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Cation and anion disordering affect the structural and electronic properties of the isometric A2B2O7 pyrochlore materials. Here, we report a study on the structural response of La2Zr2O7 at two different temperatures (300 K and ~88 K) as a function of ion fluence (1 × 1013, 5 × 1013, and 1 × 1014 ions/cm2). The effect of ion fluence and irradiation temperature on the structural properties have been investigated using the grazing angle x-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy. GIXRD results confirmed that the weakening/broadening of the diffraction peaks and lattice volume expansion increases monotonically as a function of ion fluence at both the temperatures and are more pronounced at ~88 K. The cation and anion disordering appear to be ion fluence and irradiation temperature-dependent. Raman spectroscopy shows that the atomic disordering is more pronounced with enhanced ion fluence and revealed the involvement of the X48f parameter in the enhancement of disordering in the system. The HRTEM analysis revealed that the deterioration in the atomic ordering (amorphization) is significantly more pronounced at ~88 K. The qualitative analysis of cation/anion disordering and structural deformation revealed that irradiation parameters play a crucial role in developing and altering the properties of the pyrochlore materials for the technological applications.

In the present study, the physical properties including structural, optical and magnetic of HoCr1-xMnxO3 (x = 0, 0.15) have been thoroughly investigated and compared. A detailed structural analysis of the compounds provided a way to correlate the optical and magnetic properties with the change in Cr-site ionic radius, tilt angles and distortion in CrO6 octahedra due to Mn substitution. Further, the shift in the Raman phonon modes was associated with the increased structural distortion owing to Mn substitution in HoCrO3 compound. The variation in the Urbach energy values, measured from the diffuse reflectance spectroscopy, was found to be closely related to the octahedral distortion. The optical band gap reduced from 3.22 eV to 2.01 eV after Mn substitution. Other optical parameters such as skin depth, refractive index, extinction coefficient and optical conductivity were also perceived to vary noticeably in the substituted compound. The overall structural distortion with Mn substitution resulted in the decrease of antiferromagnetic transition temperature of the pristine compound. The strong magnetic entropy change was observed at low temperatures in pure HoCrO3 compound and its value was enhanced on Mn substitution. Therefore, the present work provides a convenient method to tune the multifunctional properties of HoCrO3 compound, which has practical applications such as photocatalyst and low-temperature magnetic refrigerant.

Multiwall carbon nanotubes (MWNTs) decorated CdS nanocrystals have been synthesized by chemical method. Methylene blue dye as a probe has been used for determination of photo catalytic activity of CdS/MWNTs composites. Degradation of Methylene blue dye on CdS/MWNTs composites reveals that MWNTs could effectively increase the photocatalytic activity as well as rate of electron induced redox reaction of CdS nanocrystals. Structural, Optical and photocatalytic activity of MWNT-CdS composites have been characterized by X-ray Diffraction (XRD), UV–Vis Spectroscopy, Photoluminescence Spectroscopy (PL), and Scanning Electron Microscopy (SEM)

Structural and spectroscopy studies have been carried out on conducting polymer poly(3-octylthiophene) (P3OT) and its copper-doped ZnO (Cu-ZnO/P3OT) hybrid nanocomposites (HNCs) under swift heavy ion (SHI) irradiation at different electronic energy depositions. The photoluminescence (PL) spectra of irradiated films exhibit a significant decrease in the intensity of emissions at higher ion fluences which is ascribed to the trapping of a photo-induced electron-hole by irradiation-induced free radicals and extrinsic non-radiative trap centers leading to the quenching effects. The generation of such free radicals and non-radiative recombination centers occurred through a chemical transformation of polymers in terms of polymer chain disordering, chain scission, chain aggregation, and bond breaking by ion irradiation depending upon the electronic energy depositions and ion fluences. The structural, vibrational, morphological, and optical properties of the irradiated P3OT and Cu-ZnO/P3OT HNCs films have been studied. Interestingly, the glancing-angle x-ray diffraction patterns of irradiated films reveal that the polymer and HNC films retain their chemical structures after high electronic deposition at lower ion fluences which leads to insignificant degradation of polymer and HNCs. However, a relative change in the intensity of characteristic peaks of polymer and ZnO was observed at higher ion fluences and is attributed to the disordering of polymer chains by high electronic depositions. Fourier transform infrared spectroscopy (FTIR) measurements also show similar observation, attributed to a decrease in the intensity of a few methyl and octyl functional groups of P3OT and HNCs. Further, optical study has shown a significant modification in the process of inter-chain and interfacial charge transfer. Finally, from these concurrent effects, PL quenching and photo-induced charge carrier transfer processes are understood by developing a schematic charge transfer diagram.

This work reports on the dielectric and electrical properties of a single-phase polycrystalline pyrochlore structured Gd2Zr2O7 ceramics with a highly dense and compact microstructure. X-ray diffraction along with Raman spectroscopic studies confirmed the formation of the pyrochlore phase; while the electron microscopy investigations showed the uniformly distributed and densely packed micrometer-sized grains. The relaxation phenomena and conduction processes in Gd2Zr2O7 analyzed using complex impedance spectroscopy which showed the appearance of low-frequency dielectric dispersion suggesting the dominance of conduction by oxygen ions. Observation of double semi-circular arcs in the Nyquist plots confirms that both grains and grain boundaries contribute to the electrical impedance of Gd2Zr2O7. The temperature-dependent ac conductivity studies on Gd2Zr2O7 followed the Jonscher’s power law exhibited a strong dispersive behavior at the low temperature (

Understanding the radiation tolerance of ceramics against low energy heavy ions is important for evaluating their stability against alpha recoils, which are a significant source of damage for their...

