Two thrusts, focused on Positron Annihilation Spectroscopy (PAS) and positron trapping, have been conducted at IMR. The PAS system at WSU has been used to study Si and CdTe based compounds with incident positron energies from 0.1 eV to 70 keV. This corresponds to mean implantation depths of 15 µm in Si and 6 µm in CdTe. Doppler broadening experiments can be conducted with this system, in which vacancy and vacancy clusters can be characterized. Further, positron lifetime experiments can be conducted, capable of measuring positron lifetimes up to 142 ns, a system unique in the United States.
We have worked with a number of organizations, measuring materials using our unique positron capabilities. Some of those organizations are as follows:
- Pacific Northwest National Laboratory
- Brookhaven National Laboratory
- Idaho National Laboratory
- National Renewable Energy Lab
- Livermore National Lab
- II-VI Incorporated, including eV Products
- National Superconducting Cyclotron Laboratory Michigan State University
- Universidad Antonio Nariño, Columbia
- Instituto de Física de Materiales Tandil, Argentina
- Vanderbilt University
- University of Florida
- U of Utah, Salt Lake City
- Bekaert, Belgium
- Outermost Materials
A few selected publications of this work, showing the breadth of materials studied, are indicated below:
- Keeble, D., B. Nielsen, A. Krishnan, K. Lynn, S. Madhukar, R. Ramesh, and C. Young, “Vacancy defects in (Pb, La)(Zr, Ti)O3 capacitors observed by positron annihilation,” Applied Physics Letters, 73, 318-320 (1998).
- Weber, M.H. and K.G. Lynn, “Positron Porosimetry,” In Principles and Applications of Positron and Positronium Chemistry, Y.C. Jean, P.E. Mellon, and D.M. Schrader, World Scientific Pub. Co., Hackensack, NJ, 167-209 (2003).
- Selim, F., D. Solodovnikov, M. Weber, and K. Lynn, “Identification of defects in Y3Al5O12 crystals by positron annihilation spectroscopy,” Applied Physics Letters, 91, 104105-104105 (2007).
- Lund, K.R., K.G. Lynn, M.H. Weber, C. Macchi, A. Somoza, A. Juan, and M.A. Okuniewski, “Impurity migration and effects on vacancy formation enthalpy in polycrystalline depleted uranium,” Journal of Nuclear Materials, 466, 343-350 (2015).
- Parmar, N.S., K.G. Lynn, N. S., M. T., and S. M., “Sodium doping in ZnO crystals,” Applied Physics Letters, 106(2), 022101 (2015).
- Lund, K., K. Lynn, M. Weber, C. Liu, and E. Eissler, “Nitrogen Desorption and Positron Sensitive Defect of CVD Diamond,” Journal of Modern Physics, 8, 770-785 (2017).
- Reiser, J.T., B. Parruzot, M.H. Weber, J.V. Ryan, J.S. McCloy, and N.A. Wall, “The use of positrons to survey alteration layers on synthetic nuclear waste glasses,” Journal of Nuclear Materials, 490, 75-84 (2017).
- Parmar, N.S., L.A. Boatner, K.G. Lynn, and J.-W. Choi, “Zn Vacancy Formation Energy and Diffusion Coefficient of CVT ZnO Crystals in the Sub-Surface Micron Region,” Scientific Reports, 8(1), 13446 (2018).
- Xu, K., M.H. Weber, Y. Cao, W. Jiang, D.J. Edwards, B.R. Johnson, and J.S. McCloy, “Ion irradiation induced changes in defects of iron thin films: Electron microscopy and positron annihilation spectroscopy,” Journal of Nuclear Materials, 526, 151774 (2019).