Glancing Incidence X-ray Diffraction Research Articles

A high-throughput investigation of Fe–Cr–Al as a novel high-temperature coating for nuclear cladding materials

High-temperature alloy coatings that can resist oxidation are urgently needed as nuclear cladding materials to mitigate the danger of hydrogen explosions during meltdown. Here we apply a combination of computationally guided materials synthesis, high-throughput structural characterization and data analysis tools to investigate the feasibility of coatings from the Fe–Cr–Al alloy system. Composition-spread samples were synthesized to cover the region of the phase diagram previous bulk studies have identified as forming protective oxides. The metallurgical and oxide phase evolution were studied via in situ synchrotron glancing incidence x-ray diffraction at temperatures up to 690 K. A composition region with an Al concentration greater than 3.08 at%, and between 20.0 at% and 32.9 at% Cr showed the least overall oxide growth. Subsequently, a series of samples were deposited on stubs and their oxidation behavior at 1373 K was observed. The continued presence of a passivating oxide was confirmed in this region over a period of 6 h.

Molybdenum oxide and molybdenum oxide-nitride back contacts for CdTe solar cells

Molybdenum oxide (MoOx) and molybdenum oxynitride (MoON) thin film back contacts were formed by a unique ion-beam sputtering and ion-beam-assisted deposition process onto CdTe solar cells and compared to back contacts made using carbon–nickel (C/Ni) paint. Glancing-incidence x-ray diffraction and x-ray photoelectron spectroscopy measurements show that partially crystalline MoOx films are created with a mixture of Mo, MoO2, and MoO3 components. Lower crystallinity content is observed in the MoON films, with an additional component of molybdenum nitride present. Three different film thicknesses of MoOx and MoON were investigated that were capped in situ in Ni. Small area devices were delineated and characterized using current–voltage (J-V), capacitance–frequency, capacitance–voltage, electroluminescence, and light beam-induced current techniques. In addition, J-V data measured as a function of temperature (JVT) were used to estimate back barrier heights for each thickness of MoOx and MoON and for the C/Ni paint. Characterization prior to stressing indicated the devices were similar in performance. Characterization after stress testing indicated little change to cells with 120 and 180-nm thick MoOx and MoON films. However, moderate-to-large cell degradation was observed for 60-nm thick MoOx and MoON films and for C/Ni painted back contacts.

Effects of Annealing on the Properties of Copper Oxide Thin Films

Thin films of copper oxide were successively deposited on glass substrates by sol-gel like spin coating for 40 s and annealed in air at different temperatures (200-400°C). Precursor solutions were prepared by dissolving cupric chloride in methanol. Various stabilizers and additives were used to enhance the solubility of cupric chloride and to improve the adhesion between the films and the glass substrates. Glucopone was used as a surfactant to reduce the surface energy. The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Annealing the films in air at 300°C converts the films to CuO. The general appearances of the films were uniform and brownish in color.

Grain size effect of Ni–W–Cu seed layer film upon signal-to-noise ratio for PMR application

This study investigated the effects of W and Cu on the microstructure of Ni–W–Cu films which are used as the seed layer in perpendicular magnetic recording (PMR) media. Attributed to the relatively large radius of W, (i) the lattice mismatch between the seed layer and the intermediate layer in PMR, and (ii) the grain refining were successfully improved, in the presence of x increased in Ni80−xWxCu20 (x = 8, 14, 20). In addition, the decayed crystallinity resulting from increasing x value was ameliorated by raising y in Ni92−yW8Cuy (y = 0, 10, 20). It is believed that the reduced grain size and the enhanced crystallinity are beneficial to signal-to-noise ratio (SNR) in PMR media. Furthermore, both the adhesion and the sputtering-arcing tests passed the industrial standards. All the results were supported by glancing incident X-ray diffraction (GIXRD), transmission electron microscopy (TEM), and spatial energy dispersive spectroscopy (EDS).

