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Nano-composite Co 84 Zr 16 N (CZN) films were prepared by reactive co-sputter deposition. As-deposited CZN films have not shown any exchange bias effect. But annealed (390 K) and field cooled samples have shown exchange bias phenomena. The observed exchange bias is attributed to inter-cluster exchange coupling between ferromagnetic and antiferromagnetic nano-composite phase. High resolution transmission electron microscope study reveals that, the CZN films are composed of ordered and crystalline ferromagnetic Cobalt nano-clusters embedded in an antiferromagnetic matrix. X-ray diffraction confirms the poly-crystalline growth of the CZN films with a preferred fcc (622) phase formation. In-plane anisotropy of the exchange biased films was investigated by rotational magnetization curve, and the analysis shows that the magnetization reversal behaves according to the coherent rotation of the magnetic moment vector. Effectively, exchange bias effect in such single layer films could be attributed to co-existing antiferromagnetic and ferromagnetic phase within the single layer. Such single layer nano-composite films can be a possible alternative to the bilayer combination of antiferromagnetic/ferromagnetic exchange biased films and are ideally suited for spintronics and tunnel junction applications.

CdS–Bi2S3 bi-layer thin films have been deposited by chemical bath deposition method on Indium Tin Oxide glass substrate at room temperature. The as-deposited thin films were annealed at 250 °C in an air atmosphere for 1 h. An air annealed thin film was irradiated using Au9+ ions with the energy of 120 MeV at fluence 5×1012 ions/cm2 using tandem pelletron accelerator. The irradiation induced modifications were studied using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Raman spectroscopy, UV spectroscopy and I–V characteristics. XRD study reveals that the as-deposited thin films were nanocrystalline in nature. The decrease in crystallite size, increase in energy band gap and resistivity were observed after irradiation. Results are explained on the basis of energy deposited by the electronic loss after irradiation. The comparative results of as-deposited, air annealed and irradiated CdS–Bi2S3 bi-layer thin films are presented.

An in-situ high temperature (1000 K) setup is designed and installed in the materials science beam line of superconducting linear accelerator at the Inter-University Accelerator Centre (IUAC) for temperature dependent ion irradiation studies on the materials exposed with swift heavy ion (SHI) irradiation. The Gd 2 Ti 2 O 7 pyrochlore is irradiated using 120 MeV Au ion at 1000 K using the high temperature irradiation facility and characterized by ex-situ X-ray diffraction (XRD). Another set of Gd 2 Ti 2 O 7 samples are irradiated with the same ion beam parameter at 300 K and simultaneously characterized using in-situ XRD available in same beam line. The XRD studies along with the Raman spectroscopic investigations reveal that the structural modification induced by the ion irradiation is strongly dependent on the temperature of the sample. The Gd 2 Ti 2 O 7 is readily amorphized at an ion fluence 6 × 10 12 ions/cm 2 on irradiation at 300 K, whereas it is transformed to a radiation-resistant anion-deficient fluorite structure on high temperature irradiation, that amorphized at ion fluence higher than 1 × 10 13 ions/cm 2 . The temperature dependent ion irradiation studies showed that the ion fluence required to cause amorphization at 1000 K irradiation is significantly higher than that required at room temperature irradiation. In addition to testing the efficiency of the in-situ high temperature irradiation facility, the present study establishes that the radiation stability of the pyrochlore is enhanced at higher temperatures.

This paper reports an unusual extent of mixing in Bi/Te thin bilayer system using 90 MeV Au and 95 MeV Ag ions of energies having same electronic energy loss (S e ) value. The analysis is made using Rutherford backscattering spectroscopy and atomic force microscopy. The mixing variance as observed from the depth profiles extracted from RBS data using Rutherford universal manipulation program is found to be higher for Au irradiated samples. Similarly higher sputtering yield is observed for Au ions than Ag ions. These have been accounted to ion velocity effect of Bi/Te with Au ions having velocity ~1.3 times slower to Ag ions.

MeV Ag ions have been used to study the swift heavy ion (SHI) induced modification in Te/Bi bilayer system. The samples were analysed using Rutherford backscattering spectroscopy (RBS), Atomic force microscopy (AFM) and X-ray diffractometer (XRD). The elemental depth study with RBS results show a strong mixing between the top Te layer and the underlying Bi layer on irradiation. Surface roughness as calculated by AFM is found to increase from 8 to 30 nm on irradiation for the fluence 3x10 13 ions/cm 2 . XRD results confirm the formation of Bi-Te alloy phases on mixing and are expected to be formed due to the interfacial reaction taking place within the molten ion tracks. Ion beam mixing has the potential to induce the formation Bi-Te alloy thin films which are the promising candidate for thermoelectric applications near room temperature. Copyright © 2014 VBRI press.

TiO2 thin films deposited by electron beam evaporation technique annealed in either O2 or Ar atmosphere showed ferromagnetism at room temperature. The pristine amorphous film demonstrates anatase phase after annealing under Ar/O2 atmosphere. While the pristine film shows a super-paramagnetic behavior, both O2 and Ar annealed films display hysteresis at 300 K. X-ray photo emission spectroscopy (XPS), Raman spectroscopy, Rutherford’s backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) were used to refute the possible role of impurities/contaminants in magnetic properties of the films. The saturation magnetization of the O2 annealed film is found to be higher than the Ar annealed one. It is revealed from shifting of O 1s and Ti 2p core level spectra as well as from the enhancement of high binding energy component of O 1s spectra that the higher magnetic moment is associated with higher oxygen vacancies. In addition, O2 annealed film demonstrates better crystallinity, uniform deposition and smoother surface than that of the Ar annealed one from glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM). We conclude that although ferromagnetism is due to oxygen vacancies, the higher magnetization in O2 annealed film could be due to crystallinity, which has been observed earlier in Co doped TiO2 film deposited by pulsed laser deposition (Mohanty et al., 2012 [10] ).

