Growth, Structure, and Stability of the High-Index TbOx(112) Surface on Cu(111)
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- 作者：Jan H枚cker ; William Cartas ; Andreas Schaefer ; Marcus B盲umer ; Jason F. Weaver ; Jens Falta ; Jan Ingo Flege
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：June 25, 2015
- 年：2015
- 卷：119
- 期：25
- 页码：14175-14184
- 全文大小：670K
- ISSN：1932-7455
文摘
Low-energy electron microscopy and microillumination low-energy electron diffraction (渭LEED) were used to investigate the structural properties of TbOx films grown on Cu(111) in ultrahigh vacuum. Our results reveal that the morphology and structure of the terbia films depend sensitively on the surface temperature during growth. Deposition at room temperature produces terbia films that uniformly cover the surface but lack long-range order that is detectable with LEED. Annealing in O2 induces the formation of three-dimensional TbOx islands that grow as dendrites and cause the disordered terbia to dewet from the Cu(111) substrate. LEED measurements show that the terbia dendrites are crystalline with a hexagonal (1.4 脳 1.4) structure with respect to the Cu(111) surface, which is consistent with cubic fluorite-like TbOx(111). In contrast to room temperature growth, deposition at 475 掳C produces mainly rectangular TbOx islands that coexist with smaller quantities of irregularly shaped islands. Utilizing 渭LEED, we identify the rectangular domains as the cubic fluorite-like TbOx(112) structure while the irregularly shaped islands are TbOx(111). The TbOx(112) structure has a rectangular unit cell of dimensions (3.58 脜 脳 8.86 脜) that grows in registry with the Cu(111) surface by aligning the short side of the rectangular cell parallel to a close-packed direction of Cu(111). Analysis shows that the longer lattice vector of TbOx(112) coincides with every fourth row of the Cu(111) surface, while the shorter lattice vector has a 5:7 coincidence relation with Cu(111). Lastly, we find that the TbOx(112) phase is less stable than the (111) phase and incorporates into the TbOx(111) domains above 530 掳C.