Improving Room-Temperature Ferromagnetism in Mn-Implanted Si by High-Temperature Annealing

Mn-implanted Si with postannealing treatment at 873, 973, 1073, and 1173 K exhibited ferromagnetism at room temperature. Ferromagnetism was enhanced as the annealing temperature increased. The largest value of saturation magnetization was found in the sample annealed at 1173 K. X-ray absorption near-edge structure spectra showed no formation of substitutional–interstitial Mn–Mn dimmers in all samples. On the other hand, high-resolution transmission electron microscopy and glancing incidence X-ray diffraction revealed a variety of MnSi compounds. We propose that the ferromagnetism has the origin from the MnSi1.7 nanoparticles as well as the MnSi 1:1 phase, which possesses strong short-range spin correlation. The formation of antiferromagnetic Mn5Si3 compound in 873 and 973 K annealed samples substantially reduced the magnetism. This paper provides new insights into the understanding of ferromagnetism in Mn-implanted Si diluted magnetic semiconductors.

Room temperature magnetism and metal to semiconducting transition in dilute Fe doped Sb1−xSex semiconducting alloy thin films

The magnetism was observed in very dilute Fe doped alloy thin film Fe0.008Sb1−xSex, for x = 0.01 to 0.10. These thin films were grown on silicon substrate using thermal evaporation technique. Structural, electrical, optical, charge carrier concentration measurement, surface morphology and magnetic properties were observed using glancing incidence x-ray diffraction (GIXRD), four probe resistivity, photoluminescence, Hall measurement, atomic force microscopy (AFM) and magnetic force microscopy (MFM) techniques, respectively. No peaks of iron were seen in GIXRD. The resistivity results show that activation energy increases with increase in selenium (Se) concentration. The Arrhenius plot reveals metallic behavior below room temperature. The low temperature conduction is explained by variable range-hopping mechanism, which fits very well in the temperature range 150–300 K. The decrease in density of states has been observed with increasing selenium concentration (x = 0.01 to 0.10). There is a metal-to-semiconductor phase transition observed above room temperature. This transition temperature is Se concentration dependent. The particle size distribution ∼47–61 nm is evaluated using AFM images. These thin films exhibit ferromagnetic interactions at room temperature.

Optical and mechanical properties of nanocrystalline ZrC thin films grown by pulsed laser deposition

Thin ZrC films (<500nm) were grown on (100) Si substrates at a substrate temperature of 500°C by the pulsed laser deposition (PLD) technique using a KrF excimer laser under different CH4 pressures. Glancing incidence X-ray diffraction showed that films were nanocrystalline, while X-ray reflectivity studies found out films were very dense and exhibited a smooth surface morphology. Optical spectroscopy data shows that the films have high reflectivity (>90%) in the infrared region, characteristic of metallic behavior. Nanoindentation results indicated that films deposited under lower CH4 pressures exhibited slightly higher nanohardness and Young modulus values than films deposited under higher pressures. Tribological characterization revealed that these films exhibited relatively high wear resistance and steady-state friction coefficients on the order of μ=0.4.

The Study of Surface Plasmon Enhanced Emission of ZnO Nanorods on Plasmonic Ag Nanorods Array

Ag islands and nanorods (NRs) array were fabricated through glancing angle deposition (GLAD) method at an angle of 85°C by using thermal evaporation technique. Subsequently, ZnO NRs were grown along the side of Ag NRs arrays through hydrothermal reaction. The crystal structure of ZnO/Ag hybrid structure was studied by Glancing Incident X-Ray Diffraction (GIXRD). The surface morphologies of Ag NRs arrays and ZnO NRs were studied through AFM and SEM techniques. The presence of different vibrational energy modes of ZnO structure was studied through confocal Raman spectrometer. The surface plasmon enhanced fluorescence of ZnO NRs was probed through fluorescence spectrophotometer. The presence of strong UV emission and the absence of intense visible emission of ZnO NRs are due to the existence of fewer crystal defects which could make the hybrid structure precious for UV LEDs.

