Effect of ion current density on the properties of vacuum arc-deposited TiN coatings

The influence of ion current density on the thickness of coatings deposited in a vacuum arc setup has been investigated to optimize the coating porosity. A planar probe was used to measure the ion current density distribution across plasma flux. A current density from 20 to 50 A/m2 was obtained, depending on the probe position relative to the substrate center. TiN coatings were deposited onto the cutting inserts placed at different locations on the substrate, and SEM was used to characterize the surfaces of the coatings. It was found that lowdensity coatings were formed at the decreased ion current density. A quantitative dependence of the coating thickness on the ion current density in the range of 20-50 A/m2 were obtained for the films deposited at substrate bias of 200 V and nitrogen pressure 0.1 Pa, and the coating porosity was calculated. The coated cutting inserts were tested by lathe machining of the martensitic stainless steel AISI 431. The results may be useful for controlling ion flux distribution over large industrial-scale substrates.

Effect of ion nitriding on the microstructure and properties of Maraging steel (250 Grade)

In the present investigation, ion nitriding of Maraging steel (250 grade) has been carried out at three different temperatures i.e., at 435 degrees C, 450 degrees C and 465 degrees C for 10 h duration in order to achieve good wear resistance along with high strength required for the slat track component of aircraft. The microstructure of the base material and the nitrided layer was examined by optical and scanning electron microscope, and various phases present were determined by X-ray diffraction. Various properties, such as, hardness, case depth, tensile, impact, fatigue properties and corrosion resistance were investigated for both un-nitrided and ion-nitrided materials. It is observed that the microstructure of the core material remains unaltered and Fe4N is formed in the hardened surface layer after ion nitriding at all the three temperatures employed. Surface hardness increases substantially after ion nitriding. Surface hardness remains almost the same but case depth increases with the increase in ion nitriding temperature due to greater diffusivity at higher temperatures. Tensile strength, fatigue strength and corrosion resistance are improved but ductility and energy absorbed in impact test decrease on ion nitriding. These results are explained on the basis of microstructural observations. The properties obtained after ion nitriding at 450 degrees C for 10 h are found to be optimum when compared to the other two ion nitriding temperatures.

Ion irradiation as a tool for modifying the surface and optical properties of plasma polymerised thin films

Radio frequency (R.F.) glow discharge polyterpenol thin films were prepared on silicon wafers and irradiated with I10+ ions to fluences of 1 × 1010 and 1 × 1012 ions/cm2. Post-irradiation characterisation of these films indicated the development of well-defined nano-scale ion entry tracks, highlighting prospective applications for ion irradiated polyterpenol thin films in a variety of membrane and nanotube-fabrication functions. Optical characterisation showed the films to be optically transparent within the visible spectrum and revealed an ability to selectively control the thin film refractive index as a function of fluence. This indicates that ion irradiation processing may be employed to produce plasma-polymer waveguides to accommodate a variety of wavelengths. XRR probing of the substrate-thin film interface revealed interfacial roughness values comparable to those obtained for the uncoated substrate's surface (i.e., both on the order of 5 Å), indicating minimal substrate etching during the plasma deposition process.

Elastic properties of fast ion conducting lithium based borate glasses

Elastic properties of Li2O-PbO-B2O3 glasses have been investigated using sound velocity measurements at 10 MHz. Four series of glasses have been investigated with different concentrations of Li2O, PbO and B2O3. The variations of molar volume have been examined for the influences of Li2O and PbO. The elastic moduli reveal trends in their compositional dependence. The bulk and shear modulus increases monotonically with increase in the concentration of tetrahedral boron which increases network dimensionality. The variation of bulk moduli has also been correlated to the variation in energy densities. The Poisson's ratio found to be insensitive to the concentration of tetrahedral boron in the structure. The experimental Debye temperatures are in good agreement with the expected theoretical values. Experimental observations have been examined in view, the presence of borate network and the possibility of non-negligible participation of lead in network formation. (c) 2005 Elsevier B.V. All rights reserved.

