Experimental Study On The Electron Emission And Its Mechanism With Novel Ferroelectric Ceramic Cathodes

Ferroelectric cathode is one of the novel materials from which electrons can be emitted when voltage or laser pulse is applied on it. Now scientists from many countries pay much attention to it because of its boundless prospects. In this article, five primary research works are included: 1) the preparation of the ferroelectric samples; 2) the establishment of the testing electronic circuit for the ferroelectric electron emission; 3) the experiment of the electron emission; 4) the analyses of the ferroelectric electron emission mechanism; and 5) the preparation of the ferroelectric vacuum diode. In this article, the compositions of ferroelectric cathodes have been studied systematically. Also, the efficiency testing electronic circuit for the electron emission of ferroelectric cathode materials has been established and improved. Therefore, the kernel of experiment on ferroelectric cathode materials has been found by us. The microstructure results have been obtained and the polarization change has been observed. By analyzing the electron emission waveforms, the natural parameters of the ferroelectric electron emission and the theory of the electron emission have been generalized. Based on all these self-determination research results, the ferroelectric vacuum diode has been fabricated on trial. The main detailed work of this article is as follows:1. Based on the study of the lead zirconate titanate (PZT) ferroelectric ceramics, the barium titanate (BT) and bismuth natrium titanate (BNBT) ferroelectric materials have been systematically investigated. Using the samples with different ceramic preparation methods or different polarization factors on the different test conditions, the relationships among the electron emission, material characteristics (dielectricity, piezoelectricity, ferroelectricity, etc.) and the microstructure have been studied. Thereinto, the experiment of electron emission has been carried out for the lead-free ferroelectric ceramics BT and BNBT, and the high current density (about 30A/cm2 and 20A/cm2) is reported in the world for the first time. All these work will play enlightening role for the study of lead-free ferroelectric materials.2. The efficiency testing electronic circuit for the electron emission of ferroelectric cathode materials has been established and improved. We start this work by analyzing the origin of the electromagnetic interference (EMI), and then the jamming intensity of EMI is reduced by grounding, screening, and other methods. All...