Effect on microstructure and hardness of 1 MeV carbon ion implantation in Al, Co and W

Carbon implantation is used to change the surface properties of materials without changing the bulk properties in various fields such as microelectronics, optics, tribology and biomaterials. While this implantation is usually performed at energies lower than 200keV and thus in the low energy range of the stopping power curve, here we studied the effect of a 1MeV ion beam which is in the medium energy range. The higher energies increase the modified depth range and thereby the load-carrying ability of metal surfaces. Light (Al), medium (Co) and heavy (W) metals were chosen as substrates. Three ion fluencies of 1016 ions/cm2, 1017 ions/cm2, and 1018 ions/cm2 were used. Nuclear reaction analysis evidenced the presence of carbon at the samples surface and at a depth in accordance with Monte-Carlo (SRIM) simulations. Glancing incidence X-ray diffraction (GIXRD) allowed us to reveal the formation of aluminum carbide while no carbide was observed for Co and W. The modifications of the lattice parameters of Co and of W were studied by Rietveld refinements of X-ray diffraction patterns. For these metals the increase of the profile asymmetry of the diffraction peaks can result from the generation of dislocations induced by irradiation. The hardness measured by nano-indentation tests increases with the carbon ion dose, and the rise of hardness is larger for aluminum and tungsten than for cobalt.

Physical and biological properties of the ion beam irradiated PMMA-based composite films

Polymethyl methacrylate (PMMA) and PMMA-hydroxyapatite (PMMA-HAp) composite films, prepared by the solvent evaporation method were irradiated with 100MeV Si7+ ions. Crystallographic, morphological and the functional groups of the pristine and irradiated samples were studied using glancing incident X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) respectively. SEM reveals the creation of pores, along with an increase in porosity and cluster size on irradiation. Decrease in crystalline nature and crystallite size with an increase in ion fluence was observed from GIXRD patterns. The surface roughness and the wettability of the material were also enhanced, which could favour the cell–material interaction. The irradiated samples adsorbed significantly greater amount of proteins than pristine. Also, irradiation does not produce any toxic byproducts or leachants, and maintains the viability of 3T3 cells. The response of the irradiated samples towards biomedical applications was demonstrated by the improved antimicrobial activity, haemocompatibility and cytocompatibility. Swift heavy ion irradiation (SHI) could be an effective tool to modify and engineer the surface properties of the polymers to enhance the biocompatibility.

Interfacial Properties of CZTS Thin Film Solar Cell

Cu-deficient CZTS (copper zinc tin sulfide) thin films were grown on soda lime as well as molybdenum coated soda lime glass by reactive cosputtering. Polycrystalline CZTS film with kesterite structure was produced by annealing it at 500°C in Ar atmosphere. These films were characterized for compositional, structural, surface morphological, optical, and transport properties using energy dispersive X-ray analysis, glancing incidence X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV-Vis spectroscopy, and Hall effect measurement. A CZTS solar cell device having conversion efficiency of ~0.11% has been made by depositing CdS, ZnO, ITO, and Al layers over the CZTS thin film deposited on Mo coated soda lime glass. The series resistance of the device was very high. The interfacial properties of device were characterized by cross-sectional SEM and cross-sectional HRTEM.

High upper critical field in disordered niobium nitride superconductor

Superconducting Niobium Nitride thin films have been deposited on glass, aluminum nitride buffered glass, and oxidized silicon substrates by reactive DC magnetron sputtering at ambient substrate temperatures. The crystal structure of these thin films has been determined to be cubic fcc B1 structure by Glancing Incidence X-Ray Diffraction analysis. The superconducting transition temperatures of the thin films were measured to be greater than 11.6 K with a maximum of 13.4 K. The negative temperature coefficient of resistance observed in these thin films indicates the presence of disorder. Magneto-resistance measurements have been carried out on these thin films patterned into standard four probe geometry upto a maximum magnetic field of 12 T for two films and upto 15 T for the other two films. The dependence of transition temperature on the applied field is analyzed to estimate the upper critical field. The upper critical field for most of the films was estimated to exceed 35 T, while one of the most disordered films had an estimated upper critical field greater than 70 T.