The Al-induced crystallization of amorphous (a)-Si under thermal annealing and swift heavy ion irradiation has been investigated. The c-Al (50 nm)/a-Si (150 nm) thin films have been prepared on thermally oxidized Si-substrates. A set of samples have been annealed at temperatures ranging from 100 °C to 500 °C to achieve crystallization. Another set of similar samples have been irradiated at an elevated temperature of 100 °C using 100 MeV Ni+7 ions at fluences of 1 × 1012 ions-cm−2, 5 × 1012 ions-cm−2, 1 × 1013 ions-cm−2, and 5 × 1013 ions-cm−2. The crystallization of a-Si is observed at annealing temperature of 200 °C. The crystallinity increases with increasing temperature. On the other hand, irradiation using swift heavy ion leads to crystallization of a-Si at significantly lower temperature of 100 °C. The irradiation induced crystallization is explained in terms of creation of vacancies, interstitials and mixing of Si and Al atoms at a-Si/c-metal interface due to energy deposited by swift Ni ions.

The pyrochlore structure is of particular interest to the nuclear industry due to its potential for nuclear waste immobilization and as a host material for inert matrix fuels. Herein, the experimental results of the temperature and ion fluence dependence on the disordered ion tracks produced by the electronic excitation in the pyrochlore compound Nd2Zr2O7 are presented. The samples were exposed to extreme conditions of ion irradiation with 100 MeV 107Ag9+ ions at ion fluences ranging from 3 × 1011 ions/cm2 to 2 × 1013 ions/cm2 at temperatures of 300 K and 1000 K. The in-situ X-ray diffraction along with micro-Raman spectroscopic analysis on Nd2Zr2O7 samples irradiated at 300 K displays order-disorder phase transformation which is consistent with earlier reports. The direct-impact model is used to calculate the amorphous fraction which exists due to massive deposition of electronic-energy in a localized region, and the estimated value of track radius is 2.98 ± 0.56 nm. Furthermore, theoretical thermal spike simulations are performed to estimate the track radius (∼4.2 nm) which provides strong support for experimental results. To simulate the response of Nd2Zr2O7 under nuclear reactor environment, irradiation carried out at an elevated temperature that exhibits significant radiation tolerance. Its substantiality is revealed from comparative temperature dependent irradiation studies where a slow rate of amorphization is found at the elevated temperature because of the competition between defect production and thermal healing mechanism. Thus, obtained results strongly endorse the appositeness of Nd2Zr2O7 as inert matrix material for the fabrication of futuristic nuclear fuel.

Yttria stabilized zirconia pellets with different crystallite sizes were irradiated with 80 MeV Ag6+ ions at room temperature and 1000 K to understand the effect of crystallite size/material microstructure and irradiation temperature on the radiation tolerance against high energy heavy ions [where electronic energy loss (Se) dominates]. XRD and Raman spectroscopy measurements reveal that, irrespective of the irradiation temperature, the nano-crystalline samples suffered more damage when compared with the bulk-like sample. A reduction in the irradiation damage, i.e., improvement in the radiation tolerance, was observed for all the samples irradiated at 1000 K. The reduction in the damage, however, was remarkably higher for the nano-crystalline samples compared with the bulk-like sample, and hence the difference in the damage between the bulk-like and nano-crystalline samples was also significantly lower at 1000 K than that at room temperature. The irradiation damage, against Se, was thus found to be critically dependent on the interplay between the irradiation temperature and the crystallite size. These results are explained on the basis of the “in-elastic thermal spike” model by taking into consideration the combined effects of crystallite size and environmental (irradiation) temperature on the electron-phonon coupling strength and the lattice thermal conductivity and hence on the resulting thermal spike. These results, besides being crucial from the fundamental prospect of comprehending the size and temperature dependent radiation damage against Se, may also be important from the perspective of designing highly nano-crystalline materials for applications in various radiation environments.

We report on the effect of 80 keV Xe+ ion irradiation on the commercially available, sectioned 10B pencil-graphite specimens subjected to normal and oblique angle incidence of ions (θ i = 0°–70°) and considering a fixed ion fluence of . The pristine and irradiated samples were characterized by powder x-ray diffraction, atomic force microscopy and Raman spectroscopy studies. Unlike pristine graphite and normal incidence cases, several ripple patterns can be visualized in the atomic force micrographs of the specimens irradiated with an oblique angle incidence. Moreover, apart from conventional G-band located at , a distinct diamond-like carbon (DLC) phase has been witnessed at in the Raman spectra of the graphitic specimens subjected to ion impact and for values of 50° and 70°. The formation of the DLC phase along with surface ripple formation would find numerous scopes while dealing with properties such as surface transport, field emission and mechanically hard coating in miniaturized devices.

Effects of Co doping on the structural, optical and magnetic properties of ZnO samples prepared by the sol–gel method are reported. The X-ray diffraction, X-ray photoelectron spectroscopy and UV–visible spectroscopy confirmed the substitution of Co ions on Zn sites without changing the wurtzite structure. No segregated secondary phases or Co rich clusters were detected. Optical absorption spectra of the samples exhibit a blue shift in the absorption band edge with increasing dopant concentration. The photoluminescence measurements show a blue shift in UV emission peak with the increase in Co concentration and a slight shift in the green emission band at around 509 nm which gets suppressed for higher sintering temperature. The field dependence of magnetization observed at room temperature exhibits clear ferromagnetic behavior. Efforts have been made to fit the experimental M – H data using the magnetic polarons model (BMP) which involves localized carriers and magnetic cations. The calculated concentration of the BMPs is found to be below the typical percolation threshold in ZnO. Thus BMP model alone is not sufficient to explain the room temperature ferromagnetic behavior in ZnO. To know the exact magnetic ordering in the system, we also attempted to fit temperature dependent magnetization curves with the Curie–Weiss Law which shows antiferromagnetic ordering in all samples.

