J. M. Costantini

• Ph D; HDR
• Managing Director at Atomic Energy and Alternative Energies Commission

Transmission optical absorption spectra of ion-irradiated 3C-SiC epitaxial films on a silicon substrate are measured in the visible-near infrared range from room temperature down to about 10 K. These data show strong interference fringe patterns on top of the silicon absorption edge at about 10,460 cm¹ which limits the transmittance of the samples....

A novel Coulomb spike concept is applied to the radiation damage induced in LiF and SiO2 with about the same mass density (~2.65 g cm−3) by Ni2860 and Kr3684 ions of 1.0-MeV u−1 energy for about the same electronic energy loss (~10 MeV µm−1). This is an alternative concept to the already known models of the Coulomb spike and inelastic thermal spike...

The FTIR absorption bands of virgin and electron-irradiated CeO2 single crystals were measured from 20 K to 500 K between 4000 cm⁻¹ and 12,000 cm⁻¹ (~830 nm to 2500 nm). Three broad bands centered at about 6100 cm⁻¹ (~0.75 eV), 7000 cm⁻¹ (~0.87 eV), and 10,500 cm⁻¹ (~1.3 eV) were recorded above 100 K for the 2.5 MeV electron energy. Two smaller ban...

Ceria (CeO2) doped with Gd2O3 (Ce1−xGdxO2−x/2) is considered a surrogate of a burnable poison-doped nuclear fuel. Oxygen vacancies (VO) are induced in Ce1−xGdxO2−x/2 by the substitution of Gd³⁺ ions into the Ce⁴⁺ sites, and the oxygen deficiency is mainly controlled by the Gd2O3 concentration. Oxygen vacancies can also be generated by elastic colli...

This paper highlights the use and applications of the energy loss function (ELF) for materials analysis by using electron energy loss spectroscopy (EELS). The basic Drude–Lindhart theory of the ELF is briefly presented along with reference to reflection electron energy loss (REELS) data for several dielectric materials such as insulating high-k bin...

Epitaxial cubic (100) 3C-SiC films on a (100) silicon wafer were irradiated at room temperature with 2.3-MeV Si+ or 3.0-MeV Kr+ ions up to a fluence of 1 × 1016 cm−2. The evolutions of the epilayer and the substrate were followed as a function of ion fluence by using micro-Raman spectroscopy, optical absorption, and diffuse reflectance spectroscopy...

A novel analysis of cathodoluminescence (CL) and ion-beam induced luminescence (IBIL) is presented on the basis of virtual photon spectra (VPS) produced by charged particles (electrons or ions) passing by luminescent species such as defects or impurities, in wide band-gap ionic-covalent solids. A discussion is provided for irradiations in a wide ra...

The effects of electronic excitations on the ion sputtering of water ice are not well understood even though there is a clear dependence of the sputtering yield on the electronic stopping power of high-energy ions. Ion sputtering of amorphous water ice induced by electronic excitations is modelled by using the Coulomb explosion approach. The moment...

The microstructure of virgin and heavy ion-irradiated Ce 1–x Gd x O 2–x/2 with a wide range of Gd dopant concentrations (0 ≤ x Gd ≤ 0.5) was evaluated by x-ray diffraction (XRD), micro-Raman spectroscopy, and transmission electron microscopy (TEM) for selected area electron diffraction (SAED) analysis and plane-view bright-field (BF) imaging of ion...

Raman scattering is applied to probe the radiation damage in swift heavy ion‐irradiated ceramics, namely zirconium nitride (ZrN), ceria (CeO2), and yttria‐stabilized zirconia (ZrO2: Y, or YSZ) for about the same high electronic stopping power of heavy ions. Raman spectra show that those ceramics are radiation‐resistant materials which are not amorp...

