Pyroelectric properties of BiFeO3 ceramics prepared by a modified solid-state-reaction method

BiFeO3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopts a higher heating/cooling rate during the sintering process than usually used. It was found that the calcination temperature T (cal) (from 400 to 750A degrees C) does not influence the BFO phase formation, while the sintering temperature T (sin) (from 815 to 845A degrees C) dominates the phase purity. The optimum sintering temperature was in the range from 825 to 835A degrees C. The optimized samples exhibit saturated ferroelectric hysteresis loops with a remnant polarization of 13.2 mu C/cm(2). The measured piezoelectric coefficient d (33) was 45 pC/N. No remnant magnetization was observed in all of the samples. The pyroelectric properties were studied as a function of temperature and frequency. A pyroelectric coefficient as high as 90 mu C/m(2) K was obtained at room temperature in the optimized sample. An abrupt decrease of the pyroelectric coefficient was observed at temperatures between 70 and 80A degrees C. On the basis of our results, BFO may have the potential for pyroelectric applications.