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the main inorganic component of hard tissues like bone and teeth. HAp incorporated with magnetic ions, play an important role in cell separation, magnetic resonance imaging (MRI), targeted drug delivery and in hyperthermia treatment of cancer. In this study, the effect of 60 MeV Si 5+ ion on the hydrothermally synthesized Fe 3+ doped hydroxyapatite (Fe-HAp, 33 nm) was investigated. At higher fluences, partial amorphization with an increase in the cluster size and surface roughness was observed. Depending on the ion fluence, pores ranging from 300 to 360 nm in size were produced. Irradiated Fe-HAp samples showed enhanced haemocompatibility and bioactivity. The drug (amoxycillin, AMX) loaded irradiated samples exhibited high antimicrobial activity. Copyright © 2013 VBRI press.

We report on the high temperature ferromagnetism in Co-doped ZnO samples with 2%, 4% and 6% nominal Co concentrations prepared by the sol–gel method. X-ray diffraction and X-ray photoelectron spectroscopy analyses confirm the absence of metallic Co clusters or any other impurity phases different from wurtzite-type ZnO. It is also observed that Co has occupied Zn sites. UV–visible absorption studies show an increase in band gap with Co concentration. The field dependence of magnetization exhibited clear ferromagnetism at room temperature with saturation magnetization and coercive field of the order of 0.0066–0.0239 emu/g and 149.09–40.31 Oe, respectively. Increase of saturation magnetization value with Co doping indicated that the ferromagnetism in the samples may be due to percolation of bound magnetic polarons.

The effect of swift heavy 100 MeV Ag7+ ions irradiation was studied on hydroxyapatite (HAp) thin film prepared by pulsed laser deposition technique (PLD). The GIXRD analysis confirmed the absence of any phase in the HAp phase due to irradiation. In addition, there was a considerable decrease in crystallinity and crystallite size on irradiation. There was no significant variation in the stoichiometry of the irradiated films. Irradiation seemed to decrease the optical band gap energy of HAp thin films. The surface roughness, wettability and bioactivity were improved on irradiation of the samples. Amount of amoxicillin loading/release increased (10%) in ion beam irradiated (1 × 1012 ions cm−2) sample. Irradiated sample showed fast rate of amoxicillin (AMX) release than the pristine. Bactericidal effect was found to increase on irradiation. Surface modified and antibiotics incorporated HAp coated titanium implants may be used to prevent post-surgical infections and to promote bone-bonding of orthopedic devices.

We have investigated neutron irradiation effects on the optical, structural and chemical properties of polyallyl diglycol carbonate (PADC) polymer, commercially named as CR-39. For this purpose, PADC samples were exposed with 4 MeV Am–Be neutron source at fluences varying from 2.36 × 10 6 to 5.94 × 10 7 n/cm 2 . The modifications so induced were analyzed using UV–Visible spectroscopy, X-ray diffraction Measurement (XRD), Photoluminescence (PL) and Fourier Transform infrared (FTIR) spectroscopy in the total attenuation reflection (ATR) mode. UV–Vis spectra of pristine and neutron irradiated PADC polymer sheets exhibit a decreasing trend in optical band gap. This decline in optical band gap with increasing fluence has been discussed on the basis of neutron irradiation induced defects in PADC. The XRD pattern of PADC shows the decreasing intensity of peak positions with increasing in fluence, which suggest that semicrystallinity of PADC changes slightly to amorphous phase after irradiation. At low fluence, crystallinity was found to increase but at higher fluence, it decreased which could be ascribed to neutron- induced defects in the polymer samples. Crystallite size calculated using Scherrer formula indicates a change and reflects the formation of disordered system in the irradiated polymer samples. The PL spectra show that the intensity of PL peak decreased with increase in fluence, which may be due to the disordered system via creation of defects in the irradiated polymer. The FTIR spectrum shows an overall reduction in intensity of the typical bands, indicating the degradation of PADC polymer after irradiation. These results so obtained can be used successfully in dosimetery using well reported protocols.

Piezoelectric and other physical properties are significantly enhanced at (or near) a morphotropic phase boundary (MPB) in ferroelectrics. MPB materials have attracted significant attention owing to both fundamental physics as well as the possibility of well-regulated energy and information storage devices which are dominated by lead (Pb)-based materials. Here, we report the crystal structure, Raman spectra, dielectric constant and polarization near the MPB of lead free (1 - x) Na0.5Bi0.5TiO3 - x BaTiO3 (0.00 ⩽ x ⩽ 0.10) solid-solution, prepared by sol-gel auto combustion technique and sintered by microwave sintering technique. With the addition of BaTiO3 into Na0.5Bi0.5TiO3, it induces a structural phase transition from R3c (a single phase) to R3c + P4mm (a dual phase) close to x = 0.06 and 0.07 and transform to a high symmetry tetragonal phase P4mm at higher compositions (x = 0.08 to 0.10) as evident from our x-ray Rietveld refinement and Raman spectroscopic results. We perform first-principles calculations based on density functional theory that confirm a structural transition from a rhombohedral to a tetragonal phase under increasing x. In the prepared solid solution, an anomalous enhancement of remnant polarization ([Formula: see text]) was observed for x = 0.06 and 0.07, which has been explained based on the existence of the MPB. On the other hand, the value of coercive field [Formula: see text] was found to be decreased linearly from x = 0.00 to 0.06; it is constant for higher compositions. Further details of the ferroelectric properties on the electric field poled samples have been studied and compared with the as-grown (unpoled) samples.

