Glancing Incidence X-ray Diffraction Study Research Articles

Unraveling the effect of 600 keV carbon ion irradiation on the structural and magnetic properties of ZnO thin film

600 keV 12C+ carbon ions have been irradiated upon 800 nm thin ZnO film. The thin ZnO films have been grown by pulsed laser deposition technique upon SiO2/Si substrate. The glancing incidence X-ray diffraction study exhibits the hexagonal wurtzite crystal structure of ZnO, having space group P63mc. Systematic X-ray diffraction analysis of both unirradiated and irradiated samples, reveals that the strain decreases in the sample post irradiation. Room temperature magnetization studies have been performed using SQUID-VSM. As the 600 keV carbon ion fluence is varied, an onset of ferromagnetic ordering in the ZnO thin film is observed. The maximum average magnetic moment induced by each carbon ion is found to be about 6.71 μB. X-ray photoelectron spectroscopy has been utilized to analyze the oxidation state of the C/O/Zn, which also rules out the presence of any transition metal elements in carbon ions irradiated ZnO thin film samples. The chemical and structural analysis of the samples have been examined by Raman spectroscopy. It reveals a red shift in A1 (LO) mode, which confirms the presence of tensile strain in the sample post irradiation. These experimental results, clearly indicate that oxygen vacancies and strain in the film trigger the onset of ferromagnetism in the ZnO thin film system.

Energetic argon beam stimulated growth of plasmonic silver nanoparticles in Ag+-exchanged soda glass: A study on the structural, optical, photoluminescence and electrical behavior

Fabrication of silver nanoparticles inside soda glass by Ar+ irradiation at an incidence angle of 40° has been presented. Emergence of surface plasmon resonance peak at 410.5 nm for the specimen fabricated by implantation to 5×1016 Ar+ cm−2 at an incidence angle of 40° in optical absorption spectrum provides the signature of silver nanoparticles and the data obtained was further analyzed to evaluate refractive index, optical energy gap and Urbach’s energy of the specimens. Glancing incidence X-ray diffraction study displayed that silver nanoparticles are in face-centered cubic geometry. Their shape, size and distribution in the glass matrix were further probed using transmission electron microscopy and field emission scanning electron microscopy. Rutherford back scattering spectrometry measurement revealed that a 180 nm thick layer of silver nanoparticles is formed in the near surface layers of glass. X-ray photoelectron spectroscopy and photoluminescence spectroscopy suggested that after ion-exchange silver is primarily in the ionic form and after Ar+ implantation at an angle of 40° it acquires metallic form which further nucleate and grow to form silver nanoparticles in glass.

Molecular Engineering of a Donor-Acceptor Polymer To Realize Single Band Absorption toward a Red-Selective Thin-Film Organic Photodiode.

Herein, we explore the strategy of realizing a red-selective thin-film organic photodiode (OPD) by synthesizing a new copolymer with a highly selective red-absorption feature. PCZ-Th-DPP, with phenanthrocarbazole (PCZ) and diketopyrrolopyrrole (DPP) as donor and acceptor units, respectively, was strategically designed/synthesized based on a time-dependent density functional theory calculation, which predicted the significant suppression of the band II absorption of PCZ-Th-DPP due to the extremely efficient intramolecular charge transfer. We demonstrate that the synthesized PCZ-Th-DPP exhibits not only a high absorption coefficient within the red-selective band I region, as theoretically predicted, but also a preferential face-on intermolecular structure in the thin-film state, which is beneficial for vertical charge extraction as an outcome of a glancing incidence X-ray diffraction study. By employing PCZ-Th-DPP as a photoactive layer of Schottky OPD, to fully match its absorption characteristic to the spectral response of the red-selective OPD, we demonstrate a genuine red-selective specific detectivity in the order of 1012 Jones while maintaining a thin active layer thickness of ∼300 nm. This work demonstrates the possibility of realizing a full color image sensor with a synthetic approach to the constituting active layers without optical manipulation.

Study of vacancy defects and their thermal stability in MeV Fe ion irradiated RAFM steel using positron beam Doppler broadening spectroscopy

ABSTRACTIndian reduced activation ferritic-martensitic steel was irradiated with 1.1 MeV Fe ions to various doses from 1 to100 dpa at room temperature. The depth profiling of irradiation-induced vacancy-type defects and the defect-recovery under post-irradiation annealing was studied using variable low-energy positron beam Doppler broadening spectroscopy. The influence of irradiation-induced defects on the microstructural properties was studied by glancing incidence x-ray diffraction (GIXRD) and nanoindentation technique. Positron annihilation study showed the signatures of reduced vacancy concentration at the peak damage region due to injected interstitial effect from 30 to 100 dpa and the widening of vacancy-interstitial recombination-rich region towards the end of ion range with the increase in dose. The GIXRD results were analysed by modified Williamson–Hall plot method, and the variation of coherent domain size and micro-strain with irradiation dose was studied. Irradiation-induced hardening was observed in the nanoindentation study. The features observed in the GIXRD and nanoindentation study are correlated with the depth-resolved defect distribution observed in the positron annihilation study.

