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The characteristic size, shape and specific alignment of magnetite crystals synthesized by magnetotactic bacteria is a highly coordinated process with precise control over magnetosome vesicle formation, uptake and transport of Fe, and magnetite biomineralization. Magnetosome membranes along with some specific membrane proteins regulate crystal nucleation and morphology of magnetite. Several previous works have indicated that the morphology of mature magnetite crystals is largely unaffected by environmental conditions, though some recent studies have shown the possibility of manipulation of the biomineralization process. In this study we have examined the effects of high concentrations of Zinc and Nickel on the growth of Magnetospirillum magnetotacticum (MS-1) and the corresponding magnetosome formation. Using various characterizations it is shown that the growth of the bacterial cells, as well as the size, shape and magnetosome chain alignment is significantly influenced in the presence of high concentrations of Zn or Ni.

Radiation Processing of Surfaces: Applications of Conversion Electron Mossbauer Spectroscopy

We have investigated the structure and electronic properties of ferrimagnetic double perovskites, {A_2FeReO_6} (A = Ca, Sr, Ba). The A = Ba phase is cubic (Fm3m) and metallic, while the A = Ca phase is monoclinic {P2_1 /n} and nonmetallic. Fe{^57 Mossbauer} spectroscopy shows that iron is present mainly in the high spin S = (5/2) {Fe^3+} state in the Ca compound, while it occurs in an intermediate state between high spin {Fe^2+ and Fe^3+} in the Ba compound. It is argued that a direct {Re t_2g-Re_ t2g} interaction is the main cause for the metallic character of the Ba compound; the smaller size of Ca and the monoclinic distortion (which lifts the degeneracy of {t_2g} states seem to disrupt the Re-Re interaction in the case of the Ca compound, making it nonmetallic for the same electron count.

FET-type devices have been fabricated by using trilayers of Nd/sub 0.7/Sr/sub 0.3/MnO/sub 3/LaNiO/sub 3/ (NSMO) or LaNiO/sub 3/ (LNO) (gate)/LaAlO/sub 3/ (LAO) (barrier)/YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) (channel) in order to investigate effect of quasiparticle injection into YBCO. Here, NSMO and LNO were used as gate electrodes for injection of spin-polarized and spin-unpolarized quasiparticles into the superconducting channel, respectively. When injecting along the c-axis of YBCO, the critical current was suppressed with spin-polarized quasiparticles 30 times more efficiently than with spin-unpolarized quasiparticles. Differential current gain, defined as a differential change of the critical current to injection current change, has been achieved up to /spl sim/16 for c-axis YBCO. If the response time is limited by quasiparticle relaxation time of /spl sim/10 ps, the device may be useful for fast electronics. Preliminary high-speed measurements indicate that part of the critical current suppression may be caused by quasiparticle injection, not all by heating. When injecting along a-axis, no significant dependence on quasiparticle polarization was observed. Other superconductors such as Pr/sub 1.85/Ce/sub 0.15/CuO/sub 4/ (PCCO) and PbIn have been tested in similar devices for comparison.

Surface complexes involving silicon, germanium and carbon adatom on predefined adsorption sites of the 2×1 reconstructed Si(001) surface are investigated for their energetics and associated structural relaxations. Tersoff’s semi-empirical potential is used and the relaxations are obtained by employing the Monte Carlo simulated annealing technique. The results for the cases of Si, Ge and carbon adsorptions are compared. It is found that Si and Ge as adatoms on Si(001) 2×1 reconstructed surface behave in a similar fashion but the carbon adatom behaves in a markedly different way. Specifically, the carbon adatom induces a Si-C-Si chain configuration. It is also found that the adsorption sites between two dimer rows are the most favourable ones.

Since the rejuvenation of interest in the rare earth manganites owing to their potential use as magnetoresistive sensors, there has been adequate research to arrive at some evaluation of the potent...

