In situ electron irradiation has been carried out in transmission electron microscopes to monitor the dynamic evolution of α-quartz during the transition to the metamict state from the crystalline state. Crystals of different orientations were examined. HREM images were digitized and Fourier transformed to monitor degradation of periodicities. The final uniform metamict structure was characterized by radial distribution functions obtained from energy-filtered electron diffraction.

Using X-ray structural analysis and transmission electron microscopy of thin layers we have studied the mechanism of heat-affected zone formation in as-hardened steel irradiated by a low-energy microsecond high-current electron beam. It has been found that the above zone consists of three characteristic layers. We have analysed the conditions of formation of this layers using thermal calculations.

Using X-ray structural and transmission electron microscopy analyses, specific features of the phase and structure transformations in armco-iron and steel 45 affected by a high-current electron beam up to 1011 W/cm2 power density have been studied. It was revealed that hardening of steel with martensite structure has a quasi-periodic character that is caused by the action of a shock wave. The action of a shock wave results in formation of a thin layer on the rear side of the samples. The layer is composed of subgrains of ot-ferrite of a regular hexagonal shape with thin layers of graphite on their boundaries.

Polycrystalline MnNiCuFeO was implanted by B+, P+ and Si+ ion beams and thermally annealed. The structure and electrical properties of the sample were measured using SEM, Microprobe (MP), Low Frequency Impedance Analyzer (LFIA) and Spreading Resistance Probe (SRP). The results show that the resistance of grain boundaries is much higher than that of grains. The spreading resistance of the implanted samples is lower by factor of 2 than that of the unimplanted ones. The ratio of the real part Rs (grain effect) to imaginary part Xs (grain boundary effect) decreases with ion beam implantation. From these results, we came to the conclusion that the behavior of the grain boundaries is important to the bulk properties of polycrystalline MnNiCuFeO.

Single crystals and epitaxial films of SiC - 4H and 6H were implanted at an energy of 40 and 90 KeV by ions of Al at various temperatures and high dose.

The implanted layers were studied before and after annealing by Raman scattering, Auger electron spectroscopy and SIMS. Results of this investigation show intensive graphitization of the implanted layer surface, the formation of great associations of defects in the implanted layer and shallow defects. It was found that recrystallization of the implanted layer pushes out a considerable part of aluminum atoms. The nature of the processes in silicon carbide during implantation and annealing is discussed.

The interaction of the diamond (100) surface with pure CH4 and CF4 gases was investigated as a function of temperature and total gas exposure. We found that sp2 carbon does not form on the diamond (100) surface after exposures of up to lO9L of CH4 or 106 L of CF4 in a UHV system over the range of temperatures from room temperature to 900°C. When a high energy electron beam (5keV) intersected the path of the impinging gas or the diamond surface was exposed to a high energy electron beam before gas exposures, sp2 carbon was not produced at levels detectable by Auger spectroscopy. However, sp2 carbon was formed when the gas exposure was coincident with the electron beam on the diamond surface. The mechanisms responsible for these observations are discussed.

MgO single crystals have been irradiated at different temperatures (4 K, 300 K) with electrons of energies varying between 0.3 and 3 MeV. The irradiation induced defects and their reactions during thermal annealing have been investigated by optical absorption spectroscopy and by X-ray diffraction. The relaxation volume (Viel ≈ 1 at.vol. = a3/8) and the migration energy of the interstitial atoms (≈ 1.6 eV) are determined and an ionization induced and thermally assisted migration process is observed for the first time. The relevance of these results for the understanding of the cascade damage observed after neutron- or ion-damage is discussed.

Single crystals of silicon and diamond were implanted at 300K with 70 keV 3He. Ion channeling analyses were executed by application of Rutherford backscattering spectrometry and nuclear reaction analysis. Helium exhibits a non-random lattice site in the channeling angular distributions for silicon and diamond. A major fraction of the implanted 3He was qualitatively identified to be near to the tetrahedral interstice in both materials.

The implantation of Au into Al2O3 leads to disruption of the crystal order producing an amorphous layer. Annealing the implanted crystals at 1373 K restores the crystallinity and also imparts a purple color to the implanted layer which is attributed to a surface plasmon resulting from the formation of Au colloids.

Electron beam irradiation of oxides produces electron trapping states which store excess charge. Thermionic emission of this charge occurs during heating with emission peak temperatures related to binding mechanisms and energies. We present thermionic emission results which show both intrinsic and beam induced trapping states in OC-Al2O3 (sapphire) and sintered alumina. Five states have been identified with thermionic emission peaks at temperatures between -50°C and 500°C. Two states are electron beam induced and occur only for electron beam energies above fixed thresholds. These thresholds appear to correlate to with the Is core electron binding energies for oxygen and aluminum. The emission peaks from the sintered material are about 10 fold greater in intensity and slightly broadened in comparison to the single crystal. This suggests that structure plays an important role in charge trapping. Emission was also extremely sensitive to sample treatments such as annealing before electron irradiation.

The temperature dependence of amorphization dose for zircon under 1.5 MeV Kr ion irradiation has been investigated using the HVEM-Tandem Facility at Argonne National Laboratory. Three regimes were observed in the amorphization dose-temperature curve. In the first regime (15 to 300 K), the critical amorphization dose increased from 3.06 to 4.5 ions/nm2. In the second regime (300 to 473 K), there is little change in the amorphization dose. In the third regime (> 473 K), the amorphization dose increased exponentially to 8.3 ions/nm2 at 913 K. This temperature dependence of amorphization dose can be described by two processes with different activation energies (0.018 and 0.31 eV respectively) which are attributed to close pair recombination in the cascades at low temperatures and radiation-enhanced epitaxial recrystallization at higher temperatures. The upper temperature limit for amorphization of zircon is estimated to be 1100 K. The ion-mass dependence of the amorphization dose (in dpa) has also been discussed in terms of the energy to recoils based on data obtained from He, Ne, Ar, Kr, Xe irradiations and a 238Pu-doped sample.