Ge nanocrystals embedded in an SiO2 matrix were prepared by the atom beam co-sputtering (ABS) method from a composite target of Ge and SiO2. The as-deposited films were rapid thermally annealed at the temperatures 700 and 800 °C in nitrogen ambience. The structure of the films was evaluated by using X-ray diffraction (XRD) and Raman spectroscopy. XRD results reveal that as-deposited films are amorphous in nature whereas annealed samples show crystalline nature. Raman scattering spectra showed a peak of Ge–Ge vibrational mode shifted downwards to 297 cm−1, presumably caused by quantum confinement of phonons in the Ge nanocrystals. Rutherford backscattering spectrometry has been used to measure the thickness and Ge composition of the composite films. Size variation of Ge nanocrystals with annealing temperature has been discussed. The advantages of ABS over other methods are highlighted.

Swift heavy ion induced stress in a pulsed laser deposited textured ZnO thin film is reported. In situ X-ray diffraction (XRD) measurements are carried out during ion irradiation at incremented fluences under 120 MeV Ag(+9) ions. The average grain size, lattice constant 'c', and stress in the film are calculated from the diffraction pattern. The nature of the stress is intrinsic and the origin can be attributed to the strong density of defects like dislocations at the grain boundaries as evidenced by micro-Raman, Fourier transform infrared (FTIR) spectroscopy and Atomic Force microscopic (AFM) studies. (C) 2010 Elsevier Ltd. All rights reserved.

Our long term objective is to study the swift heavy ion (SHI) irradiation effect on photoanode of dye-sensitized solar cell (DSSC) with the aim to investigate the stability of DSSC component in space irradiations and possibility of improvement in efficiency of DSSC due to ion induced effects in oxide layer. The DSSC photoanode consists of three layers viz; transparent conducting oxide (TCO), porous oxide with wide band gap and monolayer of dye molecule on top of corning glass substrate respectively. In the present study, procured radio frequency (RF) sputtered indium tin oxide (ITO) film on corning glass substrate were irradiated by SHI using 110 MeV Ni8+ ions at different fluences ranging from 3.0 × 1011 ion/cm2 to 1.0 × 1014 ion/cm2. After irradiation significant changes have been observed in the structural, optical and electrical properties using X-ray diffraction (XRD), UV–Vis and Four Probe measurements, respectively. Overall there is 13% increase in optical transmittance which is favorable and moderate increase in sheet resistance from 8 Ω/□ to 18 Ω/□ which is still within acceptable limits for DSSC applications.

We demonstrate a highly selective and reversible NO2 resistive gas sensor using vertically aligned MoS2 (VA-MoS2) flake networks. We synthesized horizontally and vertically aligned MoS2 flakes on SiO2/Si substrate using a kinetically controlled rapid growth CVD process. Uniformly interconnected MoS2 flakes and their orientation were confirmed by scanning electron microscopy, x-ray diffraction, Raman spectroscopy and x-ray photoelectron spectroscopy. The VA-MoS2 gas sensor showed two times higher response to NO2 compared to horizontally aligned MoS2 at room temperature. Moreover, the sensors exhibited a dramatically improved complete recovery upon NO2 exposure at its low optimum operating temperatures (100 °C). In addition, the sensing performance of the sensors was investigated with exposure to various gases such as NH3, CO2, H2, CH4 and H2S. It was observed that high response to gas directly correlates with the strong interaction of gas molecules on edge sites of the VA-MoS2. The VA-MoS2 gas sensor exhibited high response with good reversibility and selectivity towards NO2 as a result of the high aspect ratio as well as high adsorption energy on exposed edge sites.

This paper reports the effect of the irradiation of 50 MeV Li+3 ions on the thermomechanical properties of PMMA/PC blends. The radiation has been carried out at fluences of 1010 to 1012 ions/cm2 to observe any kind of chain scissoring/crosslinking occurring in the sample. The irradiated as well as the pristine samples have been characterized using X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM) and dynamic mechanical analyzer (DMA) to study the induced changes in the structural, morphological and mechanical properties in blend films. The XRD results show an increase in the degree of crystallinity upon ion irradiation at low fluences (≤1011 ions/cm2) and a decrease in crystallinity at high fluences (>1011 ions/cm2), while the FTIR spectra show no appreciable change after irradiation. The mechanical characterization reveals that radiation significantly modifies the mechanical properties and the glass transition temperature of these polymeric blends.

Different concentrations (i.e., 10, 20, 30, and 40 wt%) of Al metal are dispersed in polymethylmethacrylate (PMMA) matrix and the composite films are prepared by solution casting method. The frequency and temperature dependence of dielectric constant, dielectric loss, and conductivity of pure polymer and polymer composites filled with Al-metal filler are studied in the broad frequency range from 100 Hz to 10 MHz and in the temperature range 25—80°C. It is observed that the dielectric constant, dielectric loss, and electrical conductivity gradually increase with filler concentration and also with temperature and is explained in terms of hopping conduction mechanism. The electrical conductivity of the composites obeys universal power law model (i.e., σ = Af n), where n is power exponent. A comparison of dielectric constant values of PMMA/Al composites is made with predictions of theoretical models and it is observed that an empirical power equation gives a better fit to our results. Structural property of the composites is studied by means of X-ray diffraction. The results show that the crystallinity and crystalline size increase with increasing concentration of aluminum filler. Average surface roughness is observed to change with filler concentration as obtained from atomic force microscopy and scanning electron microscopy analysis.