We have grown high quality a-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-x//PrBa/sub 2/Cu/sub 3/O/sub 7-y/ films on [100] LaSrGaO/sub 4/ substrates. We have optimized the crystalline orientation and the superconducting properties of our films. We have performed annealing studies on a- and c-axis films in vacuum and oxygen to compare the oxygen depletion of the films and found that T/sub c/ degradation of a-axis films is comparable to that of c-axis films. To further optimize the a-axis films for trilayer junction fabrication, we significantly reduced the surface roughness of the films by a gradual lowering of oxygen pressure during the deposition. >

Thin films of YBa/sub 2/Cu/sub 3-x/Fe/sub x/O/sub 7-y/ (0/spl les/x/spl les/0.2) were made by pulsed laser deposition using different O/sub 2/ pressures and annealing times. Their microwave absorption was measured and shows that the preparation conditions have a profound effect on the surface resistance. That is, if the Fe incorporation was successful, the microwave absorption had a large peak near T/sub c/. Various other diagnostics such as X-ray, ac susceptibility and atomic-force microscopy have also been performed. >

Ferromagnetism is observed at and above room temperature in pulsed laser deposited epitaxial films of Co-doped Ti-based oxide perovskite (La1-xSrxTiO3-d). The system has the characteristics of an intrinsic diluted magnetic semiconductor (metal) at low concentrations (

Diamond like carbon films and C-N films were prepared using ion beam assisted deposition technique (IBAD). Tribological properties were studied by subjecting DLC coated films to the accelerated wear tests. These tests indicated a significant improvement in the mechanical surface properties of glass by DLC coating. Better wear features were obtained for thinner DLC coating as compared to the thicker ones. We also studied the optical properties and obtained a band gap of 1·4 eV for these films. An attempt was made to prepare C3N4 films by using IBAD. We observed variation in the nitrogen incorporation in the film with the substrate temperature.

Both ferromagnetic (FM) and charge-ordered domain structures of (La/sub 1-x/Pr/sub x/)/sub 0.67/Ca/sub 0.33/MnO/sub 3/ thin film were detected by magnetic force microscopy (MFM) and electric force microscopy (EFM) operated at low temperatures near the peak resistance temperature (T/sub p/). The in-plane-like FM domains of submicrometer size emerge below T/sub p/, and their magnetic interaction with an MFM tip becomes stronger as the temperature is reduced. Charge-ordered insulating regions have the strong electrostatic interaction with an EFM tip near T/sub p/, and the interaction correlates well with the temperature dependence of resistivity of the film.

We present the results of an investigation of the magnetic properties of A/sub 2/FeReOe (A=Ca, Sr, Ba). We have studied the magnetization, high-temperature susceptibility and the ferromagnetic resonance response. The Ba and Sr systems are conducting while the Ca material is an insulator. The ordering temperature of the Ca materials is highest (/spl sim/540 K) and decreases to 315 K for the Ba system. The high-temperature susceptibility suggests a large moment, and the Curie-Weiss temperature is very close to the ordering temperature, as expected for a simple ferromagnet, although the ferromagnetic moment is somewhat less than expected. The spin dynamics are rather peculiar: the ferromagnetic resonance results suggest a magnetically inhomogeneous material. We discuss these results in terms of cation disorder.

A commercial atomic force microscope/magnetic force microscope (MFM) was modified to cool magnetic samples down to around 100 K under a high vacuum while maintaining its routine imaging functionality. MFM images of a 120 nm thick La0.7Ca0.3MnO3 film on a LaAlO3 substrate at low temperature show the paramagnetic-to-ferromagnetic phase transition. Evolution of magnetic domains and magnetic ripples with decreasing temperature are also observed near the edge of a 20 nm thick patterned Co film on a Si substrate.

Microchannel is basic functional component of microfluidic chip and every step-forward of its construction technique has been receiving concern all over the world. The present work describes a novel, rapid and simple fabrication technique for building 3D microchannels in poly(dimethyl siloxane) (PDMS) elastomer. These microchannels were used for rapid detection of antigens (E. coli) by quantum dot (QD) based approach. Luminescent QD (CdTe) were synthesized by aqueous method and characterized using high resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy and X-ray diffraction (XRD). The QDs were functionalized with anti-E. coli antibodies for immuno-detection. The reported process allowed easier and faster method of fabrication of circular 3D micochannels and demonstrated their potential use in an immuno-biosensor device.