Nano-crystalline Ni[sbnd]Ti alloy thin films fabricated using magnetron co-sputtering from elemental targets: Effect of substrate conditions

The primary goal of this work is to examine the effect of in situ substrate conditions viz., substrate bias voltage and substrate temperature on the structural, morphological, compositional, and mechanical properties of co-sputtered NiTi alloy thin films. Application of substrate bias voltage during deposition creates defect sites which facilitate the growth of nano-crystalline NiTi films by imposing restriction on the coalescence of neighboring grains which has lead to interesting properties. Glancing Incidence X-ray diffraction studies revealed the co-existence of B2 and B19′ crystal structures and thus possess potential for martensitic phase transformation, which is the prerequisite for shape memory behavior. Thermally-induced martensitic twin bands were observed within the nano-grains with high-resolution transmission electron microscopy. Surface elemental composition was investigated by X-ray photoelectron spectroscopy to understand the chemical state of NiTi thin films. Differential scanning calorimetric measurements confirms the martensitic transformation below room temperatures. Nanoidentation studies have shown higher hardness values for NiTi films processed at high substrate temperature when compared to the film deposited under the influence of bias voltage due to the deformation mechanism governed by grain boundary absorption of the localized strain in nanometer scale.

Electro-oxidation of Ascorbic Acid by Cobalt Core–Shell Nanoparticles on a H-Terminated Si(100) and by Nanostructured Cobalt-Coated Si Nanowire Electrodes

Determination of the concentration of ascorbic acid in a solution has attracted intense recent interest. Here we demonstrate the feasibility of electro-oxidation of ascorbic acid on spherical cobalt core-shell nanoparticles (10-50 nm dia.) prepared by electrochemical deposition on a H-terminated Si(100) substrate. Depth-profiling X-ray photoelectron spectroscopy reveals that these nanoparticles consist of a metallic cobalt core covered by a Co(OH)2 shell without any evidence of CoOx. Glancing-incidence X-ray diffraction studies further show that the metallic Co core consists of a mixture of hexagonal close packed and face centered cubic structures, the relative composition of which can be easily controlled by the deposition potential. We further demonstrate that when these Co nanoparticles are deposited on a high-surface-area electrode as provided by a Si nanowire template, the resulting nanostructured Co-coated Si nanowire electrode offers a promising high-performance sensor platform for ascorbic acid detection.

Corrosion performance of TiO2 coated type 304L stainless steel in nitric acid medium

The corrosion resistance of sputter deposited TiO 2 on austenitic type 304L stainless steel has been evaluated in the oxidizing medium of 1 M and 8 M nitric acid by monitoring corrosion potential, polarization behaviour and electrochemical impedance. Glancing incidence X-ray diffraction study of the TiO 2 coated surface revealed anatase phase and surface morphological study using an atomic force microscope showed evenly spaced particles with nano pores in the matrix. The particle size measurement showed that particles are within the range of 20–50 nm and measured root mean square roughness of coated surface was around 10 nm. The open circuit potential-time results in 1 M and 8 M nitric acid showed an increase in corrosion potential in both the test solutions for TiO 2 coated specimens. Electrochemical impedance analysis revealed an increase in magnitude of total impedance as well as phase angle for TiO 2 coated specimens in both the concentrations as compared to uncoated specimens. Potentiodynamic polarization study of coated specimens revealed overall resistance to corrosion by increase in corrosion potential, decrease in passive current density and increase in transpassive potential. Morphological examination of the polarized specimens using an atomic force microscope revealed resistance to surface dissolution in 1 M nitric acid and uniform surface dissolution at higher concentrations of nitric acid (8 M).