In the present study, crystallization of amorphous-Si (a-Si) in Al/a-Si bilayer thin films under thermal annealing and ion irradiation has been investigated for future solar energy materials applications. In particular, the effect of thickness ratio (e.g. in Al : a-Si, the ratio of the Al and a-Si layer thickness) and temperature during irradiation on crystallization of the Si films has been explored for the first time. Two sets of samples with thickness ratio 1 : 1 (set-A: 50 nm Al/50 nm a-Si) and thickness ratio 1 : 3 (set-B: 50 nm Al/150 nm a-Si) have been prepared on thermally oxidized Si-substrates. In one experiment, thermal annealing of the as-prepared sample (of both the sets) has been done at different temperatures of 100 °C, 200 °C, 300 °C, 400 °C, and 500 °C. Significant crystallization was found to initiate at 200 °C with the help of thermal annealing, which increased further by increasing the temperature. In another experiment, ion irradiation on both sets of samples has been carried out at 100 °C and 200 °C using 100 MeV Ni7+ ions with fluences of 1 × 1012 ions per cm2, 5 × 1012 ions per cm2, 1 × 1013 ions per cm2, and 5 × 1013 ions per cm2. Significant crystallization of Si was observed at a remarkably low temperature of 100 °C under ion irradiation. The samples irradiated at 100 °C show better crystallization than the samples irradiated at 200 °C. The maximum crystallization of a-Si has been observed at a fluence of 1 × 1012 ions per cm2, which was found to decrease with increasing ion fluence at both temperatures (i.e. 100 °C & 200 °C). The crystallization of a-Si is found to be better for set-B samples as compared to set-A samples at all the fluences and irradiation temperatures. The present work is aimed at developing the understanding of the crystallization process, which may have significant advantages for designing crystalline layers at lower temperature using appropriate masks for irradiation at the desired location. The detailed mechanisms behind all the above observations are discussed in this paper.

Zirconolite, a potential candidate for the immobilization of actinides was investigated for the induced effects of α-particles simulated through ion beam irradiation. Nd-doped zirconolite pellets (Ca0.8Nd0.2ZrTi1.8Al0.2O7) synthesized through two step solid state sintering were irradiated with 30 keV He+ ions and analyzed for irradiation induced structural modulations through glancing angle X-ray diffraction technique. Diffraction patterns showed reduction in peak intensity and broadening of peaks with increasing fluence, indicating loss of crystallinity. Though zirconolite didn’t amorphize even upon irradiation at the maximum fluence used i.e. 1 × 1017 ions/cm2. Measured lattice strain enhanced with fluence, further suggesting distortion of the structure.

Synroc minerals have been studied since decades for immobilization of high-level radioactive wastes released from nuclear weapons and nuclear reactors. Among them, the zirconolite, due to its high radiation and aqueous resistance and high waste loading, is considered as a potential candidate for containment purposes. Though irradiation damage effects of swift heavy ions in the material remain a major concern of study, a single phase Nd-doped zirconolite samples prepared through conventional solid-state reaction were irradiated with 120 MeV Au+ ions to study radiation damage effects. Irradiation-induced effects were investigated using ex-situ XRD and micro-Raman spectroscopic techniques. Zirconolite has been observed to undergo amorphization which is confirmed through disappearance of characteristic x-ray diffraction peaks and appearance of broad diffuse scattering bands. Amorphization trend with fluence appeared linear at lower fluences followed by saturation at higher fluences inferring therewith the formation of ion tracks. The ion fluence dependent Raman examination was also found to be in line with the XRD observations. However, the presence of Raman modes, characteristic of zirconolite in the 100–1000 cm−1 region, showed intact behavior of the local structure. To sum up, the 120 MeV heavy Au+ ions developed columnar defects, vacancies and induced micro-strains that lead to the bonds distortion and eventually amorphization of the zirconolite though retaining local ordering.

Free standing and flexible ferroelectric ceramic-polymer composites (PVDF+ ϕ wt.% of BNBT (0.94Na0.5Bi0.5TiO3-0.06BaTiO3)) with 0–3 connectivity were synthesized by solution-casting technique. Composite nature and homogeneous distribution of ceramic filler particles in PVDF were confirmed with x-ray diffraction and scanning electron microscopic analysis. The intensity ratio of β-phase with respect to α–phase i.e., I20.2°/I18.4° (obtained from XRD analysis) and the fraction of electro-active beta phase i.e., F(β)% (obtained from FTIR analysis) are enhanced with increase in filler concentrations and peaked for 35 wt% of the ceramic filler. An enhancement of the % of crystallinity (calculated from XRD analysis) has been observed with increase in the filler concentrations. The increase of the fraction of β-phase has been explained on the basis of ion (negatively charged surface ion of the ferroelectric ceramic filler) -dipole (-CH2 dipole of the polymer matrix) interactions, as evidenced from FTIR and UV-VIS absorbance spectra. Relative dielectric permittivity (dielectric constant) and ferroelectric polarization were found to be highest for the composite with 35 wt% of ferroelectric ceramic filler. Percolation theory has been successfully employed to explain the observed trend in the dielectric properties with the compositional variation. Significant enhancement in the electro active β-phase has been correlated with the improved dielectric and ferroelectric properties of the composite.