We report microwave absorption measurements as a function of temperature (from 290 to 125 K) and magnetic field (from 0 to 0.3 T) in mm-thick parallelepipeds of sintered $V_2O_3$ and $V_2O_3$ containing micron-size Fe precipitates. As before, it turns out that near the metal–insulator (MI) transition, the loss exhibits a sharp peak as a function of temperature. On application of a magnetic field, the peak temperature for ($V_2O_3$ + Fe) changes by a few kelvin, causing a giant magnetoimpedance ( \approx 200% in 0.1 T field) in the neighborhood of the MI transition.

An automated linear laboratory EXAFS spectrometer of the Johansson type has been indigenously developed. Only two translational motions are required to achieve the necessary Rowland circle configuration for the (fixed) X-ray source, the dispersing and focusing bent crystal and the receiving slit. With the available crystals the spectral region from 5 to 25 keV can be scanned. The linear motions of the crystal and receiving slit including the detector assembly are achieved by employing software-controlled DC motors and utilizing optical encoders for position sensing. The appropriate rotation of the crystal is achieved by the geometry of the instrument. There is a facility to place the sample alternately in the path of the X-ray beam and out of the path to record both the incident X-ray intensityI0 and the transmitted intensityI employing the scintillation detector. An arrangement with a two-window proportional detector before the sample to measureI0 and the scintillation detector to recordI is also developed; in this case it is not necessary to oscillate the sample. Fast electronic circuits are employed to minimize counting errors. The instrument is user-friendly and it is operated through a menu-driven IBM compatible PC. EXAFS spectra of high resolution have been recorded using the spectrometer and employing the Si(111) reflecting planes; the X-ray source being a Rigaku 12 kW rotating anode with Cu target. We describe the spectrometer and discuss its performance with a few representative spectra.

An attempt was made to modify the surface of an austenitic stainless steel using laser surface melting (LSM) technique to improve the localized corrosion resistance. AISI type 316 stainless steel (SS) specimens in solution annealed, cold worked (5, 10, 15 and 20%) and sensitized (923 K, 20 h) conditions were laser surface melted using a pulsed ruby laser at the energy of 6 J per pulse. The melted layers were characterized by small angle X-ray diffraction (XRD), optical microscopy and scanning electron microscopy (SEM)

The progress in the area of applications of ion implantation and laser treatment to III–V semiconductors is reviewed. The achievements till todate are discussed alongwith the yet unresolved problems.

We report on the synthesis of TbMnO3 nanoparticles by chemical co-precipitation route and their structural, chemical bonding, magnetic and dielectric properties. It is shown that the interesting multiferroic properties of this system as reflected by the concurrent occurrence of magnetic and dielectric transitions are retained in the nanoparticles (size ~40 nm). However, the nanoparticle constitution and properties are seen to depend significantly on the calcination temperature. While the nanoparticles obtained by calcination at 800 °C correspond very well with the reported properties of single phase TbMnO3 (all the key magnetic and dielectric features near 7, 27 and 41 K, albeit with reduced dielectric constant) the nanoparticles obtained by calcination at 900 °C develop a Tb deficient skin which softens the transitions, reducing the dielectric constant further.

An external electric field induced reversible modulation of a room temperature magnetic moment and coercive field is achieved in an epitaxial and insulating thin film of dilutely cobalt-doped anatase TiO 2 . This first demonstration of an electric field effect in any oxide-based diluted ferromagnet is realized in a high quality epitaxial heterostructure of PbZr 0.2 Ti 0.8 O 3 /Co: TiO 2 /SrRuO 3 grown on (001) LaAlO 3 . The observed effect, which is about 15% in strength in a given heterostructure, can be modulated over several cycles. Possible mechanisms for electric field induced modulation of insulating ferromagnetism are discussed.

Epitaxial thin films of gallium iron oxide (GaFeO3) are grown on (001) silicon by pulsed laser deposition (PLD) using yttrium-stabilized zirconia (YSZ) buffer layer. The crystalline template buffer layer is in-situ PLD grown through the step of high temperature stripping of the intrinsic silicon surface oxide. The X-ray diffraction pattern shows c-axis orientation of YSZ and b-axis orientation of GaFeO3 on Si (100) substrate. The ferromagnetic transition temperature (TC ~ 215 K) is in good agreement with the bulk data. The films show a large nonlinear second harmonic Kerr rotation of ~15 degrees in the ferromagnetic state., Comment: 16 pages, 4 figures, To be published in J. Magn. Magn. Mat

