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The effects of Ag nanoinclusions on thermoelectric properties of Ag2S semiconducting nanostructures, synthesized by a novel one-pot facile polyol method, have been investigated. The resulting produ...

Ore minerals in dolomites and Graphite Mica Schist (GMS) were studied by synchrotron radiation micro-computed tomography (SR-μCT) and optical microscopy. High resolution μCT images of ore minerals were obtained at Imaging Beamline (BL-4), Indus-2 synchrotron radiation source for the comprehensive volume characterization of minerals. Optical microscopy was used for mineral identification, mineral/rock characterization and quantification of ore mineral assemblages was also confirmed by XRD. 3D images from SR-μCT have shown spatial distribution of major minerals and crystals of different minerals in the volume of samples. The results obtained shows that the GMS and dolomitic hosted rocks mined from region near Udaipur, Rajasthan contains sulfide mineral phases. SR-μCT facilitates visualization of the association of the various metallic minerals with the host rock. The presence of economically important metallic minerals galena, sphalerite and pyrite found in the samples through SR-μCT has implications on exploration and processing of ores.

We report the growth of bismuth ferrite, BiFeO 3 (BFO), thin films by varying oxygen partial pressure (230, 100 and 10mTorr) in pulsed laser deposition system using 10% bismuth excess BFO target on SrTiO 3 (001) [STO] substrates at 700 °C each for 15 min duration. X-ray diffraction shows the presence of an impurity phase along with BFO peaks for 230 mTorr film, whereas oriented BFO film is observed for 100 mTorr film with a small impurity phase. Importantly, epitaxial growth of BFO is observed without any impurity phase and with sufficiently increased strain for the 10 mTorr film, confirmed by the reciprocal space mapping of (002) and (103) reflections. UV-Raman measurements have been performed on as grown films and the 10 mTorr BFO film after annealing up to 500 °C to check its thermal stability. Atomic force microscopic (AFM) study reveals that the 10 mTorr BFO film shows a lower roughness as compared to 100 mTorr and 230 mTorr films. Fast Fourier Transform (FFT) analysis in AFM shows a fourfold symmetric structure suggesting the presence of both modes of pattern-orientation in 230 mTorr BFO film whereas an elongated bright spot along the y-direction in the FFT of 10 mTorr BFO film suggests the growth tendency to be along the y-direction.

Temperature dependent Raman spectra of a Dy@C82 thin film are investigated between 80 and 300 K. The first order temperature coefficient is evaluated for both Dy–C and C–C vibrational modes which reveals the presence of thermal and anharmonic contributions to the phonon hardening at low temperatures. The Dy–C mode broadens while decreasing the temperature revealing that the electron–phonon coupling is dominant over phonon–phonon coupling at low temperatures. In addition, laser-power dependent Raman spectra of Dy@C82 and Gd@C82 have been analyzed for estimating their first order power coefficients and the thermal conductivities.

PbS/polyvinylpyrrolidone (PVP) nanocomposite films with tunable band gap are synthesized by solid state in situ thermolysis. Precursor films are dip-coated on glass substrates from a methanolic solution of Pb2+–thiourea complex and PVP and then heated in air at 110 °C for 10 minutes to obtain shiny brown clear films of PbS/PVP. The formation of PbS nanoparticles in PVP matrix is confirmed by X-ray diffraction studies. The size of PbS nanoparticles varied from 2 to 8 nm depending of the weight fraction of the Pb2+–thiourea complex in the PVP. Transmission electron microscopy shows that the nanoparticles are spherical. The transmission spectra of the PbS/PVP films in the wavelength range of 300 to 2600 nm showed absorption edges near 900 nm and below due to the presence of PbS nanoparticles. The band gaps of PbS/PVP films, as determined from Tauc plots, varied from 0.8 to 1.92 eV as the weight fraction of the complex decreased from 82 to 36%. Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and 13C Nuclear Magnetic Resonance (NMR) studies reveal that there is strong interaction between PbS and PVP which limits the growth of the nanoparticles.

The deposition time dependence of optical, structural and morphological properties of thin as well as ultrathin Polytetrafluoroethylene (PTFE) sputtered films have been explored in the present communication. The films were prepared by RF magnetron sputtering under high vacuum condition, as a function of deposition time. The ellipsometry as well as X-ray reflectivity data show a drastic reduction in film thickness as the deposition time increases from 5 s to 10 s, possibly as a consequence of back sputtering. With subsequent deposition, back sputtering component decreases and hence, thickness increases with increase in deposition time. Atomic force microscopy (AFM) images show a slight change in growth morphology although roughness is independent of deposition time. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) measurements showed the presence of C C and CF x (x = 1–3) bonds in all the PTFE films. Supporting this, corresponding X-ray photoelectron spectroscopy (XPS) curves fitted for C-1s and F-1s peaks revealed a major contribution from CF 2 bonds along with significant contribution from CF 3 bonds leading to an F/C ratio of ∼1.5 giving hydrophobic nature of all the films.

X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) of Nd-doped phosphate glasses have been studied before and after gamma irradiation. The intensity and the location of the white line peak of theL3-edge XANES of Nd are found to be dependent on the ratio O/Nd in the glass matrix. Gamma irradiation changes the elemental concentration of atoms in the glass matrix, which affects the peak intensity of the white line due to changes in the covalence of the chemical bonds with Nd atoms in the glass (structural changes). Sharpening of the Nd 3d5/2peak profile in XPS spectra indicates a deficiency of oxygen in the glasses after gamma irradiation, which is supported by energy-dispersive X-ray spectroscopy measurements. The ratio of non-bridging oxygen to total oxygen in the glass after gamma radiation has been found to be correlated to the concentration of defects in the glass samples, which are responsible for its radiation resistance as well as for its coloration.