Zirconolite, a potential matrix for the immobilization has been studied to investigate the doping behaviour of Ce in its structure to design a nuclear waste form that can accommodate both trivalent and tetravalent nuclear wastes. So, samples have been prepared as per the composition Ca0.8Ce0.2ZrTi1.8Al0.2O7 using solid-state method and analysed for their structural, micro-structural and chemical properties. A dense-packed structure was found in SEM with the phase of zirconolite-2M as confirmed by XRD and Raman techniques. Quantitative analysis of XPS inferred that the percentage of Ce(III) in the sample was about ~ 75% indicating the reduction of Ce at higher temperatures.

Copper metal embedded fullerene C60 thin films are deposited on various substrates via resistive heating co evaporation technique. Rutherford back scattering simulated spectrum confirms the thickness and composition of thin film to be ~ 32 nm and ~ 18 at%, respectively. The deposited thin films are irradiated by 120 MeV Ag ion beam for different fluences within the range, from 1 × 1012 to 3 × 1013 ions/cm2. UV–vis absorption spectroscopy study reveals the appearance of surface plasmon resonance (SPR) band in pristine thin film at ~ 622 nm; this phenomenon is ascribed to the presence of copper nanoparticles in C60 matrix. The SPR band intensity increases with rising fluences, which is suggestive of the growth of Cu nanoparticles. Growth of Cu nanoparticles is further confirmed by transmission electron microscopic (TEM) and X-ray diffraction (XRD) study. Whereas the conversion of C60 into amorphous carbon (a-C) is confirmed by Raman spectroscopy, XRD results of pristine Cu–C60 thin film record the presence of Cu2O within the nanocomposite thin film. However, both X-ray photoelectron spectroscopy (XPS) and XRD studies on irradiated thin film samples authenticate the growth of Cu metal nanoparticles with concurrent removal of oxygen.

The electrical transport properties of Ti/n-Si Schottky barrier structure irradiated by 100 MeV O7+ ion has been studied between 120 K and 320 K and compared with unirradiated Ti/n-Si structure to gain the understanding of carrier transport mechanism in irradiated devices. The barrier parameters have been extracted using the current-voltage (I–V) characteristics in forwarding bias. It is found that Schottky barrier height (zero bias) increases while the value of ideality factor becomes smaller with increasing temperature. Recent models consisting of inhomogeneous barrier potential at the metal-semiconductor (MS) interface have been used to explain the behavior of barrier parameters. The role played by the high energy ions at MS interface during irradiation is considered to understand the observed behavior.

Over the past 60 years, the safe disposal of high-level wastes (HLWs) produced during reprocessing of spent nuclear fuel has become a serious issue and a world-wide challenge. The radionuclides contained in HLWs severely affect the biosphere due to their long half-life and high radiotoxicity. In order to meet this challenging task, the research is underway to develop an advanced stable nuclear waste form which will be capable to accommodate the radiation effects under repository conditions and over geological time scales. Among potential waste forms, zirconolite has been proven to be a good candidate for the desired purpose due to its high radiation and thermal stability and high loading capacity to accommodate the wastes of lanthanides and actinides without any effect on the crystallinity of zirconolite material. In this article, a detailed review has been carried out on ongoing developments in these materials to contain HLWs, various synthesis methods employed to practice these materials, preparation manners of single phase zirconolite compositions and subsequently the structural characterization of zirconolites doped with various tri- and/ or tetravalent lanthanides and actinides as also their loading capacities.

The nanocomposite thin films of Tin oxide (SnO2) and Titanium dioxide(TiO2) were deposited on silicon and ITO substrate by RF magnetron sputtering technique using sintered pellet formed by mixing S...

Hydrogen is one of the alternatives as clean fuel for our growing demands for energy. However, its storage for practical applications is a challenge due to low energy density. The interaction mechanism between the hydrogen gas and the host involved plays a vital role to explore its potential application as hydrogen storage material. So, in the present work, we have studied the interaction of Graphene oxide with hydrogen gas at different pressures varying from 70 mbar to 900 mbar at room temperature using reliable in-situ X-ray diffraction technique. XRD patterns showed that the hydrogen gas induced strain up to ∼6.3% in GO films for 1% and 10% hydrogen atmosphere. The interaction mechanism was studied qualitatively using Raman spectroscopy and Fourier transform infra-red (FTIR) spectroscopy. Elastic recoil detection analysis (ERDA) technique was employed to determine the concentration of hydrogen in GO film which increased from ∼1.7 × 1022 atoms/cc (for pristine GO) to ∼ 9.5 × 1022 atoms/cc after exposing to 100% hydrogen environment at 900 mbar pressure.

Inert matrix fuel concept for minor actinide transmutation proposes stabilized zirconia as the major component for inert matrix. The present study explores Nd-stabilized zirconia (Zr0.8Nd0.2O1.9; Nd as surrogate for Am) and its composites for radiation tolerance against fission fragments. The introduction of MgO in the composite with stabilised zirconia is performed from the point of view to enhance the thermal conductivity. The radiation damage is also compared with Nd-stabilized zirconia co-doped with Y3+ (Zr0.8Nd0.1Y0.1O1.9) in order to mimic doping of minor actinides in Y3+ containing stabilized zirconia (Nd as surrogate for Am). The compositions were synthesized by gel combustion followed by high temperature sintering and characterised by XRD, SEM and EDS. Irradiation was carried out by 120 MeV Au ions at various fluences and irradiation induced structural changes were probed by in-situ X-ray diffraction (XRD). XRD demonstrated the retention of crystallinity for all the three samples but the extent of the damage was found to be highly dependent on the nominal composition. It was observed that introduction of Y3+ along with Nd3+ to stabilize cubic zirconia imparted poorer radiation stability. On the other hand, formation of a CERCER composite of MgO with Nd-stabilised zirconia enhanced its behaviour against swift heavy ion irradiation. Investigating these compositions by XANES spectroscopy post irradiation did not show any change in local electronic structure of constituent ions.

