Electrical behavior of high resistivity Ce-doped BiFeO _3 multiferroic

摘要

Bi _(1x)Ce _xFeO _3 (Ce-BFO) for x=0, 0.05, 0.1, and 0.15 monophasic ceramic samples were successfully synthesized by conventional solid-state reaction routes. The influences of Ce doping on structural, dielectric, ferroelectric, leakage current and capacitive properties of BiFeO _3 ceramics were investigated intensively. At higher concentrations of x (x=0.1 and 0.15) the samples showed good crystallinity with almost impurity free phases. No structural phase transformation took place after partial doping of Ce ions and all ceramic bulk samples remain in their rhombohedral structure with space group R3c. The dielectric behavior of the samples improved significantly and the ferroelectric hysteresis loops changed their shape from rounded to a strongly nonlinear typical ferroelectric feature mainly originating from the domain switching and became enhanced with increase in doping concentration of cerium (Ce). Experimental results also suggested that partial doping of higher valence, smaller ionic radius Ce ions in BiFeO _3 forces the reduction of oxygen vacancies, resulting in a great suppression of leakage current. It is found that the sharp capacitance peak/discontinuity present in the C-V characteristics of Ce-BFO for different Ce doping concentrations is directly associated with the polarization reversal. Incorporation of excess bismuth in the presence of Ce in BiFeO _3 is expected to compensate Bi loss during high temperature sintering and caused structural distortion which also favors enhancement of ferroelectric properties in Ce-doped BFO.