Microstructural characterisation of alumina with Ti ion implantation

The microstructure of alumina after Ti ion implantation has been investigated. A metal vapourvacuum arc (MEVVA) ion source was employed to implant Ti ions into alumina with doses of7.6 × 10¹⁶ and 3.1 × 10¹⁷ ions/cm² at 40 kV. Scanning electronmicroscopy (SEM) of the irradiated surfaces revealed topographical changes, which were dependent ondose. The implanted layer was also characterised by Rutherford backscattering (RBS) andcross-sectional transmission electron microscopy (XTEM) which showed the lower Ti dose resulted in ahighly defective surface layer. In contrast, TiO₂ precipitates in anamorphous matrix were observed at the higher dose.     

The effect of titanium ion implantation into carbon ceramic on its wettability by liquid copper

There is a growing interest in the carbon ceramics and their use in present technology. Among other problems, the joining of such ceramics with other materials presents an important challenge. Since joining with metals is associated with wetting, we studied the effect of ion implantation on wetting of various forms of carbon and of silicon carbide by copper. An essential result is that Ti ion implantation followed by ArcPVD Ti deposition results in excellent wettability in all studied cases.     

The effects of C ion implantation on the near surface microstructure and properties of alpha alumina

Biomedical grade (>99.5% purity) alpha-alumina has been implanted with carbon ions at fluences ranging from 5 × 10¹⁶ to 5 × 10¹⁷ C ions/cm² at an ion energy of 75 keV. The surfaces of the alumina have been examined in cross-section using transmission electron microscopy (TEM) and the data correlated with both nanohardness measurements and computer based simulations (Transport and Range of Ions in Matter, TRIM). TEM examination of the implanted surface has demonstrated the formation of a sub-surface amorphous layer as well as other microstructural modifications that are characteristic of ion damage. The nanohardness of the near-surface alumina was determined as a function of depth and was found to be strongly dependent on the fluence used.     

The effect of ion implantation on the wear of Co-Cr-Mo alloy

The effect of C+N and O ion implantation upon tribological properties of Co-Cr-Mo alloy was studied for fluence range 3-7×10¹⁷ cm⁻² and implantation temperature range 200-400 °C. Phase structure changes and implanted ion distributions were determined. A marked improvement of the wear rate was noticed. Higher implantation temperatures reduce the improvement. No traces of nitride or carbide phases have been found but chromium oxide phase has been detected after O implantation.     

Patterned ion beam implantation of Co ions into a SiO2 thin film via ordered nanoporous alumina masks

Spatially patterned ion beam implantation of 190 keV Co(+) ions into a SiO(2) thin film on a Si substrate has been achieved by using nanoporous anodic aluminum oxide with a pore diameter of 125 nm as a mask. The successful synthesis of periodic embedded Co regions using pattern transfer is demonstrated for the first time using cross-sectional (scanning) transmission electron microscopy (TEM) in combination with analytical TEM. Implanted Co regions are found at the correct relative lateral periodicity given by the mask and at a depth of about 120 nm.     

Rapid degradation of biomedical magnesium induced by zinc ion implantation

The degradation rate is important to biodegradable magnesium materials. In this study, Zn is implanted using a cathodic arc source into pure magnesium at an accelerating voltage of 35 kV. The nominal ion implant fluence is 2.5 × 10¹⁷ ions cm⁻². After Zn implantation, the degradation rate in simulated body fluids is increased significantly. It is postulated that because Zn exists in the metallic state in the implanted layer, the galvanic effect between the Zn rich surface region and magnesium matrix induces the observed accelerated degradation.     

