Showing papers in "Radiation Effects and Defects in Solids in 2015"
TL;DR: In this article, high dielectric constant (HfO2) films (10"nm) were deposited on Si substrates using the e-beam evaporation technique.
Abstract: The current trend in miniaturization of metal oxide semiconductor devices needs high-k dielectric materials as gate dielectrics. Among all the high-k dielectric materials, HfO2 enticed the most attention, and it has already been introduced as a new gate dielectric by the semiconductor industry. High dielectric constant (HfO2) films (10 nm) were deposited on Si substrates using the e-beam evaporation technique. These samples were characterized by various structural and electrical characterization techniques. Rutherford backscattering spectrometry, X-ray reflectivity, and energy-dispersive X-ray analysis measurements were performed to determine the thickness and stoichiometry of these films. The results obtained from various measurements are found to be consistent with each other. These samples were further characterized by I–V (leakage current) and C–V measurements after depositing suitable metal contacts. A significant decrease in the leakage current and the corresponding increase in device capacitance ar...
22 citations
TL;DR: The heat conductivity of three-dimensional Yukawa dusty plasma liquids (YDPLs) has been investigated by employing a homogenous nonequilibrium molecular dynamics (HNEMD) technique at a low normalized force field strength (F*).
Abstract: The heat conductivity of three-dimensional Yukawa dusty plasma liquids (YDPLs) has been investigated by employing a homogenous nonequilibrium molecular dynamics (HNEMD) technique at a low normalized force field strength (F*). The obtained results for plasma heat conductivity with suitable normalizations are measured over a wide range of various plasma states of the Coulomb coupling (Γ) and screening length (κ) in a canonical ensemble (NVT). The calculations for lattice correlations (Ψ) show that our YDPLs system remains in a nonideal strongly coupled regime for a complete range of Γ. It has been shown that the presented Yukawa system obeys a simple analytical temperature demonstration of λ0 with a normalized Einstein frequency. The employed HNEMD algorithm is found to have a more efficient method than that of different earlier numerical methods and it gives more satisfactory results for lower to intermediate Γ with small system sizes at low F*. The obtained simulation results at nearly equilibrium F* (= 0...
19 citations
TL;DR: In this article, the effects of 60Co gamma-irradiation on n-channel AlGaN/GaN high electron mobility transistors have been investigated using electrical testing and current measurements.
Abstract: To understand the effects of 60Co gamma-irradiation, systematic studies were carried out on n-channel AlGaN/GaN high electron mobility transistors. Electrical testing, combined with electron beam-induced current measurements, was able to provide critical information on defects induced in the material as a result of gamma-irradiation. It was shown that at low gamma-irradiation doses, the minority carrier diffusion length in AlGaN/GaN exhibits an increase up to ∼300 Gy. The observed effect is due to longer minority carrier (hole) life time in the material's valence band as a result of an internal electron irradiation by Compton electrons. However, for larger doses of gamma irradiation (above 400 Gy), deteriorations in transport properties and device characteristics were observed. This is consistent with the higher density of deep traps in the material's forbidden gap induced by a larger dose of gamma-irradiation. Moderate annealing of device structures at 200°C for 25 min resulted in partial recovery of tra...
17 citations
TL;DR: In this paper, the effect of the Portland cement mixed with different percentages of water and ilmenite ore on the attenuation of gamma radiation as shielding blocks was investigated, and the properties of the investigated blocks, as compressive strength, wet and dry density, absorption and porosity percentages, were studied.
Abstract: The current work investigated the effect of the Portland cement mixed with different percentages of water and ilmenite ore on the attenuation of gamma radiation as shielding blocks. Different concentrations of ilmenite from 5% up to 20% with different grain size were mixed with cement. The properties of the investigated blocks, as compressive strength, wet and dry density, absorption and porosity percentages, were studied. The thermal stability of the studied samples and their X-ray diffraction (XRD) patterns were examined through thermogravimetric analysis and XRD respectively. In addition, the attenuation coefficients of the considered samples for gamma radiation were performed using gamma ray spectrometer. The results revealed that, the maximum linear attenuation coefficient (µ) and minimum transmission fraction were performed for cement mixed with 10% of ilmenite and with the size range 106–250 µm.