The microstructural evolution and grain growth kinetics of the nanocrystalline Gd 2 Ti 2 O 7 drastically affect its properties and functionalities as thermal barrier coatings and nuclear waste forms for actinide incorporation. Here, we report the synthesis of the dense nano-sized Gd 2 Ti 2 O 7 by high energy ball milling (HEBM), and spark plasma sintering (SPS), and also investigated the isothermally annealing induced grain coarsening and structural properties variations. As-prepared nano powder (D∼60 nm) by HEBM exhibited an amorphous nature, which was consolidated to a dense single phase crystalline pyrochlore nano-ceramic (D∼120 ± 10 nm) by SPS sintering at 1200 °C. Isothermal annealing was performed at different temperatures (1300 °C - 1500 °C) with holding time varying from 0.5 to 8 h, and the pyrochlore phase is stable with no indication of a transformation into a defect fluorite structure. A rapid initial grain growth was observed which increased with temperature and annealing durations due to the large driving force of the curvature-driven grain coarsening of the nano-ceramics, and grain growth saturates at longer durations. The calculated value of the time constant and activation energy for the nanocrystalline Gd 2 Ti 2 O 7 were 0.52 ± 0.02 and 240 ± 20 kJ/mol (∼2.48 eV), respectively. The enhanced grain growth kinetics with a lower value of activation energy can be explained by the effect of fast diffusion across the grain boundaries for dense nanoceramics.

In present study, the effect of hydrogen gas pressure on the electrical characteristics of the Pd nanoparticle embedded in the carbon matrix was investigated. The structural characterizations of the as-prepared samples were performed using synchrotron radiation x-ray diffraction (SR-XRD), and transmission electron microscopy (TEM). In-situ electrical transport studies for high concentration sample showed a slow response time (∼30 s) and the resistance versus time curves have similar behavior that of Pd thin films, whereas the lower concentration sample has a fast response time (5 s) along with peculiar response curve. The pressure dependent studies showed that spillover effect was dominant, when samples were exposed to hydrogen gas at low pressure. The superior sensing performance of the lower concentration sample was observed due to extraordinary high surface to volume ratio of nanoparticles as well as good separation provided by the carbon matrix. The spillover effect based hydrogen absorption–desorption mechanism proposed in the present study is important for understanding the hydrogen absorption in the metal nano-composite system and its application in the design of advanced materials for hydrogen gas sensors.

We simulated the threshold displacement energies ( E d ), the related displacement and defect formation probabilities, and the energy barriers in LaPO4 monazite-type ceramics. The obtained E d values for La, P, O primary knock-on atoms (PKA) are 56 eV, 75 eV and 8 eV, respectively. We found that these energies can be correlated with the energy barriers that separate the defect from the initial states. The E d values are about twice the values of energy barriers, which is explained through an efficient dissipation of the PKA kinetic energy in the considered system. The computed E d were used in simulations of the extent of radiation damage in La0.2Gd0.8PO4 solid solution, investigated experimentally. We found that this lanthanide phosphate fully amorphises in the ion beam experiments for fluences higher than ∼1013 ions/cm2.

High-quality polycrystalline thin films of β-Ga2O3 were grown at room temperature on quartz and Si (100) substrates using e-beam evaporation followed bypost-deposition annealing at 950 °C. The thin films were characterized to investigate their structure, composition and optical properties. It is observed through x-ray diffraction, Raman spectroscopy, and UV-visible absorption measurements that thermal annealing transforms as-grown amorphous film with bandgap 4.04 eV into polycrystalline layer having a bandgap of 4.84 eV. As confirmed by Rutherford backscattering spectroscopy, as-grown films were sub-stoichiometric.

The effects of metal concentration and annealing temperature on the localized surface plasmon resonance (LSPR) properties of the Pd nanoparticles (NP) dispersed in carbon were investigated. The Pd/C nano-composite thin films with 7 to 39 atomic % concentration of metal content were deposited using the atom beam co-sputtering techniques and subjected to annealing at temperature varying from 300 °C to 600 °C. The UV-vis spectroscopy studies on as-prepared films displayed a Mie scattering profile, but not well-defined LSPR bands were observed for all the values of Pd concentration. This is attributed to the smaller size (3–4 nm) of Pd NPs and rough Pd/C interface, as confirmed from TEM studies. When samples were annealed at a temperature of 300 °C, three broad LSPR absorption bands in the visible region, along with a sharp peak at 210 nm, were observed and the effect of Pd concentration variation was insignificant on their position. The multiple LSPR bands were observed due to agglomeration NPs, which is consistent with earlier reports and is also observed in the TEM images. When annealing temperature was subsequently increased to 500 °C, a blue shift in the LSPR peak position with an increase in the Pd concentration was observed, which phenomena is attributed to the formation of bigger NPs with the formation of sharp NPs-interface at high temperature upon annealing. A monotonic increase in the magnitude and decrease in the FWHM with an increase in concentration suggested change in the dielectric function of sample due to the growth of NPs. This is further confirmed from XRD studies, where strain relaxation and grain growth were observed. The intensity of the SPR peak decreased with an increase in the annealing temperature. The LSPR peak disappeared on annealing at a temperature of 600 °C, suggesting the formation of continuous polycrystalline thin films of Pd. In summary, NPs size, metalmatrix interface, and concentration of metal play key roles in the tailoring the LSPR properties of the Pd.

