Highly adhesive hydroxyapatite coatings on titanium alloy formed by ion beam assisted deposition

A compact crystalline hydroxyapatite coating on Ti–6Al–4V substrate with an atomic intermixed coating/substrate interface about 27 nm in width was synthesized by ion beam assisted deposition (IBAD) and a following post-treatment. The coating after post-treatment was identified by X-ray diffraction as crystalline hydroxyapatite. The interface between coatings and substrates was studied by Auger electron spectroscopy. The adhesive strength between coatings and substrates was measured by scratch tester. The results showed that the adhesive strength of IBAD coatings is nearly twice that of ion beam sputtered coatings. The study also showed that coatings prepared by IBAD eliminated the interfacial deficiencies existing in plasma-sprayed coatings.     

Preparation of hard coatings by ion beam methods

The activated growth of surface coatings under the influence of impinging ionized species has been investigated by beam techniques operating in high vacuum. A brief survey of the operating parameters using one or several beam bundles of ions or neutrals is given. Some results and problems are discussed in connection with the following processes: (1) nitriding of iron by low energy ion bombardment; (2) dual beam synthesis of silicon nitride and of hard carbon; (3) preparation of chromium-carbon and of hard carbon layers by ion beam plating from organic vapours. It is concluded that beam techniques can contribute to a better understanding of activated film growth at high rates of deposition. Moreover, ion beam methods offer interesting prospects for the preparation of special layer structures, particularly unusual film phases such as the hard i-carbon.     

Structural, morphological, and mechanical properties of amorphous carbon and carbon nitride thin films deposited by reactive and ion beam assisted laser ablation

Amorphous carbon nitride thin films have been prepared on Si (100) wafers by nitrogen ion beam assisted Nd:YAG laser ablation techniques. Amorphous carbon and carbon nitride films have also been prepared by the conventional laser ablation techniques for comparison. Raman spectroscopy and spectroscopic ellipsometry have been performed for the films to analyze structural properties, atomic force microscopy to observe surface morphologies, and scratch, acoustic emission, and Vicker hardness test to examine mechanical properties. The amorphous carbon nitride films deposited by the ion beam assisted laser ablation techniques had generally better mechanical properties compared to the amorphous carbon films and amorphous carbon nitride films deposited in N₂ atmosphere. The amorphous carbon nitride films deposited at optimum ion beam current of 10 mA and laser power density of 1.7 × 10⁹ W/cm² showed excellent mechanical properties: root mean square surface roughness of 0.33 nm, friction coefficient of 0.02–0.08, the first crack and critical load of 11.5 and 19.3 N respectively, and Vicker hardness of 2300 [Hv]. It is considered that the films have high potential for protective coatings for microelectronic devices such as magnetic data storage media and heads.     

Surface modification using lasers and ion beams

Abstract

The influences of ion beam and laser treatment on the thermal oxidation and sulphidation of metallic materials and their particular features, advantages, and disadvantages are separately described and compared with conventional alloy addition. Examples of the various mechanisms involved and the associated problems are also presented. The ion beam technique considerably improves high temperature resistance, despite the shallow depths involved and ion beam deposited coatings are already in commercial production. Laser beams produce thicker coatings and have considerable industrial potential.

MST/1073     

In situ measurement on ultraviolet dielectric components by a pulsed top-hat beam thermal lens

A simple and sensitive mode-mismatched thermal lens (TL) technique with a pulsed top-hat beam excitation and a near-field detection scheme is developed to measure in situ the thermoelastic and the thermooptical responses of ultraviolet (UV) dielectric coatings as well as bulk materials under excimer laser (193- or 248-nm) irradiations. Owing to its high sensitivity, the TL technique can be used for measurements at fluences far below the laser-induced damage threshold (LIDT). We report on the measurement of both linear and nonlinear absorption of the UV dielectric coatings and bulk materials as well as the investigation of time-resolved predamage phenomena, such as laser conditioning of highly reflective dielectric coatings and irradiation-induced changes of a coating's various properties. The pulsed TL technique is also a convenient technique for accurate measurement of the LIDT of dielectric coatings and for distinguishing different damage mechanisms: thermal-stress-induced damage or melting-induced damage.     

