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Swift heavy ion (SHI) irradiation in thin films significantly modifies the structure and related properties in a controlled manner. In the present study, the 120 MeV Ag ion irradiation on AgInSe2 nanoparticle thin films prepared by the thermal evaporation method and the induced modifications in the structure and other properties are being discussed. The ion irradiation led to the suppression of GIXRD and Raman peaks with increasing ion fluence, which indicated amorphization of the AgInSe2 structure along the path of 120 MeV Ag ions. The Poisson's fitting of the ion fluence dependence of the normalized area under the GIXRD peak of AgInSe2 gave the radius of the ion track as 5.8 nm. Microstructural analysis using FESEM revealed a broad bi-modal distribution of particles with mean particle sizes of 67.5 nm and 159 nm in the pristine film. The ion irradiation led to the development of uniform particles on the film surface with a mean size of 36 nm at high ion fluences. The composition of the film was checked by the energy dispersive X-ray fluorescence (EDXRF) spectrometer. The UV-visible spectroscopy revealed the increase of the electronic bandgap of AgInSe2 films with an increase in ion fluence due to quantum confinement. The Hall measurement and EDXRF studies showed that the unirradiated and irradiated AgInSe2 films have n-type conductivity and vary with the ion fluence. The changes in the films were tuned with different ion fluence and are favorable for both optical and electronic applications.

The laser irradiation with band gap light of thermally evaporated As40Se55Bi5 and As40Se45Bi15 thin films was found to be accompanied by structural changes which in turn changed the optical constan...

The interface of Ni-NiO thin films was developed by thermal evaporation of nickel and subsequent annealing in oxygen atmosphere at 400 °C at varying duration of time. The evolution of layer thicknesses with annealing time was studied using rutherford backscattering spectrometry. The structural characterization showed grain growth stagnation for Ni at higher duration of annealing. The Ni phase had more crystallinity compared to the NiO phase. The surface was studied using atomic force microscope. The magnetic domains were also imaged. Magnetic stripe domain patterns were observed for selected films. Variation in saturation magnetisation and coercivity with annealing time was observed. The observation of weak exchange bias shows the importance of antiferromagnetic phase in determining the exchange bias properties. Thermal annealing of Ni films caused a competition among oxidation and grain growth.

Evolution of the structure and surface morphology of thin films composed of two selenium based chalcogenide phases, AgInSe2 and Ag2Se on 140 MeV ion irradiation is reported. At this high energy, the projectile Ni ions sputtered the surface of the films through energy deposition to the target electrons. The sputtering led to decrease of silver and selenium concentration, but did not affect indium concentration. Surface analysis by field emission scanning electron microscopy study revealed nanoparticles of widely varying shapes and sizes on the surface of the films. Irradiation did not affect the particle size distribution which peaked at ~100 nm. The two phases, AgInSe2 and Ag2Se exhibited different sensitivity to 140 MeV Ni ion irradiations. While Ag2Se phase was insensitive, the AgInSe2 phase showed complex structural modifications at intermediate fluences, finally getting amorphized at high ion fluences. Analysis of the fluence dependence of Grazing Incidence X-ray Diffraction (GIXRD) peak area of AgInSe2 phase indicated that each ion that penetrated the film, created an amorphous column of 1.6 nm radius. Surrounding the amorphous column, a cylindrical crystalline AgInSe2 region of radius 8.2 nm, but with reduced lattice parameters formed. High resolution transmission electron microscopy image also confirmed registration of amorphized tracks and the modified crystalline region of similar radii around the path of 140 MeV Ni ions in a grain of AgInSe2 as obtained from GIXRD study.

The structural, microstructural and electronic band gap properties of bilayer Bi/As2Se3 thin films prepared on glass substrate have been discussed in detail. The thin films prepared by thermal evaporation technique under high vacuum were characterized by X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FESEM) and UV–visible–NIR spectrophotometer. The bilayer films with small Bi thickness showed amorphous nature, while large Bi thickness film led to the development of sharp XRD peaks corresponding to Bi and Bi2Se3 phase. The band gap of the studied film decreased with increasing Bi layer thickness which is explained on the basis of high concentration of localized defect states in the band gap region. The FESEM images showed the smooth and homogeneous surface for all the films. The Raman spectra showed the different structural units like AsSe3 pyramidal unit and Se8 rings that change with the Bi layer thickness. The present study reveals the interface diffusion of Bi into As2Se3 layer and interaction of Bi with Se due to exposure of the films to UV radiation.

