Effects of polarization reversal and surface conditions on the ferroelectric electron emission

The electron emission from ferroelectric ceramics has been observed without prepoling. The grid electrodes and the solid electrode are coated on the top and the bottom of a thin lead-zirconate-titanate (PZT) ceramic plate, respectively. The ratio of the interelectrode width to the thickness of the ceramic determines the potential distribution inside the ceramic. With an appropriate ratio, the polarization can be reversed between the grid electrodes. The prepoled PZT ceramic was not essential for the electron emission, because the shape of the waveform of the emission current after prepoling is nearly the same as that obtained without prepoling. However, the peak value of the emission current depends to a large extent on the polarities of the spontaneous polarization and the applied electric field. In addition, the surface condition such as microcracking is as crucial as polarization reversal for the electron emission.