The synergistic effect of silver nanoparticle sensitization and surface disordering of mixed phased titania makes it highly active photocatalyst under visible light. The physico-chemical analysis of the samples indicates that surface plasmon induced local field enhancement, reduction in the band gap due to hydrogenation, intrinsic band offset at the phase interface and the resultant swift migration of photo-generated carrier to catalyst surface makes the catalyst highly visible active. The photoactivity of the hydrogenated mixed phase Ag/TiO2 catalyst is found to be about ~28.2 times high compared to the reference catalyst DP25 in degradation of methylene blue under visible light irradiation while an opposite behavior is observed under UV light. One the most distinctive feature of the catalyst concluded on the basis of its reusability test is the multicyclic-stability of its performance under visible light which shows it to be robust.

The possibility of combining both optical transparency and high electrical conductivity in the same material makes transparent conducting oxides one of the most sought after materials in transparent electronics. This paper presents the investigations done on the conductivity mechanisms of n-type transparent conducting silver indium oxide thin films in different temperature ranges varying from 6 to 333 K. X-ray diffraction indicates the films to be amorphous, and the morphology of the films from scanning electron microscopy and atomic force microscopy shows agglomerations with average particle size ∼30 nm. X-ray photoelectron spectroscopy and energy-dispersive analysis of X-rays establish the films to be nearly stoichiometric with In/Ag at.% ratio in the range 1.1–1.2. The transmittance percentage obtained from optical transmittance and absorbance spectra is moderately high and the bandgap energy of the thin films is ∼3.5 eV. Transport parameters, such as carrier mobility ∼103 cm2/V s and carrier concentration ∼1018/cm3, are elucidated from Hall and thermopower data.

X-ray photoelectron spectroscopy (XPS) is a well known tool in studying the physical and chemical properties of surface/interfaces which provides the element specific, non-destructive and quantitative information. In the present study, information about the surface chemical states of interfacial structure of CoFe thin films on n-Si substrates has been studied from XPS technique. The surface of the samples has also been cleaned from ion beam etching for 30 min with Ar + ions to record the XPS spectra. The observation shows that the Si atoms are present within the probed surface layer due to interfacial intermixing across the interface which is due to strong chemical reactivity of n-Si substrate. A shift in the binding energy peaks of Fe2p and Co2p has also been observed which could be due to the formation of silicide phases as a result of interfacial intermixing. XPS results have indicated the formation of silicide phases across the interfaces which poses interfacial antiferromagnetic coupling across CoFe/n-Si interface to affect the magnetic behaviour. It has been found that the present XPS results are in well support with our earlier study.

The thin film of Inorganic–Organic (Hybrid) nanocomposite (NCs) based on polyvinyl alcohol (PVA) and lead sulfide (PbS) have been synthesized using solution casting technique with different concentrations of PbS. The prepared films were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The XRD confirms the presence of PbS nanoparticle (NPs) in PVA matrix. The morphology and thickness of NCs films were characterized by transmission electron microscopy and scanning electron microscopy, respectively. The optical transmittance (typically 220 nm) and photoluminescence spectra of NCs films were investigated in the wavelength range 300–2400 and 200–800 nm, respectively. The band gap of PbS NPs varies from 0.9 to 1.58 eV by altering the concentration of PbS.

The paper reports the fabrication of Zn-doped TiO2 nanotubes (Zn-TONT)/ZnO nanoflakes heterostructure for the first time, which shows improved performance as a photoanode in dye-sensitized solar cell (DSSC). The layered structure of this novel nanoporous structure has been analyzed unambiguously by Rutherford backscattering spectroscopy, scanning electron microscopy, and X-ray diffractometer. The cell using the heterostructure as photoanode manifests an enhancement of about an order in the magnitude of the short circuit current and a seven-fold increase in efficiency, over pure TiO2 photoanodes. Characterizations further reveal that the Zn-TONT is preferentially oriented in [001] direction and there is a Ti metal-depleted interface layer which leads to better band alignment in DSSC.

Thin films of Ni 1− x Zn x O with different composition ( x = 0, 0.01, 0.05 and 0.10) were successfully fabricated on glass substrates using spray pyrolysis technique. The as-prepared films were further annealed at 623 K in room atmosphere for 2 h. The evolution of their structural, morphological, electrical and optical properties with annealing temperature was investigated. The result reveals that the annealing of the films leads to improved surface morphology and better crystallinity. The prepared films displayed increase in conductivity followed by decrease in band gap with increase in doping concentration. However, the effect is more significant in case of annealed films, where the average transparency shows an increase of about 10% over the as prepared thin films. The red-shift of the optical band gap is due to the deep states in the band gap. The increase in density of states has been confirmed by variable range hoping (VRH) mechanism. The activation energy was found to be decreased when Zn concentration increased. Added to this the dielectric function of thin films and their spectral variation has been tentatively discussed.

The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280–315 nm) or UVAB (280–400 nm), or transmitted all the ambient solar UV (280–400 nm) radiation (filter control). Qualitative observation of high-resolution X-ray PCI images obtained at 10 keV has shown the differences in major and minor vein structures of the leaves. The mid-rib width of the middle leaflet of third trifoliate leaves, for all treatments, were obtained using quantitative image analysis. The width of the mid-rib of the middle leaflet of third trifoliate leaves of UVB excluded plants was found to be more compared to leaves of filter control plants, which are exposed to ambient UV. The mid-rib or the main conducting vein transports water and sugars to the whole plant; therefore, mid-rib enhancement by the exclusion of solar UV radiation possibly implies enhancement in the leaf area which in turn causes an increased rate of photosynthesis.

