material modification by dense electronic excitations
EMSL Project ID
34315
Abstract
Material modifications by dense electronic excitations Proposal 34315 by M. Toulemonde
from CIMAP-GANIL, Caen, France.
EMSL User Proposal
Motivation:
When penetrating a solid, energetic ions lose their energy predominantely through inelastic interactions with the target electrons. In many solids, the resulting intense electronic excitation can produce a narrow trail of permanent damage in the formation of cylindrical damage zones, so-called ion tracks. Tracks have been observed in many materials, including semiconductors, insulators and various metals, beyond a material dependent threshold value of electronic energy loss. The nature of ion track damage ranges from subtle differences between track and matrix material, making difficult any interpretation. Despite that, transient thermal processes seem to be a suitable idea.
In this frame, transient thermal calculations show that the melting concept suitable for amorphizable materials does not directly apply for tracks in non-amorphizable materials. One of the problems is given by the difficulty to define a suitable track diameter. The track radii in non-amorphizable material induced by energetic ions are much smaller than typically recorded for amorphizable material. At present, it is not clear, if trends found for tracks in amorphizable crystals are of general validity. Tracks in CaF2 and SnO2 cannot be described by thermal spike calculations using the melting criterion. Triggered by the observations that energetic ions may produce empty holes in SnO2, the criterion of track formation was modified to sublimation instead of melting. Under this condition, track sizes in SnO2 as well as in CaF2 could be described quantitatively. It remains to be shown if in non-amorphizable solids tracks can be produced from a quench of a molten phase.
We propose to take advanced EMSL facilities of ion accelerator and other surface and optical analysis tools to perform a systematic study on impact of electronic damage and electronic effect to track formation in Oxide Materials. The experimental study will be compared with molecular dynamics (MD) simulations in which the energy will be delayed in time and space.
The proposal will employ multiple experimental facilities and techniques at EMSL. The proposal is closely aligned with one of the four science themes: Science of Interfacial Phenomena.
Approach and Resources: Our general approach for carrying out these investigations includes: (1) multiple iterations of the ion implantation and ion beam characterization. (2) in-situ and off-situ optical measurements, including ion-induced luminescence, Raman, IR, etc. (3) XRD measurements for irradiation-induced amorphization and stress study.
Importance of the work:
The previous investigations elucidated some aspects of the mechanism and kinetics of ion track formation. The results from the different approaches reveal the radiation damage process over different length and temporal scales. Using state-of-the-art resources at the EMSL, the careful control and subsequent understanding of material response to ionization will help fill-in these gaps in our understanding in order to develop a full and systematic understanding of electronic damage and electronic effect in oxide materials.
Potential of highly cited publication(s):
This proposed work will results in highly cited publications.
Project Details
Project type
Exploratory Research
Start Date
2009-06-26
End Date
2010-06-27
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members