Dual mode electron emission from ferroelectric ceramics

Abstract

Two modes of electron emission have been observed from the ferroelectric ceramic PLZT when subjected to a high voltage bipolar pulse. One mode is always associated with bright visible plasma on the emitting surface, while the other occurs with no visible emission. Emitted current wave forms are consistent with two distinct mechanisms for emission: surface plasma in the first case and polarization switching in the second.

Polarizability model of emission from ceramic cathodes

“…Strong emission was explained by nanosecond switching of ferroelectric domains or a fast antiferroelectric-ferroelectric-phase transition induced by the fast rising electric field on ceramics having a specific composition. [1][2][3][4][5][6] This view does not explain the emission from ceramics in the paraelectric phase 12,13 and the different behavior between cathodes with grid and with island electrodes. 11 The aim of this article is to contribute to the knowledge of the nature of the emission process, investigating in detail both electron flowing in and electron escaping from the cathode.…”

Ferroelectric cathodes in transverse magnetic fields

“…The nature of the dark emission, however, is still unclear. Angadi et al 4 and Shanon et al 6 . explain the electron emission in this mode by polarization switching, while Boscolo and Cialdi 5 consider the field emission mechanism from tripple junctions at the edges of the patterned fron electrode, which is not strong enough for the ignition of the surface discharge.…”

“…The dark emission appears at driving electric field amplitudes less than 10 kV/cm, usually without visible light emission from the ceramic surface [4][5][6] . The current pulse in dark mode has a duration less than 0.5 _s at a current density amplitude ≤ 1 A/cm 2 .…”

“…In recent publications 3,4,5,6 , dark and bright modes were distinguished from the electron emission observed from ferroelectrics. The dark emission appears at driving electric field amplitudes less than 10 kV/cm, usually without visible light emission from the ceramic surface [4][5][6] .…”

Ferroelectric Cathodes in Transverse Magnetic Fields

“…The dark emission appears at driving electric field amplitudes less than 10 kV/cm, usually without visible light emission from the ceramic surface [4][5][6] . The current pulse in dark mode has a duration less than 0.5 _s at a current density amplitude ≤ 1 A/cm .…”