The radiation damage induced in cerium dioxide CeO2 and cerium-gadolinium mixed oxides (Ce, Gd)O2-x was studied by micro-Raman spectroscopy and diffuse UV-visible reflectance spectroscopy. Sintered samples of undoped CeO2 and (Ce, Gd)O2-x for 1 mol% and 5 mol% of Gd2O3 were irradiated at room temperature with 2.5-MeV Ar2+ and 12-MeV Ar4+ ions up to...

The damage recovery of an electron-irradiated CeO2 single crystal was studied by in situ UV-visible absorption spectroscopy during isochronal thermal annealing up to 873 K. The spectrum of the as-irradiated crystal shows band tailing below the fundamental absorption edge for photon energy near 3.2 eV. Two broad Gaussian bands centered at about 0.9...

The decrease of crystal phonon peak intensities in Raman spectra of silicon carbide after heavy-ion irradiation is analysed in relation to band-gap shrinkage and Urbach edge slope increase arising from accumulation of lattice disorder. The discrepancy on amorphous fractions deduced from Raman spectroscopy and Rutherford backscattering-channelling s...

Raman spectroscopy is an efficient technique for studying the evolution of microstructure of materials under irradiation. For that purpose, a Raman spectrometer has been recently installed at the JANNUS-Saclay platform. In this paper, we describe the new setup for in situ experiments. These in situ experiments allowed following the microstructural...

ABSTRACT In-situ cathodoluminescence (CL) spectroscopy is used to study point-defect formation in cerium dioxide (CeO2) by high-energy electrons (400 keV-1250 keV) at ~100 K, 200 K, and 300 K in a high-voltage electron microscope (HVEM). Complementary CL spectra are also obtained for 20-keV electron excitation at ~300 K in a scanning electron micro...

Irradiation with energetic particles induces elastic displacement damage and electronic excitation in ceramic compounds, and evolve microstructure change. In this article, three types of ceramic compounds, (1) fluorite-type oxides (such as yttria stabilized cubic zirconia (YSZ), urania, and ceria), (2) silicon carbide, and (3) normal spinel structu...

Reflection spectra of cerium dioxide sintered samples were measured in the UV-visible range after irradiation with various heavy ions (2.4-MeV Cu, 5-MeV W, 10-MeV W, 36-MeV W, 100-MeV Kr, and 200-MeV Xe). Differential reflectance spectra of irradiated samples after subtraction of the reference sample spectrum are fit with six broad Gaussian bands c...

Single crystals of transition metal carbides from group IV, TiC1-x and ZrC1-x, have been irradiated at room temperature (RT) with 1.2 MeV gold ions for various fluences in the range 2 × 10¹⁴–3 × 10¹⁶ ions/cm² and polycrystals for fluences between 2 × 10¹³ and 4 × 10¹⁵ ions/cm². The irradiated samples were characterized by micro Raman spectroscopy....

UV-visible absorption spectroscopy and Raman spectroscopy were used to study damage production in cerium dioxide epitaxial films and polycrystalline sintered samples after irradiation with electrons for three energies to span the threshold displacement energies of cerium and oxygen atoms, and 2.4-MeV Cu ions. Neither amorphization nor specific colo...

UV-visible absorption spectroscopy and Raman spectroscopy were used to study damage production in cerium dioxide epitaxial films and polycrystalline sintered samples after irradiation with electrons for three energies to span the threshold displacement energies of cerium and oxygen atoms, and 2.4-MeV Cu ions. Neither amorphization nor specific colo...

We have studied the formation of color centers in magnesium aluminate spinel (MgAl2O4) by X-ray and electron irradiations near room temperature (RT). For this purpose, Cu K radiation and three electron energies (1.0, 1.4, and 2.5 MeV) were used for variable fluences (up to 4.2x1018 cm-2). Off-line UV-visible optical absorption spectra were recorde...

The cathodoluminescence (CL) induced in four oxide single crystals (α-Al2O3, ZrO2: Y or YSZ, MgAl2O4, and TiO2) by high-energy electrons from 400 keV to 1250 keV was studied as a function of beam parameters (flux and energy). The main CL bands are related to F center (oxygen vacancy) formation by elastic collisions above the threshold displacement...

