The diffusion of Al in 6H-SiC during high-temperature ion implantation was studied using secondary ion mass spectrometry. A 6H-SiC wafer was implanted with 50 keV Al ions to a dose of 1.4E16 cm−2 in the high temperature range 1300°–1800TC and at room temperature. There are two diffusion regions that can be identified in the Al profiles. At high Al concentrations the gettering related peak and profile broadening are observed. At low Al concentrations, the profiles have a sharp kink and deep penetrating diffusion tails. In the first region, the diffusion coefficient is temperature independent, while in the second it exponentially increases as a function of temperature. The Al redistribution can be explained with the substitutional-interstitial diffusion mechanism.

Radial density functions (RDFs) provide important information about short- and ntermediaterange structure of topologically-disordered materials such as glasses and irradiation-amorphized materials. We have determined RDFs for irradiation-amorphized SiO2, AIPO4 and SiC by energy-filtered electron diffraction methods in a field-emission scanning transmission electron microscope (FEG-STEM) equipped with a digital parallel-detection electron energy-loss spectrometer. Post-specimen rocking was used to minimize the effects of spherical aberration in the objective lens, which interfere with the acquisition of data collected by pre-specimen rocking. Useful energy-filtered data has been collected beyond an angular range defined by q = 2 sin(Θ/2)/λ = 25 nm−1

This study compares oxide and nitride formation during oxygen and nitrogen bombardment of Si. Ion bombardment is carried out both in a SIMS machine and in a conventional implanter at various temperatures. Stoichiometric SiO2 and slightly N-rich Si3N4 are formed during bombardment even at cryogenic temperatures. Implanted metals were found to have a strong tendency to be segregated at a moving Si-SiO2 interface during oxygen bombardment but little segregation is observed at a Si-Si3N4 interface.

Z-cut lithium tantalate (LiTaO3) ferroelectric single crystals were irradiated with 200 keV Art++ ions. LiTaO3 possesses a structure that is a derivative of the corundum (A12O3) crystal structure. A systematic study of the radiation damage accumulation rate as a function of ion dose was performed using ion-beam channeling experiments. An ion fluence of 2.5•1018 Ar2+ ions/m2 was sufficient to amorphize the irradiated volume of a LiTaO3 crystal at an irradiation temperature of ∼120K. This represents a rather exceptional susceptibility to ion-induced amorphization, which may be related to a highly disparate rate of knock-on of constituent lattice ions, due to the large mass difference between the Li and Ta cations. We also observed that the c− end of the ferroelectric polarization exhibits slightly higher ion dechanneling along with an apparent greater susceptibility to radiation damage, as compared to the c+ end of the polarization.

A model based on cascade melting and recrystallization is derived to describe ion irradiation-induced amorphization. The accumulation of amorphous volume fraction during irradiation is represented in a single equation. Depending on the extent of recrystallization of a subcascade, the amorphous volume accumulation can be described by a set of curves that change from exponential to sigmoidal functions. The parameters (including temperature, cascade size, crystallization rate, glass transition temperature, dose rate) that affect the extent of recrystallization are included in the model. The model also describes the temperature dependence of critical dose for amorphization.

The in-situ measurement of fluence dependence of electrical resistivity at 100K has been performed for EuBa2Cu3Oy irradiated at 100K with various energetic ions (Cl, Ni, Br, and I) at energy of 90–200MeV. Decreasing slope of resistivity-fluence curves has been observed for irradiations with 120MeV Cl, 90MeV Ni, and 185MeV Ni, while increasing slope of the curves has been observed for irradiations with 120MeV Br, 125MeV Br, and 200MeV I. It is assumed that the damaged region has a cylindrical shape along ion path and a higher resistivity than the undamaged matrix region. The calculated resistivity-fluence curve fitted well with the experimental data when using the diameter and the resistivity of the damaged region as fitting parameters. The obtained diameter and the resistivity of the damaged region have increased with increasing the electronic stopping power, Se. Successive annealing of the specimens up to 300K after irradiation has resulted in 50–70% recovery of irradiation-induced resistivity change at 100K. The diameter of the damaged region has been larger than that of amorphous tracks observed by transmission electron microscope. This result is discussed in relation to the result of annealing experiment.

