LaB6 has been used as a commercial electron emitter for decades. Despite the large number of studies on the work function of LaB6, there is no comprehensive understanding of work function trends in the hexaboride materials family. In this study, we use Density Functional Theory (DFT) calculations to calculated trends of rare earth hexaboride work function and rationalize these trends based on the electronegativity of the metal element. We predict that alloying LaB6 with Ba can further lower the work function by ~0.2 eV. Interestingly, we find that alloyed (La, Ba)B6 can have lower work functions than either LaB6 or BaB6, benefitting from an enhanced surface dipole due to metal element size mismatch. In addition to hexaborides we also investigate work function trends of similar materials families, namely tetraborides and transition metal nitrides, which, like hexaborides, are electrically conductive and refractory and thus may also be promising materials for electron emission applications. We find that tetraborides consistently have higher work functions than their hexaboride analogues as the tetraborides having less ionic bonding and smaller positive surface dipoles. Finally, we find that HfN has a low work function of about 2.2 eV, making HfN a potentially promising new electron emitter material.
Elastic and electronic properties of hexagonal rhenium sub-nitrides Re3N and Re2N in comparison with hcp-Re and wurtzite-like rhenium mononitride ReN
最近，两个新的六方晶系亚氮化物Re 3 N和Re 2N，它们属于已知的4d，5d重金属的富金属（M/N > 1）氮化物的相当罕见的组，已经被成功地合成，并且它们作为超不可压缩材料的潜在的技术应用已经被提出。在这项工作中，我们提出了一个详细的从头算研究的新的六方亚氮化物相比，六方Re和纤锌矿状的六方单氮化物ReN，与这些六方系统的弹性，电子性能和化学键的Re/N的化学计量比的函数的趋势进行评估：Re \rightarrow Re 3 N \rightarrow Re 2 N \rightarrow Re N。
Defect engineering of ultrathin gallium nitride via electric fields for advanced electronic, magnetic, and gas sensing applications
Nanyang Technological University（南洋理工大学）；Infineon Technologies Asia Pacific Pte. Ltd.（英飞凌亚太私人有限公司）；China-Singapore International Joint Research Institute（中新国际联合研究院）