BACKGROUND Application of high resolution synchrotron micro-imaging in microdefects studies of restored dental samples. OBJECTIVE The purpose of this study was to identify and compare the defects in restorations done by two different resin systems on teeth samples using synchrotron based micro-imaging techniques namely Phase Contrast Imaging (PCI) and micro-computed tomography (MCT). With this aim acquired image quality was also compared with routinely used RVG (Radiovisiograph). METHODS Crowns of human teeth samples were fractured mechanically involving only enamel and dentin, without exposure of pulp chamber and were divided into two groups depending on the restorative composite materials used. Group A samples were restored using a submicron Hybrid composite material and Group B samples were restored using a Nano-Hybrid restorative composite material. Synchrotron based PCI and MCT was performed with the aim of visualization of tooth structure, composite resin and their interface. RESULTS The quantitative and qualitative comparison of phase contrast and absorption contrast images along with MCT on the restored teeth samples shows comparatively large number of voids in Group A samples. CONCLUSIONS Quality assessment of dental restorations using synchrotron based micro-imaging suggests Nano-Hybrid resin restorations (Group B) are better than Group A.

In the present work, along with the short cut synthesis of bismuth rich BiFeO3 (BFO) ceramic, the room temperature X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Scanning calorimetry (DSC), P-E loop, high temperature visible Raman and impedance spectroscopy studies are presented. XRD patterns show the prominent BFO peaks along with a few numbers of bismuth rich peaks, SEM picture shows the grain sizes in micron range, DSC results show the Neel temperature (TN) of 371°C. Room temperature Raman spectrum shows the A1 and E modes and with the increase of temperature the modes shift towards lower frequency attaining prominent red shift around TN. In impedance spectroscopy, the shift of fmax peak position towards higher frequency side of dielectric loss (tanδ) spectrums shows that the dispersion moves towards higher frequency side with the increase of temperature and activation energy calculated from Arrhenius lnfmax(1/T) plot is around 1eV for the temperature range of 240-400°C. Temperature dependent complex impedance plots (Z″ vs. Z′) reveal that at low temperature the sample is highly resistive and evolution of semicircles for both grain and grain boundary contributions start around 240°C and the depressed semicircles of both complex impedance plots and Modulus plots (M″ vs. M′) depict that the sample follows a non-Debye type process.

Cubic nanocrystalline silicon carbide (3C-SiC) films have been deposited by using the hot wire chemical vapor deposition (HW-CVD) method at a low substrate temperature and at high deposition rate. Structural, optical and electrical properties of these films have been investigated as a function of H2 dilution ratio. The formation of 3C-SiC films has been confirmed from low angle XRD analysis, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS) and dark and photoconductivity measurements. The FTIR spectroscopy analysis revealed that the bond densities of Si-H and C-H decrease while that of Si-C increases with increase in the H2 dilution ratio. The total hydrogen content decreases with increase in H2 dilution ratio and was found < 15 at. % over the entire range of H2 dilution ratio studied whereas the band gap show an increasing trend with increase in the H2 dilution ratio.

Nanowires of undoped and cobalt doped ZnS were synthesized by a hydrothermal method. The samples of pure and Co doped ZnS were characterized by ADXRD. The structural parameters were evaluated using the ADXRD data. The atomic structures of pure and Co doped ZnS nanowires have been studied using pair distribution function (PDF) analysis. It was confirmed that the samples have a hexagonal (wurtzite) structure. The interatomic distance was calculated using PDF analysis. The energy band gaps of pure and Co doped ZnS nanowires were estimated using UV-vis spectra, and a red shift was clearly observed. It was also observed that the energy band gap decreases as the Co content increases. The FTIR spectra indicate that Co is substituted in the ZnS lattice. The TEM micrographs clearly show the growth of nanowires of the synthesized samples. A vibrating sample magnetometer (VSM) was used to outline the presence of magnetism in the sample. It was confirmed from the VSM that as-synthesized pure and Co doped ZnS nanoparticles exhibit weak ferromagnetism at room temperature.

We studied the band offset and alignment of pulsed laser deposited TiO 2 /CuGaO 2 hetero-structure using x-ray photoelectron spectroscopy. Valance band offset (VBO) of TiO 2 /CuGaO 2 interface was calculated using Kraut equation as 2.15 eV, which was in corroboration with VBO obtained directly from valance band onsets. A schematic band alignment diagram for the TiO 2 /CuGaO 2 interface was constructed which showed a type II band alignment with a significant band bending of 0.48 eV. Interface studies of TiO 2 /CuGaO 2 hetero-structure, showing type II band alignment, is important for gaining insight to the design of various photovoltaic devices based on such hetero-structures.

Bulk nanocomposites ZnO–SnO2–TiO2 were synthesized by solid-state reaction method. The X-ray diffraction patterns and Raman spectra of bulk nanocomposite as a function of sintering temperature (700 °C–1300 °C) indicate that the structural phases of SnO2 and TiO2 depend on the sintering temperature while the ZnO retains its hexagonal wurtzite phase at all sintering temperatures and SnO2 started to transform into SnO at 900 °C and completely converted into SnO at 1100 °C, whereas the titanium dioxide (TiO2) exhibits its most stable phase such as rutile at low sintering temperature (≤900°C) and it transforms partially into brookite phase at high sintering temperature (≥ 900 °C). The optical band gap of nanocomposite ZnO–SnO2–TiO2 sintered at 700 °C, 900 °C, 1100 °C and 1300 °C for 16 hours is calculated using the transformed diffuse reflectance ultra violet visible near infra red (UV–VisNIR) spectra and has been found to be 3.28, 3.29, 3.31 and 3.32 eV, respectively.

