Abstract:In this article, a large scale multi-particle molecular dynamics (MD) simulation model was developed to study the dynamic structural changes in single crystal diamond under 5 keV Ga + irradiation in conjunction with a transmission electron microscopy (TEM) experiment. The results show that the thickness of ion-induced damaged layer (~ 9.0 nm)obtained from experiments and simulations has good accordance, which demonstrates the high accuracy achieved by the developed MD model. Using this model, the evolution of … Show more
“…These effects are particularly relevant in metals 19 , and the presence of vacancies and extended defects is likely to accelerate diffusional processes taking place subsequent to implantation. In contrast, molecular dynamics (MD) simulations have been shown to better reproduce experimental observations of the damage induced by the implantation of energetic ions into crystalline materials 20–22 , and has been used to investigate FIB damage in detail 18 .…”
Hydrogen pick-up leading to hydride formation is often observed in commercially pure Ti (CP-Ti) and Ti-based alloys prepared for microscopic observation by conventional methods, such as electro-polishing and room temperature focused ion beam (FIB) milling. Here, we demonstrate that cryogenic FIB milling can effectively prevent undesired hydrogen pick-up. Specimens of CP-Ti and a Ti dual-phase alloy (Ti-6Al-2Sn-4Zr-6Mo, Ti6246, in wt.%) were prepared using a xenon-plasma FIB microscope equipped with a cryogenic stage reaching −135 °C. Transmission electron microscopy (TEM), selected area electron diffraction, and scanning TEM indicated no hydride formation in cryo-milled CP-Ti lamellae. Atom probe tomography further demonstrated that cryo-FIB significantly reduces hydrogen levels within the Ti6246 matrix compared with conventional methods. Supported by molecular dynamics simulations, we show that significantly lowering the thermal activation for H diffusion inhibits undesired environmental hydrogen pick-up during preparation and prevents pre-charged hydrogen from diffusing out of the sample, allowing for hydrogen embrittlement mechanisms of Ti-based alloys to be investigated at the nanoscale.
“…These effects are particularly relevant in metals 19 , and the presence of vacancies and extended defects is likely to accelerate diffusional processes taking place subsequent to implantation. In contrast, molecular dynamics (MD) simulations have been shown to better reproduce experimental observations of the damage induced by the implantation of energetic ions into crystalline materials 20–22 , and has been used to investigate FIB damage in detail 18 .…”
Hydrogen pick-up leading to hydride formation is often observed in commercially pure Ti (CP-Ti) and Ti-based alloys prepared for microscopic observation by conventional methods, such as electro-polishing and room temperature focused ion beam (FIB) milling. Here, we demonstrate that cryogenic FIB milling can effectively prevent undesired hydrogen pick-up. Specimens of CP-Ti and a Ti dual-phase alloy (Ti-6Al-2Sn-4Zr-6Mo, Ti6246, in wt.%) were prepared using a xenon-plasma FIB microscope equipped with a cryogenic stage reaching −135 °C. Transmission electron microscopy (TEM), selected area electron diffraction, and scanning TEM indicated no hydride formation in cryo-milled CP-Ti lamellae. Atom probe tomography further demonstrated that cryo-FIB significantly reduces hydrogen levels within the Ti6246 matrix compared with conventional methods. Supported by molecular dynamics simulations, we show that significantly lowering the thermal activation for H diffusion inhibits undesired environmental hydrogen pick-up during preparation and prevents pre-charged hydrogen from diffusing out of the sample, allowing for hydrogen embrittlement mechanisms of Ti-based alloys to be investigated at the nanoscale.
“…In contrast, the direct collision model proposed by some researchers [20,61,68] recently were able to describe the whole collision process considering the spatial distribution of impact particles and the interactions between the incident particles and the workpiece atoms. In these models, the ion fluence was calculated as the number of collision atoms from the irradiation area.…”
Section: Key Parameters In MD Simulation Of Ion Bombardmentmentioning
Background: Although various advanced FIB processing methods for the fabrication of 3D nanostructures have been successfully developed by many researchers, the FIB milling has an unavoidable result in terms of the implantation of ion source materials and the formation of damaged layer at the near surface. Understanding the ion-solid interactions physics provides a unique way to control the FIB produced defects in terms of their shape and location.
Methods:We have carefully selected peer-reviewed papers which mainly focusing on the review questions of this paper. A deductive content analysis method was used to analyse the methods, findings and conclusions of these papers. Based on their research methods, we classify their works in different groups. The theory of ion-matter interaction and the previous investigation on ion-induced damage in diamond were reviewed and discussed.
Results:The previous research work has provided a systematic analysis of ion-induced damage in diamond. Both experimental and simulation methods have been developed to understand the damage process. The damaged layers created in FIB processing process can significantly degrade/alter the device performance and limit the applications of FIB nanofabrication technique. There are still challenges involved in fabricating large, flat, and uniform TEM samples in undoped non-conductive diamond.
Conclusions:The post-facto-observation leaves a gap in understanding the formation process of ion-induced damage, forcing the use of assumptions. In contrast, MD simulations of ion bombardment have shed much light on ion beam mixing for decades. These activities make it an interesting and important task to understand what the fundamental effects of energetic particles on matter are.
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