Xie Kelvin Y, An Qi, Sato Takanori, Breen Andrew J, Ringer Simon P, Goddard William A, Cairney Julie M, Hemker Kevin J
Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218.
Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125.
Proc Natl Acad Sci U S A. 2016 Oct 25;113(43):12012-12016. doi: 10.1073/pnas.1607980113. Epub 2016 Oct 6.
Findings of laser-assisted atom probe tomography experiments on boron carbide elucidate an approach for characterizing the atomic structure and interatomic bonding of molecules associated with extraordinary structural stability. The discovery of crystallographic planes in these boron carbide datasets substantiates that crystallinity is maintained to the point of field evaporation, and characterization of individual ionization events gives unexpected evidence of the destruction of individual icosahedra. Statistical analyses of the ions created during the field evaporation process have been used to deduce relative atomic bond strengths and show that the icosahedra in boron carbide are not as stable as anticipated. Combined with quantum mechanics simulations, this result provides insight into the structural instability and amorphization of boron carbide. The temporal, spatial, and compositional information provided by atom probe tomography makes it a unique platform for elucidating the relative stability and interactions of primary building blocks in hierarchically crystalline materials.
碳化硼激光辅助原子探针层析成像实验的结果阐明了一种用于表征与非凡结构稳定性相关的分子的原子结构和原子间键合的方法。在这些碳化硼数据集中发现的晶体平面证实了在场蒸发点仍保持结晶性，对单个电离事件的表征给出了单个二十面体被破坏的意外证据。对场蒸发过程中产生的离子进行统计分析，以推断相对原子键强度，并表明碳化硼中的二十面体不如预期的稳定。结合量子力学模拟，这一结果为碳化硼的结构不稳定性和非晶化提供了深入了解。原子探针层析成像提供的时间、空间和成分信息使其成为阐明分层晶体材料中基本结构单元的相对稳定性和相互作用的独特平台。