We report on the optical properties of magnetic cobalt-doped anatase phase titanium dioxide ${\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{O}}_{2\ensuremath{-}\ensuremath{\delta}}$ films for low doping concentrations, $0l~xl~0.02,$ in the spectral range $0.2l~\ensuremath{\Elzxh}\ensuremath{\omega}l5\mathrm{eV}.$ For well oxygenated films $(\ensuremath{\delta}\ensuremath{\ll}1)$ the optical conductivity is characterized by an absence of optical absorption below an onset of interband transitions at 3.6 eV and a blueshift of the optical band edge with increasing Co concentration. The absence of below band gap absorption is inconsistent with theoretical models which contain midgap magnetic impurity bands and suggests that strong on-site Coulomb interactions shift the O band to Co-level optical transitions to energies above the gap.

Arrays of perpendicular ferromagnetic nanowires have recently attracted considerable interest for their potential use in many areas of advanced nanotechnology. We report a simple approach to create self-assembled nanowires of alpha-Fe through the decomposition of a suitably chosen perovskite. We illustrate the principle behind this approach using the reaction 2La(0.5)Sr(0.5)FeO(3) --LaSrFeO(4) + Fe + O(2) that occurs during the deposition of La(0.5)Sr(0.5)FeO(3) under reducing conditions. This leads to the spontaneous formation of an array of single-crystalline alpha-Fe nanowires embedded in LaSrFeO(4) matrix, which grow perpendicular to the substrate and span the entire film thickness. The diameter and spacing of the nanowires are controlled directly by deposition temperature. The nanowires show uniaxial anisotropy normal to the film plane and magnetization close to that of bulk alpha-Fe. The high magnetization and sizable coercivity of the nanowires make them desirable for high-density data storage and other magnetic-device applications.

We report a detailed magnetic and structural analysis of highly reduced Co doped rutile TiO2 films displaying an anomalous Hall effect (AHE). The temperature and field dependence of magnetization, and transmission electron microscopy clearly establish the presence of nano-sized superparamagnetic cobalt clusters of 8-10 nm size in the films at the interface. The co-occurrence of superparamagnetism and AHE raises questions regarding the use of the AHE as a test of the intrinsic nature of ferromagnetism in diluted magnetic semiconductors., Comment: Physical Review Letters (In press)

The occurrence of room temperature ferromagnetism is demonstrated in pulsed laser deposited thin films of Sn(1-x)Co(x)O(2-delta) (x

We present the results of Raman and photoluminescence (PL) studies on epitaxial anatase phase Ti$_{1-x}$Co$_x$O$_2$ films for $x$ = 0-0.07, grown by pulsed laser deposition. The low doped system ($x$=0.01 and 0.02) shows a Curie temperature of ~700 K in the as-grown state. The Raman spectra from the doped and undoped films confirm their anatase phase. The photoluminescence spectrum is characterized by a broad emission from self-trapped excitons (STE) at 2.3 eV at temperatures below 120 K. This peak is characteristic of the anatase-phase TiO$_2$ and shows a small blueshift with increasing doping concentration. In addition to the emission from STE, the Co-doped samples show two emission lines at 2.77 eV and 2.94 eV that are absent in the undoped film indicative of a spin-flip energy., 8 pages, 4 figures

Transport across an ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}/{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$ (LSMO/YBCO) interface is studied as a function of temperature and surface morphology. For comparison, control measurements are performed in nonmagnetic heterostructures of ${\mathrm{LaNiO}}_{3}/\mathrm{YBCO}$ and Ag/YBCO. In all cases, YBCO is used as bottom layer to eliminate the channel resistance and to minimize thermal effects. The observed differential conductance reflects the role of Andreev bound states in the $a\ensuremath{-}b$ plane, and displays the suppression of such states by the spin-polarized transport across the interface. The theoretical analysis of the measured data reveals decay of the spin polarization near the LSMO surface with temperature, consistent with the reported photoemission data.