Swift Heavy Ion (SHI) irradiation of the polymeric materials modifies their physico-chemical properties. Lexan polycarbonate films were irradiated with 95 MeV oxygen ions to the fluences of 1010, 1011, 1012, 1013 and 2 × 1013 ions/cm2. Characterization of optical, chemical, electrical and structural modifications were carried out by UV–Vis spectroscopy, FTIR spectroscopy, Dielectric measurements and X-ray Diffraction. A shift in the optical absorption edge towards the red end of the spectrum was observed with the increase in ion fluence. The optical band gap (Eg), calculated from the absorption edge of the UV–Vis spectra of these films in 200–800 nm region varied from 4.12 eV to 2.34 eV for virgin and irradiated samples. The cluster size varied in a range of 69–215 carbon atoms per cluster. In FTIR spectra, appreciable modification in terms of breaking of the cleavaged C–O bond of carbonate and formation of phenolic O–H bond was observed on irradiation. A rapidly decreasing trend in dielectric constant is observed at lower frequencies. The dielectric constant increases with fluence. It is observed that the loss factor increases moderately with fluence and it may be due to scissoring of polymer chains, resulting in an increase in free radicals. A sharp increase in A.C. conductivity in pristine as well as in irradiated samples is observed with frequency and is attributed to scissoring of polymer chains. XRD analyses show significant change in crystallinity with fluence. A decrease of ∼9.02% in crystallite size of irradiated sample at the fluence of 2 × 1013 ions/cm2 is observed.

In this study, composite films consisting of an insulating polymethyl methacrylate (PMMA) polymer matrix and metal powder (Cu) additive were prepared by solution costing method. These films were irradiated with 140 MeV silver ions at the fluences of 1 × 1011 ions/cm2 and 1 × 1012 ions/cm2. The radiation induced changes in dielectric, structural and surface properties of PMMA/Cu composites were studied using impedance/gain phase-analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was observed that the dielectric properties and ac electrical conductivity increased significantly with the concentration of dispersed metal powder (Cu) and also with the fluence. This reveals that ion beam irradiation creates free radicals, unsaturation etc. due to emission of hydrogen and/or other volatile gases, which makes the polymer more conductive. XRD analysis of the pristine and irradiated samples shows that the crystallinity improved upon irradiation at low fluence and deteriorated on further increase of the fluence, which could be attributed to cross linking of polymer chains at low fluence and degradation at higher fluence. High energy ion beam irradiation of semicrystalline polymer composite films changes its Tg behavior as observed from DSC analysis. This result is also corroborated with the results of XRD. The average surface roughness and topography of surfaces changed with the concentration of filler and also with the ion fluence as revealed from AFM/SEM analysis.

Swift heavy ion (SHI) induced modification at metal/Si interfaces has emerged as an interesting field of research due to its large applications. In this study, we investigate SHI-induced mixed molybdenum silicide film with ion fluences. The molybdenum thin films were deposited on silicon substrates using e-beam evaporation at 10−8 torr vacuum. Thin films were irradiated with Au ions of energy 120 MeV to form molybdenum silicide. The samples were characterized by grazing incidence X-ray diffraction (GIXRD) technique for the identification of phase formation at the interface. Rutherford backscattering spectrometry (RBS) was used to investigate the elemental distribution in the films. The mixing rate calculations were made and the diffusivity values obtained lead to a transient melt phase formation at the interface according to thermal spike model. Irradiation-induced effects at surface have been observed and roughness variations at the surface were calculated using atomic force microscopy (AFM) technique. Copyright © 2009 John Wiley & Sons, Ltd.

Poly(vinylidene fluoride-co-hexafluoropropylene) (HFP) nanocomposites with layered silicate have been synthesized via the melt extrusion route. The intriguing nanostructure, crystalline structure, morphology, and thermal and mechanical properties of the nanocomposites have been studied and compared critically with pristine polymer. HFP forms intercalated or partially exfoliated nanostructure (or both) in the presence of nanoclay, depending on its concentration. The bombardment of high-energy swift, heavy ions (SHI) on HFP and its nanocomposites has been explored in a wide range of fluence. The nanoclay induces the piezoelectric beta-phase in bulk HFP, and the structure remains intact upon SHI irradiation. SHI irradiation degrades pure polymer, but the degradation is suppressed radically in nanocomposites. The heat of fusion of pristine HFP has drastically been reduced upon SHI irradiation, whereas there are relatively minute changes in nanocomposites. The coarsening on the surface and bulk of HFP and its nanocomposite films upon SHI irradiation has been measured quantitatively by using atomic force microscopy. The degradation has been considerably suppressed in nanocomposites through cross-linking of polymer chains, providing a suitable high-energy, radiation-resistant polymeric material. A mechanism for this behavior originating from the swelling test and gel fraction (chemical cross-linking) as a result of SHI irradiation has been illustrated.

CdTe polycrystalline thin films possessing hexagonal phase regions are obtained by spray deposition in presence of a high electric field. Thin film samples are irradiated with 100 MeV Ag ions using Pelletron accelerator to study the swift heavy ion induced effects. The ion irradiation results in the transformation of the metastable hexagonal regions in the films to stable cubic phase due to the dense electronic excitations induced by beam irradiation. The phase transformation is seen from the X-ray diffraction patterns. The band gap of the CdTe film changes marginally due to ion irradiation induced phase transformation. The value changes from 1.47 eV for the as deposited sample to 1.44 eV for the sample irradiated at the fluence 1 × 10 13 ions/cm2. The AFM images show a gradual change in the shape of the particles from rod shape to nearly spherical ones after irradiation.

High-energy ion beam irradiation of the polymers is a good technique to modify the properties such as electrical conductivity, structural behaviour and mechanial properties. Polyaniline thin films doped with hydrochloric acid (HCl) were prepared by oxidation of ammonium persulphate. The effect of Swift Heavy Ions irradiation on the electrical and structural properties of polyaniline has been measured in this study. Polyaniline films were irradiated by oxygen ions (energy 80 MeV, charge state O+7) with fluence varying from 1 × 1010 to 3 × 1012 ions/cm2. The studies on electrical and structural properties of the irradiated polymers were investigated by measuring V-I using four probe set-up and X-ray diffraction (XRD) using Bruker AXS, X-ray powder diffractometer. V-I measurements shows an increase in the conductivity of the film, XRD pattern of the polymer shows that the crystallinity improved after the irradiation with Swift Heavy Ions (SHI), which could be attributed to cross linking mechanism.