In the present study, Bi/As2Se3 bilayer thin films (100 nm Bi as top layer and 800 nm As2Se3 as bottom layer) were prepared by thermal evaporation technique and were annealed at 165 °C for ½ h, 1 h and 2 h. The structural, micro-structural and optical studies of the films were characterized by X-ray diffractometer (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM) and Fourier transform infrared (FTIR) Spectrophotometer. The XRD study revealed the annealing induced diffusion of Bi into As2Se3 layer and its reaction with Se leading to the formation of Bi3Se2 phase. The as deposited Bi/As2Se3 bilayer film exhibited strain at the interface leading to localized states in the band gap of the bottom As2Se3 layer with a consequent reduction of its band gap. The increase in annealing time from 1/2 h–2 h led to strain relaxation and increased the band gap towards that of the pristine As2Se3 along with the precipitation of a second Bi3Se2 phase. The increase in optical band gap has been explained by the density of localized states in the gap. The change in refractive index, transmission, absorption coefficient, dielectric constant is the consequence of annealing effect. The FESEM images revealed the smooth surface for as deposited bilayer film and a large number of agglomerated grains of As2Se3 have been seen in the annealed films. The AFM study showed the grain growth stagnation or even decrease of grain size on prolonged annealing.

Aligned ZnO nanorods (NRs) were synthesized by a simple and inexpensive hydrothermal method. Morphological, structural, photoabsorbance and photoluminescence studies have been carried out using field emission scanning electron microscopy (FE-SEM), grazing incidence X-ray diffraction (GIXRD), Raman, UV–visible and Photoluminescence spectroscopy. Results show that crystallinity and alignment of ZnO NRs lead to good photocatalytic activity in the presence of visible light. The Photoluminescence spectra revealed a decrease in the UV emission, suggesting a reduced recombination of the photo generated carriers. The visible region emission is due to the surface oxygen vacancies. Increase of charge separation rate observed from emission spectra and the vacancy related sub-bands in the absorbance spectra are together responsible for the enhanced visible light photocatalytic activity of ZnO NRs. Vertically aligned 1-D morphology of ZnO NRs and the presence of oxygen vacancy states assist in the visible light photocatalytic degradation of Methylene Blue dye.

Swift heavy ion (SHI) irradiation in thin films significantly modifies the structure and related properties in a controlled manner. In the present study, the 120 MeV Ag ion irradiation on AgInSe

The use of in vivo haploid induction system makes the doubled haploid (DH) technology easier to adopt for the conventional maize breeders. However, despite having played an important role in the initial developmental phases of DH technology, Indian maize research has yet to harvest its benefits. Haploid Inducer Lines (HILs) developed by CIMMYT are being widely used in maize breeding programmes in many countries including India. There, however, is no published information on the efficiency of DH line production using CIMMYT HILs in Indian maize breeding programmes. In the present study, the efficiency of DH production using CIMMYT’s tropically adapted inducer line TAILP1 was investigated with eight source populations including two of sweet corn. The average haploid induction rate (HIR) of TAILP1 was 5.48% with a range of 2.01 to 10.03%. Efficiency of DH production ranged from 0.14 to 1.87% for different source populations with an average of 1.07%. The information generated will be useful for maize breeders intending to use DH technology for accelerated development of completely homozygous lines.

The effect of Ni doping in BiFe1−xNixO3 (BFNO) multiferroics are studied by X-ray diffraction (XRD), Fourier transmission infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), hysteresis loop (M–H), temperature dependent magnetization (FC-ZFC) measurements and electron spin resonance (ESR) techniques. The XRD and FTIR studies indicate that the BFNO compounds remain in rhombohedral (R3c) phase without appearance of any structural transformation due to Ni doping. The XPS studies show the oxidation states of Fe ions as 3+, whereas Bi is found to be in a mixed valence state of 2+ and 3+ in BFNO. The Ni ion doping enhances the saturation magnetization from 0.179 emu/g (x = 0.025) to 2.38 emu/g (x = 0.20), which is higher than the reported values found in literature. The FC-ZFC magnetization studies suggest the presence of a magnetic phase transition from a weak ferromagnetic to a spin glass state at low temperature. The ESR studies confirm the ferromagnetic state of BFNO samples.

