NBT基陶瓷中相变致电子发射的研究

在无铅铁电阴极钛酸铋钠（NBT）中获得了20 A/cm2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

Study of phase transition induced electron emission from NBT based ceramics

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.