17 citations
TL;DR: In this article, the effects of γ-irradiation on the optical properties and optical constants of the films have been studied by using Ultra Violet-Visible (UV-Vis) spectrophotometer.
Abstract: In the present work the Bombyx mori silk fibroin (SF) films were prepared by the solution casting method and effects of γ-irradiation on the optical properties and optical constants of the films have been studied by using Ultra Violet–Visible (UV–Vis) spectrophotometer. The recorded UV–Vis absorption and transmission spectra have been used to determine the optical band gap (Eg), refractive index (n), extinction coefficient (k), optical conductivity (σopt) and dielectric constants (e*) of virgin and γ-irradiated films. Reduction in optical band gap and increase in refractive index with increasing radiation dosage were observed. It is also found that there is an increase in dielectric constants with increasing photon energy. The obtained results reveal that the refractive index of the SF films may be efficiently changed by γ-irradiation.
16 citations
TL;DR: In this paper, the authors used nano-sized bismuth trioxide and molybdenum instead of lead as a shielding element for X-ray radiation shielding fibers.
Abstract: In this study, radiation shielding fibers using non-hazardous nano-sized bismuth trioxide and molybdenum instead of lead were developed and evaluated. Among the elements with high densities and atomic numbers, non-hazardous elements such as bismuth trioxide and molybdenum were chosen as a shielding element. Then, bismuth trioxide (Bi2O3) with average particle size 1–500 µm was ball milled for 10 min to produce a powdered form of nanoparticles with average particle size of 10–100 nm. Bismuth trioxide nanoparticles were dispersed to make a colloidal suspension, followed by spreading and hardening onto one or two sides of fabric, to create the radiation shielding fabric. The thicknesses of the shielding sheets using nano-sized bismuth and molybdenum were 0.4 and 0.7 mm. According to the lead equivalent test of X-ray shielding products suggested by KS, the equivalent dose was measured, followed by calculation of the shielding rate. The shielding rate of bismuth with 0.4 mm thickness and at 50 kVp was 90.5%, w...
13 citations
TL;DR: In this paper, electron paramagnetic resonance of γ-irradiated single crystals of N-Trifluoroacetyl-α-amino isobutyric acid (F3Ac-Aib-OH) was investigated at room temperature and analyzed for different orientations of the crystal in the magnetic field.
Abstract: In this study, electron paramagnetic resonance of γ-irradiated single crystals of N-Trifluoroacetyl-α-amino isobutyric acid (F3Ac-Aib-OH) was investigated at room temperature and analyzed for different orientations of the crystal in the magnetic field. The paramagnetic species in N-Trifluoroacetyl-α-aminoisobutyric acid was attributed to the ĊF2-R radical (R= CONHC(CH3)COOH). Hyperfine coupling constants and g value were also determined. In addition, the single crystal of F3Ac-Aib-OH was UV-irradiated and paramagnetic species formed was studied at room temperature. The effects of gamma irradiation on fluoroamino acid and stability were discussed.
11 citations
TL;DR: In this paper, the effects of gamma irradiation on structural and optical properties of polycrystalline Ga10Se85Sn5 thin films with a thickness of ∼300 nm were investigated on cleaned glass substrates.
Abstract: The present study focuses on the effects of gamma irradiation on structural and optical properties of polycrystalline Ga10Se85Sn5 thin films with a thickness of ∼300 nm deposited by the thermal evaporation technique on cleaned glass substrates. X-ray diffraction patterns of the investigated thin films show that crystallite growth occurs in the orthorhombic phase structure. The surface study carried out by using the scanning electron microscope (SEM) confirms that the grain size increases with gamma irradiation. The optical parameters were estimated from optical transmission spectra data measured from a UV–vis-spectrophotometer in the wavelength range of 200–1100 nm. The refractive index dispersion data of the investigated thin films follow the single oscillator model. The estimated values of static refractive index n0, oscillator strength Ed, zero frequency dielectric constant e0, optical conductivity σoptical and the dissipation factor increases after irradiation, while the single oscillator energy Eo de...