Present study investigates the structural and magnetic properties of TiO2 thin films prepared by electron beam evaporation technique, annealed at 900 °C and irradiated with 500 keV Ar2+ ions. The films before irradiation exhibit anatase phase. Irradiation leads to diffused XRD peaks indicating amorphisation of the anatase phase at the fluence of 1 × 1014 ions/cm2. Increasing the fluence to 5 × 1016 ions/cm2 leads to evolution of brookite phase out of the amorphous TiO2. In addition, an impurity phase, Ti4O7 is observed in pristine as well as in irradiated films, which show radiation resistant behavior to 500 keV Ar2+ ion irradiation upto the highest fluence 5 × 1016 ions/cm2. Anatase to brookite phase transformation followed by an intermediate amorphous phase occurs without showing either grain growth or change in film thickness as evidenced from Atomic Force Microscopy (AFM) and Rutherford’s Back Scattering (RBS) measurements, respectively. Further, both pristine and irradiated films exhibit ferromagnetic behavior at room temperature (RT) irrespective of their phase and crystallinity. The difference in magnetization observed in pristine and film irradiated at ion fluence 5 × 1016 ions/cm2 is ascribed to the difference in oxygen vacancies.

In the present study, the AgInSe2 (AIS) thin films 500 nm in thickness were prepared by selenization of the Ag/In/Ag/In multilayer deposited by DC magnetron sputtering. The selenization was carried out at 250 °C and was followed by annealing at 450 °C, 475 °C and 500 °C. The selenized and annealed films were characterized by grazing incidence X-ray diffraction (GIXRD), UV-Visible-NIR spectroscopy, Field-Emission Scanning Electron Microscopy (FESEM) and Raman spectroscopy. The XRD analysis revealed the formation of the desired AgInSe2 phase along with Ag2Se (AS) impurity phase. The impurity Ag2Se phase is being diminished at higher annealing temperature (500 °C) resulting the formation of AgInSe2 phase. The super ionic nature of α-Ag2Se phase facilities the diffusion of Ag ion with its neighbouring tetrahedral sites. The low band gap Ag2Se impurity phase suppression by annealing at 500 °C lead to optical band gap increase. The Raman spectrum shows individual AgInSe2 and Ag2Se peaks and also the overlapping of these two phases. The Ag2Se peaks are vanished after annealing. The EDXRF study revealed that the film is off-stoichiometric and exhibit n-type conductivity. The RBS analysis indicates the diffusion of the film material to the glass substrate. From Hall measurement it is confirmed that the film shows n-type conductivity and the resistivity decreases with increasing the annealing temperature.

In the present report, we have studied the structural and optical change in the In2Se3 thin films prepared by the thermal evaporation method, deposited on a glass substrate and annealed at 250°C. B...

In our earlier report, where we have demonstrated ferromagnetic behavior at room temperature (RT) in TiO2 thin films deposited through electron beam evaporation technique followed by annealing either in Ar or O2 atmosphere [Mohanty et al., Journal of Magnetism and Magnetic Materials 355 (2014) 240–245], here we have studied the evolution of structure and magnetic properties after irradiating the TiO2 thin films with 500 keV Ar2+ ions. The pristine film while exhibits anatase phase, the films become amorphous after irradiating at fluence in the range 1 × 1014 to 1 × 1016 ions/cm2. Increasing the fluence up to 5 × 1016 ions/cm2, amorphous to crystalline phase transformation occurs and the structure becomes brookite. Although anatase to rutile phase transformation is usually reported in literatures, anatase to brookite phase transformation is an unusual feature which we have reported here for the first time. Such anatase to brookite phase transformation is accompanied with grain growth without showing any change in film thickness evidenced from Rutherford’s Back Scattering (RBS) measurement. From scanning probe micrographs (SPM), roughness is found to be more in amorphous films than in the crystalline ones. Anatase to brookite phase transformation could be realized by considering the importance of intermediate amorphous phase. Because due to amorphous phase, heat deposited by energetic ions are localized as dissipation of heat is less and as a result, the localized region crystallizes in brookite phase followed by grain growth as observed in highest fluence. Further, we have demonstrated ferromagnetic behavior at RT in irradiated films similar to pristine one, irrespective of their phase and crystallinity. Origin for room temperature ferromagnetism (RTFM) is attributed to the presence of oxygen vacancies which is confirmed by carrying out XPS measurement.

