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Slow positron beam and optical absorption measurements are carried out to study structural defects and positronium formation in 40 keV B(+)-implanted polymethylmethacrylate (B:PMMA) with ion doses from 6.25 × 10(14) to 5.0 × 10(16) ions/cm(2). Detailed depth-selective information on defects in implanted samples was obtained by measuring of Doppler broadening of positron annihilation γ rays as a function of incident positron energy and these experimental results were compared with SRIM (stopping and range of ions in matter) simulation results. Two general processes, appearance of free radicals at lower ion doses (10(16) ions/cm(2)) and carbonization at higher ion doses (10(16) ions/cm(2)), are considered from the Doppler S-E and W-E dependences in the framework of the concept of defects formation during radiation damage of polymer structure. Probabilities of ortho-positronium (o-Ps) formation are analyzed using S-W plot and slow positron annihilation lifetime measurements. Dose dependence of o-Ps lifetime τ3 and intensity I3 at the incident positron energy of 2.15 keV correlates well with the dose dependence of S-parameter and seems to account for the existence of the expected two processes, i.e., scission of polymer chains and appearance of free radicals preceding the aggregation of the clusters resulting in the formation of network of conjugated bonds at lower ion doses and carbonization at higher ion doses. The increase of optical absorption observed with increasing ion implantation dose also suggests a formation of carbonaceous phase in the ion-irradiated PMMA.

Unirradiated and γ-irradiated (average energy E = 1.25 MeV and dose Φ = 2.41 MGy) chalcogenide glassy semiconductors (CGSs) As2S3 and Ge15.8As21S63.2 are studied by positron annihilation lifetime spectroscopy (PALS) and Doppler broadening of the 0.511-MeV annihilation line (DBAL). Two 22Na positron sources with activities of 0.6 and 2.0 MBq and Kapton film thicknesses of 8.0 and 25.0 μm, respectively, are used. It is shown that radiation-induced changes in the PALS parameters of the CGS types under study are within measurement errors. The DBAL method appeared more efficient and accurate for studying radiation-stimulated processes in CGSs.

The femtosecond Z-scan measurements with open-aperture of nonlinear absorption of the R2O-B2O3-SiO2 (R = Li, Na, K) polarizing oxide glass containing Ag nanorods at polarizing angle Θ = 0 and 90 degrees are performed and compared with the earlier Z-scan data obtained for the chalcogenide glasses with Cu nanoparticles (Cu:As2S3 and Cu:Ge15.8As21S63.2). The results of the present study reveal that (i) when the polarization of the laser is parallel to the long axis of the Ag nanorods (Θ=0 degrees), the saturated nonlinear absorption takes place; and (ii) when the polarization of light is perpendicular to the long axis of the Ag nanorods (Θ=90 degrees), the saturated nonlinear absorption and two-photon nonlinear absorption are observed likely to Cu:chalcogenide glasses. Ellipsometric measurements show also a dependence of the properties of the investigated polarizing glass on the sample orientation in consistence with Ag nanorod locations.

Substrates of chalcogenide glassy semiconductors As2S3 and Ge15.8As21S63.2 are implanted with Cu+ ions (energy 40 keV, radiation dose 1.5 × 1017 ion/cm2, fixed current density in the ion beam 1 μA/cm2). The composite layers are analyzed by measuring linear optical transmittance and recording nonlinear optical absorption using the Z-scan technique at 780 nm (probe laser radiation with 150-fs pulses; intensity of 25–100 mW). It is ascertained for the irradiated materials that (1) the linear transmission characteristic of the optical surface plasmon resonance (SPR) band, which indicates the formation of copper nanoparticles in the near-surface region, has emerged and (2) there are simultaneously saturated and two-photon nonlinear absorption types; the latter prevails as the intensity of laser irradiation is increased.