The samples have been prepared in the form o f pellets of SnO 2 nanoparticles and synthesized via the liquid - phase co precipitation technique. The ac electrical conductivity of samples is found to be frequency dependent . The dielectric constant increase s with temperature and decreases with frequency o f applied field . The semiconducting behavior of SnO 2 nanoparticles have been studied f rom I - V characteristics . The characterization of samples ha s been studied by XRD, FESEM, U V - spectra and TG - DTA plot . Copyright © 201 5 VBRI press.

Sol–gel autocombustion as an efficient method in the preparation of monophasic Cr and Nd co-doped Ce:YAG compounds has been demonstrated. A reduction in the formation temperature to 1000 °C as compared to the classical ceramic method has been effectively shown. Monophasic formation of the compounds has been confirmed from the X-ray diffraction study which is equally supported by the Raman spectroscopy. The TEM analysis confirms the formation of submicron sized particles (around 100 nm) which are equally supported by SEM micrographs revealing the granular morphology for the compounds. Photoluminescence (excitation) studies carried out for the compounds at 468, 341 and 685 nm display excellent emission intensity for the compounds with similar emission pattern pointing towards a common emission centre in all the three cases. Decrease in Ce 3+ emission intensity for the Cr and Nd co-doped Ce:YAG is observed. Energy transfer mechanism is suggested for the lowering of emission intensity confirming the activity of Ce 3+ as a sensitizer.

This paper reports rapid, continuous and carbon-nanotube free synthesis of carbon encapsulated magnetic nanoparticles by thermal-plasma expansion technique, which combines the typical advantages of high-temperature plasma assisted synthesis method with efficient particle-size control. Core nanocrystals were encapsulated with few layers of graphitized carbon, which could provide protection against both oxidation and intense chemical treatment. The average iron/iron-carbide nanoparticle diameter (7.7, 9 and 10 nm) and the width of the size distribution increased with pressure in the sample collection chamber, as a result of the decreasing quenching rate of the plasma jet. This also resulted in the smaller particles remaining frozen predominantly in the high-temperature γ-Fe phases, part of which was oxidized subsequently and eliminated preferentially during the purification process. All samples could be correlated with smooth variation of magnetic properties; saturation magnetization, remnant magnetization and coercive-field enhancing with increasing chamber pressure or average particle size. The low pressure synthesized sample with smallest average particle size approached super-paramagnetic behavior (saturation magnetization = 51.8 emu/g, ratio of remnant to saturation magnetization = 4.9 and coercive field = 52 Oe), which may be ideal for biomedical applications. High-pressure samples on the other hand have a higher saturation magnetization (76.3 emu/g) and coercive fields (123 Oe).

We have studied the electronic transport and magnetic properties of a nanocrystalline La0.7Sr0.3MnO3 system. The samples were prepared by sol–gel method and were sintered at different temperatures to achieve few nanometre grain sizes. The temperature dependent resistivity revealed Kondo like electronic transport at low temperature (T < 50 K) and variable range hopping in the paramagnetic insulating regime under zero and high magnetic field. The reduced grain size sample showed marginal increase in electrical resistivity. The temperature-field dependent ac-susceptibility measurement indicated the FM-cluster formation. A neck like magnetic hysteresis loop was observed due to the competition between ferromagnetic core and paramagnetic shell. The ferromagnetic clusters with paramagnetic interfaces impart glassy behavior.

Deposition of nanocomposite films of lead sulphide (PbS) nanoparticles in blend (1:1) of polyvinyl pyrrolidone (PVP) and Polyvinyl alcohol (PVA) by dip-coating from a precursor aqua-methanolic solution containing of Pb+2-TU complex (LTUC) is reported. To obtain nanocomposite films, solid precursor films are heated at about 110 °C in air for 10 mins to convert the LTUC in to PbS nanoparticles in PVP-PVA by in-situ thermolysis. PbS/PVP-PVA films with different loading of PbS was prepared by varying the concentration of LTUC in precursor solutions. The effect of LTUC on the microstructural, optical, thermal and electrical properties of the films was investigated. The X-ray diffraction of films confirms the presence of PbS nanoparticles in PVP-PVA matrix. The band gaps of PbS/PVP-PVA films varied from 1.8 to 0.8 eV as the concentration of LTUC varied from 0.0125 to 0.1 M due to formation of PbS nanoparticles. Transmission electron microscopy (TEM) shows that PbS nanoparticles are spherical with maximum diameter of 18 to 22 nm. The Fourier transformed infrared (FTIR) spectroscopy and X-Ray photoelectron spectroscopy (XPS) indicate the formation of hydrogen bond between –O–H group of PVA and –C = O group of PVP. However, PbS nanoparticles does not interact with either of the polymers. Thermogravimetric analysis (TGA) reveals that there was an improvement in thermal stability of PbS/PVP-PVA nanocomposites as compared to PVP-PVA blend. The dc conductivities of PVP-PVA and PbS/PVP-PVA(0.1 M) NC were found to be 3.2 × 10−6 S cm−1 and 14.2 × 10−6 S cm−1, respectively.