The effect of Y-ion implantation on the oxidation of AZ31 magnesium alloy

The beneficial effect of Y-ion implantation on the oxidation behavior of AZ31 magnesium alloy was investigated. Yttrium ions having energy of 90 keV were implanted with a concentration of 5 × 10¹⁷ ions/cm². Isothermal oxidation tests have been conducted at 773 K in pure O₂. The experimental results indicated that after treatment the oxidation resistance of AZ31 was significantly improved. AES, XRD and SEM revealed that the pre-oxidation layer could play an important role in further oxidation of the alloys. Finally, cyclic-oxidation test was performed at 773 K in air for 96 h. The implanted AZ31 showed an improved oxidation resistance. With longer oxidation time the beneficial effect of Y-ion implantation vanished gradually.     

The adhesion of metal/alumina interfaces

Cylinders of copper and nickel have been melted under various conditions to form sessile drops on alumina plaques. The resultant metal/ceramic adhesion at room temperature has been measured using the commonly adopted test in which the drops are pushed off the ceramic plaques. The stress system involved in the test has been analysed and it has been shown that the standard interpretation of the test, as a measure of interfacial shear strength, is not valid; the revised interpretation makes it a measure of adhesion in tension. Results for the Cu/Al₂O₃ and Ni/Al₂O₃ systems show that non-wetted interfaces can be strong and have strengths that are independent of contact-angle changes caused by wetting-temperature variations.     

Controllable degradation of biomedical magnesium by chromium and oxygen dual ion implantation

The surface stability of biodegradable magnesium is crucial to tissue growth on implants in the initial healing stage. Inspired by the design principle of biomedical stainless steels, we implant chromium as a passive element into pure magnesium to alter the surface biodegradation behavior. However, because Cr exists in the metallic state in the implanted layer to induce the galvanic effect, excessively fast degradation is observed. Ensuing implantation of oxygen produces a thicker surface oxidized layer composed of chromium oxide, which successfully retards the surface degradation of pure magnesium. The dual implantation process offers a promising means to improve the initial surface stability of Mg in the physiological environment.     

氮离子注入对纯铁表面显微形貌的影响

铁基材料由于其可降解性和无毒性,在血管支架材料领域具有潜在的应用前景.采用40kV的氮离子注入工业纯铁,注入剂量为1×1017～7×1017ions/cm2, X射线衍射表征了材料表面的物相结构,采用原子力显微镜研究了离子注入剂量对材料表面形貌的影响,并用Ra、RMS和Rz定量研究了离子注入后的表面粗糙度.结果表明,氮离子注入对纯铁表面形貌产生了一定的影响,随着注入离子剂量的增加,材料表面的粗糙度也随之增加.     

The ion implantation of ZnS

The properties of ZnS single crystals doped by the Ag ion implantation (an acceptor) and zinc (a donor) were investigated. The annealing of the Ag doped samples in H₂ resulted in an occurrence of the “silver” luminescence centres with the photoluminescence maximum at 454 nm. The doped layer depth is ～500Å at the ion energy of 45 keV. At the annealing of the samples in the S and ZnS vapours the doped layer acquires the p-type conductivity. The doping of n-type ZnS crystals by Zn ions increases their conductivity. At the smooth decrease in the ion beam energy the “ohmic” contact is obtained on the samples.     

Detailed computer simulation of ion implantation processes into crystals

Abstract

A modified version of the binary collision computer code Marlowe that can deal with low energy implant simulations is presented. In this version the trajectories of the particles are calculated by numerically solving their equations of motion instead of simply using the asymptotes, which is the usual approach. The model has been applied to the simulation of 0·5 keV boron implants into amorphous and crystalline silicon. The agreement with the experimental secondary ion mass spectrometry profiles is better than that obtained using the asymptotic approximation.

MST/3302     

The effect of ion implantation on cyclic stress-strain response of polycrystalline copper

The effect of aluminum and boron ion implantation on strain-controlled (low cycle) and stress-controlled (high cycle) fatigue behavior of polycrystalline copper was investigated. The cyclic stress-strain, strain-life and stress-life relations, cyclic slip and crack nucleation behavior of implanted copper are compared with those of unimplanted copper.Under strain control, ion-implanted samples show a lower degree of cyclic hardening and longer fatigue lives than their non-implanted counterparts. Aluminum implantation has a larger effect than boron implantation. Under stress control the fatigue life and the fatigue limit are observed to increase for the aluminum-implanted samples compared with their non-implanted counterparts. These changes in fatigue behavior are associated with changes in deformation behavior in the surface region and surface residual stresses created by ion implantation.     

