Effects of Defect Control on the Polarization Properties in Bi2WO6-Based Single Crystals

Abstract

Leakage-current and polarization-switching properties of defect-controlled Bi 2 WO 6 single crystals have been investigated along the crystallographic a axis at 25°C. High-pressure oxygen annealing decreased leakage current, indicating that electron is a detrimental carrier of the leakage-current property. 2-mol% Mn substitution at the W site is shown to be effective for suppressing leakage current density to the order of 108 A/cm2. Mn-doped crystals annealed under high-pressure oxygen atmosphere showed a well saturated polarization hysteresis loop with a remanent polarization of 50 μC/cm2 and a coercive field of 39 kV/cm. It is found that high-pressure oxygen annealing is effective for decreasing coercive field of Mn-doped crystals due to less oxygen vacancies. It is concluded that Mn substitution and the subsequent oxygen annealing enhance polarization switching as well as reduce leakage current in the BW system.