This article examines the properties of iron-oxide nanostructures, with particular emphasis on nanowires. It begins with an overview of iron-oxide nanostructures and nanowires, followed by a discussion of the synthesis of aligned ?-Fe2O3 nanowires and nanosheets by a simple thermal oxidation route. It then describes the preferential bending of [110] grown ?-Fe2O3 nanowires about the C-axis and quantitative estimation of nanowire alignment using X-ray diffraction and grazing incidence X-ray diffraction. It also considers the growth mechanism of ?-Fe2O3 nanowires and nanosheets, different nanowire morphologies, rotational slip in ?-Fe2O3 nanosheets, and the influence of local environment and substrate microstructure on nanowire growth.

Nickel oxide thin films were successfully fabricated with various deposition time ( t d = 5, 10, and 15 min) on glass substrates using spray pyrolysis technique. The deposited films undergo thermal treatment at 350 °C for various annealing time ( t a = 0, 15, 30 and 60 min). In this study, the effect of t d and t a on film thickness was observed and their influence on structural, morphological and optical properties were investigated. The films deposited with t d = 5 min showed amorphous structure while the films grown at higher deposition time became partially crystallized with preferred growth along (1 1 1) direction. Heat treatment carried out in air allowed us to tune the polycrystalline structure and the diffraction intensity at preferred peak increases with the increase in t a which is a consequence of better crystallinity. This was reflected in the AFM micrographs of the films which suggested that the thermal annealing (or increasing t a ) facilitates the process of grain-growth, and improves the crystalline microstructure. The optical transmission of the films was found to vary with t d and t a and thus film thickness. The thinner films show higher transparency in the UV–vis spectral region. The optical band gap was blue-shifted from 3.35 eV to 3.51 eV depending on t a . The effect of t a on the various optical constants of the NiO films has also been discussed.

The present communication reports the structural, optical and electrical properties of p-CdTe films deposited by using spray pyrolysis technique on thoroughly cleaned sodalime glass substrates at 350 °C in inert N 2 atmosphere. The films were characterized by using XRD, Raman spectroscopy, XPS, thickness profiler, SEM, EDAX and UV–Visible spectroscopy and Hall parameters measurement. The structural studies showed the formation of pure cubic CdTe in resultant films with crystallite size = 32 nm. The texture coefficient TC ( h k l ) indicated preferential orientation of films along [3 1 1] and [5 1 1] directions. The SEM image showed almost spherical granules with average size of 0.25 μm. From UV–Visible spectral data, the maximum absorbance and direct band gap obtained using Tauc plot are found to be 0.94 and E g = 1.44 eV respectively for films having thickness, t = 3.2 μm. The Hot probe experiment, Hall coefficient R H = 1.478 × 10 3 cm 3 /C, and resistivity ρ = 2.228 × 10 1 Ω cm confirmed the p-type semiconducting behavior of CdTe films. The mobility of majority charge carriers – holes is found to be μ = 6.63 × 10 1 cm 2 /Vs. The films processed using present work can be treated as possible p-type candidate for fabrication of hetero-junction solar cell.

In this study, transparent thin films of cobalt-doped nickel oxide (Co x Ni 1− x O; x =0, 0.005, 0.01, 0.05, 0.075 and 0.15) were deposited on to microscopic glass substrates using a spray pyrolysis technique. The effect of cobalt doping on structural, morphological and optical properties was investigated. XRD studies reveal that all the films are polycrystalline with cubic structure and exhibit (111) preferential orientation. Co is well incorporated in the host lattice, i.e. octahedrally coordinated on the Ni site without altering the structure. The effect of Co doping was observed to have a strong influence on the surface morphology of NiO films. An interesting correlation between the optical transmittance and the RMS roughness was observed. All the coatings retain high transparency throughout the visible spectral regime. The optical band gap varies from 3.44 eV to 3.26 eV due to the presence of Ni vacancies and/or oxygen defects. The optical reflectance spectra along with refractive index and extinction coefficients of the prepared films have also been discussed. Among all the Co-doped NiO thin films in this study, films doped with 1 at% Co concentration exhibited the best properties, namely improved crystallinity, smooth and compact surface morphology, lowest RMS roughness value of 2.26 nm and highest transmittance of ~85% in the visible region.

Cu2SnS3 (CTS) is a simple and potential material for low-cost thin film solar cells. The present work incorporates the study of changes in structural and optical properties of layer-by-layer solution deposited CTS films with annealing. Raman spectroscopy is used to ascertain structural modification upon annealing. Increase in annealing temperature leads to a structural transition from tetragonal to cubic phase. Effect of annealing on optical properties of the films is evaluated in the wavelength range of 400–2,400 nm. It is proposed that layer-by-layer growth method fundamentally defines the optical behaviour of these films. Optical constants and parameters such as refractive indices, dielectric constants and electron energy loss function are calculated from transmittance and reflectance data. The refractive indices, n and k are determined to be in ranges of 1.8–2.2 and 0.18–1.2, respectively. The real and imaginary dielectric constants vary from 1.5 to 4.6 and 0.7 to 5, respectively. Dispersion of refractive index is analyzed using two different theoretical models of Wemple–diDomenico and Spitzer–Fan.

A simple and rapid process for the synthesis of Cu2SnS3 (CTS) nanoparticles by microwave heating of metal–organic precursor solution is described. X-ray diffraction and Raman spectroscopy confirm the formation of tetragonal CTS. X-ray photoelectron spectroscopy indicates the presence of Cu, Sn, S in +1, +4, −2 oxidation states, respectively. Transmission electron microscopy divulges the formation of crystalline tetragonal CTS nanoparticles with sizes ranging 2–25 nm. Diffuse reflectance spectroscopy in the 300–2,400 nm wavelength range suggests a band gap of 1.1 eV. Pellets of CTS nanoparticles show p-type conduction and the carrier transport in temperature range of 250–425 K is thermally activated with activation energy of 0.16 eV. Thin film solar cell (TFSC) with architecture: graphite/Cu2SnS3/ZnO/ITO/SLG is fabricated by drop-casting dispersion of CTS nanoparticles which delivered a power conversion efficiency of 0.135 % with open circuit voltage, short circuit current and fill factor of 220 mV, 1.54 mA cm−2, 0.40, respectively.

