Ellipsometric measurements of plastically deformed copper

Chemically pure copper (99.99) prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm was extremely plastically deformed with the repeated application of equal channel angular pressing. Equal channel angular pressing was applied as an effective technique for producing bulk nanoscaled structures. It is well known that severe plastic deformation of metallic materials often leads to microstructure with ultrafine grains and cross-sections which remain about equal before and after deformation. Optical properties of the sample were studied using spectroscopic ellipsometry in UV-VIS range. The parameters of the sample like copper oxide and surface roughness overlayer were calculated using two-film model together with the Bruggeman effective medium approximation

Optical properties of plastically deformed copper

Pure copper (99.99), prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm, was extremely plastically deformed with the repeated application of Equal Channel Angular Pressing (ECAP). ECAP was applied as an effective technique for producing bulk nano-scaled structures. Optical properties of the sample were investigated using Raman spectroscopy. Two types of lines: narrow (with width of 7 cm¡1) and wide ( 40 cm¡1) are registered. Existence of two types of lines indicates that in the specimen exists nano-sized crystal structures of both Cu and CuO related with three dimensional amorphous boundary spaces, which indicates that plastic deformation of the sample did not lead to total amorphisation of the specimen

Optične lastnosti plastično deformiranega bakra: študij elipsometrije

In this paper the results of optical properties investigations on plastically deformed copper are presented. The optical properties of the plastically deformed copper were studied using spectroscopic ellipsometry in the ultraviolet-visible (UV-VIS) range. Chemically pure copper was deformed by applying the Equal Channel Angular Pressing (ECAP) technique. During the last decade, equal-channel angular pressing procedure was used for the fabrication of ultrafine-grained metals and alloys. The plastic deformation of metallic materials leads to the production of bulk nano-scale structures with ultrafine grains and cross-sections, which remain about equal before and after deformation. The parameters of the sample were calculated using a two-film model together with the Bruggeman effective medium approximation.V članku so predstavljeni rezultati raziskav optičnih lastnosti plastično deformiranega bakra. Te so bile raziskane s spektralno elipsometrijo v območju vidne UV-svetlobe. Kemijsko čist baker je bil deformiran z uporabo ECAP-metode (enakokotno koničasto stiskanje). V zadnjem času se ECAP-postopek uporablja za izdelavo ultra udrobnjenih kovin in zlitin. Takšna plastična deformacija kovinskih materialov vodi k izdelavi masivnih nanostruktur z ultra drobnimi zrni in prečnim prerezom, kar omogoča približno enakost pred deformacijo in po njej. Parametri preiskanih vzorcev so bili izračunani na osnovi uporabe dvojne plasti - filma skupaj s Bruggemanovo srednjo efektivno aproksimacijo

Control system of ECR ion source within FAMA

Recent upgrading of the Facility for Modification and Analysis of Materials with Ion Beams (FAMA), in the Laboratory of Physics of the Vinča Institute of Nuclear Sciences, included modernization of its electron cyclotron resonance (ECR) ion source. The ECR ion source was extensively used for production of multiply charged ions from gases and solid substances for more than 15 years, during which time its major subsystems were expended and therefore, it required complete reconstruction. As a part of this reconstruction we designed and put together a completely new control system of the ECR ion source. It is a distributed and fiber-optically linked control system based on the Group3 Control hardware and the control application written in the Wonderware’s In Touch software. The control system should help and assist an operator in obtaining the appropriate operating parameters of the ECR ion source, maintaining and controlling operating parameters of the machine during its operation, as well as in monitoring weather the safety conditions are fulfilled during the operation of the machine. We tested the operation and performances of the new control system during the commissioning of the upgraded ECR ion source. Compared to the old one, the new system is more reliable, more userfriendly oriented, and it comprises several new useful control applications. [Projekat Ministarstva nauke Republike Srbije, br. III 45006

Numerical model of proton beam transport through electric scanner

In this work, using the numerical simulation method, the vertical and horizontal displacement of the proton beam is analyzed, by changing the voltage of the plan parallel electrodes of the electric scanner. The initial proton beam was modeled by centered Gaussian distribution. The electrostatic field of the scanner was obtained using the finite element method. The dependence of the beam center trensverse shift, as well as the beam losses at the output of the scanner, on the applied electrode voltage, has been determined. Comparison between proton trajectories calculated using analytical/numerical electric field has been performed. Based on this, the effective length of the scanner electrodes was determined. The results of this paper are applied in a technical solution that provides homogeneous fluence distribution in sample irradiation by 3 - 30 keV proton beams, obtained from a light ion source