Ar ions irradiation effects in ZrN thin films grown by pulsed laser deposition

Thin ZrN films (<500nm) were grown on (100)Si substrates at a substrate temperature of 500°C by the pulsed laser deposition (PLD) technique using a KrF excimer laser under CH4 or N2 atmosphere. Glancing incidence X-ray diffraction showed that films were nanocrystalline, while X-ray reflectivity studies indicated that the films were very dense and with a smooth surface. The films were used to study the effect of 800keV Ar ion irradiation on their structure and properties. After irradiation with a dose of 1014at/cm2 the lattice parameter and crystallites size did marginally change. However, after irradiation with a 1015at/cm2 dose, a clear increase in the lattice parameter accompanied by a significant decrease in nanohardness and Young modulus were observed.

Size-dependent radiation tolerance and corrosion resistance in ion irradiated CrN/AlTiN nanofilms

This paper demonstrates a substantial enhancement in radiation tolerance and corrosion resistance for the CrN/AlTiN multilayered nanofilms with the decreasing of period-thickness. After irradiation by 190keV Ar+ ions to the dose of 81dpa, the amorphization region in the CrN/AlTiN 3nm multilayered nanofilm is much smaller than that in the CrN/AlTiN 7nm multilayered nanofilm and the CrN film based on glancing-incidence X-ray diffraction measurements. Potentiodynamic polarization and impedance measurements show that the CrN/AlTiN multilayered nanofilms have good corrosion resistance to irradiation. With increasing the irradiation fluence, the irradiated samples are more susceptible to corrosive electrolyte. However, the CrN/AlTiN multilayered nanofilm with smaller period-thickness shows significant enhancement of the corrosion resistance under both irradiation and un-irradiation conditions. Under the same irradiation fluence of 5×1016 ions/cm2, the corrosion current density increased 9.47 times for the CrN film, while it only increased 2.08 times for the CrN/AlTiN 3nm multilayered nanofilm. The interfaces of multilayered nanofilms act as effective sinks for irradiation-induced defects and are responsible for the enhanced radiation tolerance and corrosion resistance properties.

A probe into compositional and structural dependence of optical properties of lanthanum fluoride films prepared by resistive heating

The paper describes investigations into the correlation between the optical properties and the composition, structure and morphology of lanthanum fluoride films deposited at 373–473K substrate temperatures by resistive heating of lanthanum fluoride powders. The composition of the films that includes depth profiling of fluorine has been determined non-destructively by ion beam analysis while their structure and morphology have been investigated by glancing incidence X-ray diffraction and atomic force microscopy respectively. The films are polycrystalline, exist in hexagonal phase and display substrate temperature dependent texturing. The substrate temperature has an important influence on composition as well. The films deposited at 373K or 398K substrate temperatures are deficient in fluorine but tend to acquire stoichiometric composition at 473K. Possessing granular (∼100nm) morphology, the films, in general, are UV transparent but their optical loss increases with texturing. Carbon and oxygen, present as impurities, lower the density and consequently the refractive index (1.47) of the films. Annealing in vacuum at 573K brings about deterioration in the optical properties of the films which are related mainly to morphological changes and thermal stress.