Effect of ion beam etching on metal-Si and metal-GaAs barriers

A hot filament ion source was used in this investigation. The ion beam acceleration system consisted of two graphite grids for extraction of a 1 mA cm⁻² ion beam density of energy between 500 and 1000 eV. A very low energy ion beam [50–200 eV] with the same current density was obtained by using a 〈100〉 single-crystal silicon grid.I-V and C-V measurements of AlSi Schottky diodes pre-cleaned with a 100 eV ion beam before metal evaporation showed no change in the diode barrier height suggesting minimal surface damage (a barrier lowering). Ion etching of the Si surface at an energy higher than 100 eV leads to lowering of the barrier, with a tendency to saturation at a given energy. The induced damage in Si can be completely annealed at 700°C (as indicated by both I-V and C-V measurements) before metal evaporation.The GaAs surface is more sensitive to ion bombardment than Si. Only AlGaAs Schottky diodes pre-cleaned with a 50 eV ion beam did not change the barrier height. Any other higher ion energy drastically lowers the potential barrier of the metal-GaAs system.     

Fabrication and characterization of bioactive glass coatings produced by the ion beam sputter deposition technique

Ion beam sputtering and ion beam sputtering/mixing deposition techniques were used to produce thin bioactive glass coatings on titanium substrate. It was found that as-deposited coatings were amorphous. Scanning electron microscopical examination showed that the coatings had a uniform and dense structure and that fabrication parameters affected the surface morphology of the coatings. The surface Ca/P ratio of the coatings, which varied from 5.9 to 8.6 according to semi-quantitative EDX analyses, was correlated with the fabrication condition. Depth profiling of the coatings revealed four distinct zones: the top surface, the thin coating zone, the intermixed zone of coating and substrate, and the substrate. Scratch tests showed that the coatings adhered well to the substrate.     

Low energy focused ion beam milling of silicon and germanium nanostructures

In this paper focused ion beam milling of very shallow nanostructures in silicon and germanium by low energy Ga( + ) ions is studied with respect to ion beam and scanning parameters. It has been found that, using low energy ions, many scanning artefacts can be avoided and, additionally, some physical effects (e.g. redeposition and ion channelling) are significantly suppressed. The structures milled with low energy ions suffer less subsurface ion beam damage (amorphization, formation of voids) and are thus more suitable for selected applications in nanotechnology.     

Electrospray ion beam deposition of clusters and biomolecules

An ion beam source using electrospray ionization is presented for nondestructive vacuum deposition of mass-selected large organic molecules and inorganic clusters. Electrospray ionization is used to create an ion beam from a solution containing the nanoparticles or molecules to be deposited. To form and guide the ion beam, radio frequency and electrostatic ion optics are utilized. The kinetic energy distribution of the particles is measured to control the beam formation and the landing process. The particle mass-to-charge ratio is analyzed by in situ time-of-flight mass spectrometry. To demonstrate the performance of the setup, deposition experiments with gold nanoclusters and bovine serum albumin proteins on graphite surfaces were performed and analyzed by ex situ atomic force microscopy. The small gold clusters are found to form three-dimensional agglomerations at the surface, preferentially decorating the step edges. In contrast, bovine serum albumin creates two-dimensional fractal nanostructures on the substrate terraces due to strong intermolecular interactions.     

Influence of beam polarisation in laser bending process

Abstract

In this paper, the influence of beam polarisation in the laser bending process was experimentally studied. Based on the laser beam polarisation, the laser absorption of the metallic specimen could be enhanced by increasing the incident angle. The bending angles are achieved in stainless foil specimens without absorptive coatings, and larger bending angles can be produced by single laser scanning with higher incident angles. Multipass laser bending experiments were also carried out on the same material with graphite coatings. The results show that the bending angle per pass is affected obviously by the beam polarisation at lower laser line energy; and the bending angle per pass increases significantly when the total bending angle is large enough. When using polarised light, the laser beam distortion and laser absorption change induced by the variation of the absorptive coatings and laser incident angle are the two main factors that affect the coupled laser energy. The bending rule is the synthesis effect of the two factors.     