11 citations
TL;DR: In this paper, the effect of gamma irradiation on poly allyl diglycol carbonates (PADC) within the dose range from 50 to ǫGy was studied.
Abstract: Kinetic thermogravimetric technique was used to study the effect of gamma irradiation on the poly allyl diglycol carbonates (PADC) within the dose range from 50 to Gy. The approach of Coats-Redfern was used to analyze the data. Results showed that low doses around 50 Gy make the polymer slightly more resistive to heat treatment. Higher radiation doses cause severe effects in the samples accompanied by the formation of lower molecular mass species and consequent crosslinking. Results support the domination of re-polymerization and crosslinking for the γ radiation interaction PADC at dose below about Gy, while the situation is inverted above Gy in which chain secession dominates.
10 citations
TL;DR: In this paper, the influence of high-energy heavy ions on magnetic susceptibility of VITROPERM®-type metallic glasses was studied. But the results of the experiments were performed at the UNILAC accelerat...
Abstract: Some soft magnetic metallic glasses are considered for use in magnetic cores of accelerator radio frequency cavities. Due to losses of the circulating ion beam, they may be exposed to irradiation by different ions at different energies. This paper presents data and review results of irradiation experiments concerning the influence of high-energy heavy ions on magnetic susceptibility of VITROPERM®-type metallic glasses. Samples of the VITROPERM® magnetic ribbons were irradiated by Au, Xe and U ions at 11.1 MeV/A (per nucleon) and 5.9 MeV/A, respectively. Irradiation fluences from 1 × 1011 up to 1 × 1013 ions/cm2 were applied. In case of the Au and U ions, the total fluence was accumulated in one beamtime, whereas two separate beamtimes were used to accumulate the final fluence in case of the Xe ions. Relative change in the samples’ magnetic susceptibility after and before irradiation was evaluated as a function of the irradiation fluence. The irradiation experiments were performed with the UNILAC accelerat...
10 citations
TL;DR: In this article, the effect of the chromium and carbon atoms on the formation and kinetics of point defects clusters has been taken into account, and the results confirm the non-monotonic dose dependence of the vacancy clusters mean size for irradiation doses from 0.15 to 0.74
Abstract: Cluster dynamics (CD) study of damage accumulation has been performed for helium-implanted Fe–2.5 at%Cr alloy with the flux of 7 × 10−6 dpa/s at the temperature of 343 K. Findings confirm the non-monotonic dose dependence of the vacancy clusters mean size for irradiation doses from 0.15 to 0.74 dpa, observed in the positron annihilation spectroscopy experiment. The effect of the chromium and carbon atoms on the formation and kinetics of point defects clusters has been taken into account. The ratio of vacancies formed to cluster to the total number of surveillance vacancies at the end of the cascade stage (irradiation parameter fvcl) and migration energy of vacancies in bcc iron (material parameter Emv) have been varied to provide the best fit of CD simulation results to positron annihilation spectroscopy data on the positron lifetime in defects. The calibrated CD model has been used to study the effect of the presence of vacancy clusters in the non-irradiated state Fe–2.5at%Cr alloy on the evolution of po...
TL;DR: In this article, the radiation effects on semicrystalline poly(vinylidene fluoride-chlorotrifluoroethylene) copolymer [poly(VDF-CTFE)] induced by proton beam irradiation were investigated.
Abstract: The radiation effects on semicrystalline poly(vinylidene fluoride–chlorotrifluoroethylene) copolymer [poly(VDF–CTFE)] induced by proton beam irradiation were investigated. The poly(VDF–CTFE) films were exposed to 4 MeV protons at different fluence in the range of 2.7 × 1013 to 65.0 × 1013 protons/cm2. Changes in the chemical structural and thermal properties of pristine films as well as irradiated samples were studied using Fourier Transform Infrared (FTIR) and thermal analytical techniques, namely Thermogravimetric Analysis and Differential Scanning Calorimetry (DSC), respectively. FTIR spectroscopic data revealed two new bands at 1650 and 1747 cm−1 for irradiated samples whose intensities gradually increased with increasing ion fluence from 2.7 × 1013 to 27.0 × 1013 protons/cm2 due to the formation of carbon–carbon double bonds. The thermal stability was found to decrease after proton irradiation due to chain-scission. DSC data revealed that the proton irradiation was found to change in heat of fusion a...
