Comparative study of radiationinduced damage in m

Authors: Iwona Jozwik Jacek Jagielski Grzegorz Gawlik Przemyslaw Jozwik Renata Ratajczak Gerard Panczer Nathalie Moncoffre Anna Wajler Agata Sidorowicz Lionel Thomé

Publish Date: 2016/03/23

Volume: 43, Issue: 6, Pages: 439-445

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Abstract

A comparative study of damage accumulation in magnesium aluminate spinel MgAl2O4 has been conducted using ionoluminescence IL cathodoluminescence CL and Rutherford Backscattering Spectrometry/channeling RBS/C techniques MgAl2O4 single crystal and polycrystalline samples were irradiated with 320 keV Ar+ ions at fluencies ranging from 1 × 1012 to 2 × 1016 cm−2 in order to create various levels of radiation damage RBS/C measurements provided quantitative data about damage concentration in the samples These values were then compared to the luminescence measurements The results obtained by IL and RBS/C methods demonstrate a twostep character of damage buildup process The CL data analysis points to the threestep damage accumulation mechanism involving the first defect transformation at fluencies of about 1013 cm−2 and second at about 1015 cm−2 The rate of changes resulting from the formation of nonluminescent recombination centers is clearly nonlinear and cannot be described in terms of continuous accumulation of point defects Both IL and CL techniques appear as new complementary tools bringing new possibilities in the damage accumulation studies in single and polycrystalline materialsThe development of new material expected to be used in a radiative environment requires the solution of numerous problems one of them being related to the quantitative analysis of radiation disorder in materials As a first step in material properties assessment an irradiation with low and high energy ions is frequently used as this method offers numerous advantages the absence of sample’s radioactivity and possibility to get very high damage levels in short times are the main benefits The problem of information about damage buildup intensively studied for single crystals by the Rutherford Backscattering Spectrometry/channeling RBS/C technique Tesmer et al 1995 poses many difficulties for polycrystalline materials It is especially a serious practical problem as most of the investigated materials are single crystals while these are the polycrystals which find the practical application in construction of nuclear reactorsThe aim of the present paper was to use luminescence techniques as an experimental method of quantitative analysis of the radiation damage in polycrystalline materials The studied case is one of the candidates for inert matrix fuels and alternative waste immobilization matrix MgAl2O4 Zinkle and Snead 1996 Georgenthum et al 2001 Pantelica et al 2005 Schram et al 2003 Thomé et al 2006 Allen et al 2010 The use of luminescence techniques is an interesting option as they may be applied to both single and polycrystalline solids are nondestructive fast and can be easily implemented in situ Townsend et al 2007 Skuratov et al 2006 Jagielski et al 2014 Gawlik et al 2011 similar to other techniques such as XRD Grygiel et al 2012Synthetic singlecrystal samples of MgAl2O4 SCI Engineered Materials Inc with a 100 surface and polycrystalline samples obtained at the Institute of Electronic Materials Technology by the hot pressing Astro Thermal Technology of magnesium aluminate nanopowder Baikowski La Balme de Sillingy France were used in the present study The samples were organized in three groups sets N1 and N2 of polycrystalline samples of different grain sizes 56 and 11 μm respectively and a set of monocrystalline samples MThe specimens were subjected to 320 keV Ar+ ion irradiations at fluencies ranging from 1 × 1012 to 2 × 1016 cm−2 in order to create various levels of radiation damage All irradiations were performed at room temperature the Ar+ beam power density was kept below 01 W/cm2 to avoid significant heating of samples during irradiation According to SRIM Ziegler et al 1985 calculations the range of 320 keV Ar+ ions in MgAl2O4 was estimated to be around 200 nmThe RBS/C measurements were performed using 22 MeV 4He2+ ion beam The RBS/C spectra were fitted using McChasy a Monte Carlo simulation package allowing the quantitative analysis of channeling spectra Nowicki et al 2005 The final outcome of this analysis is the damage accumulation kinetics ie the plots of the damage level versus the irradiation fluenceThe CL measurements were performed using a CL system EM Systems mounted on Auriga CrossBeam Workstation Carl Zeiss The energy of the electron beam was set at 10 keV to sufficiently excite the luminescence signal According to Casino simulation results Drouin et al 2007 in this case the penetration depth of electrons is approximately 750 nm

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