Abstract: According to the method proposed by Swarts and Shrout, PMN ceramic material with single perovskite phase was prepared, and no any
pyrochloride one was detected by X-ray diffraction analyses. SEM observation shows that the sample was dense without the apparent
pores. The hysteresis (P～E) loop was measured by using a Radiant Technology RT 66a and an amplifier. The change of P～E loop of the
sample with the frequency measured shows that the dependence of the polarization on the field of PMN relaxor ferroelectric ceramic material
at low frequency (e.g.10 Hz) is a curve without any hysteresis at room temperature, and P～E loop appears with the increase of frequency
measured(e.g.>100 Hz), the higher the frequency, the larger the P～E loop, which differs from that of normal ferroelectrics.

Key words: relaxor ferroelectrics, normal frroelectrics, hysteresis loop