The photon energy dependence of optical Cooper pair breaking rate (CPBR) is studied for compressibly strained La1.85Sr0.15CuO4 (LSCO) films and YBa2Cu2.92Zn0.08O7-delta (YBCZO) thin films, and compared to that in YBa2Cu3O7-delta (YBCO). Unlike in the case of YBCO, the CPBR for LSCO does not show obvious photon energy dependence. In YBCZO the CPBR shows strong photon energy dependence similar to YBCO, but with a red shift in the peak position. Analysis of these results strongly favours a physical picture based on electronic phase separation in high Tc superconductivity., 11 pages, 3 figures, Phys. Rev. B, in press

Growth of MgB2 thin films by pulsed laser deposition is examined under ex situ and in situ processing conditions. For the ex situ process, Boron films grown by PLD were annealed at 900 C with excess Mg. For the in situ process, different approaches involving ablation from a stoichiometric target under different growth conditions, as well as multilayer deposition involving interposed Mg layers were examined and analyzed. Magnetic measurements on ex situ processed films show TC of ~39 K, while the current best in situ films show a susceptibility transition at ~ 22 K., Comment: 3 pages, PDF

The growing body of experimental evidence for the existence of complex textures of charges and spins in the high-temperature superconductors has drawn attention to the so-called 'stripe-phase' models as a possible basis for the mechanism of superconductivity in these materials. Such observations have until now been restricted to systems where the texture dynamics are slow or suppressed altogether, and do not include the important case of YBa2Cu3O(7-delta). It seems likely that the dynamic behaviour of stripes, which has been suggested to undergo several phase transitions as a function of temperature, should also be reflected in the lattice properties of the host materials, and this forms the motivation for our present experiments. Specifically, we use MeV helium ion channelling, an ultrafast real-space probe of atomic displacements (with sub-picometre resolution), to probe incoherent lattice fluctuations in YBa2Cu3O(7-delta) as a function of temperature and oxygen doping. We detect lattice fluctuations that are larger than the expected thermal vibration component, and which show anomalies characteristic of the phase transitions anticipated for a dynamic stripe phase. Comparison of our lattice results with single-particle-tunnelling and photoemission data highlights the importance of spin-charge separation phenomena in the copper oxide superconductors.

Role of swift heavy ion irradiation on the modification of transport and structural properties of high temperature superconductors is studied. Good quality YBCO thin films prepared by high pressure oxygen sputtering and laser ablation were used in this investigation. Resistivity and atomic force microscopy (AFM) were mainly used to probe superconducting and microstructural modifications resulted from the irradiation of high energy and heavy ions like 100 MeV oxygen and 200 MeV silver. Radiation induced sputtering or erosion is likely to be a major disastrous component of such high energy irradiation that could be powerful in masking phase coherence effects, atleast in grain boundaries. The extent of damage/nature of defects other than columnar defects produced by swift heavy ions is discussed in the light of AFM measurements. The effect of high energy oxygen ion irradiation is anomalous. A clear annealing effect at higher doses is seen. (C) 1999 Elsevier Science B.V. All rights reserved.

Sparfloxacin, a new quinolone antibacterial was used to treat one hundred and thirty two patients with acute purulent sinusitis, at a dosage of 400 mg on the first day followed by 200 mg once daily for a further four days. A clinically successful outcome (defined as disappearance of nasal discharge, fever, pain, tenderness over the sinuses and headache) was recorded in 122 ( 95.3%) patients. Sparfloxacin was well tolerated. Fourteen adverse experiences were reported in 7 patients ( 5.3%); they were mainly gastrointestinal and mild. No phototoxic or cardiological adverse events occurred. An unusual feature was that Staphylococcus aureus and Pseudomonas spp. were the most common bacterial species isolated from middle meatal was of patients in this study.

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

A case of malignant melanoma of the nasal cavity is reported. The rarity of its occurrence warrants its mention.

It is shown that dilute niobium doping has significant effect on the ferromagnetism and microstructure of dilutely cobalt-doped anatase TiO2 films. Epitaxial films of anatase TiO2 with 3% Co, without and with 1% niobium doping were grown by pulsed-laser deposition at 875 C at different oxygen pressures. For growth at 10^{-5} Torr niobium doping suppresses the ferromagnetism, while it enhances the same in films grown at 10^{-4} Torr. High-resolution Z-contrast Scanning Transmission Electron Microscopy and Electron Energy Loss Spectroscopy show uniform surface segregation of cobalt-rich Ti_{1-x-y}Co_{x}Nb_{y}O_{2-d} phase, but without cobalt metal clusters., Comment: 17 pages, 3 figures