The photo-annealing of colour centres in yttria-stabilised zirconia (YSZ) was studied by electron paramagnetic resonance spectroscopy upon UV-ray or laser light illumination, and compared to thermal annealing. Stable hole centres (HCs) were produced in as-grown YSZ single crystals by UV-ray irradiation at room temperature (RT). The HCs produced by...

Micro-Raman spectroscopy, X-band electron paramagnetic resonance (EPR) spectroscopy, and UV-visible optical absorption spectroscopy were used to study the damage production in cerium dioxide (CeO2) single crystals by electron irradiation for three energies (1.0, 1.4, and 2.5 MeV). The Raman-active T2g peak was left unchanged after 2.5-MeV electron...

The damage induced in cerium dioxide by swift heavy ion irradiation was studied by micro-Raman spectroscopy. For this purpose, polycrystalline sintered pellets were irradiated by 100-MeV Kr, 200-MeV Xe, 10-MeV, and 36-MeV W ions in a wide range of fluence and stopping power (up to ∼28 MeV μm⁻¹). No amorphization of ceria was found whatsoever, as sh...

The damage induced by heavy-ion irradiation has been studied in yttrium iron garnet (Y3Fe5O12 or YIG) films, doped with Ca, Tb and Tm, grown by liquid-phase epitaxy on gadolinium gallium garnet (Gd3Ga5O12 or GGG) substrates. Irradiations of doped-YIG epitaxial films and GGG substrates with 36-MeV 183W and 12-MeV 197Au ions were applied for fluences...

We have studied the color-center production in sapphire and yttria-stabilized zirconia (YSZ) single crystals by cathodo-luminescence(CL) spectroscopy for electron energies ranging between 400 and 1250 keV in a high-voltage electron microscope. Emission spectra were collected for in-beam conditions near room temperature and at 200 K. Comparison was...

We have measured at room temperature (RT) the Fourier-transform infra-red (FTIR) absorption spectra of ion-irradiated thin epitaxial films of cubic silicon carbide (3C–SiC) with 1.1 µm thickness on a 500 µm thick (1 0 0) silicon wafer substrate. Irradiations were carried out at RT with 2.3 MeV ²⁸Si⁺ ions and 3.0 MeV ⁸⁴Kr⁺ ions for various fluences...

Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientatio...

Raman spectroscopy is an efficient technique for studying the evolution of microstructure of materials under irradiation. For that purpose, a Raman spectrometer has been recently installed at the JANNUS-Saclay platform. In this paper, we describe the new setup for in situ experiments. These in situ experiments allowed following the microstructural...

The objective of the present work is to study the irradiation effects on third generation SiC fibers which fulfill the minimum requisites for nuclear applications, i.e. Hi-Nicalon type S, hereafter HNS, and Tyranno SA3, hereafter TSA3. With this purpose, these fibers have been ion-irradiated with 4 MeV Au ions at room temperature and increasing flu...

In this work, recrystallization of ion-amorphized Hi Nicalon Type S and Tyranno SA3 SiC fibers (4 MeV Au3+, 2 × 1015 cm−2) has been studied via in situ TEM annealing. Both fibers show a two-step recovery process of the radiation damage. First recovery stage starts at temperatures as low as 250 °C and implies recovery of the radiation swelling. Even...

Pure and (Ca and Si)-substituted yttrium iron garnet (Y3Fe5O12 or YIG) epitaxial layers and amorphous films on gadolinium gallium garnet (Gd3Ga5O12, or GGG) single crystal substrates were irradiated by 50 MeV (32)Si and 50 MeV (or 60 MeV) (63)Cu ions for electronic stopping powers larger than the threshold value (~4 MeV μm(-1)) for amorphous track...