Commercially available biaxially oriented polypropylene (BOPP) films were irradiated with 90 MeV Ni 8+ ions and 120 MeV Ag 11+ ions at different fluencies varying from 10 10 to 3 x 10" ions/cm 2 and then grafted with glycidyl methacrylate (GMA) using benzoyl peroxide (BPO) as chemical initiator. As the reaction temperature was below the melting point, PP was modified in the solid phase. A comparative study for the GMA grafting using BPO initiator in virgin as well as in the SHI irradiated BOPP indicates that the heterogeneity of the grafted GMA domains on the BOPP surface was higher in SHI irradiated system. Contact angle measurements showed an increasingly hydrophilic nature in the direction from pure PP to grafted PP-g-GMA. These results are intended to benefit the synthesis and properties of a functional polymer, useful in developing a compatibilizer for PP/Cloisite 30B nanocomposites.

Polymethyl methacrylate (PMMA) was synthesized by solution polymerization technique. Different concentrations of organometallic compound/palladium (II) acetylacetonate [Pd(acac)] were dispersed in PMMA. The composite films were irradiated with 3 MeV proton beam at a fluence of 10 13 ions/cm 2 . The radiation induced changes in structural and chemical properties were studied by means of X-ray diffraction (XRD) and FTIR spectroscopy. The XRD results reveal that the crystalline size and crystallinity of the composite films decrease after irradiation, however crystallinity increases with filler concentration. This is due to the crystalline behavior of Pd(acac). Fourier transform infrared spectroscopy has been studied in transmittance mode. The decrement in the peak intensity is attributed to chain scissioning of the polymeric bonds. Chain scissioning is also responsible for the decrement in the crystallinity of the composites. The glass transition temperature was observed to decrease after irradiation as revealed from differential scanning calorimetry (DSC) thermograms. Scanning electron microscopy (SEM) reveals that the surface roughness increases due to irradiation.

Poly(m-toluidine) (PmT), a derivative of polyaniline, has been prepared by chemical oxidation polymerization method. The synthesized PmT powder is blended with plasticized polyvinyl chloride (PVC) ...

Commercially purchased CR-39 and PET polymers were irradiated by 100 MeV O7+ ions of varying fluences, ranging from 1×1011 to 1×1013 ions/cm2. The effects of swift heavy ions (SHI) on the structural, optical and chemical properties of CR-39 and PET polymers were studied using X-ray diffraction (XRD), UV–visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The XRD patterns of CR-39 show that the intensity of the peak decreases with increasing ion fluence, which indicates that the semicrystalline structure of polymer changes to amorphous with increasing fluences. The XRD patterns of PET show a slight increase in the intensity of the peaks, indicating an increase in the crystallinity. The UV–visible spectra show the shift in the absorbance edge towards the higher wavelength, indicating the change in band gap. Band gap in PET and CR-39 found to be decrease from 3.87 to 2.91 and 5.3–3.5 eV, respectively. The cluster size also shows a variation in the carbon atoms per cluster that varies from 42 to 96 in CR-39 and from 78 to 139 in PET. The FTIR spectra show an overall reduction in intensity of the typical bands, indicating the degradation of polymers after irradiation.

Zn–Te bilayer thin films have been deposited on well-cleaned glass substrate using vacuum thermal evaporation technique under a vacuum of 5 × 10 −5 Torr. These bilayer films have been modified by Swift heavy ion (SHI) irradiation, vacuum thermal annealing (VTA) and rapid thermal annealing (RTA). Characterization of ZnTe bilayer thin films have been performed by X-ray diffraction, optical reflectance, atomic force microscopy (AFM) and X-ray fluorescence (XRF) measurements. Irradiated ZnTe bilayer thin films have been obtained in cubic phase, Optical band gap values have been found in between the range of ZnTe compound. Increased surface roughness has been observed in irradiated films, compositional analysis has been confirmed by XRF measurements.

Poly(vinylidene fluoride) (PVDF) has been made radiation-resistant through a nanocomposite (NC) route. The bombardment of high-energy swift heavy ions (SHI) on PVDF and its NCs with layered silicate has been studied in a range of fluences. The degradation of PVDF after SHI irradiation is suppressed radically in NCs. PVDF forms an intercalated nanostructure in the presence of nanoclay and, further, the ion fluence raises the extent of intercalation. The crystallinity and the heat of fusion of pristine PVDF have drastically been reduced after SHI irradiation, while there are relatively small changes in NCs even at higher fluences. The metastable piezoelectric beta form of PVDF gets stabilized by the presence of layered silicate, and the structure is retained upon SHI irradiation. The clay platelets act as nucleating agents, and SHI irradiation causes two crystallization temperatures for the samples exposed to high fluences. The damages created on the surface and bulk of PVDF and its NC films upon SHI irradiation have been measured quantitatively by using atomic force microscopy. The pitting dimensions and degradation are enhanced significantly beyond 10(11) ions/cm(2) fluence for pristine PVDF, which limits the use of PVDF for any ion irradiation application. The degradation is considerably suppressed in NCs, providing a suitable high-energy radiation-resistant thermoplastic polymer.