Effects of thermal annealing on the properties of zirconia films prepared by ion-assisted deposition

The effect of thermal annealing in the range 300–800 °C on the properties of zirconia films prepared by ion assisted deposition was studied. It was found that at low temperature the cubic phase is formed. This phase is stable up to 700 °C. All the films exhibit a monophasic monoclinic structure at 800 °C. The stress, estimated from X-ray patterns, shows a transition from tensile to compressive with increasing ion fluence. The refractive index and extinction coefficient do not seem to change appreciably up to 700 °C, showing a marked degradation thereafter. Single step annealing to the highest temperature was found to result in better stability than multistep annealing.

Properties of ion assisted deposited titania films

Thin films of titanium dioxide have been deposited using ion assisted deposition with oxygen ions in the energy range 100�500 eV and current densities up to 100 ?A/cm2. It has been observed that the refractive index of the films increases up to 300 eV and the extinction coefficient increased only nominally up to 300 eV. Optical band gap calculations have shown a strong dependence of the gap on the energy of incident ions. Beyond a critical energy and current density of the ions the refractive index and extinction coefficient of the films start deteriorating. It has also been found that beyond the critical values the optical band gap value decreases. The maximum refractive index obtained was 2.49 at an energy of 300 eV and 50 ?A/cm2 current density. Post?deposition annealing of the films at 500?°C resulted in a slight increase in refractive index without affecting the extinction coefficient. X?ray diffraction studies revealed a monophasic anatase structure in these films. ?

Magnetism, exchange and crystal field parameters in the orbitally unquenched Ising antiferromagnet FePS3

FePS3 is a layered antiferromagnet (T N=123 K) with a marked Ising anisotropy in magnetic properties. The anisotropy arises from the combined effect of the trigonal distortion from octahedral symmetry and spin-orbit coupling on the orbitally degenerate5 T 2g ground state of the Fe2+ ion. The anisotropic paramagnetic susceptibilities are interpreted in terms of the zero field Hamiltonian, ?=?i [?(L iz 2 ?2)+|?|L i .S i ]?? ij J ij S i .S j . The crystal field trigonal distortion parameter ?, the spin-orbit coupling ? and the isotropic Heisenberg exchange,J ij, were evaluated from an analysis of the high temperature paramagnetic susceptibility data using the Correlated Effective Field (CEF) theory for many-body magnetism developed by Lines. Good agreement with experiment were obtained for ?/k=215.5 K; ?/k=166.5 K;J nn k=27.7 K; andJ nnn k=?2.3 K. Using these values of the crystal field and exchange parameters the CEF predicts aT N=122 K for FePS3, which is remarkably close to the observed value of theT N. The accuracy of the CEF approximation was also ascertained by comparing the calculated susceptibilities in the CEF with the experimental susceptibility for the isotropic Heisenberg layered antiferromagnet MnPS3, for which the high temperature series expansion susceptibility is available.

Modulation of vesicular properties by variation of shapes of bolaform counter ions in hybrid-ion paired surfactants

Four new vesicle-forming bolaphile/amphiphile ion pairs are synthesized; the bolaphile shapes in such hybrid systems strongly control their vesicular properties.

Vesicle formation from dimeric surfactants through ion-pairing. Adjustment of polar headgroup separation leads to control over vesicular thermotropic properties

Eight new vesicle-forming dimeric surfactants are synthesized: the polar headgroup separation in such dimeric amphiphiles strongly influences their vesicular thermotropic phase-transition behaviour.

Optical and structural properties of reactive ion beam sputter deposited CeO2 films