Optical and magnetic properties of PbTe(Ni)

Far-infrared and magnetic properties of Ni doped PbTe (ZNi = 1 £ 1019 at./cm3)single crystal are investigated in a broad range of temperature and magnetic elds. Far-infrared re°ection spectra were analyzed using a tting procedure based on the modi ed plasmon{two phonon interaction model. Together with the strong plasmon{two longitudinal optical phonon coupling we obtained a local mode of Ni at about 180 cm¡1. This mode intensity depends on temperature. Magnetic measurements shows that PbTe alloys doped with Ni reveals weak ferromagnetic interaction between magnetic ions

Raman spectroscopy of multiphonon emission process in Ni-doped PbTe

In this paper, we present room temperature unpolarized Raman scattering spectra of Ni doped PbTe single crystal sample. Crystal of PbTe(Ni) was grown by the Bridgman method. The Ni concentration in the sample used here was 1* 1019 at./cm3. Well resolved peaks appear at about 126, 143, 181, 362 and 724 cm-1. The modes at 126 and 143 cm-1, which are also observed in other telluride compounds, originate from vibrations in TeO2. We assume that the mode at about 181 cm-1 is connected to excitations of a local phonon mode in the vicinity of an impurity atom (donor Ni3+ state). Modes at about 362 cm-1 and 724 cm-1 are the second and fourth harmonic of a local phonon mode, registered here due to multiphonon emission

Upgrading the ECR ion source within FAMA

Recent upgrading of the Facility for Modification and Analysis of Materials with Ion Beams - FAMA, in the Laboratory of Physics of the Vinča Institute of Nuclear Sciences, included the modernization of its electron cyclotron resonance ion source. Since the old ion source was being extensively used for more than 15 years for production of multiply charged ions from gases and solid substances, its complete reconstruction was needed. The main goal was to reconstruct its plasma and injection chambers and magnetic structure, and thus intensify the production of multiply charged ions. Also, it was decided to refurbish its major subsystems - the vacuum system, the microwave system, the gas inlet system, the solid substance inlet system, and the control system. All these improvements have resulted in a substantial increase of ion beam currents, especially in the case of high charge states, with the operation of the ion source proven to be stable and reproducible. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45006

Structural and electrochemical properties of carbon ion beam irradiated 12-tungstophosphoric acid

In recent years polyoxometalates (POMs) have attracted significant research interest due to versatile properties. These properties are determined by the size, structure and elemental composition of POMs and hence play an important role in their application. In the present study, the ion beam irradiation (10 keV C+ ions, 5 × 1014–2.5 × 1015 ions/cm2) has been utilized for modification of physicochemical properties of 120 nm-thick layer of 12-tungstophosphoric acid (WPA). Scanning electron microscopy analysis of irradiated films showed change of morphology i.e. an increase of WPA grain size with irradiation and coalescence of grains at the highest fluence. This was accompanied by structural changes. Attenuated total reflectance Fourier transform infrared analysis revealed that vibration bands of Keggin anion became less pronounced as fluence increased, while Raman spectra appeared as strongly modified. The effect of irradiation with 1.25 × 1015 ions/cm2 on the structure of WPA was similar to the effect of thermal treatment at 600 °C. Irradiation of WPA led to decrease of the band gap (from 4.07 to 3.92 eV), which was correlated to transformation Keggin anions into a network of WO6 octahedra and PO4 tetrahedra. This is in line with increased number of W=Od bonds observed by UV–Visible diffuse reflectance spectroscopy. Beside transformation to bronzes a reduction of WPA was observed by X-ray Photoelectron Spectroscopy (shift to lower binding energy) and Raman methods, whereas the Raman spectra of irradiated samples were similar to heteropoly blue. The electrochemical properties of irradiated WPA were also assessed. Cyclic voltammetry measurements showed that at up to 1.25 × 1015 ions/cm2 lithiation capacity of WPA increases and activity for hydrogen evolution reaction (HER) improves. The highest fluence caused interconnection of WO6 octahedra, closing of lithiation pathways and decrease in the number of active sites for HER. Our results provide a novel insight into the effects of ion beam irradiation on WPA and demonstrate high potential for tuning of physicochemical properties of POMs that are relevant in wide range of applications. © 2021 Elsevier Lt