Poly(m-toluidine) (PmT) and Poly(o-toluidine) (PoT) have been synthesized from derivatives of aniline (m-toluidine), (o-toluidine) monomers by chemical oxidative polymerization method. After polymerization, PoT powder was doped with p-toluene sulphonic acid (p-TSA) and the polymer powders were blended with poly vinyl chloride (PVC) to achieve PmT and p-TSA doped PoT dispersed films. XRD, FTIR and UV–visible studies were carried out to get their structural changes and optical information. These blends were irradiated by 60 MeV C5+ ions with different fluences. Post Irradiation XRD, FTIR and UV–visible spectroscopy were also performed on all films. On p-TSA doped PoT–PVC blends dc-conductivity measurements are also carried out before and after irradiation. The results show structural modifications which lead to changes in optical and electrical properties.

The films of polymethyl methacrylate (PMMA) were synthesized by solution polymerization technique. Nickel dimethylglyoxime (Ni-DMG) compound was dispersed in polymethyl methacrylate (PMMA) films at different concentrations. These films were irradiated with 120 MeV Ni10+ ions at the fluences of 1 × 1011 and 1 × 1012 ions/cm2. These irradiated films were characterized by means of X-ray diffraction (XRD), Vickers’ microhardness tester, atomic force microscopy (AFM) and scanning electron microscopy (SEM). X-ray diffraction patterns revealed that the particle size of Ni-DMG nanoparticles is reduced upon irradiation. It indicates that there is a significant interaction of ion beam with Ni-DMG particles in polymer matrix which leads to deposition of large amount of energy and resulted in splitting/melting of nanometric grains. It also revealed that semi crystalline phase of pristine films has been changed with respect to concentration and with the fluence. It is observed that the hardness of the film increases as fluence increases. This suggests that ion beam irradiation promotes (i) the metal to polymer bonding (ii) convert the polymeric structure in to hydrogen depleted carbon network due to the emission of hydrogen gas and/or other volatile gases. The surface average roughness increases as concentration of filler increases and decreases due to ion beam irradiation as revealed from AFM studies. SEM micrographs show partial agglomeration of filler and flake-like structure upon irradiation.

The effect of low temperature swift heavy ion (LT-SHI) implantation on InAs(1 0 0) and InSb(1 0 0) wafers have been investigated. SHI implantation was carried out with 70 MeV silicon (Si5+) ions with fluences of 1 × 1010, 1 × 1011, 1 × 1012 and 1 × 1013 ions/cm2 at room temperature (RT) and liquid nitrogen temperature (LNT). The X-ray diffraction peak intensity of the LT-SHI implanted sample increases with respect to the ion fluences, while the full width half maximum (FWHM) value decreases correspondingly with the increase of ion fluences for both InAs and InSb samples. Whereas the X-ray diffraction peak intensity decreases with respect to the increase of ion fluences for the samples implanted at RT. Scanning electron microscopy (SEM) was used in cross-sectional mode to analyze the penetration depth of silicon ions in InAs and InSb wafers. Atomic force microscopy revealed that the average surface roughness values (Rrms) of InAs and InSb samples implanted at LNT, decreased with the increase of ion fluences while an opposite effect has been observed in the case of RT implanted samples. The present study has confirmed the improvement in the structural and surface properties of InAs and InSb wafers when they are subjected to LT-SHI implantation with 70 MeV silicon (Si5+) ions.

The induced damage in single crystals of Sodium sulphanilate dihydrate (SSDH) irradiated at IUAC, New Delhi with 15 MV Pelletron accelerator with 100 MeV Ag7+ and 70 MeV Li3+ ions has been studied by optical measurements, mechanical hardness measurements, Electrical and ERDA measurements. Optical absorption measurements increase with the increase in fluence. The mechanical hardness of the crystal decreases on irradiation. The dielectric constant of SSDH increases on irradiation.

The effect of swift heavy ion irradiation on hydroxyapatite (HAp) ceramic – a bone mineral was investigated. The irradiation experiment was conducted using oxygen ions at energy of 100 MeV with three different fluences of 10 12 , 10 13 , 10 14 ions/cm 2 . The irradiated samples were characterized by glancing angle X-ray diffraction (GXRD), atomic force microscopy (AFM), dynamic light scattering (DLS), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). GXRD confirmed incomplete amorphisation of HAp with increase in fluence. There was considerable reduction in particle size on irradiation leading to nanosized HAp (upto 53 nm). PL studies showed emission in the visible wavelength region. The irradiated samples exhibited better bioactivity than the pristine HAp.

Polymethyl methacrylate (PMMA) was synthesized by solution polymerization technique. Films of polymer composites were prepared by dispersion of different concentrations of nickel dimethylglyoxime in PMMA. These films were irradiated with 3 MeV proton beam at a dose of 1.48×105 Gy. The dielectric, structural properties and surface morphology of pristine and irradiated samples were studied by means of an LCR meter, X-ray diffraction (XRD) analysis and atomic force microscopy (AFM), respectively. The dielectric properties are observed to enhance with increase in metal compound concentration as well as with irradiation dose. This may be due to metal/polymer bonding and conversion of polymeric structure into hydrogen-depleted carbon network. AFM shows that the surface average roughness decreases after irradiation. Crystallite size of organometallic compound is observed to decrease after irradiation as revealed from XRD analysis.

Poly (o-toluidine) was synthesized from a derivative of aniline (o-toluidine) monomer by chemical oxidative polymerization method. After polymerization, the polymer prepared was blended with poly vinyl chloride and irradiated by 60-MeV C5+ ions at five different fluences of 1×1011, 3.3×1011, 1×1012, 3.3×1012 and 1×1013 ions/cm2. The swift heavy ion irradiation effects on crystallinity and DC conductivity were studied. X-ray diffraction study showed variations in crystallinity of the blend films upon irradiation. The crystallinity, DC conductivity and activation energy were found to vary discontinuously with fluence. The DC conductivity and activation energy were obeying Meyer–Neldel rule.