Influence of transition metal doping on the tribological properties of pulsed laser deposited DLC films

Doped or alloyed diamond-like carbon (DLC) films exhibit superior properties compared to undoped DLC films. But the choice of dopant plays a vital role in tailoring specific properties of the DLC film desired for specific application. In the present work, a comparative study has been carried out in order to bring out the effect of transition metal (TM) doped DLC film on the tribological properties. Nanocomposite DLC/TM (TM=Ag, Ti and Ni) films were deposited by nanosecond pulsed laser deposition (PLD) technique on to AISISS304 substrates. Films microstructure and chemical behavior was studied by glancing incidence X-ray diffraction (GI-XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and high resolution transmission electron microscopy (HRTEM). The sp2 and sp3 fraction in the films are well described by electron energy loss spectroscopy (EELS) analysis. The Raman spectra of DLC/TM films showed peak shift towards lower wavenumber indicating the reduction of internal compressive stress. Formation of TM nanoclusters and TiC phases were confirmed in DLC/TM films by GI-XRD, XPS and HRTEM. DLC film doped with nanocrystalline Ag showed low friction behavior due to the formation of large amount of sp2 lubricant phase. However, high friction coefficient measured in DLC film doped with Ni and Ti. Such a high friction is explained by the presence of hard TiC and sp3 phase in the DLC/Ti and DLC/Ni films respectively.

Influence of temperature in arc-activated plasma nitriding of maraging steel in solution annealed and aged conditions

Maraging alloys are a group of high performance steels that combine high strength and good fracture toughness. Their excellent combination of properties is due to their microstructure, formed by nanometer-sized intermetallic precipitates embedded in a ductile martensite matrix. Their hardening treatments consist of aging processes that are compatible with thermochemical treatments such as nitriding or nitrocarburizing.An arc-activated plasma nitriding technique has been used in this study to investigate the effect of simultaneous aging and ion nitriding of maraging steel grade 300 at temperatures from 450°C to 510°C. The paper compares the results obtained for solution annealed and aged hardened samples in order to verify the compatibility of both processes, aging and nitriding.Chemical composition and micro-hardness profiling, glancing incidence X-ray diffraction (GIXRD), metallographic tests, corrosion studies and wear resistance tests were carried out. The results demonstrate the feasibility of arc-activated ion nitriding to achieve significant improvements of the surface properties of maraging steels and to merge together thermochemical and aging processes, thus reducing their processing time and energy consumption.

Durability of Pt/Graphitized Carbon Black Catalysts Under Gas Exchange Start-up Operating Conditions for Fuel Cell Vehicles