Many different methods, such as screen printing, gravure, flexography, inkjet etc., have been employed to print electronic devices. Depending on the type and performance of the devices, processing is done at low or high temperature using precursor- or particle-based inks. As a result of the processing details, devices can be fabricated on flexible or non-flexible substrates, depending on their temperature stability. Furthermore, in order to reduce the operating voltage, printed devices rely on high-capacitance electrolytes rather than on dielectrics. The printing resolution and speed are two of the major challenging parameters for printed electronics. High-resolution printing produces small-size printed devices and high-integration densities with minimum materials consumption. However, most printing methods have resolutions between 20 and 50 μm. Printing resolutions close to 1 μm have also been achieved with optimized process conditions and better printing technology.

Ni1−xZnxO/Ni nanocomposite samples synthesized by wet chemical method were characterized by X-ray powder diffraction, Fourier Transform Infrared (FTIR) spectrometer, UV–Vis spectrometer and Nine Tesla Physical Property Measurement System (PPMS)-based vibrating sample magnetometer (VSM). XRD spectra contained peaks due to NiO and Ni. Rietveld refinement of XRD data indicated the change in lattice parameter is more than twice in NiO than in Ni suggests that Zn goes more favorably into NiO than in Ni. The band gap of NiO in Ni1−xZnxO/Ni samples increased from 3.58 to 3.81 eV with increasing x from 0 to 0.07 and thereafter the band gap slightly decreases. NiO/Ni nanocomposites show strong room temperature ferromagnetism. The ferromagnetic interaction further enhanced with 1% of Zn doping into NiO in NiO/Ni nanocomposite. Beyond this doping concentration, the magnetic interaction does not show any systematic variation. The observation of room temperature ferromagnetism in nanocomposite samples is explained by combining the effect of bound magnetic polaron and the magnetization of system with the distribution of magnetic ions as meagerly dispersed in large clusters. Our study indicated that Ni0.99Zn0.01O/Ni nanocomposite sample could be useful for magnetic recording device application.

With progressing miniaturization of modern electronic devices, interconnects become increasingly smaller. Additionally, as electronic devices move away from rigid substrates toward flexible ones, understanding their mechanical and structural stability is becoming crucial. In this work, a thorough mechanical characterization of copper thin films deposited on flexible substrates was performed with two techniques, namely well-established synchrotron X-ray diffraction (sXRD) and the rather new usage of reflectance anisotropy spectroscopy (RAS) for mechanical characterization of thin films. The comparison of these two techniques shows that RAS can be reliably used for the accurate and prompt yield stress measurements. The acquisition time of RAS is much faster than that of sXRD: 1 second per data point compared to several seconds per data point for sXRD experiments. Moreover, the signal-to-noise ratio of the RAS data is much higher than that of the sXRD. Our results show that yield stress of Cu films increases with the decrease in the film thickness, going from 352 MPa for a 500 nm films to 793 MPa for a 50 nm thick film. Microstructure analyses of the films by electron microscopy allowed correlation of the mechanical behavior of the films to their grain morphologies. We have shown that RAS can supplement sXRD measurements due to a faster acquisition rate which allowed us to analyze the creep behavior of our copper thin film at different strain rates.

Present study investigates the photoabsorption properties of single crystal rutile TiO2 (110) surfaces after they have been implanted with low fluences of cobalt ions. The surfaces, after implantation, demonstrate fabrication of nanostructures and anisotropic nano-ripple patterns. Creation of oxygen vacancies (Ti3+ states), development of cobalt nano-clusters as well as band gap modifications have also been observed. Results presented here demonstrate that fabrication of self organized nanostructures, upon implantation, along with the development of oxygen vacancies and ligand field transitions of cobalt ion promote the enhancement of photo-absorbance in both UV (∼2 times) and visible (∼5 times) regimes. These investigations on nanostructured TiO2 surfaces can be important for photo-catalysis.