Optical and structural properties of reactive ion beam sputter deposited CeO2 films as a function of oxygen partial pressures (P-O2) and substrate temperatures (T-s) have been investigated. The films deposited at ambient temperature with P-O2 of 0.01 Pa have shown a refractive index of 2.36 which increased to 2.44 at 400 degrees C. Refractive index and extinction coefficient are sensitive up to a T-s of similar to 200 degrees C. Raman spectroscopy and X-ray diffraction (XRD) have been used to characterise the structural properties. A preferential orientation of (220) was observed up to a T-s of 200 degrees C and it changed to (200) at 400 degrees C: and above. Raman line broadening, peak shift and XRD broadening indicate the formation of nanocrystalline phase for the films deposited up to a substrate temperature of 300 degrees C. However, crystallinity of the films were better for T-s values above 300 degrees C. In general both optical and structural properties were unusual compared to the films deposited by conventional electron beam evaporation, but were similar in some aspects to those deposited by ion-assisted deposition. Apart from thermal effects, this behavior is also attributed to the bombardment of backscattered ions/neutrals on the growing film as well as the higher kinetic energy of the condensing species, together resulting in increased packing density. (C) 1997 Elsevier Science S.A.

Structural and transport properties of high energy ion irradiated YBCO

The effects of 100 MeV Oxygen and 200 MeV Silver ions on the structural and transport properties of YBCO thin films are reported. Both normal state and superconducting properties were studied on Laser ablated and high pressure oxygen sputtered films. Precise electrical resistance and critical current measurements near T-c were made and the data obtained were analysed in the light of existing models of para-coherence near T-c and the other aspects of radiation damage arising from microstructural studies such as atomic force microscopy (AFM). There was evidence of sputtering by high energy ions from AFM measurement. (C) 1998 Elsevier Science Ltd. All rights reserved.

Effect of lithium ion irradiation on the transport and optical properties of Bridgman grown n-type InSb single crystals

Single crystal (100) wafers of n-InSb were implanted with 50 MeV Li3+ ions at various fluences ranging from 10(10) to 10(14) ions/cm(2) at room temperature. Investigations of the optical, electrical, and structural properties of the as-grown, irradiated, annealed wafers were carried out by infrared and Raman spectroscopies, Hall measurements, and high resolution x-ray diffraction (HRXRD). In the case of samples irradiated with an ion fluence of 1.6x10(14) ions/cm(2), electrical measurements at 80 K reveal that there is a decrease in carrier concentration from 8.5x10(15) (for unirradiated) to 1.1x10(15)/cm(3) and an increase in mobility from 5.4x10(4) to 1.67x10(5) cm(2)/V s. The change in carrier concentration is attributed to the creation of electron trap centers induced by ion beam irradiation and the increase in mobility to the formation of electrical inactive complexes. Nevertheless, even with the irradiation at 1.6x10(14) ions/cm(2) fluence the crystalline quality remains largely unaffected, as is seen from HRXRD and Raman studies. (C) 2001 American Institute of Physics.

Critical properties of the double-exchange ferromagnet Nd(0.6)Pb(0.4)MnO(3)

Results of a study of dc magnetization M(T,H), performed on a Nd(0.6)Pb(0.4)MnO(3) single crystal in the temperature range around T(C) (Curie temperature) which embraces the supposed critical region \epsilon\=\T-T(C)\/T(C)less than or equal to0.05 are reported. The magnetic data analyzed in the critical region using the Kouvel-Fisher method give the values for the T(C)=156.47+/-0.06 K and the critical exponents beta=0.374+/-0.006 (from the temperature dependence of magnetization) and gamma=1.329+/-0.003 (from the temperature dependence of initial susceptibility). The critical isotherm M(T(C),H) gives delta=4.54+/-0.10. Thus the scaling law gamma+beta=deltabeta is fulfilled. The critical exponents obey the single scaling equation of state M(H,epsilon)=epsilon(beta)f(+/-)(H/epsilon(beta+gamma)), where f(+) for T>T(C) and f(-) for T

Properties of Al2O3 films prepared by argon ion assisted deposition

Aluminum oxide films have been prepared by ion assisted deposition using argon ions with energy in the range 300 to 1000 eV and current density in the range 50 to 220 μA/cm2. The influence of ion energy and current density on the optical and structural properties has been investigated. The refractive index, packing density, and extinction coefficient are found to be very sensitive to the ion beam parameters and substrate temperatures. The as-deposited films were found to be amorphous and could be transformed into crystalline phase on annealing. However, the crystalline phases were different in films prepared at ambient and elevated substrate temperatures.