Gd2Ti x Zr2−x O7 (x = 0 to 2) pyrochlore was irradiated by 30 MeV C60 clusters, which provide an extremely high ionizing energy density. High-resolution transmission electron microscopy revealed a complex ion-track structure in Gd2Ti2O7 and Gd2TiZrO7, consisting of an amorphous core and a shell of a disordered, defect-fluorite structure. As compare...

Subcritical crack growth in SiC based composites is controlled by fiber creep processes. This lifetime limiting mechanism is of special concern under irradiation as it can enhance creep related mechanisms. To evaluate the impact of irradiation on the mechanical behavior of Tyranno SA3 fibers, in situ tensile tests were conducted on single fibers. T...

This work is an overview of the physical approaches required for characterizing and understanding the long-term evolution of ceramics under irradiation. Because this subject is complex and has many ramifications, we have chosen to address the problem by looking at the behavior of a number of key ceramics. In the first part of this work, we present...

Hi Nicalon type S (HNS) SiC fiber and 6H-SiC single crystals have been irradiated with 4 MeV Au3+ at room temperature (RT) and to a fluence of 2 × 1015 cm−2. These irradiation conditions lead to the complete amorphization of the irradiated layer in both samples. Post-irradiation thermal annealing effect on the amorphized samples has been characteri...

Yttria-stabilized zirconia (YSZ) single crystals (for 9.5 and 18 mol% yttria) were irradiated at room temperature (RT) by X-rays (W white spectrum) and 2.5-MeV electrons. The growth curves of the so-called T-centre (for trigonal centre, i.e. Zr3+ sitting in a trigonal symmetry site) were studied as a function of absorbed dose, or irradiation time,...

6H–SiC single crystals and two types of SiC fibers, Hi‐Nicalon type S and Tyranno SA3, have been irradiated with 4‐MeV Au³⁺ up to 2 × 10¹⁵ cm⁻² (4 dpa) at room temperature, 100°C and 200°C. These fibers are composed of highly faulted 3C–SiC grains and free intergranular C. Stacking fault linear density and grain size estimations yield, respectively...

Silicon carbide (SiC) single crystals with the 6H polytype structure were irradiated with 4.0-MeV Au ions at room temperature (RT) for increasing fluences ranging from 1 × 1012 to 2 × 1015 cm−2, corresponding to irradiation doses from ~0.03 to 5.3 displacements per atom (dpa). The damage build-up was studied by micro-Raman spectroscopy that shows a...

We have studied the effect of yttria content on the recovery of paramagnetic centres in electron- and ion-irradiated yttria-stabilized zirconia (ZrO2: Y3+). Single crystals with 9.5 or 18 mol% Y2O3 were irradiated with 1.0-2.5 MeV electrons, 145-MeV carbon ions, 200-MeV iodine ions, 1.45-GeV xenon ions and 2.25-GeV gold ions at various fluences. Th...

Third generation silicon carbide fibers, mainly Hi-Nicalon Type S and Tyranno SA3, have improved the irradiation resistance of silicon carbide composites. In this work the microstructural evolution of these fibers due to ion irradiation is investigated in terms of Raman micro-spectrometry. In comparison with a 6H–SiC single crystal, similar amorphi...

The in situ strain behavior upon ion beam irradiation of a Tyranno SA3 SiC fiber was investigated in real time. For this purpose, a tensile test device suitable for micrometrical samples was developed to allow studies in various irradiation facilities. A 7.44 μm diameter SiC fiber was submitted to both low mechanical loading at 300 MPa and 92-MeV X...

Electron paramagnetic resonance (EPR) spectroscopy is used to study the point defect production in yttria-stabilized zirconia (YSZ) (1 0 0) single crystals by swift heavy ion, electron and X-ray irradiations. A common color center known as the "T center" (for "trigonal" center) with an axial <1 1 1> symmetry is produced in all cases. We show that t...