Ion beams of widely varying energies from keV to GeV have played a significant role in the modification of materials. The manuscript reports the influence of 120 MeV Ag swift heavy ion irradiation (SHI) at two different fluence on As40Se58Bi02 and As40Se45Bi15 thin films. The irradiation has shown strong impact on the optical constants like transmittivity, absorption coefficient, extinction coefficient, optical band gap and disorderness with no structural change. The optical transmittance decreased while absorption coefficient and extinction coefficient increased with increase in the fluence from 5 × 1012yions/cm2 to 5 × 1013ions/cm2. The decreased optical band gap with irradiation is explained on the basis of bond distribution model and density of defect states with increase in disorder. The p-type to n-type conductivity switching was observed at higher Bi content and the Hall measurement showed the increase in conductivity with irradiation. The Raman study on these ion irradiated films also confirmed no structural transformation. The surface morphological evolution of the films by Ag ion irradiation was studied by Field Emission Scanning Electron Microscopy.

In the present work, we probe into the phase transition of amorphous Bi10As40Se50 to a crystalline one upon thermal annealing. The Bi10As40Se50 thin films were prepared through thermal evaporation method and were annealed at 130° for 5h. The as-prepared and annealed films were characterized by XRD, FESEM and Raman spectroscopy. X-ray diffraction study revealed the amorphous nature of the as-prepared film and Bi3Se4 crystallite phase formation in the annealed film. This clearly indicates annealing induced diffusion of Bi into As2Se3 and hence the formation of Bi3Se4 phase. FESEM images show the smooth and homogeneous surface for the Bi10As40Se50 film whereas the annealed film shows these crystallites covers the surface. The Raman spectra shows a broad band corresponds to AsSe3 unit and a raman peak of bismuth selenide in the asprepared film whichshows shifting in case of annealed film.

The In/Se thin films were prepared by thermal evaporation method on glass substrate and were annealed at 200 °C for 1 hr. The indium diffusion into selenium matrix to form indium selenide phases like In2Se3, In4Se3 due to annealing was revealed from the X-ray diffraction study and also supported by the Raman spectra analysis. The optical band gap decreased with annealing as a result of different phase formation as studied from UV-visible spectroscopy. The formation of nano rod like structure in the as-prepared film and their disappearance upon annealing is probed by FESEM characterization.

Sensitivity of the anatase and rutile phases of titanium dioxide to Swift Heavy Ion (SHI) irradiation was experimentally probed and compared with the predictions of the Coulomb explosion, analytical and inelastic thermal spike models of ion-matter interaction. Conforming to the predictions of all these models, our study indicated higher sensitivity of anatase to these ions than the rutile phase. A detailed examination however revealed that Coulomb explosion model cannot explain either the nature of variation of the interaction cross section of SHI with the energy deposited by these ions, Se to the target electrons, or the relative values of the threshold electronic energy loss, Seth of anatase and rutile. The analytical thermal spike (a-TS) model, using the available physicochemical data for this oxide, predicted that tracks cannot form either in anatase or in rutile by 297 MeV and 511 MeV Ni ions, while inelastic thermal spike (i-TS) model predicted formation of ion tracks by 297 MeV Ni ions and their absence with 511 MeV Ni ions in both anatase and rutile. Our observation agreed with the predictions of i-TS model albeit with a difference in the radius of the tracks. In addition, we observed halo of defect ridden crystalline region of much larger radius around the ion track. Interestingly, the radius of the halo scales with the velocity of the ions, which is opposite to the conventionally observed velocity effect.

