Ab initio and work function and surface energy anisotropy of LaB6.
Ab initio and work function and surface energy anisotropy of LaB6.
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DOI：
10.1021/jp063347i
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发表时间：
2006-09
期刊：
影响因子：
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通讯作者：
Uijttewaal;D. Wijs;de Groot
中科院分区：
文献类型：
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作者：
Uijttewaal;D. Wijs;de Groot
六硼化镧是大功率电子技术中最常用的阴极材料之一，但许多实验结果并没有提供一致的表面性质。因此，我们报告的第一个从头计算的功函数和表面能的（001），（011），（111），（112）和（012）表面考虑不同的表面终端和结构弛豫。（111）B-或（001）La-终止表面是最稳定的，取决于La化学势。后者的功函数是所考虑的表面中最低的（2.07 eV）。当表面La被Ba取代时，功函数和表面能都进一步降低，并且在元素镧和钡体的化学势下分别变为1.43和7.7 eV/nm（2）。这些结果与以前对金属间化合物BaAl（4）、CaAl（4）和BaAuIn（3）的工作相比是有利的。它们最稳定的表面具有最低的功函数。现在，我们研究一种晶体类型完全不同的化合物，其组成元素来自周期表第3列，其中一种是非金属。
Lanthanum hexaboride is one of the cathode materials most used in high-power electronics technology, but the many experimental results do not provide a consistent picture of the surface properties. Therefore, we report the first ab initio calculations of the work functions and surface energies of the (001), (011), (111), (112), and (012) surfaces by considering the different surface terminations and structural relaxation. Either the (111)B- or the (001)La-terminated surface is the most stable, depending on La chemical potential. The work function of the latter is the lowest (2.07 eV) of the surfaces considered. Both the work function and surface energy decrease further when surface La is replaced by Ba and become, respectively, 1.43 and 7.7 eV/nm(2) at the chemical potentials of elemental lanthanum and barium bulk. These results compare favorably with previous work on the intermetallics BaAl(4), CaAl(4), and BaAuIn(3). Their most stable surfaces possess the lowest work function. Now, we study a compound with a decidedly different crystal type and with its constituting elements from column 3 of the periodic table, of which one is nonmetallic.