Cubic yttria-stabilized zirconia (YSZ) can be used for nuclear applications as an inert matrix for actinide immobilization or transmutation. Indeed, the large amount of native oxygen vacancies leads to a high radiation tolerance of this material owing to defect recombination occurring in the atomic displacement cascades induced by fast neutron irra...

Cubic zirconium dioxide, or zirconia (ZrO2-x), generally stabilized by yttrium substitution, is a refractory material with a large oxygen sub-stoichiometry inducing a high ionic conductivity that can be used for solid oxide fuel cell (SOFC) applications, oxygen sensors and other electrochemical applications. Yttria-stabilized zirconia (YSZ) can be...

The present work focuses on two fluorite-structured groups of materials: The hydrides of the rare earths (and actinides) and several specific metal oxides, and is authored by researchers among the most competent and active in the field. By contrast to the classical "historic" alkaline-earth halides, non-stoichiometry appears as a key issue for both...

We have measured the transmission Fourier transform infrared spectra of cubic silicon carbide (3C–SiC polytype) epitaxial layer with a 20 µm thickness on a 200 µm thick silicon substrate. Spectra were recorded in the 400–4000 cm−1 wavenumber range. A novel approach of IR spectra computations based on the recursion capability of the C programming la...

Single crystals of 6H–SiC were implanted at room temperature with 4-MeV Au ions to a fluence of 10cm. Raman spectra showed that full amorphization was achieved. The recrystallization process was studied by micro-Raman spectrometry after isochronal thermal annealing between 700 and 1500°C. The spectra permitted the evolution upon annealing of Si–C b...

3C-SiC single crystal epitaxial layers, 6H-SiC single crystal plates and α-SiC Hexoloy sinters were irradiated with 4.0 MeV Xe or 4.0 MeV Au ions at room temperature. Mechanical and dimensional evolutions of silicon carbide are studied by means of nano-indentation and step-height measurements which are correlated with Rutherford backscattering spec...

Barium hollandite-type ceramics have been envisaged for the immobilization of radioactive cesium. To evaluate their stability under irradiation, a hollandite ceramic of composition Ba1.16Al2.32Ti5.68O16 was irradiated with electrons at a temperature close to room temperature to simulate the effect of β- and γ-decays of cesium. Ti3+ and O2- paramagn...

We have studied the damage induced in fluorapatite (Ca10(PO4)6F2) sinters after 70-MeV Kr, 120 MeV I and 163-MeV Au ion irradiations at room temperature. On the basis of X-ray powder diffraction data we conclude that fluorapatite is not completely amorphized due to ion-induced recrystallization. This recrystallization of the amorphous phase is grea...

Single crystals of 4H-SiC were irradiated with swift heavy ions (332 MeV Ti, 106 MeV Pb and 2.7 GeV U) in the electronic energy loss regime. The resulting damage was investigated with UV-visible optical absorption spectroscopy and micro-Raman spectroscopy. The evolution of the Raman data with fluence shows an accumulation of isolated point defects...

Controversy over nature and existence of the velocity effect [G. Szenes, Phys. Rev. B 87, 056101 (2013)], [M. Toulemonde et al., Phys. Rev. B 87, 056102 (2013)] reignited after new experimental data on swift heavy ion tracks in CaF2 was reported recently [M. Toulemonde et al., Phys. Rev. B 85, 054112 (2012)]. Here we show that results of the analys...

We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic...

Yttria-stabilized zirconia (ZrO2 : Y3+) single crystals (with 9.5 mol% Y2O3) were irradiated with x-rays and α particles. Thermally stimulated luminescence (TSL) data show a main broad peak centred at ∼500-550 K in the glow curves of all irradiated samples. The TSL peak maximum temperature is consistent with the characteristic recovery temperature...

Raman spectroscopy was used to study the radiation damage of fluorapatite single crystals and sinters. Krypton and iodine ion irradiations were performed at high energies (∼1 MeV amu−1) for fluences ranging between 1 × 1011 and 5 × 1013 cm−2. Evolution of the symmetric stretching mode of the PO43− tetrahedral building blocks (strongest Raman mode o...