Thin films made with a thin embedded marker layer of iron or iron oxide in amorphous alumina were ion mixed with 210 keV Ar over a temperature range of RT to 750°C in vacuum. The dose range was 5×l015-7×l016ions/cm2 with an average dose rate of 4.5×1012ions/cm2-sec. The resulting marker distributions were analyzed using RBS. Spreading of the iron RBS peak due to mixing into the alumina matrix was observed in the Fe2O3 marker samples and was clearly seen to be a function of temperature (>400°C) and dose, whereas for the Fe marker sample, no such temperature dependence was observed. An activation energy for the thermally assisted ion mixing in the Fe2O3 marker sample was determined to be 0.69 eV in comparison to an activation energy of 1.77 eV for samples that underwent only a thermal treatment.

The appropriate fluence of 2.0 MeV H1 ions has been shown previously to enhance the critical current density Jc by a factor of two at a magnetic field of 0.9 tesla in 1000 Å thick epitaxial films of YBa2Cu3O7-δ grown by the ex situ BaF2 process. The as-grown films exhibit single crystal-like behavior in both atomic ordering and Jc versus temperature and magnetic field. TRIM simulations suggest that H+ irradiation generates mainly point delects throughout the crystal structure. We show here that such defects result in an even greater enhancement of Jc for fields above 1 tesla plus a significant increase in the apparent vortex pinning potential deduced from magnetization relaxation data.

About 2 μm thick commercial coatings of TiN on high speed steel substrates were implanted at RT with Ar ions of 95 keV energy to doses between 0.1–1.0×1017 ions/cm2. An ultramicrohardness machine was used to measure hardness, and a (sapphire) ball-on-disk machine to measure wear, friction and adhesion. Hardness enhancements up to about 50% were observed as dose increased. However, at the highest dose, hardness reduced by nearly 2 times the unimplanted value. Friction coefficient and relative wear are correlated and reduce with ion dose. Films undergo brittle fracture during sliding tests. These results are found to be very sensitive to small changes in relative humidity. All implants lead to improved wear and adhesion as compared to an unimplanted surface. These results are discussed in terms of ion damage, accumulation of Ar gas bubbles and a possible break-up of the TiN phase during ion bombardment.

The impact of irradiation and stresses onto the preferential orientation of hexagonal ε-nitrides in N-implanted steels is investigated. For this purpose, the contribution of the heterogeneous nucleation, which counteracts a preferential orientation, is varied.

Ni foils and samples consisting of bilayers of Ni or Fe on Al, Ti or Si were implanted at room temperature with 15N+ ions to fluences of around 1×l017 N/cm2. The concentration depth profiles of 15N were determined with nuclear reaction analysis before and after vacuum annealing. It was found that the penetrability for N atoms of the surface and the solid/solid interface plays an important role in the N redistribution during implantation or annealing. The formation of a nitride layer or nitride clusters in Ni and Fe was deduced. Parameters for N migration determined for the metals under investigation are discussed in terms of models.

The behaviour of 300 keV Ba ions implanted at room temperature with doses between 1015 and 1017 cm−2 in Mg single crystal and foils was investigated. The results show that the Ba ions do not occupy substitutions sites in Mg, either after the implantation or the annealing treatments. However, pronounced migration of Ba to the surface is observed above 380 °C. The remaining fraction overlaps with the aa-implanted distribution and forms small precipitates. This behaviour is not correlated with the recovery of the Mg lattice which is already complete at about 250 °C. The surface segregation of Ba delays the evaporation of Mg to temperatures near the melting point.

Experiments were performed demonstrating that ion irradiation enhances diffusion-induced grain boundary migration (DIGM) in polycrystalline Au/Cu bilayers. Here, a model is presented relating film-averaged Cu composition in Au with treatment time, grain size and film thickness. Application of this model to the experimental results indicates that irradiation enhances DIGM by increasing the grain boundary velocity. The effects of DIGM and irradiation-induced grain growth on the temperature dependence of ion mixing in bilayers are discussed.

Recent computer simulation studies of electron-bombarded metallic alloys have concentrated on finding a criterion for amorphization. It has been suggested that the thermodynamic properties of volume and total energy can be used as a gauge for defect induced amorphization. Our simulation results indicate that these properties can not be used due to their dependence on processing history. We propose that the distribution of the atomic level shear stresses can be used as this amorphization criterion. Using Finnis-Sinclair type many-body potentials and Lennard-Jones pair potentials, molecular dynamics (MD) simulations on several model systems have been performed. By quantifying the analysis using the average shear stress normalized, by the average shear modulus of the glass, we will present evidence that the crystal becomes amorphous at the defect concentration where the normalized average shear stress reaches a critical value, which is equivalent to the state obtained through quenching from the liquid.

We have studied the electron irradiation-induced amorphization of the ordered intermetallic compound NizR2 by molecular dynamics simulations in conjunction with embedded-atom potentials. Randomly chosen Frenkel pairs and chemical disorder were introduced into the system in separate processes. In both cases, the energy and volume of the system rose above the corresponding levels of a quenched liquid and the calculated diffraction patterns indicated the occurence of a crystalline-to-amorphous transition. In addition, the average shear elastic constant fell to about 50% of its value in the perfect crystal and the system became elastically isotropie. These results indicate that NiZr2 can be amorphized by chemical disorder as well as Frenkel pairs and are in good agreement with experimental observations.