We report the liquid phase epitaxial growth of Zn3As2 on InAs (1 1 0) substrates using 100% In solvent. The zinc concentration in the layers was varied by changing the zinc mole fraction in the growth melt from 3 × 10−3 to 15 × 10−3, keeping all other growth parameters constant. Layers grown with 3 × 10−3, 5 × 10−3 and 8 × 10−3 mole fractions of zinc seem to be polycrystalline, while layers grown with more than 8 × 10−3 mole fraction of zinc resulted in highly oriented and single crystalline material. Composition of the epilayers was confirmed by energy dispersive x-ray microanalysis. Scanning electron microscopy was used to determine the thickness of the epilayers and the growth rate was calculated. Furthermore it was found that a linear dependence exists between the growth rate and the zinc mole fraction in the growth melt. Atomic force microscopy results reveal that the smoothness of the epilayers improve when the zinc concentration in the epilayer approaches the stoichiometric value of Zn3 As2. Room temperature Hall measurements showed that the grown epilayers were unintentionally doped p-type with an increase in the carrier mobility and a decrease in the carrier concentration with respect to the increase in the zinc mole fraction in the growth melt.

Conducting poly(o-toluidine) (PoT) was synthesized from a derivative of aniline (o-toluidine) monomer by chemical oxidative polymerization method. After polymerization, the polymer prepared was then blended with Poly Vinyl Chloride (PVC) to achieve films. FTIR and UV-Visible studies were carried out to get their optical information. The blends were irradiated by Swift Heavy Ion (SHI) beam of 60 MeV C 5+ ions with different fluences. Post Irradiation FTIR and UV-Visible spectroscopy were carried out on these films, which revealed changes in the band gap with irradiation. There are also changes in the functional groups, which are confirmed by FTIR spectra. Optical band gap is found to decrease at all fluences and increased with increase in fluence.

Poly (o-toluidine) (PoT), a derivative of polyaniline was synthesized by chemical oxidative polymerization method in aqueous media. After polymerization, the polymer prepared is doped with p-toluene sulfonic acid with different concentrations (2, 4, 6, 8 and 10% w/w). These polymers are blended with polyvinyl chloride (PVC) to make self-supported films. The DC conductivity of both powder and blends is measured in the temperature range of 300–450 K and is found to increase with temperature. The Arrhenious plot of DC conductivity of PVC blended PoT shows two phases with different slopes. The samples are characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The XRD pattern of the powder PoT and their blend shows the semi-crystalline nature of the samples. FTIR studies show the information of changes in functional groups with doping and blending of PoT with PVC.

Swift heavy ion irradiations were carried out on metal organic chemical vapour deposition- grown GaN epilayers on sapphire (0 0 0 1) substrates at room temperature, with 100 MeV O7+ ions and fluences varying from 1×1012, 1×1013 and 5×1013 ions cm−2. The pristine and irradiated GaN samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and UV–visible optical transmittance studies. XRD results indicate the presence of gallium oxide phases after O7+ ion irradiation and the increase in the Ga2O3 peak intensity and full-width half-maximum of irradiated GaN with increasing ion fluences. Surface morphology was observed from AFM analysis, which indicates a decrease in the root-mean square of roughness from 3.9 to 0.5 nm. PL measurements show a red shift as compared to the as-grown GaN. The UV–visible optical transmittance studies show a decrease in band gap after ion irradiation.

Pure single crystals of Potassiumtetrakisthioureabromide (KTTB) were irradiated at room temperature with 40 MeV lithium ions at fluences varying from 10 10 to 10 12 ions/cm 2 from the 15 UD Pelletron facility at Inter University Accelerator Centre (IUAC), New Delhi. The pristine as well as irradiated KTTB single crystals were characterized by photoluminescence at room temperature under 2.8 eV blue excitation by a He–Cd laser and UV–Vis absorption to study the radiation induced defects. The ion-induced changes have also been studied with respect to their mechanical response using Vickers micro hardness technique. The effect of swift heavy ion beam on dielectric dispersion is explained in detail. Surface morphology was also studied for pristine and irradiated crystals.

Organic nonlinear optical crystal l -asparaginium picrate was subjected to 100 MeV Ag 8+ ions and 100 MeV Si 8+ ions. The dielectric properties of the crystals were studied before and after irradiation from 100 Hz to 5 MHz at various temperatures (308 K to 358 K). A drastic increase in the dielectric constant is seen due to irradiation. The dielectric constant and dielectric loss increase with increasing irradiation fluence. The UV–vis spectra of the pristine and irradiated samples were recorded and quantified. There is a small shift in absorption edge towards lower wavelength for the irradiated crystals due to the decrease in bandgap of the material. The observed results are discussed in detail.

The topography of Si(1 0 0) and Si(1 1 1) surfaces after irradiation with 1.5 keV Ar atoms beam incident at 45° with respect to the surface normal has been studied as a function of atom fluence using atomic force microscopy. The sputtered silicon (1 0 0) samples exhibit ripple pattern, with the average value of the ripple wavelength increasing from 15 nm to 19 nm as fluence increases from 1.7 × 10 17 atoms/cm 2 to 5.1 × 10 17 atoms/cm 2 , though the height of ripples remains same i.e. 1.02 nm. On the other hand, in case of Si(1 1 1) samples, the average value of the ripple wavelength increases from 22 nm to 40 nm with fluence increasing from 1.7 × 10 17 atoms/cm 2 to 5.1 × 10 17 atoms/cm 2 . A close view of the surface morphologies of Si(1 0 0) and Si(1 1 1) showed that the ripples on Si(1 1 1) surface are, more regular than Si(1 0 0). When the fluence is further increased, it is found that the wavelength of ripple tends to saturate and the height tends to decrease, as a result the surface becomes smooth at higher (∼6.8 × 10 17 atoms/cm 2 ) fluence.