Tuesday, August 19, 2014

US-Korean Joint Research Developing New Material Using Atomic Layer-manipulating Tech (MBE)

As reported by Business Korea: A Korean research team has successfully synthesized a new material that can be used in the development of materials in the energy area such as fuel cells, thermal conductors, and superconductors. The Korea Atomic Energy Research Institute (KAERI) announced on August 18 that a Korean research team led by Lee Joon-hyeok, a senior researcher at KAERI, and a U.S. counterpart was able to improve a method for molecular beam deposition that makes nanometer-scale film by stacking up atomic layers one by one.
 
The team also succeeded in synthesizing thin films made of layers of monocrystal lanthanum nickel oxides (Lan+1NinO3n+1 oxides). Since lanthanum nickel oxides have excellent ion conductivity and can respond to catalysts very well, they are actively studied as a material in the energy field like an electrode or a catalyst. In the past, it was difficult to conduct pure research on their characteristics and develop a new material by synthesizing them with other kinds of thin films, because the arrangement of existing polycrystalline lanthanum nickel oxides was irregular. Moreover, the bigger the size, the less regular the material. The joint research team observed in real-time the process where atomic layers of the oxides were piled up, using Oxide Molecular Beam Epitaxy (Oxide MBE) installed in the Advanced Photon Source (APS) Synchrotron at Argonne National Laboratory. During the process, the team discovered the phenomenon of voluntary rearrangement between layers, which means that the order of some atomic layers was not fixed, but reversed instead. By applying this phenomenon, the team manipulated the order that atomic layers of lanthanum oxides and nickel oxides were piled up, and was able to synthesize thin films made of layered compound-type monocrystal lanthanum nickel oxides as a result.
 

a–e, Optimized structures and relative energies of different stackings of two (a,b) or three (c–e) ​SrO and one ​TiO2 layer on a ​TiO2-terminated ​SrTiO3 substrate. (Nature Materials (2014)DOI:doi:10.1038/nmat4039)
 
KAERI is planning to apply the research findings in the development of new materials, such as a change in layer-structure materials and the measurement of material properties, using a neutron reflectometer in the Cold Neutron Research Facility (CNRF). The research findings were first published online on August 3 by Nature Materials.