The effect of helium ion implantation on the relaxation of strained InGaAs thin films

Previous work on pseudomorphic SiGe on Si has shown that a significant reduction in the threading dislocation density can be achieved through appropriate ion beam processing. Helium ion implantation was used in an analogous study to induce strain relaxation within strained pseudomorphic InGaAs layers on GaAs through the intentional introduction of subsurface damage without the introduction of surface nucleated dislocations and their associated threading segments. Wafers of fully-strained 28 nm thick films of In_0.24Ga_0.76As were separately implanted with helium doses of 5 × 10¹⁴, 2 × 10¹⁵, and 1 × 10¹⁶ cm⁻² at 25 keV. These wafers became substrates for additional InGaAs film growth. The final InGaAs films always exhibited lower residual strain as compared to films grown directly on a control substrate of non-implanted GaAs. The broadening of the X-ray peaks indicates an increase in dislocation density within the InGaAs films and the strain relaxation was found to occur with a significant increase in surface roughness. This result stands in contrast to related work on SiGe films on Si where a reduction of the threading dislocation density within a SiGe film was observed. The reaction of the InGaAs/GaAs structure and materials to ion irradiation, with local disturbance to the stoichiometry, could preclude the use of ion beam techniques for realizing a reduction in threading dislocation density during strain relaxation.     

Chemical effect of inert argon beam on nitride nanolayer formed by ion implantation into GaAs surface

The composition of a nitride nanolayer formed on a GaAs(100) surface by the implantation of ions with an energy of E _i = 2.5 keV and the chemical state of nitrogen in this layer have been studied by the method of Auger electron spectroscopy. It is established that, in addition to GaN, a GaAsN solid solution phase is formed in the ion-implanted layer. The energies of N KVV Auger electron transitions in these phases are determined as E _A (GaN) = 379.8 ± 0.2 eV and E _A (GaAsN) = 382.8 ± 0.2 eV (relative to the Fermi level), which allowed the distribution of nitrogen between these phases to be evaluated as [N(GaN)] = 70% and [N(GaAsN)] = 30%. It is established that an argon ion beam produces a chemical effect on the nitride layer, which is related to a cascade mixing of the material. Under the action of the argon ion bombardment, the distribution of nitrogen in the indicated phases changes to opposite. As a result a nitride nanolayer is formed in which the narrow-bandgap semiconductor (GaAsN) predominates rather than the wide-bandgap component (GaN).     

The effect of copper implantation on the mechanical, structural properties and residual stress of polycrystalline alumina

The effect of copper implantation on the mechanical properties, such as hardness, fracture toughness, and residual stress of alumina is addressed herein. The implantation conditions are conducted at room temperature on the polycrystalline alumina with doses ranged from 3 × 10¹⁶ to 10¹⁷ Cu cm⁻² (110 keV). The ion profile distribution was examined by Rutherford backscattering spectroscopy. Surface morphology was observed directly using scanning electron microscopy. Using the X-ray diffraction, we determined the crystallographic nature of the precipitates formed after heat treatment. The residual surface compressive stresses produced by these implantations, as determined by an indentation technique, ranged from 950 to 1720 MPa. Implantation caused a modification in the mechanical properties and an increase in the residual stress. The average residual compressive stress in the implanted region increases with fluence.     