Owing to their low swelling under irradiation and excellent creep properties, oxide dispersion strengthened (ODS) materials are expected to play an important role as structural components for fusion reactors. These materials are reinforced by a nano-oxide dispersion. Hence, to ensure their good in-reactor mechanical properties, ODS materials have t...

Oxide Dispersion Strengthened (ODS) ferritic/martensitic (F/M) steels are promising materials as structural components for fusion reactors. Their excellent creep properties are provided by the nano-dispersed oxides reinforcing the material. This oxide dispersion has to be as stable as possible under irradiation at high temperatures.In the present w...

4H-SiC and 6H-SiC single crystals were implanted at room temperature with 3-MeV 3He ions at a fluence of 1×1016cm−2. Analysis of helium migration was carried out with the 3He(d, p)4He nuclear reaction. No clear thermally-activated migration in the end-of-range (EOR) region is found below 1100°C, meaning that helium is strongly trapped probably in h...

A pronounced swelling effect occurs when irradiating SiO2 quartz with heavy ions (F, S, Cu, Kr, Xe, Ta, and Pb) in the electronic energy loss regime. Using a profilometer, the out-of-plane swelling was measured by scanning over the border line between an irradiated and a virgin area of the sample surface. The step height varied between 20 and 300 n...

Using electron paramagnetic resonance (EPR) under band-gap illumination, we show experimental evidence of a defect center in n-type cubic silicon carbide (3C-SiC) single crystal irradiated with 1-MeV electrons. This defect is diamagnetic (S=0) in its ground state and can be pumped into a paramagnetic (S=1, MS=0) state by above-band-gap photon excit...

We present an extensive study of point-defect creation in yttria-stabilized zirconia (ZrO(2):Y) exposed to 2.5 MeV electrons and various heavy ions (from C to U) covering an energy range from 100 MeV to several GeV. A synthesis of results from UV-visible optical absorption spectroscopy and electron paramagnetic resonance spectroscopy is provided wi...

Yttria-stabilized zirconia (ZrO(2):Y(3+)) single crystals (with 9.5 mol% Y(2)O(3)) were irradiated with ions (from 1 MeV He to 2.6 GeV U). Electron paramagnetic resonance (EPR) data show that two kinds of colour centres (F(+)-type and T centres) are produced. Thermo-stimulated luminescence (TSL) data exhibit a quite strong peak at ∼ 500-550 K in th...

We present a study of point-defect creation in yttria-stabilized zirconia (ZrO2: Y) or YSZ exposed to various heavy ions (from C to U) covering an energy range from 100 MeV to several GeVs. It is concluded that F +-type centers (involving singly-ionized oxygen vacancies) are produced by elastic-collision processes. The ion-induced out-of-plane expa...

Unfortunately, an error occurred in equation (2) of the above article. The correct equation is as follows: αmaxW = (αW)∞(1 − e−σopt).

We have studied the colour centre production in yttria-stabilized zirconia (ZrO(2):Y(3 +)) by heavy ion irradiation in the GeV range using on-line UV-visible optical absorption spectroscopy. Experiments were performed with 11.4 MeV amu(-1) (127)Xe, (197)Au, (208)Pb and (238)U ion irradiations at 8 K or room temperature (RT). A broad and asymmetrica...

This work aims specifically at studying the evolution of point defects induced by electron irradiation in the cubic polytype of SiC (3C -SiC ) at temperatures ranging from 10 to 1450 K by means of photoluminescence (PL) spectroscopy. We identified a first annealing stage between 200 and 245 K, which probably results from migration of interstitials...

