DC-bias dependent impedance spectroscopy of BaTiO3–Bi(Zn1/2Ti1/2)O3 ceramics

Abstract

This report discusses the voltage-stability of the dielectric and transport properties of BaTiO₃–Bi(Zn_1/2Ti_1/2)O₃ (BT–BZT) ceramics which have shown excellent properties for emerging energy applications. For p-type BaTiO₃, the ceramics deviated from Ohm's law behavior at very low voltage levels along with a reversible drop in bulk resistivity by several orders of magnitude starting at bias fields as low as 0.1 kV cm⁻¹ (∼8 V). In contrast, n-type BT–BZT ceramics exhibited a small (i.e. less than one order of magnitude) increase in resistivity on application of small field levels. These data indicate a hole-generation mechanism which becomes active at a low voltage threshold. The bulk capacitance values calculated using AC impedance spectroscopy, however, were relatively unaffected (<15% change) by this application of a DC bias (up to ∼0.25 kV cm⁻¹). These findings provide important insights into the electric transport mechanisms in BT-based ceramics.