Lattice defects are introduced into the structure to suppress the motion of magnetic vortices and enhance the critical current density in high temperature superconductors. Point defects are not very effective pinning sites for the cuprate superconductors; however, extended defects, such as linear tracks, have been shown to be strong pinning sites. We study the superconducting cuprate TI-2212 (the numbers designate Tl-Ba-Ca-Cu stoichiometry). Large enhancements of vortex pinning potential were observed in TI-2212 after high-intermediate energy heavy-ion irradiations where non-continuous extended defects were induced at dE/dx of 9 to 15.2 keV/nm (60 MeV Au, 60 MeV Cu, and 30 MeV Au) and continuous linear defects were induced at 19.5keV/nm (88MeV Au). Our research addresses the question of pinning in highly anisotropic materials like Tl-2212 where the vortices are “pancakes” rather than “rods” and suitable defect structures may be discontinuous extended damage domains. The defect microstructure and the effectiveness of the pinning potential in TI-2212 after irradiation by intermediate energy Au at lower dE/dx of 5–15 keV/nm, where recoils are more significant, is studied using high resolution transmission electron microscopy digital imaging and a SQUID magnetometer. The nature of the ion irradiation damage at these intermediate dE/dx will be correlated to the average vortex pinning potential and the TRIMRC calculations for recoils.

The change of calcium fluoride (CaF2) by electron beam irradiation has been investigated in TEMs operated at 200 kV. By irradiation fluorine is desorbed rapidly from CaF2 crystal. Although plasmon peaks in EELS spectra suggest the formation of Ca metal, no evidence for the existence of Ca metal is found in electron diffraction pattern or HRTEM images. This is due to perfect topotactic formation of Ca metal from CaF2 with a similar crystal structure and closely similar lattice parameters. Irradiation also forms amorphous material near the edge of Ca/CaF2 and randomly oriented CaO crystallites grow from the amorphous material. This amorphous material is regarded as hydroxide formed through the reaction of Ca and water, considering the residual gas composition and the formation rate of the material.

The basic mechanisms driving the collapse of point defects produced in collision cascades are investigated by transmission electron microscope (TEM) characterization of defect microstructures produced in fcc-Cu irradiated with low-fluences of heavy (100 keV Kr) ions at elevated temperature (23–600°C). Areal defect yields are determined from direct TEM observation of the total defect production integrated over the duration of the in-situ ion-irradiation. They are unequivocally demonstrated to decrease with increasing lattice temperature. This decrease in defect yield indicates a proportional decrease in the probability of collapse of cascade regions into defects of size where visible contrast is produced in a TEM.

X-ray reflectivity and magnetotransport studies have been used to probe the effects of ion-beam irradiation and subsequent thermal annealing on the structure and giant magnetoresistance (GMR) in Co/Cu multilayers. Low-dose ion bombardment produces interfacial mixing which is accompanied by a systematic suppression of the anti ferromagnetic (AF) coupling and the GMR. For ion doses not exceeding 5 × 1014 ions/cm2, subsequent thermal annealing restores the abrupt interlayer structure as well as the GMR. The combination of low-dose ion bombardment and thermal annealing provides an ex situ technique to modify interface structure reversibly over a gnificant range.

The magnetoresistive behavior of granular thin films prepared by Fe and Co implantation in Ag thin films is reported. Ag thin films (∼2000Å) were implanted with Fe or Co at fluences up to 8×1016 at./cm2. The magnetoresistive response obtained after implantation was found to increase with the implanted fluence. A further increase by a factor of 3–4 can be achieved annealing the films in a conventional furnace at 620 K under vacuum. The best value of the magnetoresistance obtained so far is 9% at 10 K for a film implanted with Co at a fluence of 8×1016 at./cm2.

Samples of Fe66Co18B15Si1, Fe40Ni38Mo4B18 and Fe72.6Cr22Al4.8Si0.3Y0.3 metallic glasses were irradiated with a pulsed alexandrite laser (λ=750 nm, τ=60 μs) using different laser fluences. Irradiation-induced structural and property modifications were characterized using Mössbauer spectroscopy. Complementary information was obtained from hysteresis loop measurements and scanning electron microscopy (SEM). The experimental data obtained demonstrate the key role played by the magnetostriction constant in explaining the mechanism of irradiation-induced phase transformations in amorphous magnets.

The amorphization of the Fe/Ti multilayers due to ion-beam mixing induced by Ar and Kr ions is studied by conversion electron Mossbauer spectroscopy. Formation of the bcc-FeTi solid solution and the amorphous FeTi phase is studied as a function of ion dose for samples with the Fe to Ti thickness ratio of 1 and the modulation wavelengths of 20 and 60 nm. After reaching maximum abundance the amorphous fraction decreases at high ion doses.

Defect accumulation behavior in Fe irradiated with high energy (∼100MeV) ions, low energy (∼1MeV) ions and 2MeV electrons was studied by measuring the electrical resistivity change of the specimen at ∼80K as a function of particle fluence. From the experimental results, the defect production cross-section, the defect annihilation cross-section and the damage efficiency (the ratio of the experimental defect production cross-section to the calculated one) were derived for each irradiation. By comparing the results for high energy ion-irradiations with those for low energy ion- and electron-irradiations, the dependence of defect production and radiation annealing on the electronic excitation is discussed.