Formation and growth of embedded indium nanoclusters by In2+ implantation in silica

Indium nanoclusters are synthesized in an amorphous silica matrix using an ion-implantation technique. Indium ions (In2+) with energy of 890 keV are implanted on silica to fluences in the range of 3×1016–3×1017 cm-2. The formation of indium nanoclusters is confirmed by optical absorption spectrometry and glancing incidence X-ray diffraction studies. A low frequency Raman scattering technique is used to study the growth of embedded indium nanoclusters in the silica matrix as a function of fluence and post-implantation annealing duration. Rutherford backscattering spectrometry studies show the surface segregation of implanted indium. Photoluminescence studies indicate the formation of a small quantity of indium oxide phase in the ion-implanted samples.

Absorption and luminescence of silver nanocomposite soda-lime glass formed by Ag +–Na + ion-exchange

Metal nanocomposite glasses are formed by a multi step methodology which involves incorporation of the metal ions into the glass by ion-exchange process followed by suitable treatments like low mass ion irradiation or thermal annealing resulting in the aggregation of the metal ions to form nano dimension metal clusters. These embedded metal nanoclusters are well investigated by the optical absorption spectroscopy which gives information regarding the size and shape of the metal clusters embedded in the dielectric matrix. The Ag + ion-exchanged and annealed soda-lime glasses exhibit photoluminescence around 445 nm at two excitation wavelengths. He + ion irradiation of the ion-exchanged soda-lime glass resulted in the formation of Ag metal nano crystallites with a thin metal film on the irradiated surface. The Glancing incidence X-ray diffraction study confirmed the formation of Ag nano crystals inside the dielectric matrix. Photoluminescence vanished in the irradiated samples with the neutralization of Ag + ions into Ag metal nano crystallites.

SIMS, RBS and glancing incidence X-ray diffraction studies of thermally annealed Ru/β-SiC interfaces

Thermal stability of the Ru/β-silicon carbide (SiC) interfaces up to 800 °C is investigated using secondary ion mass spectrometry (SIMS), Rutherford backscattering spectrometry (RBS) and glancing incidence X-ray diffraction (GIXRD) studies. The objective of this work is to assess the potentiality of ruthenium to be used as a stable gate metal of the Schottky junction gas sensors working at high temperature. The SIMS and RBS studies indicate no significant change in the interface after short-term as well as long-term annealing at 400 °C, the optimum operating temperature of the Ru/β-SiC (epilayer on Si) Schottky junction gas sensors. Glancing incidence X-ray diffraction study does not detect any silicide formation at the Ru/SiC interface after heat treatment at this temperature. However, annealing the junction at a substantially higher temperature (800 °C) results in the formation of ruthenium silicides at the interface over a narrow region along with the oxidation of the top few Ru layers.

Ruthenium as Schottky metal for SiC-based high temperature hydrogen sensors

ABSTRACTSensor response characteristics of Ru/3C-SiC (epitaxial layer of SiC on Si substrates) Schottky junctions were studied at different temperatures (200 – 400 °C) in presence of varying concentrations of hydrogen from 5000 – 20000 ppm. The output signal of the sensor, the response time and the reversibility were investigated from the transient response characteristics of the sensors. The sensor parameters improved with higher operating temperature, up to 400 °C. The sensitivity of the sensors was found to be a function of applied bias across the Schottky junction. As compared with the Pd/3C-SiC junctions, the Ru/3C-SiC Schottky sensors showed higher resolution and better reversibility in the hydrogen concentration range 10000 to 20000 ppm. The SIMS (Secondary Ion Mass Spectrometry), RBS (Rutherford Backscattering Spectrometry) and GIXRD (Glancing Incidence X-ray Diffraction) studies indicated that up to 400 °C there was no formation of ruthenium silicide at the Ru/3C-SiC interface.

Irradiation induced dissolution of Cu and growth of Ag nanoclusters in Cu/Ag ion-exchanged soda-lime glass

Complex metal nanoclusters of Cu/Ag are formed in a soda-lime glass matrix by sequential copper and silver ion-exchange followed by ion irradiation. Optical absorption measurements showed signature of copper clusters alone in the Cu/Ag ion-exchanged sample. Irradiation of the ion-exchanged sample with He + ions of energy 100 keV of different fluences resulted in the growth of the silver clusters with, the optical absorption spectrum exhibiting two peaks corresponding to the surface plasmon resonance of copper and silver in the same matrix. It was found that with increase in fluence the silver clusters begin to grow while the already formed copper clusters segregate, which can be visualized from the absorption spectra, where the copper band disappears while the silver band grows with the increase in dose. Vacuum annealing of the Cu/Ag ion-exchanged samples resulted in complete disappearance of copper clusters while the silver clusters grew till they attained saturation. The glancing incidence X-ray diffraction study of the Cu/Ag ion-exchanged and irradiated sample showed silver peaks alone with no information of alloying between the two species.