We have measured the temperature (T) dependencies of the dc resistances (Rdc) and the microwave loss (Rμw) in a variety of samples of (La1−xPrx)0.7Ca0.3MnO3 while varying x from 0 to 0.4. Whereas both the sets of data exhibit maxima, the ac loss peak is much flatter and, during cooling, appears at a much lower temperature than the peak temperature in Rdc. The discrepancy, which vanishes for x=0, increases with lowering tolerance factor (t) (or increasing x). Also Rμw vs T exhibits large thermal hysteresis for x=0.4 indicating that the transition is first order. Cooling in a magnetic field of 9 kOe causes an upward shift of about 20 K in the Rμw peak, in some of the x=0.4 films, yielding a large magnetoimpedance. Further, once these films are exposed to a magnetic field at low T, they fail to recover their virginal behavior on subsequent cooling from room T. These films could be brought to their original state by annealing at high T. The discrepancy between Rdc and Rμw implies that the system is inhomogene...

Recent results on high-power pulsed-laser-induced transformations at liquid-solid interface are described in the context of synthesis of new metastable phases of materials. Specifically two types of problems are reported: (i) laser-induced synthesis of compound film at liquid solid interface, this process being termed “reactive quenching”, and (ii) laser-induced alloying of layered structure under liquid medium wherein the reactive aspect plays the minimal role. So far the reactive quenching process has been studied for different metals, compounds and thin film sandwiches in various liquid ambients such as H2O, liquid ammonia (NH3), liquid N2 and benzene (C6H6). The identification of the metastable phases and the microstructural transformations therein subsequent to laser processing and thermal annealing have been brought out by employing a range of techniques such as conversion electron Mossbauer spectroscopy (CEMS), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), etc. Laser-induced alloying of layered structure in liquid ambient has been investigated in case of Fe/Al and Fe/B systems. The possible mechanism which could be responsible for the observed effects is discussed on the basis of time-resolved reflectivity measurements.

Thermally stimulated current spectra of nitrogen implanted fluorinated ethylene propylene polymer foils have been studied. Two characteristic peaks have been obtained for samples implanted with nitrogen ions with energies ranging from 20 to 60 keV. The variations in the activation energies and relaxation times of charge carriers, as a function of implantation energy, have been attributed to the corresponding changes in the carrier distribution in the polymer. The carrier mobilities and mobility life-time products have also been estimated for the two characteristic peaks.

The field of laser-induced synthesis, deposition and etching of materials is reviewed with an emphasis on the emerging trends and novel adaptations of the basic laser processing concepts. A number of examples are cited to illustrate the issues involved. These include rapid synthesis of titanium nitride by pulsed laser induced reactive quenching at Ti:liquid NH3 interface, laser deposition of good quality thin films of such materials as hot oxide superconductors, zinc ferrite, iron oxide, stainless steel, etc. and laser etching of superconductor films.

The oxidation kinetics and associated structural and chemical transformations in the Fe67Co18B14Si1 metallic glass have been investigated by using the techniques of conversion electron Mossbauer spectroscopy (CEMS) and x‐ray photoemission spectroscopy (XPS). The as‐quenched as well as vacuum‐annealed samples of the metallic glass have been subjected to thermal treatment in air at 100, 300, and 390 °C for 1/2 h in each case. The information regarding the structural transformations and chemical reactions has been obtained by deconvoluting the complex CEMS spectra and analyzing the contributions of various elements to the XPS spectra. It is shown that oxygen incorporation in the glass initiates the process of recrystallization of the glassy state at a temperature which is lower as compared to its temperature of recrystallization in vacuum. The oxygen‐coordinated phases in the oxide scale and the other phases precipitated due to the reactive thermal treatment have been identified and the physical mechanisms u...

Resistance changes in thin films of copper, aluminium and bismuth have been studied under the bombardment of nitrogen, carbon and argon ions. Variations in resistance with implantation dose have been observed upto doses of ∼ 3 × 1017 ions/cm2 for ion energies in the range 40 to 120 keV. The results are discussed in terms of desorption of gases from the film and a composite action of sputter removal of the film and its structural changes upon ion bombardment. A simple theoretical model is discussed which can qualitatively explain the experimental observations.