The silver-doped titanium dioxide (Ag–TiO2) photocatalysts with varied silver content ranging from 0.75 at % to 3.5 at % were synthesized by a single-step sol–gel method. The role of silver content on the properties of photocatalyst has been studied. The doping of 0.75 at % silver in TiO2 produced thermally stable TiO2 anatase phase with smallest particle size, uniform particles size and morphology, high surface area and low-energy excitation characteristics. The Ag–TiO2 sample with 0.75 at % silver possesses predominantly finely dispersed silver species (Ag2O and AgO) on the surface. The proportion of surface agglomerated silver metal (Ag0) increases as the silver content in the Ag–TiO2 sample increases. The silver oxide species were observed to be responsible for better physicochemical and catalytic properties. The TiO2 with 0.75 at % silver was found to be an efficient photocatalyst showing enhanced photocatalytic activity for aqueous medium photocatalytic degradation of phthalic acid in the presence o...

In the present study, we have shown the effects of ferrocene (FeC10H10) addition on the superconducting properties of polycrystalline MgB2 superconductor using transport and magnetic measurements. The addition of FeC10H10 up to 2 wt% in the MgB2 sample has shown enhanced critical current density, JC in the entire magnetic field region without affecting much the transition temperature. At 10 K, with respect to a pristine MgB2 sample, JC has improved by a factor of 6.55 at 6 T applied field for 1 wt% FeC10H10. An improvement in the upper critical field, HC2 and irreversibility field, Hirr has also been observed up to 2 wt% addition of FeC10H10. The value of HC2(0) as obtained using the Ginzburg–Landau (GL)-theory fit of the experimental data increases by almost 2 T for 2 wt% FeC10H10-added MgB2 as compared to the pristine samples. From X-ray photoemission spectroscopy (XPS), we observed that the Fe is present in sample in the form of ferromagnetic oxides, Fe3O4 and γ-Fe2O3. These ferromagnetic inclusions provide efficient pinning centers to improve JC(H) behavior. The flux pinning mechanisms present in the FeC10H10-added samples are described and discussed in this paper.

Cu 2 SnS 3 (CTS) powder has been synthesized at 200 °C by solid state reaction of pastes consisting of Cu and Sn salts and different sulphur compounds in air. The compositions of the products is elucidated from XRD and only thiourea is found to yield CTS without any unwanted CuS x or SnS y . Rietveld analysis of Cu 2 SnS 3 is carried out to determine the structure parameters. XPS shows that Cu and Sn are in oxidation states +1 and +4, respectively. Morphology of powder as revealed by SEM shows the powder to be polycrystalline with porous structure. The band gap of CTS powder is found to be 1.1 eV from diffuse reflectance spectroscopy. Cu 2 SnS 3 pellets are p-type with electrical conductivity of 10 −2 S/cm. The thermal degradation and metal–ligand coordination in CTS precursor are studied with TGA/DSC and FT-IR, respectively, and a probable mechanism of formation of CTS has been suggested.

Antimony doped and undoped nanostructured thin films of AgIn1 − xGaxSe2 and Ag(InGa)5Se8 on optically flat soda lime glass substrates are prepared by a three stage co-evaporation process. Energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy in conjunction with atomic force microscopic technique and scanning electron microscopic technique are used, respectively, for compositional and surface morphological analysis of the films. X-ray diffraction (XRD) data on the films are analysed to estimate the influence of antimony doping and indium replacement by gallium, on the structure of the films, by determining the anion–cation bond lengths and anion displacement in the thin films. The obvious dependence of band gap on the composition of the films establishes the possibility of band gap tailoring of the films. Low temperature optical absorbance measurements in the temperature regime 90–301 K are used for investigating the effect of doping on the temperature coefficient of band gaps of the films. Rutherford scattering spectra quantify the thickness of the films for conductivity (σ) measurements. The films exhibit n-type conductivity with two linear regions in the ln(σ) versus temperature inverse graphs, which indicate a defect activated conduction and intrinsic conduction, respectively, in the near room temperature and high temperature regions.

Synchrotron based X-ray diffraction (XRD) and X-ray reflectivity (XRR) were used to study the structural and magnetic properties of ion beam sputtered Fe/Al multilayer sample (MLS) as a function of annealing temperature. The structural studies show substantial intermixing between the layers which results in multilayer of complicated structures i.e. formation of thin intermixed FeAl layer at the interface during deposition, the nucleation and precipitation of disordered FeAl layer, and its subsequent growth to Fe3Al at higher temperature. The results were also supported by TEM measurements. Magnetization decreases with increase in temperature and Curie temperature (Tc) is found to be much less than that of bulk bcc Fe.

The chemical interactions and surface chemical states of exchange coupled structures of Fe/NiO bilayer interfaced with silicon substrate has been studied from X-ray photoelectron spectroscopy (XPS) technique. The structure has been irradiated from swift (∼100 MeV) heavy ions (of Fe7+) with a fluence of ∼5 × 1012 ions/cm2. The surface of the samples has also been cleaned from ion beam etching for various durations to record the XPS spectra. On the irradiation, signals due to Fe2p and Ni2p are emerging along with the signal of Si2p whereas no signal of Si2p has been observed, prior to irradiation. The observation shows that the Si atoms are present within the probed surface layer due to irradiation induced interfacial intermixing. We also observed a shift in the binding energy position of Si2p which could be due to the formation of silicide phases as a result of irradiation induced interfacial intermixing. XPS results have indicated the presence of ionic Fe (Fe2+ or Fe3+) and metallic Ni at the Fe/NiO interface, which could be due to the different chemical reactions at the Fe/NiO interface.