TL;DR: In this paper, the structural and optical properties of thin polyimide composites with nanosilica particle content of 15 wt, prepared via sol-gel process, were studied as a function of the gamma dose.
Abstract: The structural and optical properties of thin films of polyimide composites with nanosilica particle content of 15 wt%, prepared via sol–gel process, were studied as a function of the gamma dose. The resultant effect of gamma irradiation on the properties of polyimide/silica nanocomposite has been investigated using X-ray diffraction and UV spectroscopy. Absorption and reflectance spectra were collected by a spectrophotometer giving UV-radiation of wavelength range 200–800 nm. The optical data obtained were analyzed and the calculated values of the optical energy gap exhibited gamma dose dependence. The direct optical energy gap for the nonirradiated polyimide/silica nanocomposite is about 2.41 eV, and increases to a value of 2.65 eV when irradiated with gamma doses up to 300 kGy. It was found that the calculated refractive index of the polyamide/silica increases with the gamma dose in the range 50–300 kGy.
TL;DR: In this paper, the effect of thickness (100, 200 and 300) on the physical properties of indium tin oxide (ITO) thin films was investigated systematically, and it was observed that with an increase in thickness, the X-ray diffraction data indicate polycrystalline films with grain orientations predominantly along (222) and (400) directions.
Abstract: Transparent and conducting indium tin oxide (ITO) thin films were deposited on soda lime glass substrates by RF plasma magnetron sputtering at room temperature. The effect of thickness (100, 200 and 300 nm) on the physical (structural, optical, electrical) properties of ITO thin films was investigated systematically. It is observed that with an increase in thickness, the X-ray diffraction data indicate polycrystalline films with grain orientations predominantly along (222) and (400) directions; the average grain size increases from 10 to 30 nm; the optical band gap increases from 3.68 to 3.73 eV and the transmission decrease from 80% to 70% . Four-point probes show a low resistivity (2.4×10−5 Ω cm) values for film with a thickness 300 nm. Present work shows that the ITO is a promising transparent conductive oxide material for the solar cell application.
TL;DR: In this paper, a new unitary quantum lattice gas (QLG) algorithm is proposed as a mesoscopic unitary perturbative representation of the mean field Gross Pitaevskii equation for Bose-Einstein Condensates (BECs).
Abstract: A new unitary quantum lattice gas (QLG) algorithm is proposed as a mesoscopic unitary perturbative representation of the mean field Gross Pitaevskii equation for Bose–Einstein Condensates (BECs). T...
TL;DR: In this paper, the effects of UV radiation on the preparation of polypyrrole were investigated and the morphology, conductivity and thermal stability of the products were also characterized, showing that the product poly pyrrole was overoxidized partly depending on the concentrations of H2SO4 and H2O2.
Abstract: Conductive polypyrrole was synthesized with hydrogen peroxide (H2O2) as the oxidant. To promote the polymerization of pyrrole, UV radiation was employed. The effects of UV radiation on the preparation of polypyrrole were investigated. The polymerization of pyrrole was conducted with the H2O2 concentration in the range of 0.12–0.96 M and the H2SO4 concentration in the range of 6.8×10−4–0.19 M. The structure characterization indicated that the product polypyrrole was overoxidized partly depending on the concentrations of H2SO4 and H2O2. The increase in H2O2 concentration led to a slight increase in the oxidation and overoxidation of polypyrrole, simultaneously. However, the increase in H2SO4 concentration effectively suppressed the overoxidation of polypyrrole. The morphology, conductivity and thermal stability of the products were also characterized.
TL;DR: In this paper, a detailed study of the RadFET energy response simulated with PENELOPE Monte Carlo code was performed for capped and uncapped configurations of devices irradiated by point and extended sources.