Gold thin films of varying thickness (10–100 nm) grown on silica substrates by e-beam evaporation method were irradiated by 120 MeV Au ions at 3 × 1012 and 1 × 1013 ions cm−2 fluences. Irradiation induced modifications of these films were probed by glancing angle X-ray diffraction (GAXRD), atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS) and surface enhanced Raman scattering (SERS). Irradiation didn’t affect the structure, the lattice parameter or the crystallite size, but modified the texturing of grains from [1 1 1] to [2 2 0]. RBS indicated thickness dependent sputtering on irradiation. The sputtering yield was found to decrease with increasing thickness. AFM indicated increase of roughness with increasing irradiation fluence for films of all thickness. In agreement with the AFM observation, the gold nanostructures on the surface of 20 nm thick film were found to increase the SERS signal of acridine orange dye attached to these structures. The SERS peaks were amplified by many fold with increasing ion fluence. The effect of 120 MeV Au ion irradiation on the grain texture, surface morphology and SERS activity in addition to the thickness dependent sputtering in gold thin films are explained by the thermal spike model of ion-matter interaction.

Modifications induced by 79 MeV Br ions in rutile titanium dioxide thin films, synthesized by dc magnetron sputtering are presented. Irradiations did not induce any new XRD peak corresponding to any other phase. The area and the width of the XRD peaks were considerably affected by irradiation, and peaks shifted to lower angles. But the samples retained their crystallinity at the highest fluence (1 × 10 13 ions cm −2 ) of irradiation even though the electronic energy loss of 79 MeV Br ions far exceeds the reported threshold value for amorphization of rutile TiO 2 . Fitting of the fluence dependence of the XRD peak area to Poisson equation yielded the radius of ion tracks as 2.4 nm. Ion track radius obtained from the simulation based on the thermal spike model matches closely with that obtained from the fluence dependence of the area under XRD peaks. Williamson–Hall analysis of the XRD spectra indicated broadening and shifting of the peaks are a consequence of irradiation induced defect accumulation leading to microstrains, as was also indicated by Raman and UV–Visible absorption study.

Nanostructures (NS) have been fabricated on rutile TiO 2 (1 1 0) single crystal surfaces using Ar ion beam sputtering technique. Pronounced quantum confinement effects in TiO 2 nanodots lead to reduction in optical reflectance and bandgap widening. Moreover, a direct correlation between the size of NS and magnetic behavior is observed. This suggests that the size of NS plays crucial role in the evolution of magnetic nature. Though the smallest (∼5 nm) NS display superparamagnetic (SPM) behavior, ferromagnetism is observed for larger nanostructures. Single domain nature of TiO 2 quantum dots is responsible for the observed SPM behavior.

Two sets of gold thin films of thickness of about 20 and 50 nm, grown by thermal evaporation method on (100) silicon wafers were irradiated by 197 MeV Au ions. Grazing incidence X-Ray diffraction (GIXRD) study has been revealed lattice expansion on decreasing the film thickness. 197 MeV Au ion irradiation was not affect either the cubic crystal structure of gold or its lattice parameter. Atomic force microscopy (AFM) study indicated that the evolution of the surface morphology with ion fluence crucially depended on the film thickness, the thinner film being more sensitive than the thicker one. Irradiation led to nanoparticles formation on the surface of the films. This observation is in contrast to the generally perceived damaging role of swift heavy ion (SHI) irradiation. Power spectral density analysis of the roughness along both the lateral and vertical directions demonstrated dominance of surface diffusion over volume diffusion induced by SHI irradiation. A comparison of the sputtering yield obtained from Rutherford back scattering (RBS) spectra of the irradiated films and transmission electron microscopy (TEM) of the particles sputtered from the films and collected by a catcher grid during irradiation indicated that more than the surface and volume diffusion processes, it is the irradiation induced sputtering that controls the overall surface morphology of the films. The surface roughness increase with ion fluence and the irradiation induced sputtering yield was found to be larger in thinner films. Film thickness dependence of the evolution of surface morphology and sputtering yield with 197 MeV Au ion irradiation clearly indicates the dominance of the electronic energy loss over the nuclear energy loss of the projectiles ions in the target medium and opens up the ways for examining the applicability of different models of ion-matter interaction in systems with reduced dimensions. Copyright © 2015 VBRI press.