The Mn/n-Si interfacial structure is susceptible to intermixing even at room temperature. To investigate the chemistry as a result of the intermixing, valence band and core level photoelectron spectroscopy of Mn/Si has been carried out using synchrotron radiation of 134 eV energy and Al Kα X-ray (λ = 1,486.6 A) source. The fabricated structures have also been irradiated from swift heavy ions (Fe7+ of ~100 MeV) to investigate the ion beam mixing in such structures. Valence band photoelectron spectroscopy with 134 eV photons shows the evolution of Mn3d, Mn3p and Si2p levels with a shifting towards lower binding energy side compared to their elemental values of the binding energy. This binding energy shift shows the formation of chemical compound of Si and Mn. Evolution of Si2p core level prior to and after the swift heavy ion irradiation shows strong chemical reactivity of manganese thin film with silicon. Deconvolution of Mn3d valence band has shown the formation of silicide phase due to the hybridization of Mn3d and Si3sp states. Mn2p core level study shows that the oxide and silicide formation takes place during the growth and for successive etching, oxide part is decreasing whereas silicide part is increasing.

A process for deposition of tetragonal Cu 2 SnS 3 (CTS) thin films from methanolic precursor solution of metal-thiourea complex by direct liquid coating (DLC) is described. For synthesis of CTS films, precursor films are first deposited by dip-coating and then thermolysed at 200 °C in air for 10 min. Formation of tetragonal Cu 2 SnS 3 is confirmed by X-ray Diffraction (XRD). X-ray Photoelectron Spectroscopy (XPS) disclosed that Cu and Sn are in oxidation states +1 and +4, respectively. The films are smooth and homogenous with roughness (RMS) of 1–2 nm as revealed by atomic force microscope (AFM) and scanning electron microscopy (SEM). Optical studies show that the energy band gap ( E g ) of Cu 2 SnS 3 is 1.12 eV and absorption coefficient ( α ) is >10 5 cm −1 . The films are p-type with electrical conductivity ( σ ) of 0.5 S/cm. The concentration and mobility of holes are about 10 18 cm −3 and 1 cm 2 /V/s, respectively as determined from Hall measurement. The variation of conductivity in the temperature range 5 to 290 K can be explained by considering a combination of Mott variable range hopping, nearest neighbour hopping and thermionic emission over GB barriers as conduction mechanism. Non-toxic thin film solar cell (TFSC) of graphite/Cu 2 SnS 3 /ZnO/ITO/SLG are fabricated by DLC which had power conversion efficiency (PCE) of 2.10% with open circuit voltage, short circuit current and fill factor of 0.816 V, 6.14 mA/cm 2 , 0.42, respectively.

Drastic changes in the bonding are found in amorphous hydrogenated carbon nitride (a-CNx:H) film as a function of nitrogen concentration (or N/C ratio). The total C-sp3 fraction and hardness shows a sharp decrease (at N/C = 0.40) whereas optical band gap and resistivity shows a gradual increase as nitrogen concentration increases from 0.07 to 0.58. Raman spectrum of a-CNx:H film is fitted with both Gaussian (integrated intensity ratios are used instead of the height ratios of the Lorentzian (D mode)) and Breit–Wigner–Fano (BWF, G Mode) method for a comparative study of optical properties and crystalline size of the graphite domain. Visible Raman (488 nm) spectroscopy finds that the in-plane crystalline size of graphite domains (La) is increased (from 34 to 38 A) with nitrogen incorporation. Optical band gap of a-CNx:H solid measured by means of ellipsometry differs from the one obtained from Raman spectroscopy. In addition, we propose a simple extension of the existing band gap model to obtain the optical band gap of a-CNx:H film from Raman spectrum. Our estimation agrees well with the experimental value.

We report the synthesis of polycrystalline BiFeO3 compound by solid state route and its structural and magnetic properties were investigated. The structure confirmation and phase purity of the samples were investigated by X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. No signature of thermodynamically probable impurity phases was observed in these samples. The Rietveld refined structural parameters of the XRD pattern revealed rhombohedral (R3c) structure. Scanning Electron Microscopy images show samples with larger grain size. The Raman active modes predicted by the group theory confirmed the rhombohedral symmetry. The study of the oxidation states of Bi, Fe and O through XPS analysis indicated that the sample quality is not deteriorated by vacancies or other defects formation. The absence of iron based impurity phases is confirmed by the antiferromagnetic nature of the sample obtained by magnetization measurements.

We report intensity-dependent transient photodarkening (TPD) in As50Se50 thin film when illuminated with sub-bandgap light of wavelength 671 nm. TPD is always accompanied by concurrent changes in the far infrared absorption spectrum and points out the structural units associated with such changes. Strikingly TPD and its kinetics show an exponential dependence on the pump beam intensity and we foresee that light intensity can be used as an effective tool to control such processes.