The physical and chemical properties of soft polymer–ceramic composites with 50 MeV swift heavy, Li3+ ion irradiation were studied. A solution-casting technique was employed to synthesize free standing, flexible composite films of ferroelectric polymer PVDF and ferroelectric ceramic BNBT mixtures with 0–3 connectivity. However, only 35 wt% ceramic was chosen for the study as it showed the highest dielectric constant and enhanced ferroelectric properties without irradiation. The effects of ion irradiation on the structural, microstructural, morphological, dielectric and ferroelectric properties of this particular composition were systematically investigated and conclusions were drawn. The mechanism for the enhancement of the electroactive β-phase due to the swift heavy ion irradiation was discussed and the enhancement was well correlated with its ferroelectric and dielectric properties.

The difference in the defect structures produced by different ion masses in a tungsten lattice is investigated using 80 MeV Au7+ ions and 10 MeV B3+ ions. The details of the defects produced by ions in recrystallized tungsten foil samples are studied using transmission electron microscopy. Dislocations of type b = 1/2[111] and [001] were observed in the analysis. While highly energetic gold ion produced small clusters of defects with very few dislocation lines, boron has produced large and sparse clusters with numerous dislocation lines. The difference in the defect structures could be due to the difference in separation between primary knock-on atoms produced by gold and boron ions.

State of the art applications (nuclear waste host, scintillators, piezoelectric, SOFCs, etc.) of isometric pyrochlore, A2B2O7, are very sensitive to the structural assessment upon ion irradiation. In the present study, La2Zr2O7 is irradiated using 1 MeV Xe4+ ions with fluence of 1 × 1013, 5 × 1013, and 1 × 1014 ions/cm2 at ~ 88 K and 300 K. The impact of irradiation temperature and ion fluence on the structural properties of the La2Zr2O7 are investigated using the GIXRD, Raman spectroscopy and high resolution transmission electron microscopy (HR-TEM). The GIXRD and Raman results indicate that the degradation of the crystallinity (i.e., damage/amorphization) are significantly higher with enhanced fluence at ~ 88 K than that of 300 K. The induced lattice strain also increases with an increase of ion fluence and it is more pronounced at ~88 K. The HR-TEM results of the La2Zr2O7 samples exhibit that degradation of the atomic ordering are more pronounced at ~ 88 K. The prominent induced strain and degradation of crystallinity (i.e., damage/amorphization) at ~ 88 K appear to be ion fluence and irradiation temperature-dependent. This study is enlightening the effect of the ion fluence and irradiation temperature on the degradation of crystallinity (i.e., damage/amorphization).

Self-sustained films of biodegradable chitosan (CS) and chitosan-Ag nanocomposites (CSN) were prepared by chemical route followed by C+5 and Ni+7 ions irradiation with varying fluences. The crystallite size decreased from 11.1 to 2.7 nm for CS and 17.6 to 14.2 nm for CSN with increasing ions fluence as observed from the analysis of X-ray Diffraction (XRD) spectra. ATR-FTIR spectra revealed assorted vibrational modes and degradation of polymeric chains in both, CS and CSN matrices upon irradiation. The molecular interactions between main and side-chain functional groups impeded due to nanoparticles confining effects. MeV ions yield low-molecular-weight fragments with degassing of some volatile gaseous species during irradiation. An acute amendment in absorption spectra ascribed to change in surface color and differential absorbance at the wavelength of 370 nm showing blocking of UV radiation. The formation of conjugated linkages and carbonization of CS and CSN matrices lead to decrease in bandgap. Modifications in the physicochemical properties were found to be in persuasive association with changes in frequency-dependent dielectric responses. The shape parameter was moderately decreased and indicating non-Debye relaxation. The conductivity of CS and CSN matrices enhanced and follows the universal dielectric response. The amendment in surface morphology was also revealed upon irradiation.

Grain size driven effects on electronic excitation-induced structural modifications have been investigated in nanocrystalline (NC) Nd2Zr2O7 on irradiation with 100 MeV iodine ions. Characterizations have been performed with in situ x-ray diffraction, Raman spectroscopy, and plane-view high-resolution transmission electron microscopy techniques. NC-powders of Nd2Zr2O7 were synthesized by auto gel-combustion and sintered at different temperatures to obtain different grain-sized samples. XRD analysis of the smallest grain-sized sample reveals the highest order–disorder transition (from pyrochlore to a more radiation-resistant phase; anion-deficient fluorite) rate at initial ion fluences followed by least amorphization at higher ion fluences. A strong correlation of the transformation build-up with the double ion impact model confirms the two step amorphization process in NC-Nd2Zr2O7 with the disordered anion-deficient fluorite structure as an intermediate phase. TEM result supports the formation of circular ion track consisting of randomly distributed regions (anion-deficient fluorite structure and amorphous regions), surrounded by a microstrain induced defect-rich pyrochlore superstructure. Lesser ordering at cationic sites and a relatively larger number of grain boundaries are responsible for the highest radiation tolerance exhibited by the smallest grain-sized sample. The present study reports a relatively higher radiation stability of NC-ternary pyrochlore oxide, Nd2Zr2O7, with a grain size of a few tens of nm, which establishes its application as a potential inert matrix for nuclear applications.