Abstract: Radiation-sensing Field Effect Transistors (RadFETs or MOSFET dosimeters) with SiO2 gate dielectric have found applications in space, radiotherapy clinics, and high-energy physics laboratories. More sensitive RadFETs, which require modifications in device design, including gate dielectric, are being considered for personal dosimetry applications. This paper presents results of a detailed study of the RadFET energy response simulated with PENELOPE Monte Carlo code. Alternative materials to SiO2 were investigated to develop high-efficiency new radiation sensors. Namely, in addition to SiO2, Al2O3 and HfO2 were simulated as gate material and deposited energy amounts in these layers were determined for photon irradiation with energies between 20 keV and 5 MeV. The simulations were performed for capped and uncapped configurations of devices irradiated by point and extended sources, the surface area of which is the same with that of the RadFETs. Energy distributions of transmitted and backscattered photons were...
TL;DR: In this article, the stabilization of a two-dimensional fluid jet from the Kelvin-Helmholtz (KH) instability by an external parallel magnetic field is examined by lattice Boltzmann techniques.
Abstract: The stabilization of a two-dimensional fluid jet from the Kelvin–Helmholtz (KH) instability by an external parallel magnetic field is examined by lattice Boltzmann techniques. For sufficiently strong magnetic fields, the jet does not break up into large-scale vortices but retains the major features of the jet, albeit somewhat expanded. There are time-dependent striations within the expanded jet.
TL;DR: In this paper, the electron paramagnetic resonance (EPR) parameters (g factors gx, gy, gz and hyperfine structure constants Ax, Ay, Az) for Cu2+ in (NH4) 2Mg(SO4)2·6H2O (DHMS) crystal are theoretically investigated using the high-order perturbation formulas of these parameters.
Abstract: The electron paramagnetic resonance (EPR) parameters (g factors gx, gy, gz and hyperfine structure constants Ax, Ay, Az) for Cu2+ in (NH4)2Mg(SO4)2·6H2O (DHMS) crystal are theoretically investigated using the high-order perturbation formulas of these parameters. In the calculations, the ligand orbital and spin–orbit coupling for the impurity Cu2+ are taken into account; the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the EPR parameters with the local structure of the impurity center. The ligand orbital and the spin–orbit coupling contributions are included on the basis of the cluster approach. Based on the calculation, the theoretical EPR parameters show good agreement with the observed values. The results are discussed.
TL;DR: In this paper, the effect of γ-radiation on the photoluminescence behavior of YPO4:Eu3+/Dy3+ and co-doped with Ce3+ was investigated.
Abstract: Hexagonal YPO4 phosphors doped with Eu3+/Dy3+ and co-doped with Ce3+ were synthesized by a hydrothermal route assisted using lauric acid as a capping agent. The prepared phosphors were characterized by transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction and photoluminescence spectra. YPO4: Eu3+ gives two red emission peaks at 587 and 610 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions, respectively. YPO4: Dy3+ exhibits two emission peaks at 485 nm (blue) and 575 nm (yellow) corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. Ce3+ ions enhanced the emission intensity as a co-dopant in both phosphors. Moreover, the effect of γ-radiation in the dose range 5–300 kGy on the photoluminescence behaviour of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ was also investigated. Quenching of emission intensity, after irradiation at 5 and 300 kGy, was observed in both the phosphors due to loss of excess energy through a non-radiative relaxation process.
TL;DR: In this paper, a comparative ablation experiments by femtosecond, picosecond and millisecond pulsed lasers were carried out on titanium and the final surface morphology, aspect ratio, chemical composition and microstructural state of the ablated titanium were analyzed by laser scanning confocal microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy.
Abstract: In order to realize the qualitative control of the laser-induced changes trend and the quantitative control of the laser-induced changes range in titanium upon laser irradiation with different pulse duration, comparative ablation experiments by femtosecond, picosecond and millisecond pulsed lasers were carried out on titanium in this study. Then the final surface morphology, aspect ratio, chemical composition and microstructural state of the ablated titanium were analyzed by laser scanning confocal microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy, respectively. The dependency of the morphology, size, composition and microstructure of ablated titanium on laser pulse duration variation were emphatically discussed. It is found that, as the laser pulse duration increases from femtosecond to millisecond scale, surface morphology quality of ablated titanium gets worse, aspect ratio of microgroove decreases, proportion of titanium oxides in final ablation products becomes larger ...