We report the structural difference of amorphous carbon nitride (a-CNx) and hydrogenated carbon nitride (a-HCNx) films as a function of annealing temperature. The spectroscopic analysis suggests that the presence of oxide layer is not the prime cause but the surface chemical property is equally responsible for the shake up satellite peak in X-ray photoelectron spectrum (XPS). XPS spectra of a-HCNx films show a strong shake up peak whereas it is absent in XPS of a-CNx films. XPS core level peak of a-HCNx shows a higher chemical shift compared to a-CNx. Shake up peak disappeared at 500 °C and the core peak intensity is increased. Raman spectra display a strong fluorescence effect of a-HCNx and a-CNx at room temperature but a promising G and D band is observed only in a-CNx film. A drastic phase transition is observed at/above 300 °C in Fourier transform infrared spectroscopy (FTIR) for a-HCNx film whereas the changes in a-CNx film are less dramatic. At 500 °C the hypsochromic shift of the sp 1 -band energy in a-HCNx film is 7 times higher compared to the same a-CNx film.

This study explores the feasibility of a micro-focus based tabletop X-ray $$\upmu $$ CT system for the micro-structural characterization of human teeth and later its application to the non-destructive evaluation of teeth restored with different composite resin for their interface integrity and micro-imperfections. In the first part of this study, extracted human primary and permanent molar teeth were used to explore potential of micro-focus based tomography setup for their micro-structural characterization. The details of root canal structure of human teeth were visualized and quantified with polychromatic $$\upmu $$ CT. In the second part identification and comparison of defects in a set of six human teeth samples, which were restored with two different composite resins, was carried out. Group ‘A’ samples were restored using a submicron hybrid composite material and Group ‘B’ were restored with a Nano-hybrid restorative composite material. The quantitative analysis of $$\upmu $$ CT data for composite resin restored teeth showed more number of voids or defects in Group ‘A’ restorations compared to Group ‘B’. A comparative evaluation of $$\upmu $$ CT techniques based on synchrotron source and micro-focus source is also illustrated to show their respective merits and limitations.

Cu doped ZnO thin films are prepared by the Spray Pyrolysis Technique (SPT) on glass substrate. XRD analysis shows that the films are polycrystalline with hexagonal structure. Intensity of (002) peak is highest indicating a c-axis oriented grains in pure ZnO film. The crystallite size reduces and strain increases with Cu incorporation in the direction of c-axis. AFM images indicate that the grains are self-assembled in the horseshoe type ring shape. At higher doping these rings are totally converted into small grains. Optical band gap decreases from 3.28 eV (pure ZnO film) to 3.25 eV (3% Cu doped ZnO film) and increases further with Cu incorporation. This may be attributed to the presence of excitons in the system.Cu doped ZnO thin films are prepared by the Spray Pyrolysis Technique (SPT) on glass substrate. XRD analysis shows that the films are polycrystalline with hexagonal structure. Intensity of (002) peak is highest indicating a c-axis oriented grains in pure ZnO film. The crystallite size reduces and strain increases with Cu incorporation in the direction of c-axis. AFM images indicate that the grains are self-assembled in the horseshoe type ring shape. At higher doping these rings are totally converted into small grains. Optical band gap decreases from 3.28 eV (pure ZnO film) to 3.25 eV (3% Cu doped ZnO film) and increases further with Cu incorporation. This may be attributed to the presence of excitons in the system.

The present report adds to the ongoing research on Si/Ge nanostructures by discussing the results obtained utilizing unique features of Synchrotron radiation (SR). Based on the structural and electronic properties of this system investigated in our earlier work, we have synthesized [Si(5 nm)/Ge(5 nm)] ×10 multilayers (MLS) and exposed it to a range of incident photon energies (utilizing synchrotron radiation) and at different incident angles for the photoemission spectroscopic measurements. It is shown how the interface features are enhanced simultaneously suppressing the signals from topmost atomic layers. Also the effect of incident angle variation is discussed, which gives a clear picture of interface electronic properties of Si/Ge system. Significant changes in Si 3p, Ge 4p and s band features are observed in the valence band density of states. The overall results present an interesting observation of thoroughly investigating the basic building bilayer stack of the multilayer structure by combining energy and/or angle variation with low energy sputter depth profiling.

Polyethersulphone (PES) was modified to improve the hydrophilicity of its surface, which in turn helps in improving its adhesive property. The modified PES surface was characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Vicker’s microhardness measurement. The contact angles of the modified PES reduces from 49° to 10° for water. The surface free energy (SFE) calculated from measured contact angles increases from 66.3 to 79.5 mJ/m2 with the increase in plasma treatment time. The increase in SFE after plasma treatment is attributed to the functionalization of the polymer surface with hydrophilic groups. The XPS analysis shows that the ratio of O/C increases from 0.177 to 0.277 for modified PES polymer. AFM shows that the average surface roughness increases from 6.9 nm to 23.7 nm due to the increase in plasma treatment time. The microhardness of the film also increases with plasma treatment.

We report the observations on optical and structural properties of thermally treated undoped and doped poly(vinyl) alcohol (PVA) films as a function of doping and annealing temperature. The crystalline peaks of both PVA and Rhodamine B are seen in the X-ray diffraction (XRD) of the as prepared samples where the crystallinity of Rhodamine B increases with doping. At 2 wt% doping, Rhodamine B crystals segregate and are seen at the surface. However, after annealing only PVA peaks remain and Rhodamine B becomes amorphous as seen from XRD and micro-Raman measurements. It is shown how the thermal energy imparted to host PVA and dopant Rhodamine B molecules results in the movement of molecules, breaking the bonds inside the material. The intensity and frequency of Raman active modes is observed to be modified with increasing temperature due to structural changes in polymer bonds. It is also observed that thermal annealing leads to a shift in the optical absorption edge towards lower energies. This is attributed to the modified electronic states. The overall results are interpreted in terms of modifications in structural and optical properties.