Hydrogen gas sensing response of RF sputtered nano-crystalline ZnO thin film is improved by $\sim 34.73$ % using swift heavy ion irradiation technique. X-ray diffraction reveals single crystalline wurtzite structure of ZnO thin films. Full width half maximum (FWHM) of (0002) diffraction peak is decreased with increase in ion fluences. However, at very high fluence $1\times 10^{13}$ ions/cm2, crystallinity is degraded while FWHM of diffraction peak increases. The ZnO films were grown under highly compressive stress, which was relaxed with incremental ion fluences up to $1\times 10^{13}$ ions/cm2. Cathodoluminenscence spectroscopy shows intense predominant peak around $\sim 3.23$ eV, which indicates good optical quality of the films. As ion fluence increases, a blue shift appears in near band emission peak from 3.23 to 3.33 eV, which indicates that in-plane stress is decreased. Surface morphology shows generation of self-affine nanostructure and grain fragments as ion fluences were increased. Grain fragmentations had enhanced the surface reaction, and as a result, gas sensor’s relative response has improved. It was observed that the gas sensor’s sensitivity is strongly dependent on ion fluences and operating temperature. The sensitivity was enhanced from 66.68% to 89.84% with fluence variations from pristine to $1\times 10^{12}$ ions/cm2 at 175 °C operating temperature.

Effect of 80 MeV 16 O 6+ ion irradiation in amorphous Fe 77 P 8 Si 3 C 5 Al 2 Ga 1 B 4 alloy is reported. Electronic energy loss induced modifications in the structural and, magnetic properties were monitored by synchrotron X-ray diffraction (SXRD), Mossbauer and, magnetic measurements. Broad amorphous hump seen in SXRD patterns reveals the amorphous nature of the studied specimens. Mossbauer measurements suggest that: (a) alignment of atomic spins within ribbon plane, (b) changes in average hyperfine field suggests radiation-induced decrease in the inter atomic distance around Mossbauer (Fe) atom, (c) hyperfine field distribution confirms the presence of non-magnetic elements (e.g. – B, P, C) in the first near-neighbor shell of the Fe atom, thus reducing its magnetic moment, and (d) changes in isomer shift suggests variation in average number of the metalloid near neighbors and their distances. Minor changes in soft magnetic behavior – watt loss and, coercivity after an irradiation dose of 2 × 10 13 ions/cm 2 suggests prospective application of Fe 77 P 8 Si 3 C 5 Al 2 Ga 1 B 4 alloy as core material in accelerators (radio frequency cavities).

The immobilization of minor actinides and alkaline-earth metal is a major concern in nuclear industry due to their long-term radioactive contribution to the high level waste (HLW). Materials having zirconolite, pyrochlore, and perovskite structure are promising candidates for immobilization of HLW. The zirconolite which exhibits high radiation stability and corrosion resistance behavior is investigated for its radiation stability against alpha particles in the present study. CaZrTi 2 O 7 pellets prepared using solid state reaction techniques, were irradiated with 30 keV He + ions for the ion fluence varying from 1 × 10 17 to 1 × 10 21 ions/m 2 . Scanning electron microscopy (SEM) images of the un-irradiated sample exhibited well separated grains with average size of about 6.8 μm. On the ion irradiation, value of the average grains size was about 7.1 μm, and change in the microstructure was insignificant. The X-ray photoelectron spectroscopy (XPS) studies showed a shift in the core level peak position (of Ca 2p, Ti 2p and Zr 3d) towards lower binding energy with respect to pristine sample as well as loss of oxygen was also observed for sample irradiated with the ion fluence of 1 × 10 20 ions/m 2 . These indicate a decrease in co-ordination number and the ionic character of M O bond. Moreover, core level XPS signal was not detected for sample irradiated with ion fluence of 1 × 10 21 ions/m 2 , suggesting surface damage of the sample at this ion fluence. However, X-ray diffraction (XRD) studies showed that zirconolite was not amorphized even on irradiation up to a fluence order of 1 × 10 21 ion/m 2 . But, significant decrease in peak intensity due to creation of defects and a marginal positive peak shift due to tensile strain induced by irradiation, were observed. Thus, XRD along with XPS investigation suggests that reduction, decrease in co-ordination number, and increase in covalency are responsible for the radiation damage in zirconolite.

Effect of (80 MeV) 16 O 6 + ion irradiation on the structural properties and cation distribution of the as-burnt samples (i.e. the samples are without any thermal/sintering treatment) with the following compositions: MnFe 2 O 4 , Mn 0.5 Zn 0.5 Fe 2 O 4 and ZnFe 2 O 4 prepared by sol–gel auto-combustion technique have been studied through in-situ and ex-situ X-ray diffraction (XRD) technique. Well characterized single phase MnFe 2 O 4 and Mn 0.5 Zn 0.5 Fe 2 O 4 samples were irradiated at fluence 1 × 10 11 , 1 × 10 12 , 1 × 10 13 and 1 × 10 14 ions/cm 2 to see the effect of the electronic energy loss induced changes in the structural properties and in cation distribution monitored through ex-situ XRD. ZnFe 2 O 4 samples were irradiated with ion fluence values ranging between 1 × 10 11 − 2 × 10 14 ions/cm 2 to observe the effect of in-situ XRD on structural properties and cation distribution. Results very clearly depict the redistribution of cations in the samples, which show noticeable changes in: ionic radii of A-site ( r A ) and B-site ( r B ), experimental and theoretical lattice parameter ( a exp. , a th. ), unit cell volume ( V ), Scherrer’s Grain diameter ( D ), oxygen positional parameter ( u ), tetrahedral and octahedral bond length ( R A , R B ), shared tetrahedral and octahedral edge ( d AE , d BE ) and bond angles ( θ 1 , θ 2 , θ 3 , θ 4 , θ 5 ). Results are interpreted in terms of irradiation induced changes in the above mentioned parameters.