TL;DR: In this paper, all experimental data suitable for analysis confirm the validity of the Gaussian temperature distribution Θ(r) in insulators which depend neither on the physical properties of the solid nor on the kind of the projectiles.
Abstract: Swift heavy ions induce a Gaussian temperature distribution Θ(r) in insulators which depend neither on the physical properties of the solid nor on the kind of the projectiles. In this paper, we show that all experimental data suitable for analysis confirm the validity of Θ(r). The same result is obtained for ZrSiO4, MgAl2O4, KTiOPO4, Al2O3 and Y2O3, where systematic experiments have not been performed yet. The analysis demonstrates that Θ(r) may be valid in biomolecular targets and in high-Tc superconductors as well. The Fourier equation cannot reproduce the relation Θ(r); thus, it is not suitable for the estimation of the ion-induced temperatures. The consequences of the uniformity in track formation must also affect other radiation-induced effects.
TL;DR: In this paper, the effects of gamma irradiation on chemical structure, thermal and morphological properties of biodegradable semi-crystalline poly (glycolic acid) (PGA) were investigated.
Abstract: We have investigated the effects of gamma irradiation on chemical structure, thermal and morphological properties of biodegradable semi-crystalline poly (glycolic acid) (PGA). PGA samples were subjected to irradiation treatment using a 60Co gamma source with a delivered dose of 30, 60 and 90 kGy, respectively. Gamma irradiation induces cleavage of PGA main chains forming ∼OĊH2 and ĊH2COO∼ radicals in both amorphous and crystalline regions. The free radicals formed in the amorphous region abstract atmospheric oxygen and convert them to peroxy radicals. The peroxy radical causes chain scission at the crystal interface through hydrogen abstraction from methylene groups forming the ∼ĊHCOO∼ (I) radical. Consequently, the observed electron spin resonance (ESR) doublet of irradiated PGA is assigned to (I). The disappearance of the ESR signal above 190°C indicates that free radicals are formed in the amorphous region and decay below the melting temperature of PGA. Fourier transform infrared and optical absorption...
TL;DR: In this paper, the structure of the grown crystals was confirmed by XRD diffraction spectrum to be the desired KHSeO4 single crystal and the effect of the irradiation on the optical energy gap was reported along the principle crystallographic directions.
Abstract: Potassium hydrogenselenate KHSeO4 single crystals were successfully grown by the solution growth technique. The structure of the grown crystals was confirmed by XRD diffraction spectrum to be the structure of the desired KHSeO4 single crystal. The crystals were irradiated by different doses of γ-irradiation in the range 0.4–2.4 kGy and the optical absorption spectra were recorded along the a-, b- and c-axes. The optical inter-band transitions were of the indirect allowed ones and the optical energy gap Eg was determined along the three crystallographic directions. The effect of the irradiation on the optical energy gap is reported along the principle crystallographic directions. Urbach rule suggested the formation of Urbach tail and the effect of irradiation on this band tail is reported. These observations are attributed to the radiation-induced defects on the bulk crystal.
TL;DR: In this article, a change in mechanical properties of binary systems subjected to irradiation influence described by ballistic flux of atomic mixing having regular and stochastic contributions is studied by using numerical modeling based on the phase field approach.
Abstract: We study a change in mechanical properties of binary systems subjected to irradiation influence described by ballistic flux of atomic mixing having regular and stochastic contributions. By using numerical modeling based on the phase field approach we study dynamics of deformation fields in a previously irradiated system and in the binary system deformed during irradiation. An influence of both deterministic and stochastic components of ballistic flux onto both yield strength and ultimate strength is studied. We have found that degradation of mechanical properties relates to the formation of percolating clusters of shear bands. Considering a hardening coefficient we analyze stages of plastic deformation of both initially irradiated alloy and alloy subjected to sustained irradiation. Stability of binary alloy under mechanical loading in the form of shear strain with a constant rate and cyclic deformation is discussed.
TL;DR: In this article, nano-crystalline tungsten nitride thin films are synthesized on AISI-304 steel at room temperature using Mather-type plasma focus system.