Erbium ion implantation into different crystallographic cuts of lithium niobate

Single crystals like lithium niobate are frequently doped with optically active rare-earth or transition-metal ions for a variety of applications in optical devices such as solid-state lasers, amplifiers or sensors. To exploit the potential of the Er:LiNbO₃, one must ensure high intensity of the 1.5 μm luminescence as an inevitable prerequisite. One of the important factors influencing the luminescence properties of a lasing ion is the crystal field of the surrounding, which is inevitably determined by the crystal structure of the pertinent material. From that point it is clear that it cannot be easy to affect the resulting luminescence properties - intensity or position of the luminescence band - without changing the structure of the substrate. However, there is a possibility to utilise a potential of the ion implantation of the lasing ions, optionally accompanied with a sensitising one, that can, besides the doping, also modify the structure of the treated area od the crystal. This effect can be eventually enhanced by a post-implantation annealing that may help to recover the damaged structure and hence to improve the desired luminescence.In this paper we are going to report on our experiments with ion-implantation technique followed with subsequent annealing could be a useful way to influence the crystal field of LN. Optically active Er:LiNbO₃ layers were fabricated by medium energy implantation under various experimental conditions. The Er⁺ ions were implanted at energies of 330 and 500 keV with fluences ranging from 1.0 × 10¹⁵ to 1.0 × 10¹⁶ ion cm⁻² into LiNbO₃ single-crystal cuts of both common and special orientations. The as-implanted samples were annealed in air and oxygen at two different temperatures (350 and 600 °C) for 5 h. The depth concentration profiles of the implanted erbium were measured by Rutherford Backscattering Spectroscopy (RBS) using 2 MeV He⁺ ions. The photoluminescence spectra of the samples were measured to determine the emission of 1.5 μm.It has been shown that the projected range Rp of the implanted erbium depends on the beam energies of implantation. The concentration of the implanted erbium corresponds well with the fluence and is similar in all of the cuts of lithium niobate used. What was different were the intensities of the 1.5 μm luminescence bands not only before and after the annealing but also in various types of the crystal cuts. The cut perpendicular to the cleavage plane 〈10-14〉 exhibited the best luminescence properties for all of the experimental conditions used. In order to study the damage introduced by the implantation process, the influence of the annealing procedure on the recovery of the host lattice was examined by RBS/channelling. The RBS/channelling method serves to determine the disorder density in the as-implanted surface layer.     

Effects of serum and serum heat-inactivation on human bone derived osteoblast progenitor cells

Generally, heat inactivated foetal calf serum (FCS) containing media are used for the cultivation of animal and human cells. The role of serum source and serum treatment on the behaviour of cells has long been neglected. The present study was performed to investigate the effects of serum heat inactivation and serum source on trabecular bone derived progenitor cells (HBC). Furthermore, it was investigated in how far these reactions differed from those seen in bone marrow derived mesenchymal progenitor cells (HBMC) cultures. We found that HBC cultures performed differently in the presence of FCS and HS with or without heat inactivation. The reactions similar to some degree those observed in HBMC cultures. The implications of the results on cell-implant surface interaction studies are discussed.     

离子注入技术及离子注入对不锈钢腐蚀电化学行为的影响

离子注入方法及注入工艺对改变金属表面成分和表面性能是极为有效的技术．离子注入对金属腐蚀行为的研究已有约30年的历史。本文概述了离子注入技术及离子注入对不锈钢腐蚀电化学行为的影响，涉及的注入离子达十余种。     

用PBⅡ方法在硼膜中注入氮形成BN的结构

用电子束蒸发纯硼,在硅片上沉积不同厚度的硼膜,然后用等离子体基离子注入（ＰＢⅡ）技术在硼膜上主入氮以形成氮化硼（ＢＮ）,用ＸＰＳ分析膜的成分深度分布及化学价态;用傅里叶变换红外（ＦＴＩＲ）透射谱分析膜的结构。氮在膜中呈类似高斯分布,随着注入电压增大,膜的Ｎ／Ｂ比增大且影响氮在膜中的分布,在较高的注入电压时,膜基间产生界面混合,对ＸＰＳＢｌｓ谱进行Ｇａｕｓｓ－ｏｒｅｎｔｚ拟合表明,硼在膜中以ＢＮ及游