In polymer electrolyte fuel cells (PEFC), Pt nanoparticles on high surface area carbon black (CB) supports are used as the cathode catalyst. However, it has been found that Pt/CB catalysts are degraded under PEFC operating conditions due to a combination of processes, which include loss of electrochemically active surface area (ECA) due to agglomeration or dissolution of Pt nanoparticles, and corrosion of the CB supports1). During the start-up of fuel cell vehicles (FCVs), the cathode potential can momentarily climb to more than 1.5 V due to the “reverse current mechanism”, which significantly accelerates the carbon corrosion2). In order to reduce the cost of PEFCs, it is necessary to reduce the amount of Pt by improving the durability, especially for the cathode catalysts. To mitigate the corrosion of the carbon support, the use of graphitized carbon blacks (GCB), for which there is a high degree of graphitization, was found to be effective3).In this study, we investigated the cathode catalyst durability during a start-up process like that in actual FCV operation. Pt/graphitized carbon black catalysts were tested in this practical start-up process, i.e., the anode gas was successively cycled between air, hydrogen, and nitrogen. First, air was flowed to the anode and cathode for 90 s. Second, H2 gas was flowed to the anode to start up the fuel cell for 90 s. Finally, N2 gas was flowed to the anode and cathode for 60 s. These three steps are defined as one cycle. The effect of the start-up process on the cell performance was evaluated using three types of catalysts (commercial 50 wt% Pt/GCB and commercial 30 wt% Pt/GCB supplied by Tanaka Kikinzoku Kogyo K.K., and 30 wt% n-Pt/GCB prepared in house by the nanocapsule-method). The average Pt particle sizes of 50 wt% Pt/GCB, 30 wt% Pt/GCB and n-Pt/GCB were 3.4 ± 0.7 nm, 3.3 ± 0.5 nm and 2.6 ± 0.4 nm, respectively. All of the catalysts were tested for 1000 cycles. The I-V performances were evaluated under O2 and air at 65 °C with 100% RH before and after the durability test, which consisted of given numbers of start-up cycles (N). Cyclic voltammetry (CV) was also examined to estimate the ECA under N2 at the cathode and H2at the anode at 65 °C and 100% RH every 200 cycles.Figure 1 shows the changes of ECA values for each catalyst. Before the durability test, n-Pt/GCB showed the highest ECA. This is due to the highly uniform dispersion of small Pt particles on the surface of the GCB support by the nanocapsule method. After 1000 cycles of durability testing, the ECA advantage of n-Pt/GCB was maintained.Figure 2 shows the changes in mass activity at 0.85 V before and after the durability test for each catalyst. The 30 wt% Pt/GCB and the n-Pt/GCB showed nearly the same initial mass activity. However, n-Pt/GCB exhibited a higher mass activity than that of Pt/GCB after 1000 cycles.From these electrochemical measurements, it was found that n-Pt/GCB had higher performance and durability compared with those for both commercial Pt/GCB catalysts. It is considered that the both Pt/GCB easily underwent agglomeration and/or increase of particle size by electrochemical Ostwald ripening, because the Pt particles were situated quite closely together. However, the particle agglomeration of n-Pt/GCB was relatively suppressed due to the uniformity both of the Pt dispersion and of the Pt particle size, as described in our previous report4). We also investigated the degradation of the cathode catalysts in detail by using Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and the glancing incidence X-ray diffraction (GIXD) method.This work was supported by funds for the “Research on Nanotechnology for High Performance Fuel Cells (HiPer-FC)” project from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

Nanoflower rod wire-like structures of dual metal (Al and Cr) doped ZnO thin films: Structural, optical and electronic properties

Transition metal (TM) doped ZnO thin-films are increasingly being investigated for the advancement of optoelectronic devices. Functional dual TMs doping into ZnO nanostructures might influence of the charge carrier recombination rate, optical, structural and interfacial electron-transport rate performance. In this study, we demonstrated the fabrication of nanostructured thin-films of pure-ZnO, aluminium doped-ZnO (Al:ZnO or AZO) and Al with chromium doped-ZnO (Al+Cr:ZnO or ACZO) by the pulsed laser deposition (PLD). Surface morphology of prepared thin-films resembled the distinctive shapes such as (pure-ZnO) nanowires, (AZO) nanorods and (ACZO) nanoflower-like structures, respectively. Variation of structural, optical, morphological and electrical properties were characterized by glancing incidence X-ray diffraction (GIXRD), micro-Raman scattering (μ-RS), electron microscopy and transport field emission (F–E) techniques. The electron transport F–E result shows that ACZO has high conductivity than the undoped films.

Microstructure, Mechanical and Tribological Properties of the Tialn Coatings after Nb and C Dual Ion Implantation

Ion implantation is an effective method to enhance hardness and wear resistance of the TiAlN coatings. In this paper, Nb and C ions are co-implanted into TiAlN coatings deposited by Magnetic Filter Arc Ion Plating (MFAIP), using a Metal Vacuum Vapor Arc (MEVVA) ion source implantor with doses of 1×1017and 5×1017ions/cm2. The microstructure, chemical composition, mechanical and tribological properties of Nb+C-implanted TiAlN coatings have been investigated by glancing incidence X-ray diffraction, X-ray photoelectron spectroscopy, nanoindentation test and SRV friction &amp; wear tester, respectively. The results showed that the NbN and TiC phases could be detected both from the XRD and XPS profiles of as-prepared films. Nb and C ion implantation could improve the hardness, plastic deformation resistance and wear behavior of TiAlN coatings due to the energetic Nb and C ion bombardment and the formation of NbN and TiC phases.