摘要
在无铅铁电阴极钛酸铋钠(NBT)中获得了20 A/cm2的电流发射密度。在施加激励电压过程中,观察到了和其他阴极材料不同的3个发射电流峰。通过考虑相变因数对电流发射的影响,修正了基于极化反转致电子发射模型的电流发射公式,由此定量解释了在NBT基陶瓷中观察到的不同电流发射现象,揭示了电流发射不仅仅由已有文献中提出的快极化反转产生,也可以由极化的变化(比如相变)产生。为进一步验证该结论和弄清不同种类铁电阴极电子发射的机理,进行了NBT与锆钛酸铅(PZT)的电子发射比较实验。在电子发射前后观察到NBT的压电常数和介电常数没有变化,而在PZT中有变化,由此得出PZT的电子发射机制主要基于极化反转,而NBT的电子发射机制主要基于相变。相变致电子发射机理的提出和实验验证,为新型抗疲劳铁电阴极的研制指明了一个切实可行的方向。
The emission current density up to 20 A/cm^2 from bismuth sodium titanate is reported. During the period of excited field, three peaks of current are observed which is different to other ferroelectric cathodes. Phase transition induced electron emission is considered and the formula based on polarization switch induced electron emission is revised. This amendment can explain the above phenomenon observed from NBT based ceramics well and shows that electron emission can not only be produced by polarization switch but also by other kind of polarization change such as phase transition. The unchanging of dielectric and piezoelectric constants in NBT before and after emission but decrease of these two parameters in PZT are tested. Phase transition induced emission in NBT and polarization switch induced emission in PZT can be testified by the above comparisons.
出处
《重庆邮电大学学报（自然科学版）》
2007年第6期764-766,共3页
Journal of Chongqing University of Posts and Telecommunications(Natural Science Edition)
基金
This work is supported by National Natural Science Foundation(No.60471027)
关键词
相变致电子发射
抗疲劳铁电阴极
快极化反转
电流发射密度
phase transition induced electron emission
lead free cathode
fast polarization switch
emitted current densities
