摘要
采用硼/碳热还原-热压烧结集成工艺制备了高纯致密的Ce_(1-x)Gd_xB_(6)(x=0.1~0.4)多晶块体,研究Gd共掺杂Ce B_(6)对其结构、力学性能与电学特性的影响。结果表明:Ce_(1-x)Gd_(x)B_(6)呈Cs Cl型简单立方单相结构,多晶块体力学性能优异,显微硬度可达22.72 GPa(x=0.1),Ce_(1-x)Gd_(x)B_(6)阴极电阻率随着Gd含量的增加逐渐上升。热电子发射性能结果表明,Gd掺杂能够改善Ce B_6阴极材料的发射特性,在测试温度1573 K,外加电压1k V条件下,Ce_(0.9)Gd_(0.1)B_6阴极的发射电流密度为956 m A·cm^(-2),零场发射电流密度为213.8 m A·cm^(-2),Ce_(1-x)Gd_xB_(6)阴极在1323~1573 K中低温范围平均有效功函数为1.985~2.01 e V。第一性原理计算结果表明,Gd掺杂Ce B_6可减弱近费米能级Ce 4f态电子的局域化程度,引起费米能级升高,减小电子逸出功,增强阴极的发射电流密度。
High-purity and dense Ce_(1-x)Gd_(x)B_(6)(x=0.1-0.4)polycrystals were prepared by a boron/carbon thermal reduction-hot pressing sintering(BCTR&HP)integrated process.The effect of Gd doping in the CeB6 matrix on the structure,mechanical and electrical properties of Ce_(1-x)Gd_(x)B_(6)bulks was investigated.The results show that the Ce_(1-x)Gd_(x)B_(6)polycrystals produced by BCTR&HP integrated process provide a simple cubic(CsCl type)singlephase structure and show excellent mechanical properties with a microhardness of 22.72 GPa(x=0.1).The resistivity of Ce_(1-x)Gd_(x)B_(6)cathodes gradually increases with the increase of Gd content.The results of thermal electron emission performance show that Gd doping can improve the emission characteristics of CeB6 cathodes and the emission current density and zero-field emission current density of Ce0.9Gd0.1B6 cathodes are 956 and 213.8mA·cm^(-2)under the applied voltage of 1 kV at 1573 K,respectively.The average effective work function of Ce_(1-x)Gd_(x)B_(6)cathodes is 1.985-2.01 eV in the low-mid temperature range of 1323-1573 K.Furthuemore,the firstprinciples calculations reveal that the Gd-doping can weaken the localization of electrons of Ce 4f state at near Fermi level of CeB6,which rises its Fermi level,reducing the work function and enhancing the emission current density of the CeB6 cathodes.
作者
杨露辉
袁铁锤
邱东东
赵瑞山
刘华
黄美松
Yang Luhui;Yuan Tiechui;Qiu Dongdong;Zhao Ruishan;Liu Hua;Huang Meisong(Powder Metallurgy Research Institute,Central South University,Changsha 410083,China;Hunan Institute for Rare Earth Metal Materials Research,Changsha 410126,China;The Second Military Representative Office of the Equipment Department of PLA Air Force in Changsha,Changsha 410000,China;Hunan Key Laboratory for Rare Earth Functional Materials,Changsha 410126,China)
出处
《中国稀土学报》
EI
CAS
CSCD
北大核心
2023年第6期1104-1110,I0003,共8页
Journal of the Chinese Society of Rare Earths
基金
湖南省科技创新计划项目(2017TP1031)资助。