Numerical study on modification of ceramic coatings by high-intensity pulsed ion beam

ZrO₂ ceramic coatings, which often call thermal barrier coatings (TBCs), fabricated by electron beam physical vapor deposition (EB-PVD), are widely used in high-temperature environment of aircraft and industry gas-turbine engines, because of the excellent strain tolerance imparted by the columnar structure. However, channels separating the columnar grains in EB-PVD TBCs provide paths for oxygen or other aggressive species from ambient atmosphere into the bond coat, resulting in the premature spallation-failure during high-temperature service. In our previous study, high-intensity pulsed ion beam (HIPIB) technique has been proposed to modify the EB-PVD TBCs, where a melted, densified top layer can be produced as a result of extremely thermal effect induced by the HIPIB irradiation. In this paper, HIPIB melting process is investigated numerically using a physical model based on experimental data, taking into account the surface morphology of HIPIB-melted TBCs to explore the mechanism of interaction between HIPIB and the coatings. Deposition process of the beam energy in TBCs was simulated by Monte Carlo method, and the non-linear equations describing the thermal conducting process were solved numerically based on the deposited energy to obtain the evolution of the temperature field of TBCs. The calculated melting depth of irradiated EB-PVD TBCs is consistent with results obtained in the HIPIB irradiation experiments.     

Argon ion beam and electron beam-induced damage in Cu(In,Ga)Se2 thin films

Ar ion beam and electron beam-induced damages in Cu(In,Ga)Se₂ thin films are investigated by transmission electron microscopy and X-ray energy-dispersive spectroscopy. We find that a high-energy Ar ion beam can cause severe damage in Cu(In,Ga)Se₂ surface regions by preferentially depleting Se and In. The depletion can occur with an Ar ion beam at energy as low as 0.5 keV. High-energy electron beams also cause damage in Cu(In,Ga)Se₂ thin films by preferentially depleting In and Ga. Our results imply that special care must be taken for measurements involving surface treatments using high-energy Ar ion beams or electron beams.     

Characterisation of TiN and TiAlN thin films deposited on ground surfaces using focused ion beam milling

TiN and TiAlN/TiN PVD coatings deposited onto as-ground surfaces have been characterised via direct cross-sectional imaging and transmission electron microscopy with the aid of a focused ion beam system. Cross-sections showed that the coatings exhibit consistent coverage, even in sheltered areas such as at the base of grooves resulting from prior grinding. A columnar grain structure was observed in all coatings. A number of defects were observed such as seams and voids resulting from coating onto the as-ground surface and macroparticles which were shown to be deposited during the metal ion etching stage. Cross-sections through nanoindents revealed that the coatings deform by through-thickness shear cracking.The combination of the excellent coverage provided by PVD and the deformation mechanisms, which are related to the microstructure, contribute to the excellent performance of these coatings that has lead to their widespread application.     

Focused ion beam fabrication of novel core-shell nanowire structures

A novel method of indirect deposition by means of a focused ion beam (FIB) is utilized to develop metal/insulator/semiconductor nanowire core-shell structures. This method is based upon depositing an annular pattern centered on a nanowire, with secondary deposition then coating the wire. Typical cross-sectional deposition area increments as a function of ion doses are 1.3 × 10(-2)?μm(2)?nC(-1) for Pt and 3.5 × 10(-2)?μm(2)?nC(-1) for SiO(2). The structures are examined with a transmission electron microscope (TEM) using a new nanowire TEM sample preparation method that allows direct examinations of individually selected core-shell nanowires fabricated under different indirect FIB deposition conditions. Elemental analyses by means of energy dispersive x-ray spectroscopy and electron energy filtered TEM imaging verify the deposition of SiO(2) and Pt layers. Relatively uniform Pt and SiO(2) coatings on individual GaP nanowires can be achieved with overall thickness deviation of about 10% for deposition up to 25-30?nm thick Pt or SiO(2) shells. It should be possible to extend this approach to any nanowire/nanotube system, and to a wide range of coatings in any desired layer sequences.     