Poly ethylene oxide (PEO) films were synthesized by solution cast method. These self-standing films were exposed with 60 MeV C +5 ion and 100 MeV Ni +7 ion at different fluences. SHI induced effect was investigated by employing various techniques. The crystalline size decreased upon irradiation as observed from XRD analysis. FTIR analysis reveals the decrement in the peak intensity upon irradiation. Tauc’s method was used to determine the optical band gap ( E g ), which shows decreasing trends with increase of fluence. The dielectric properties were investigated in the frequency range 10 Hz to 10 MHz for unirradiated and irradiated films. The dielectric constant remains same for the broad-spectrum of frequency and increases at lower frequency. The dielectric loss also moderately influence as a function of frequency due to irradiation. DSC analysis validated the results of XRD. Scanning electron microscopy (SEM) reveals that there is significant change in the surface morphology due to irradiation.

The CdS–Bi2S3 bi-layer thin films have been deposited on Indium Tin Oxide (ITO) glass substrates at room temperature by Chemical Bath Deposition Technique (CBD) and bi-layer thin films were annealed in air atmosphere for 1 h at 250 °C. The air annealed sample was irradiated using Au9+ ions at the fluence 5 × 1011 ion/cm2 with 120 MeV energy. Effects of Swift Heavy Ion (SHI) irradiation on CdS–Bi2S3 bi-layer thin films were studied. The results are explained on the basis annealing and high electronic excitation, using X-ray diffraction (XRD), Selective Electron Area Diffraction (SEAD), Atomic Force Microscopy (AFM), Raman Spectroscopy, UV spectroscopy and I–V characteristics. The photosensing property after illumination of visible light over the samples is studied. These as-deposited, annealed and irradiated bi-layer thin films are used to sense visible light at room temperature.

Crystalline Si films incorporated with Al are important for applications in microelectronics and solar cells. In this paper, we report on the morphology of crystalline Si surfaces in Al/amorphous-Si bilayer thin films under ion beam irradiation at 100 °C. Micro-Raman and transmission electron microscopy studies show that best crystallization is achieved at a fluence of 1 × 1012 ions cm−2. The contact angle of Si surfaces (after chemically etched unreacted Al), referred to as absorber surfaces, decreases with increasing ion fluence. These surfaces are hydrophobic in nature and the hydrophobicity decreases with increasing ion fluence. Fractal and multifractal analysis of atomic force microscopy images, along with system energy/unit cell and Laplace pressure calculations, supports our observations. Moreover, the calculated multiple scattering cross sections of light, along with reflectivity measurements, indicate that absorber surfaces of best crystalline films have the lowest reflectivity. The present results suggest that such surfaces having low optical reflectance and a hydrophobic nature can be used as photon absorber layers for advanced solar cell devices.

The isometric pyrochlore structure type A2B2O7 possesses a wide range of technological applications such as electrolytes in solid oxide fuel cell, thermal barrier coating, and nuclear waste form for actinides incorporation. Pyrochlore series Gd2Ti2-yZryO7 with y = 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0 was prepared using standard solid-state method. X-ray diffraction along with SEM studies was carried out to investigate the effect of Zr content on microstructure and the swift heavy ion irradiation-induced effects on the structural integrity of Gd2Ti2-yZryO7 pyrochlore family. Rietveld refinement showed a systematic increase in the lattice parameter on increasing the value of y in Gd2Ti2-yZryO7 and an abrupt enhancement in the value of the O48f positional parameter at y ≥ 1.6. The intensity of superstructure peaks gradually decreases in the X-ray diffraction pattern on increasing the Zr content, which indicates the transformation from the ordered pyrochlore structure to disordered anion-deficient fluorite structure. On irradiation with swift heavy ion (120 MeV Au+9), the compositions with y = 0.0 and 0.4 were completely amorphized and the composition with y = 0.8 and 1.2 partially amorphized whereas no sign of amorphization was observed in the Zr rich (y = 1.6 and 2.0) compositions. The composition with y ≥ 1.6 retains its crystallinity even at higher ion fluence of 1 × 1014 ions/cm2. These results are explained on the basis of the ratio of cationic radii rA/rB and in turn the ‘x’ parameter of 48f oxygen.

SnO2 thin films have been deposited on Si substrates using RF-magnetron sputtering and implanted by 200 keV Cu− ions with ion fluence of 2.79 × 1016 ion/cm2 and 4 × 1016 ion/cm2. Post annealing is done on the pristine and Cu− ion-implanted SnO2 thin films. Samples were characterized using the grazing-incidence X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FESEM) and near-edge X-ray absorption fine structure (NEXAFS). After the annealing, amorphous to crystalline phase transition and growth of particles are seen. It is also evidenced that Cu ions do not make metallic/oxide phases up to the implantation dose of 2.79 × 1016 ion/cm2. Cu L-edge NEXAFS has confirmed the Cu2+ ions in the samples. The O K-edge NEXAFS spectra of annealed films have shown diminished peak intensity of O 2p to Sn 5s hybridized orbitals which signify the O vacancy formation. A pre-edge peak in the O K-edge NEXAFS of Cu implanted films has evolved and confirms the additional hybridization of unoccupied Cu d orbitals with O 2p orbitals. The improved intensity of Sn M5,4-edge features is due to the enhanced crystallinity in annealed samples. Ion-solid interaction induced structural and electronic structure amendments are briefly discussed in the light of energy-loss mechanism.

