Influence of Processing Method on Dielectric Properties of BaBi4Ti4O15 Ceramics

Abstract

Bismuth layer-structured ferroelectrics (BLSF), first described by Aurivillius, have attracted much attention for their application in non-volatile random access memory and high temperature piezoelectric devices. BaBi4Ti4O15 (BBT) is a well-known member of BLSFs. Considering the grain size affect reduction of conductivity of most of BLSF compounds [1] this paper dealing with effect of mechanochemical assisted synthesis method on electrical, dielectric and conductive propefties of BBTcompounds. BBT was prepared by solid state reaction from mixture of oxides: BaO, Ti02 and BizO: which was previously milled for 6 h (BBT-MA). The mixture was heated at 850 oCfor 4 h. As a comparison, the same ceramics were prepared throught conventional solid state reaction (BBT-SS). The same oxides mixture was homogenized for 24 h in isopropanol and calcinated at 950 oC for 4 h which is 100 oC higher temperature than for MA procedure. Sintering process was carried out at 1130 oC for t h in both synthesis methods. Smaller plate like grains are noticed in BBT ceramics prepared from powders obtained by MA process comparing to SS process (Fig 1.). In the temperature dependence of the dielectric permittivity, the maximum associated to the Curie temperature was higher and narrower in ceramics prepared by SS method. Influence of the grain and grain boundaries contribution to the dielectric behaviour in both ceramics were analyzed through impedance spectroscopy.