A C60 primary ion beam system for time of flight secondary ion mass spectrometry: its development and secondary ion yield characteristics

A buckminsterfullerene (C60)-based primary ion beam system has been developed for routine application in TOF-SIMS analysis of organic materials. The ion beam system is described, and its performance is characterized. Nanoamp beam currents of C60+ are obtainable in continuous current mode. C60(2+) can be obtained in pulsed mode. At 10 keV, the beam can be focused to less than 3 microm with 0.1 nA currents. TOF-SIMS studies of a series of molecular solids and a number of polymer systems in monolayer and thick film forms are reported. Very significant enhancement of secondary ion yields, particularly at higher mass, were observed using 10-keV C60+ for all samples other than PTFE, as compared to those observed from 10 keV Ga+ primary ions. Three materials (PS2000, Irganox 1010, PET) were studied in detail to investigate primary ion-induced disappearance (damage) cross sections to determine the increase in secondary ion formation efficiency. The C60 disappearance cross sections observed from monolayer film PS2000 and self-supporting PET film are close to those observed from Ga+. The resulting C60 efficiencies are 30-100 times those observed from gallium. The cross sections observed from C60 bombardment of multilayer molecular solids are approximately 100 times less, such that essentially zero damage sputtering is possible. The resulting efficiencies are > 10(3) greater than from gallium. It is also shown that C60 primary ions do not generate any more low-mass fragments than any other ion beam system does. C60 is shown to be a very favorable ion beam system for TOF-SIMS, delivering high yield, close to 10% total yield, favoring high-mass ions, and on thick samples, offering the possibility of analysis well beyond the static limit.     

离子束辅助脉冲激光沉积硼碳氮薄膜

以烧结B4C为靶材料、在氮离子束辅助下用脉冲激光沉积方法制备了三元化合物硼碳氮（BCN）薄膜.用X光电子谱和傅立叶变换红外谱方法表征了制备的薄膜.结果表明,膜层中包含B-C、N-C、B-N键等复合结构,以B-C-N原子杂化的形式结合成键,而并非各种成分的简单混合.还探讨了成膜过程和相关机理,离子束中的活性氮有效地和脉冲激光对B4C靶烧蚀产生的硼和碳结合成键,氮离子束的辅助还能在一定程度上抑制氧杂质进入膜层,给衬底适当加温有利于提高氮的含量并影响薄膜的化学结构.     

Measurement of ion beam profiles in a superconducting linac with a laser wire

A laser wire ion beam profile monitor system has been developed at the Spallation Neutron Source accelerator complex. The laser wire system uses a single laser source to measure the horizontal and vertical profiles of a pulsed hydrogen ion (H(-)) beam along a 230 m long superconducting linac, which accelerates H(-) from 200 MeV to 1 GeV. In this paper, we describe the laser optics requirement for the system, the performance of the profile measurement, and the effects of laser parameters on the measurement reliability. The result provides a practical guideline for the development of a large-scale, operational, laser-based diagnostics in accelerator facilities.     

The role of electronic energy loss in ion beam modification of materials

The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. These results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.     

Irradiation effects of water cluster ion beam on PMMA surface

We investigated the irradiation effects of a water cluster ion beam on a PMMA surface. The incident angle dependence of the sputter depth of the PMMA surface induced by the irradiation of a water cluster ion beam was measured. The sputter depth had a broad peak around the incident angle of 60°. The surface roughness caused by the irradiation of the water cluster ion beam was small compared with the sputter depth.     

Effects of ion energy on ion beam assisted deposition textured yttria stabilized zirconia buffer layer of coated conductor

High quality biaxially textured yttria stabilized zirconia (YSZ) thin films, as buffer layers of coated conductors, were deposited on hastelloy substrates by ion beam assisted deposition (IBAD) method with different assisting ion energy E_i. The roles of assisting ion beam and the influences of ion energy E_i on the structure of the films were studied. It was found that both the out-of-plane alignment and in-plane texture of the IBAD-YSZ films are sensitive to the variation of E_i. The results are explained in the paper by different damage tolerance of the differently oriented grains to ion bombardment.