Ion-implantation was applied to the surface modification of ZrNi for improving the surface activation of hydrogen absorbing alloys. At the condition of low temperature, only implanted areas showed micro-cracks and pulverization. At high temperature, the reaction was very rapid and both implanted and shielded areas showed the pulverization. The results indicate hydrogen ion-implantation can enhance the activation of this alloy, and the roles of radiation-induced implanted hydrogen and surface film are discussed.

The influence of nitrogen ion implantation on the hydrogen accumulation in titanium was investigated as function of sample temperature and ion fluence. 150 keV nitrogen (15N) ions were implanted at different sample temperatures up to 700°C with fluences ranging from 1 × 1017 to 1 × 1018 ions/cm2. The amount of accumulated hydrogen and its depth distribution was measured quantitatively with the 15N depth profiling method. The implanted 15N depth profiles were measured by the reverse reaction 15N(p, αγ)12C at 429 keV. The binary phases of the implanted nitrogen with titanium are detected by grazing incidence x-ray diffraction. The results are compared with those obtained for samples implanted at RT and subsequently thermally treated.

Energetic particle methods have been used to synthesize two metastable layers with superior mechanical properties: amorphous Ni implanted with overlapping Ti and C, and amorphous diamond-like carbon (DLC) formed by vacuum-arc deposition or pulsed laser deposition. Elastic modulus, yield stress and hardness were reliably determined for both materials by fitting finiteelement simulations to the observed layer/substrate responses during nanoindentation. Both materials show exceptional properties, i.e., the yield stress of amorphous Ni(Ti,C) exceeds that of hardened steels and other metallic glasses, and the hardness of DLC (up to 88 GPa) approaches that of crystalline diamond (∼100 GPa). Tribological performance of the layers during unlubricated sliding contact appears favorable for treating Ni-based micro-electromechanical systems: stick-slip adhesion to Ni is eliminated, giving a low coefficient of friction (∼0.3–0.2) and greatly reduced wear. We discuss how energetic particle synthesis is critical to forming these phases and manipulating their properties for optimum performance.

Low temperature (about 50°C) fabrication of diamond like carbon (DLC) films with a high hardness (>3000Hv) and a high electrical resistivity (>1011 Ωm) has been achieved.

In order to obtain such a result, the effect of ion impingement on the growth and structural change of DLC films in an electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (CVD) method was investigated. It was confirmed that ion impingement was fundamentally required in the growth of DLC films. Furthermore, impingement with ions energized by bias voltages between 50V and 150V had a major influence on the sp 2/sp 3 configuration in DLC films. This configuration is found to be rather sensitive to optoelectronic properties but not so sensitive to film hardness.

Additionally, this method could fabricate ultrathin DLC films that exhibited excellent wear resistance for protective applications.

Hard, adherent, and low-friction silicon-containing diamond-like carbon coatings (Si-DLC) have been synthesized at room temperature by 40 keV (N+ plus N2+), 50%Ar+/50% (N+ plus N2+), and Ar+ ion beam assisted deposition (IBAD) of a tetraphenyl-tetramethyl-trisiloxane oil on silicon and sapphire substrates. X-ray diffraction analysis indicated that all coatings were amorphous. The average coating wear rate and the average unlubricated steel ball-on-disk friction coefficient, μ, decreased with increasing fraction of nitrogen in the ion beam, along with an increase in the average coating growth rate. The Knoop microhardness and nanohardness values of the coatings synthesized by the mixed argon and nitrogen ion beam were higher than the values for the coatings synthesized with 100% nitrogen or 100%argon ion beams. These friction/wear improvements are tentatively attributed to both increased hardening due to greater penetration and ionization induced hardening by the lighter (N) ions and to the presence of Si02 on the surface of N-bombarded samples.

Polycarbonate is one of the most widely used engineering plastics because of its transparency and high impact strength. The poor wear and scratch properties of polycarbonate have limited its application in many fields. In order to improve the wear and scratch properties of polycarbonate we have deposited diamond like carbon (DLC) coatings. The diamond like carbon coatings were made using a high frequency ion beam gun by introducing H2 and CH4 gases. The coatings were characterized with scanning electron microscope, Raman spectroscopy, ellipsometer, and microscratch tester. Polymer hard coating was applied onto the polycarbonate substrate before depositing a diamond like carbon coating to see the effect of interlayer on the system's failure mechanism.