of BaTi_2O_5 at high temperatures, the decomposition of BaTi_2O_5 was accompanied with solid solution of SrO in BaTi_2O_5. Lattice parameters of Ba_<1-x>Sr_xTi_2O_5 decreased with increasing SrO, and the solubility limit of SrO in Ba_<1-x>Sr_xTi_2O_5 was about x=0.12. A small amount of second phases of BaTiO_3 and Ba_6Ti_<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 BaTi_2O_5. 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 paraelectric second phases.
社団法人日本セラミックス協会の論文
2007-10-01