Structural, mechanical, and dimensional evolutions of silicon carbide (SiC) induced by heavy-ion irradiations are studied by means of Rutherford backscattering spectrometry and channeling (RBS/C), nanoindentation, and surface profilometry measurements. 4H - and 6H -SiC single crystals were irradiated with 4 MeV Au ²⁺ and 4 MeV Xe <sup>+<...

This article presents a study of the damage production in yttria-stabilized cubic zirconia single crystals irradiated with swift heavy ions. The combination of techniques which probe the material at different spatial scales (Rutherford backscattering spectrometry in channeling geometry, x-ray diffraction, transmission electron microscopy, and atomi...

In view of the potential use of silicon carbide (SiC) in the nuclear industry, it is of major interest to understand point defect formation in this material. This work is a contribution to the determination of the silicon threshold displacement energy in the cubic polytype of SiC using electron irradiations with increasing energies from 275 to 680...

The lattice damage was investigated by x-ray diffraction techniques in yttria-stabilized zirconia single crystals with the (100) or (110) orientation upon irradiation with swift heavy ions (from 100-MeV C to 2.6-GeV U) in a broad electronic stopping power range (from about 0.3 to 48 keV   nm ^-1 ). The θ-2θ scans show that no amorphizatio...

Pyrochlore pellets with Gd2(Ti2−xZrx)O7 stoichiometry were irradiated with heavy ions at energies ranging from a few MeV to a few GeV in order to compare the effects of nuclear collisions and electronic excitations. The damage created by irradiation was characterized as a function of the ion fluence by X-ray diffraction. The structural modification...

The damage and the residual stresses induced by 4MeV Au ion irradiation in selected ceramic oxides (cubic zirconia and Gd2(Ti2−xZrx)O7 pyrochlores with x=1 and 2) were investigated by X-ray diffraction. The variations of the lattice parameter and of residual stresses upon irradiation were shown to depend on the compound. The highest compressive str...

Yttria-stabilized zirconia (YSZ) single crystals were irradiated with heavy ions at energies ranging from a few MeV to a few GeV in order to compare the effects of nuclear collisions and electronic excitations. The amount of damage created by irradiation was measured as a function of the ion fluence by Rutherford backscattering and channeling spect...

Yttria-stabilized zirconia single crystals were irradiated with a variety of different swift heavy ions (from 145 MeV C to 2.6 GeV U) in a broad fluence range (between 10¹¹ and 10¹⁵ cm ^-2 ). Surface profilometry measurements show that the out-of-plane expansion of the samples increases versus ion fluence up to an as...

In the context of nuclear waste storage, the knowledge of the effect of irradiation on the diffusion of helium produced by α-decays in apatites is an important issue. The analysis of implanted 3He diffusion for two compositions was carried out with the 3He(d,p)4He nuclear reaction by using a deuteron milli- or micro-beam. Upon 163-MeV Au-ion irradi...

X-ray diffraction (XRD) was used to investigate the damage and the correlated stress induced by the slowing-down of swift heavy ions in cubic zirconia polycrystals doped with 10 mol% Y 2O 3. Samples were irradiated at room temperature with 944 MeV Pb ions at the GANIL accelerator in Caen and 2.6 GeV U ions at the UNILAC accelerator in Darmstadt at...

We have studied the color center production in yttria-stabilized zirconia single crystals (i.e. ZrO2: Y with 9.5 mol% Y2O3) with the (100) orientation, by electron irradiations at energies ranging between 1.0 and 2.5 MeV. Electron paramagnetic resonance (EPR) measurements show that three paramagnetic centers are stable at room-temperature: i) an F+...

UV-visible absorption and Raman scattering spectroscopy were used to investigate the effects of 4 MeV Xe-ion and 4 MeV Au-ion irradiations on α-SiC single crystals. The evolution of transmission spectra upon irradiation evidences an increase of the optical absorption. The optical band-gap energy decreases versus fluence, which is linked to band-gap...