Solar-blind photodetectors are critically important for civil and military applications. Several of these applications, such as space exploration and nuclear energy infrastructure, demand the use of a photodetector under extreme environments. In this paper, we have studied the radiation hardness and device performance of amorphous and polycrystalline gallium oxide thin films against heavy ion (Ag7+) irradiation with a high energy of 100 MeV. Gallium oxide thin films show great tenacity against massive and highly energetic ions. The amorphous and polycrystalline phases undergo structural and morphological changes that initially induce degradation in the device performance. Nano-pore like structures are formed in the amorphous film, while the polycrystalline film shows the destruction of large crystallites. The responsivity of the photodetector device reduces fourfold in the amorphous phase; however, a sixfold reduction in the performance is observed in the polycrystalline phase of the gallium oxide photodetector. The degradation is attributed to the annealing of pre-existing optical defects that are otherwise responsible for the huge photoconductive gain in the detector and confirmed by photoluminescence studies. The effect of self-annealing at room temperature and annealing at moderate temperature is investigated to recover the irradiated photodetector devices. Partial recovery in the polycrystalline based photodetector and two orders of magnitude enhanced responsivity and an almost twice faster response time compared to the control photodetectors in the amorphous phase are observed. This work investigates the effect of heavy and energetic ions on the performance of gallium oxide based solar-blind photodetector and provides the guideline to use high energy irradiation as a tool for defect engineering.

The understanding of the influence of energetic ions on the transport properties of semiconductor materials is essential to design the devices for use in a radiation environment. In this article, an in-situ investigation of the effect of 100 MeV O7+ irradiation on the current-voltage characteristics of the Pd/n-Si Schottky barrier structure is carried out. It is observed that the interface barrier parameters (Ideality Factor, Schottky barrier height and reverse saturation current) are a strong function of ion fluence. The voltage dependence of conduction mechanisms indicates the presence of defects near the interface as well as in bulk silicon. The energy loss mechanisms of energetic ions in the Pd/n-Si structure are used to explain the observed results after irradiation.

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) Na

We demonstrate a highly selective and reversible NO

The dependence of radiation stability of Gd 2 Zr 2 O 7 on stoichiometry and structure under swift heavy ion irradiation was investigated. Gd 2 Zr 2 O 7 , lies on the borderline of pyrochlore to fluorite phase transition, hence, it is highly sensitive to variations in the composition and/or synthesis conditions. The Gd 2 Zr 2 O 7 was synthesized in two sets (Set-A and -B) by solid state synthesis and gel combustion yielding different phases and stoichiometry as confirmed by Resonant Rutherford backscattering spectrometry (RRBS) and field emission scanning electron microscopy (FESEM). Both sets of Gd 2 Zr 2 O 7 were irradiated with 120 MeV Au ions with fluences varying from 3×10 11 to 1×10 14 ions/cm 2 . The pristine and irradiated samples were studied by X-ray diffraction (XRD) and Raman spectroscopy. The Set-A sample with pyrochlore structure remained crystalline upto the highest fluence 10 14 ions/cm 2 employed, whereas Set-B sample having anion-deficient fluorite structure lost crystallinity at the fluence of 5×10 13 ions/cm 2 , as revealed by in-situ XRD experiment. The in-situ XRD along with Raman studies elucidated that sample synthesized using solid state reaction process exhibits better stability under swift heavy ion irradiation, implying that the sample with perfect stoichiometric pyrochlore structure possess better radiation stability.

In order to simulate radiation damages in tungsten, potential plasma facing materials in future fusion reactors, surrogate approach of heavy ion irradiation on polycrystalline tungsten is employed. Tungsten specimen is irradiated with gold heavy ions of energy 120 MeV at different fluences. Positron annihilation lifetime measurements are carried out on pristine and ion beam irradiated tungsten specimens. The variation in positron annihilation lifetime in ion irradiated specimens confirms evolution of vacancy clusters under heavy ion irradiation. The pristine and irradiated tungsten specimens have also been characterized for their microstructural, structural, electrical, thermal, and mechanical properties. X-ray diffractograms of irradiated tungsten specimens show structural integrity of polycrystalline tungsten even after irradiation. Nevertheless, the increase in microstrain, electrical resistivity and microhardness on irradiation indicates creation of lattice damages inside polycrystalline tungsten specimen. On the other hand, the thermal diffusivity has not change much on heavy ion irradiation. The induction of damages in metallic tungsten is mainly attributed to high electronic energy loss, which is 40 keV/nm in present case as obtained from SRIM program. Although, concomitant effect of nuclear losses on damage creation cannot be ignored. It is believed that the energy received by the electronic system is being transferred to the atomic system by electron-phonon coupling. Eventually, elastic nuclear collisions and the transfer of energy from electronic to atomic system via inelastic collision is leading to significant defect generation in tungsten lattice.

Effect of nanoparticle size and alloying has been well studied in Pd and Pd alloy nanoparticles and explained on the basis of modifications in the crystal structure and Pd 4d binding energy position. In the present study, the effect of carbon shell thickness on the hydrogenation properties of gas phase synthesized Pd–C core–shell nanoparticles having controllable nanoparticle core and shell thickness has been investigated. A large improvement in H/Pd ratio and increased hydrogen induced lattice expansion is observed in Pd–C nanoparticles. These results are explained on the basis of lowering of coordination number of Pd surface sites at Pd–C core–shell interface revealed by the increase in the Pd 4d binding energy on increase in shell thickness. By combining the modification in electronic properties due to the size and the alloying effects with that due to carbon shell thickness, as reported in the present study, Pd–H interaction can be significantly enhanced.