The micro-/nanoscopic structure of the hybrid organic-inorganic materials, based on polyether chains covalently linked to a silica framework through urea bridges, referred as ureasilicates or ureasils, and As2S3-ureasil composites with ion-implanted Ag nanoparticles is investigated. The formation of Ag nanoparticles is confirmed using optical transmission (surface plasmon resonance band of Ag nanoparticles) at ion-implantation doses of 2.5×1016 and 5.0×1016 ion/cm2 on the example of ureasil. It is established with scanning electron microscopy that incorporation of the As2S3 clusters into ureasil assists to ion-synthesis of Ag nanoparticles in polymer matrix, more effectively at higher doses of ion-implantation and for silver containing (As2S3)95Ag5-ureasil composite. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The original experimental results on the study of structural modification of chalcogenide glasses by 60Co γ-irradiation with energy of 1.25 MeV and dose of 2.41 MGy for As2S3, Ge15.8As21S63.2, Ge9.5As28.6S61.9 and Ge23.5As11.8S64.7alloys using Doppler broadening of annihilation line (DBAL) technique are reported. The γ-irradiation-induced effect is analyzed in terms of Doppler S and W annihilation parameters. In particular, the observed different slope of S -W plots for glassy (g-) As2S3 and g-Ge15.8As21S63.2studied in the unirradiated and γ-irradiated states indicates that the defect structure of these alloys in the radiation-modified state is different, obviously, as a result of various mechanisms of radiation-induced defect formation. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A technology of intercalation of layered AIIIBVI single crystals by elements of the Fe 3d group during their growth has been developed. The X-ray structural and X-ray phase analyses of the thus-obtained Ni x InSe samples confirmed their homogeneity and showed a nonmonotonic dependence of the InSe lattice parameter along the anisotropy axis on the incorporated Ni concentration. The dependence of the magnetic susceptibility on magnetic field, χ(H), has been studied by the Faraday method, and a nonmonotonic change in χ with an increase in the incorporated nickel concentration has been revealed for Ni x InSe crystals. This nonmonotonicity can be qualitatively explained within a modification of the Anderson model for layered crystals, which takes into account the main specific features of layered crystals and the intercalation mechanism.

The impact of proton irradiation and high magnetic field on the electroconductivity and magnetoresistance of Si1-xGex (õ = 0,03) whiskers with resistance of ρ = 0,008–0,025 Ohm∙cm in the temperature range of 4,2–300 Ê.is studied. It is fount a decreasing of resistance of the crystals in the temperature range of 4,2–40 Ê upon radiation with low dose of protons and a significant increasing of resistance in the whole temperature range examined at the irradiation dose of 1∙1017 ð+/cm2 . The interpretation of the observed changes in the physical parameters of the whiskers is proposed., Вивчено вплив протонного опромінення та сильних магнітних полів на електропровідність та магнітоопір ниткоподібних кристалів (НК) Si1-xGex (х = 0,03) з питомим опором ρ = 0,008–0,025 Ом∙см в інтервалі температур 4,2–300 К. Виявлено зменшення опору кристалів у температурній області 4,2–40 К в процесі опромінення малими дозами протонів та істотне збільшення опору у всій дослідженій температурній області при опроміненні дозою 1∙1017 р+/см2. Запропоновано інтерпретацію виявлених змін фізичних параметрів ниткоподібних кристалів., Изучено влияние протонного облучения и сильных магнитных полей на электропроводимость и магнитосопротивление нитевидных кристаллов (НК) Si1-xGex (х = 0,03) с удельным сопротивлением ρ = 0,008–0,025 Ом∙см в интервале температур 4,2– 300 К. Обнаружено уменьшение сопротивления кристаллов в температурной области 4,2– 40 К в процессе облучения малыми дозами протонов и существенное увеличение сопротивления во всей исследуемой температурной области при облучении дозой 1∙1017 р+/см2. Предложено интерпретацию обнаруженных изменений физических параметров нитевидных кристаллов.

The magnetic susceptibilities of Si and Si0.95Ge0.05 alloy whiskers of different diameters have been studied. Its significant difference from the magnetic susceptibility of a bulk material has been found. The presence of paramagnetic centers, some of which form magnetic nanoclusters in samples, is assumed. To explain the experimental results obtained, a model within Langevin superparamagnetism has been suggested. The distribution function of clusters over their magnetic moments has been constructed. The most probable sizes and magnetic moments of clusters are determined.

The magnetic, electric, and magnetoresistive properties of bulk samples of La1−xNaxMnO3±δ (x=0.08–0.16) are studied. It is shown that at low temperatures all samples are ferromagnetic and the temperature of the transition from the paramagnetic into the ferromagnetic state increases with increasing sodium content. It is found that the saturation magnetization reaches its maximum value, close to that computed theoretically, in samples with x=0.12. A deviation of x from 0.12 decreases the saturation magnetization and broadens the magnetic transition. Analysis of the behavior of the magnetoresistance shows that there exists, together with the ferromagnetic conducting phase, a disordered weakly conducting phase, the volume fraction of the latter increasing as x deviates away from 0.12. The characteristic behavior of the magnetic and magnetoresistive properties of La1−xNaxMnO3±δ samples are tied to the particulars of the evolution of the chemical composition and defectiveness of the samples as a function of the...