Sintered samples of monoclinic zirconia (alpha-ZrO2) have been irradiated at room temperature with 6.0-GeV Pb ions in the electronic slowing down regime. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements showed unambiguously that a transition to the 'metastable' tetragonal phase (beta-ZrO2) occurred at a fluence of 6.5x10^12 cm-2 fo...

In the context of nuclear waste disposal, the knowledge of the diffusion of helium produced by α-decays is an important issue, in order to assess the long-term behavior of the containment matrices. Apatite is one of these potential hosts, which can incorporate many radionuclides as trivalent minor actinides and fission products. In order to determi...

Sintered samples of monoclinic zirconia (α- Zr O ₂) have been irradiated at room temperature with 6.0 GeV Pb ions in the electronic slowing down regime. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements showed unambiguously that a transition to the “metastable” tetragonal phase (β- Zr O ₂) occurred at a fluence...

A study performed with a dedicated scanning electron microscope (SEM) on the surface electrical properties of (1 0 0)-oriented yttria-stabilized zirconia (YSZ) single crystals irradiated with 1 MeV electrons is presented. When compared with virgin YSZ, the 1 MeV-irradiated YSZ shows a decrease of the intrinsic total electron emission coefficient σ0...

Raman spectroscopy was used to investigate the structure of ion-irradiated α-SiC single crystals at room temperature and 400 °C. Irradiations induce a decrease of the Raman line intensities related to crystalline SiC, the appearance of several new Si–C vibration bands attributed to the breakdown of the Raman selection rules, and the formation of ho...

We have used electron paramagnetic resonance to study the thermal annealing of colour centres induced in cubic yttria-stabilized zirconia by swift electron and heavy ion irradiations. Single crystals were irradiated with 1 or 2 MeV electrons, and 200 MeV ¹²⁷I or 200 MeV ¹⁹⁷Au ions. Electron and ion beams produce the same colour centres, namely (i)...

We have studied by electron paramagnetic resonance the mechanism of defect production by electron irradiation in barium hollandite, a material used for immobilization of radioactive caesium. The irradiation conditions were the closest possible to those occurring in Cs storage waste forms. Three paramagnetic defects were observed, independently of t...

Several single phase hollandite ceramics having Ba2+x Cs+y (C = Al,Fe)3+2x+y Ti4+8−2x−y O16 composition have been synthesized and irradiated under external electron beams simulating the β-irradiation of radioactive cesium. These samples have been characterized by 57Fe transmission Mössbauer spectroscopy. Mössbauer results show that the irradiation...

Single crystals of gadolinium gallium garnet, Gd3Ga5O12 have been irradiated with various swift heavy ions (32S, 52Cr, 63Cu, 86Kr, 128Te, 129Xe, 181Ta, 208Pb, 238U) in the electronic stopping power regime. The extent of the induced damage is extracted from channelling Rutherford backscattering experiments and the corresponding track radii are deduc...

We have studied the carbonization of polyimide Kapton-H (pyromellitic dianhydride-oxydialinine, PMDA-ODA) thin films under heavy ion irradiations in the electronic slowing down regime. Irradiations were performed with 650-MeV Ni, 843-MeV Xe, 2.6-GeV Xe, 1.1-GeV Ta, and 707-MeV Pb ions that were transmitted through the polymer films with the electro...

We have used X-band electron paramagnetic resonance (EPR) measurements at room-temperature (RT) to study the thermal annealing and RT ageing of color centers induced in yttria-stabilized zirconia (YSZ), i.e. ZrO2:Y with 9.5mol% Y2O3, by swift electron and ion-irradiations. YSZ single crystals with the 〈100〉 orientation were irradiated with 2.5MeV e...

X-ray powder and high-resolution single-crystal diffraction techniques were used to study the irradiation damage of fluorapatites. Krypton, iodine and carbon irradiations were performed at high energy (≈1 MeV/a) in the 1011 to 5 × 1013 cm−2 fluence range. Both diffraction techniques showed a strong unit-cell increase of the fluorapatite structure,...