Ferroelectric cathodes as electron beam sources

In the past decade a number of research groups have studied electron emission from ferroelectric ceramics. These materials have saturation polarization P_s, of up to 100 μC/cm². The emission occurs when the polarization state of the ferroelectric is changed rapidly by an applied electric field, and a fraction of the surface screening charge is released. We report experimental results obtained using Lead-Zirconate-Titanate (PZT) ceramic as the electron source in a planar diode geometry. Experimental measurements of time-dependent variations in the emission are presented and results from a theoretical model are compared to these measurements. We also present new data on the scaling of the emission current density for anode voltages of up to 50 kV. The new data will be used in the design of an electron gun using a ferroelectric cathode