The principal circuit of a helium ionization detector with a thermionic electron emitter (He-IDTEE) is described. The detector works at atmospheric pressure. The characteristics of the detector were studied. The difference between the voltammetric characteristics of He-IDTEE and that of a helium ionization detector with a radioactive source was shown. The dependences of the analytical signal, background signal, and noise on an accelerating voltage were analyzed. The dependences of the signal-to-noise ratio on the accelerating voltage were studied at different cathode temperatures. The optimal working conditions of the detector were selected. The detection threshold and linear dynamic range were measured. For isobutane, they were 3 × 10−9 vol % and 2–4 orders of magnitude, respectively.

Solid solutions in the Tm-Ge-Si system have been studied by X-ray diffraction data and magnetic susceptibility (MS) techniques. It was found that the crystal structure of the alloys corre sponds to the hexagonal type AlB2 , in which tri-capped trigonal prism coordination is observed for the small atoms (Si, Ge). The results of MS measurements as a function of temperature (80-800 K) and magnetic field (0.5-4.0 kOe) show the existence of a field-independent paramagnetic component well described by the Curie-Weiss law. The magnetic characteristics of the materials (Weiss parameter, effective magnetic moment per formula unit and Curie constant) were also determined.

The nature of paramagnetic centers formed in Cz-Si monocrystals after their high-temperature treatment in the temperature range of 650–1100 °C and repeated high-temperature treatment at 1150 °C are studied. The regions of increase and decrease of paramagnetic center concentration are determined by means of the measurements of magnetic susceptibility (MS). It is found that the MS changes observed experimentally are attributed to the generation of oxygen-related clusters and dislocation loops. The amount of impurity-structural complexes in these crystals is investigated by the XRD method. The radii and concentration of clusters and dislocation loops are determined. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Critical comments of Shpotyuk et al. [O. Shpotyuk, J. Filipecki, M. Hyla, A. Ingram, Solid State Ionics 208 (2012) 1] are shown to be inconsistent with the experimental results obtained for a size of free-volume defects in ion-conducting Ag/AgI–As 2 S 3 glasses in view of a new formula for positron lifetime τ 2 versus radius of voids R for R 3 can be effective positron traps with more prolonged lifetimes of τ 2 = 0.35–0.38 ns is at least inconclusive in terms of a new approach. The experimental results and schematic model reported by Kavetskyy et al. [T. Kavetskyy, J. Borc, P. Petkov, K. Kolev, T. Petkova, Solid State Ionics 183 (2011) 16] are a direct evidence of validity of a newly modified equation for τ 2 - R correlation in the case of inorganic polymeric chalcogenide glasses without orthopositronium component in positron annihilation lifetime spectroscopy.

Magnetic measurements and resonance measurements have been carried out on ultrathin (20 nm) films of sodium-doped lanthanum manganite fabricated by magnetron sputtering on single crystalline LaAlO3 (001) substrates. Complex behavior of magnetization and magnetic anisotropy has been revealed. It is shown that an out-of-plane alignment of the film magnetization is characteristic of the films at low temperatures. As temperature increases, a spin-reorientation transition occurs at about 160 K and in-plane alignment of magnetization becomes more preferable. Further increase in temperature results in an isotropic behavior of magnetization as temperature approaches and crosses the Curie point (≈270 K). It is concluded that anisotropy energy, originated from a substrate-induced compressive strain, is responsible for the unusual behavior of the ultrathin films of sodium-doped manganites. Es wurden magnetische Messungen und Resonanzmessungen von ultradunnen Filmen der Natrium-dotierten Lanthanmanganiten, die mittels Magnetron-Sputtertechnik auf einkristallinem LaAlO3 (001) hergestellt wurden, durchgefuhrt. Es wurde ein komplexes Verhalten der Magnetisierung und der magnetischen Anisotropie entdeckt. Es wurde gezeigt, dass die out-of-plane Anordnung der Magnetisierung bei tiefen Temperaturen charakteristisch fur die Filme ist. Bei Temperaturanstieg findet die Spin-Reorientierung bei ca. 160 K statt, und es wird eine in-plane Ausrichtung der Magnetisierung beobachtet. Die weitere Temperaturerhohung fuhrt zum isotropischen Verhalten der Magnetisierung, wenn sich die Temperatur der Curie-Temperatur (≈270 K) nahert und diese uberschreitet. Es wird daraus geschlossen, dass die Anisotropie-Energie, die aus der Substrat-induzierten Druckspannung resultiert, fur das ungewohnliche Verhalten ultradunner Natrium-dotierter Filme verantwortlich ist.