Abstract: Nano-crystalline tungsten nitride thin films are synthesized on AISI-304 steel at room temperature using Mather-type plasma focus system. The surface properties of the exposed substrate against different deposition shots are examined for crystal structure, surface morphology and mechanical properties using X-ray diffraction (XRD), atomic force microscope, field emission scanning electron microscope and nano-indenter. The XRD results show the growth of WN and WN2 phases and the development of strain/stress in the deposited films by varying the number of deposition shots. Morphology of deposited films shows the significant change in the surface structure with different ion energy doses (number of deposition shots). Due to the effect of different ion energy doses, the strain/stress developed in the deposited film leads to an improvement of hardness of deposited films.
TL;DR: In this article, the authors described the phenomenon of mechanoluminescence (ML) in ZrO2:Ti (cubic) phosphors and found that the intensity increases with time, attains a maximum value and then it decreases.
Abstract: The present manuscript provides a description of the phenomenon of mechanoluminescence (ML) in ZrO2:Ti (cubic) phosphors. When the ML is excited impulsively by the impact of a load on the phosphors the ML intensity increases with time, attains a maximum value and then it decreases. In the ML intensity versus time curve, the peak increases and shifts towards shorter time values with increasing impact velocities. The sample was synthesised using the combustion synthesis method with variable concentrations of Ti (0.1, 0.2, 0.5, 1, 1.5 mol%) and characterised by X-ray diffraction technique. The total ML intensity IT is defined as the area below the ML intensity versus time curve. Total ML intensity increases linearly with the mass of the phosphors for higher impact velocities. The ML intensity Im, corresponding to the peak of ML intensity versus time curve, increases linearly with the impact velocities. The time tm is found to be linearly related to 1000/V0. The ML induced by impulsive excitation in titanium-...
TL;DR: In this article, the effect of fluence and pulse duration on the growth of nanostructures on chromium surfaces has been investigated upon irradiation of femtosecond (fs) laser pulses in a liquid confined environment of ethanol.
Abstract: The effect of fluence and pulse duration on the growth of nanostructures on chromium (Cr) surfaces has been investigated upon irradiation of femtosecond (fs) laser pulses in a liquid confined environment of ethanol. In order to explore the effect of fluence, targets were exposed to 1000 pulses at various peak fluences ranging from 4.7 to 11.8 J cm–2 for pulse duration of ∼25 fs. In order to explore the effect of pulse duration, targets were exposed to fs laser pulses of various pulse durations ranging from 25 to 100 fs, for a constant fluence of 11.8 J cm–2. Surface morphology and structural transformations have been analyzed by scanning electron microscopy and Raman spectroscopy, respectively. After laser irradiation, disordered sputtered surface with intense melting and cracking is obtained at the central ablated areas, which are augmented with increasing laser fluence due to enhanced thermal effects. At the peripheral ablated areas, where local fluence is approximately in the range of 1.4–4 mJ cm–2, ve...
TL;DR: In this article, the effects of hydrostatic pressure on the line position and fluorescence lifetime τ for 5D0 → 7F2 transitions in GdVO4: Eu3+ nanocrystals were investigated.
Abstract: This study considers the effects of hydrostatic pressure on the line position and fluorescence lifetime τ for 5D0 → 7F2 transitions in GdVO4: Eu3+ nanocrystals. The results indicate that the pressure induced the red shift toward longer wavelengths for all the considered lines with different rate. The fluorescence lifetime τ nonlinearly decreases with pressure in the considered pressure range. High pressure induced the fluorescence lifetime τ that can be explained with a simple theoretical model. The measured line position and τ are in a satisfactory agreement with the theoretical calculations.
TL;DR: In this article, the free electron interacted with environmental protons and 14N nucleus in both radicals, and the EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation.
Abstract: Gamma irradiated powders of glycine anhydride and betaine hydrochloride have been investigated at room temperature by electron paramagnetic resonance (EPR). In these compounds, the observed paramagnetic species were attributed to the R1 and R2 radicals, respectively. It was determined that the free electron interacted with environmental protons and 14N nucleus in both radicals. The EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation. Also, the Fourier Transform Infrared (FT-IR), FT-Raman and thermal analyses of both compounds were investigated. The functional groups in the molecular structures of glycine anhydride and betaine hydrochloride were identified by vibrational spectroscopies (FT-IR and FT-Raman).