Structure, electrical, dielectric and ferroelectric properties of (1 − x)BiFeO3 − xAl2O3 ceramics

Abstract

Lead-free ferroelectric composite ceramics of (1 − x)BiFeO3 − xAl2O3 (x = 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) were synthesized using the traditional solid-state reaction method. The effects of Al2O3 addition on structural (crystal data and microstructure), ferroelectric, dielectric properties, and leakage current characteristic were investigated. X-ray diffraction and scanning electron microscopy demonstrated that the addition of Al2O3 promoted the formation of the secondary phases (Bi2Fe4O9 and Bi24Al2O39) and the average grain size significantly reduced from 1.49 μm for x = 0.00 to 0.45 μm for x = 0.10. The samples with Al2O3 addition had lower dielectric constant and dielectric loss. The Curie temperature (TC) decreased gradually from 475 °C for x = 0.02 to 390 °C for x = 0.10. Leakage current density decreased significantly with the addition of the Al2O3, and the leakage conduction mechanism was changed from Ohmic relationship to space charge limited conduction (SCLC) mechanism. The ferroelectric hysteresis loops became more typical in shape with the addition of the Al2O3.