The electrical properties, magnetic susceptibilities, and low-temperature photoluminescence spectra of semi-insulating CdTe{Cl} single crystals grown from the melt in graphitized and nongraphitized quartz ampules were compared. The crystals contaminated with carbon were found to be inhomogeneous and contain carbon-related deep centers affecting their detector performance. The possible mechanisms of compensation and defect complexing were discussed.

The effect of radiation defects on the field and temperature dependences of the magnetic susceptibility of single-crystal Si was studied. A nonlinear magnetic-field-dependence of the magnetic susceptibility of irradiated Si was observed. This behavior can be explained by magnetic ordering of A centers. It was concluded that clusters of these centers with a local density of the order of 1021 cm−3 exist. An explanation of the “diffusion paradox” in the formation of oxygen-containing thermal donors was proposed on the basis of micrononuniformities of the spatial distribution of thermal donors and interstitial oxygen in Si.

The present work aims to study magnetic, electric, magnetoresistance and resonance properties of partially crystallized La 0.84 Na 0.16 MnO 3 thin films. Peculiar behavior resulting from the wide-range coexistence of highly conductive ferromagnetic and weakly conductive paramagnetic phases has been analyzed. Based on the results of magnetic measurements and theoretical calculations, the dependence of the volume fraction of ferromagnetic phase, V FM , on temperature is calculated. The V FM values whereby electric resistance and magnetoresistance display maxima are determined.

Ces sources incontrolees jouent un role negligeable dans la formation de defauts de radiation par rapport aux principales impuretes technologiques dans le silicium commercial tres pur. Ces sources peuvent surtout affecter la formation de defauts de radiation a travers l'annihilation indirecte des composantes des paires de Frenkel

Institute of Physics, Ukrainian National Academy of Sciences, 252650 Kiev, Ukraine Fiz. Tekh. Poluprovodn. 32, 8, 1026 ~August 1998! @S1063-7826~98!02308-4# © 1998 American Institute of Physics. A major correction was reported by the Semiconductors Editorial office in St. Petersburg. Specifically, the title was incorrect. The correct title should read: Magnetic ordering of radiation defects in silicon.

This study exaines CdS single crystals subjected to a special nonalloying treatment, alloyed with copper, and annealed in a cadmium atmosphere. Irradiation of the test specimens by electrons with E ≈ 1.2 MeV led to the formation of mobile defects and to decomposition of the original donor-acceptor associates. Over time, the primary radiation defects form secondary defects which act as fast recombination centers responsible for impurity photoconductivity. New donor-acceptor pairs are formed when the irradiated specimens are stored, these pairs being paramagnetic centers. Conclusions are made as to the nature of the secondary radiation defects, which are distributed both in the body of the specimens and near their surface.