Multiferroic bismuth ferrites (BFO) and Ni substituted bismuth ferrites (BFNO) were synthesized by standard solid state reaction route. The structural and microstructural studies were carried out. The effect of Ni substitution on dielectric constant and dielectric loss of the samples was studied in a wide range of frequency (100 Hz- 1 MHz) and temperature (27 o C – 420 o C). It has been observed that the dielectric constant increases with increase in Ni doping concentration and attained a maximum value for BFNO(x = 0.075) sample while the dielectric loss has been found to decrease with the doping concentration. This implies a reduction in the conductivity and hence improved the dielectric properties of Ni doped BFO. The anomalous peaks in temperature dependent dielectric studies indicate the increase in antiferromagnetic ordering temperature and possible existence of spin glass states upon Ni substitution in place of Fe. The complex impedance spectroscopic analysis suggests purely the intrinsic nature of the dielectric anomalies. Temperature dependent non-Debye type of dielectric relaxation has also been observed. The Nyquist plots show the negative temperature coefficient of resistance behavior of these compounds. Further it would be interesting to study their magnetic and magnetoelectric properties with the aim of identifying new multifunctional device applications. Copyright © 2014 VBRI press.

BiFeO3 (BFO) thin films of thickness about 800 nm deposited on Si (100) substrates by sol–gel spin coating method were irradiated by 200 MeV Ag ions. Modification of structure and surface morphology of the films under irradiation was studied using glancing incidence X-ray diffraction (GIXRD) and atomic force microscope (AFM). Fluence dependence of GIXRD peak intensity indicated formation of 10 nm diameter cylindrical amorphous columns in crystalline BFO due to 200 MeV Ag ion irradiation. AFM analysis indicated that the pristine film consists of agglomerated grains with diffuse grain boundary. Irradiation led to reduced agglomeration of the grains with the formation of sharper grain boundaries. The rms roughness (σ rms) estimated from AFM analysis increased from 6·2 in pristine film to 12·7 nm when the film irradiated at a fluence of 1 × 1011 ions cm − 2 . Further irradiation led to decrease of σ rms which finally saturated at a value of 7–8 nm at high ion fluences. The power spectral density analysis indicated that the evolution of surface morphology of the pristine film is governed by the combined effect of evaporation condensation and volume diffusion processes. Swift heavy ion irradiation seems to increase the dominance of volume diffusion in controlling surface morphology of the film at high ion fluences.

In the present study, 300 nm thick films of AgInSe2 were prepared by selenization of the multilayer of Ag/In/Ag/In deposited by DC magnetron sputtering. Selenization was done at the 300 C and a few of the selenized film were annealed at 500 C. The films were characterized by X-ray diffraction (XRD) and UV-Visible-NIR spectroscopy. XRD revealed the presence of about 24 vol% of Ag2Se as impurity phase in the AgInSe2 films, which were only selenized. Annealing of the selenized films at 500 C suppressed the impurity phase to about 5 vol%. Annealing also led to increase of crystallite size and improvement of crystallinity. Associated with the suppression of the impurity phase, the band gap of the film was found to increase on annealing at 500 C.

Photo-absorption properties of Co implantation in rutile TiO2(110) have been investigated. Nearly five times enhancement in absorbance of visible light and 1.7 times increase in UV light have been observed. Formation of crystalline CoTiO3 and Ti1−x Co x O2 phases at high and low fluences, respectively, demonstrates a crucial role in increasing the photo-absorbance, especially in the visible regime. Ti-rich nanostructures and Ti3+ vacancies that develop after ion implantation also reveal significant contribution in these observations. These Co implanted rutile TiO2 surfaces will be useful for visible light photo-catalysis.

Temperature dependent resistivity of YBa2Cu3O7−y (YBCO) thick films irradiated with 200 MeV Ag ions has been investigated. The YBCO thick films were prepared by solid state diffusion reaction technique. In contrast to the general perception that the energetic ion induces defects and disorders, which lead to decrease of Tc and increase of normal state resistivity in a superconductor, 200 MeV Ag ions in the present case led to an increase in Tc and decrease in normal state resistivity at low ion fluence (1011 ions cm−2) in YBCO. At this fluence, the electronic energy loss, Se induced amorphous ion tracks are well separated from each other and hence are not expected to influence the Tc. The observed changes in transport properties is explained as being caused by irradiation-induced chain oxygen ordering of the oxygen defects in the CuO chains. Subsequent increase of irradiation fluence leads to decrease of Tc and increase of normal state resistivity.