Tang Jun, Li Zhaofei, Ju Jing, Kumashiro Ryotaro, A Avila Marcos, Suekuni Kouichirou, Takabatake Toshiro, Guo FangZhun, Kobayashi Keisuke, Akai Koji, Tanigaki Katsumi
Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba Aramaki Aoba-ku, Sendai, Miyagi 980-8578, Japan.
Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan.
Sci Technol Adv Mater. 2009 Jan 28;9(4):044207. doi: 10.1088/1468-6996/9/4/044207. eCollection 2008 Dec.
Extensive soft x-ray photoelectron spectroscopy studies are performed on Ba Ga Ge (BGG) and SrGaGe (SGG) single crystals ranging from Fermi to core levels, at a high-energy facility. Valence band x-ray photoelectron spectroscopy (XPS) experiments with theoretical calculations revealed that the valence band is mainly constructed by the Ge/Ga 4s and 4p wave functions with little contribution of the Ba/Sr atomic orbitals. Surprisingly, unexpected features evidencing the different shift for the 2a- and 6d- sites between Ba 4d and Sr 3d are observed. The detailed analyses including theoretical support by first-principles band-structure calculations lead to the conclusion that the component distributions of the larger tetrakaidecahedral cage are different depending on the endohedral atoms, which contrasts with the past consensus that BGG and SGG have the same framework structure. This may give thorough reconsiderations on earlier interpretations of experimental data.
在一个高能设施上，对从费米能级到芯能级的BaGaGe（BGG）和SrGaGe（SGG）单晶进行了广泛的软X射线光电子能谱研究。价带X射线光电子能谱（XPS）实验结合理论计算表明，价带主要由Ge/Ga的4s和4p波函数构成，Ba/Sr原子轨道贡献很小。令人惊讶的是，观察到了表明Ba 4d和Sr 3d的2a和6d位点有不同位移的意外特征。包括第一性原理能带结构计算的理论支持在内的详细分析得出结论，较大的十四面体笼的组分分布因内包原子而异，这与过去认为BGG和SGG具有相同框架结构的共识形成对比。这可能会促使人们对早期实验数据的解释进行全面重新思考。