A study was made of the magnetic susceptibility, Hall effect, and conductivity from 4.2 to 290°K on CdxHg1−xTe crystals prepared by the Bridgman technique and annealed in mercury vapour. The electron and hole concentrations at liquid helium temperature did not exceed 1.5 × 1016 and 3.3 × 1015 cm−3, respectively. Experimental curves relating susceptibility and Hall coefficient to temperature and composition x are presented. An analysis shows the susceptibility of the alloys studied to be a sum of three principal terms associated with the lattice, complex lattice defects, and electronic gas. The diamagnetic susceptibility of the crystal lattice decreases linearly as mercury atoms in the alloy are substituted by cadmium atoms. The paramagnetic susceptibility component due to the polarization paramagnetism of complex lattice defects varies non-monotonically with composition. The susceptibility of the electron gas experiences an abrupt rise at the semimetal-semiconductor transition point with a reversal of the susceptibility sign. Es wurde die magnetische Suszeptibilitat, der Hall-Effekt und die Leitfahigkeit im Temperaturbereich von 4,2 bis 290°K von CdxHg1−xTe untersucht, das nach der Bridgman-Methode hergestellt und in Quecksilberdampf getempert wurde. Die Elektronen- und Locherkonzentrationen sind bei der Temperatur des flussigen Heliums nicht groser als 1.5 × 1016 bzw, 3.3 × 1015 cm−3. Es werden experimentelle Kurven der Suszeptibilitat und des Hall-Koeffizienten als Funktion der Temperatur und der Zusammensetzung x angegeben. Eine Analyse zeigt, das sich die Suszeptibilitat der untersuchten Legierungen aus drei Termen zusammensetzt, die mit dem Gitter, komplexen Gitterdefekten und dem Elektronengas zusammenhangen. Die diamagnetische Suszeptibilitat des Kristallgitters vermindert sich liner in dem Mase, wie die Quecksilberatome in der Legierung durch Kadmiumatome substituiert werden. Die von der paramagnetischen Polarisation der komplexen Gitter-defekte herruhrende paramagnetische Suszeptibilitatskomponente andert sich nicht-monoton mit der Zusammensetzung. Die Suszeptibilitat des Elektronengases zeigt einen abrupten Anstieg beim Halbmetall–Halbleiter-Ubergangspunkt mit einer Umkehr des Vorzeichens der Suszeptibilitat.

Magnetic susceptibility of n- and p-type CdTe was measured from 4.2 to 290°K. The o bserved susceptibility consists of the diamagnetic susceptibility of the lattice and the param agnetic susceptibility of defects. The paramagnetic component is temperature independent and reaches 10% of the measured value. On the basis of the results obtained on crystals grown under different conditions and subjected to different thermal treatment, the conclusion is drawn that the observed paramagnetism is the Van-Vleck paramagnetism of donor–acceptor complexes. [Russian Text Ignored]

Methods of growing Si whiskers are considered and the results of studying their magnetic susceptibility χ are reported. Silicon whiskers are grown using the method of chemical transport reactions in a closed bromide system. The crystals studied were divided into four groups: (i) crystals 0.1–0.9 μm in diameter, (ii) twinned crystals 1–2 μm in diameter, (iii) needle-like crystals from 5 to 1500 μm in diameter, and (iv) isometric crystals (the latter were not measured). With an increase in diameter, the whiskers of the first group changed their state from paramagnetic to diamagnetic, while the crystals of the third group showed a transition from a diamagnetic to a paramagnetic state. All these crystals show a nonlinear dependence of χ on the strength of an external magnetic field H; the nonlinearity increases with increasing the sample paramagnetism. The susceptibility of twinned samples is diamagnetic and close to the value of χ for bulk silicon, and the nonlinearity of the dependence χ (H) is insignificant. The measured values of χ of Si whiskers are explained by features of their crystal structure and chemical composition.

Temperature dependent positron annihilation lifetime spectroscopy (PALS) measurements in the range of 50–300 K are carried out to study positronium formation in 40 KeV B+-ion implanted polymethylmethacrylate (B:PMMA) with two ion doses of 3.13 × 1015 and 3.75 × 1016 ions/cm2. The investigated samples show the various temperature trends of ortho-positronium (o-Ps) lifetime τ3 and intensity I3 in PMMA before and after ion implantation. Two transitions in the vicinity of ∼150 and ∼250 K, ascribed to γ and β transitions, respectively, are observed in the PMMA and B:PMMA samples in consistent with reference data for pristine sample. The obtained results are compared with room temperature PALS study of PMMA with different molecular weight (Mw) which known from literature. It is found that B+-ion implantation leads to decreasing Mw in PMMA at lower ion dose. At higher ion dose the local destruction of polymeric structure follows to broadening of lifetime distribution (hole size distribution).

Three methods are given to reduce the vibrational energy that causes cracking in machines: strength of materials may be increased, resonance phenomena may be eliminated, or vibration may be absorbed by use of polymerics. All three methods have limitations, increasing cost and complexity. The use of additive alloys having a high ability to absorb vibration is recommended. These alloys convert vibrational energy into thermal energy, increasing the effectiveness of the damping process, and creating higher crack resistance. Soft magnetics and alloys with high dislocation densities are recommended.