The effect of electron irradiation on electrophysical properties of CdS,CdSe and ZnTe thin films

The effect of electron irradiation on electrophysical properties of CdS, CdSe and ZnTe thin films and CdS-PbTe and CdS-Te heterojunctions were studied. It was found that the effect of irradiation on thin films and devices strongly depend on the electron-irradiation doses and the preparation conditions.     

Nanostructure formation on metal-chalcogenide surface using electron beam irradiation

In this letter, we demonstrate a method to form a nano-structured pattern on metal-chalcogenide sandwich like structures, using electron beam (EB) irradiation. After pointing EB at surface, we observed nano-dots and nano-lines formation on metal-chalcogenide (AgS, AgSe, CuS, CuSe) surface, considerably made of Ag or Cu, depending on metal in compound (Ag or Cu). This technique is based on the solid-state electrochemical reaction between EB and surface. Our results demonstrate repeatable metal structures with dimension of nanometers. As this process is carried out with scanning electron microscope (SEM) and does not require wet chemicals, it has potential for use as a simple metal patterning technique to fabricate functional structures and devices.     

The effect of electron irradiation on the luminescence of cadmium and lead tungstates

It is shown that the intensity of luminescence of cadmium tungstate crystals changes nonmonotonically under electron irradiation. At low irradiation doses, an increase in the luminescence intensity can be observed. However, with an increase in the irradiation dose, the luminescence intensity decreases. The effect observed can be explained by the competition of two processes: increase in the number of luminescence centers and nonradiative recombination under the action of irradiation.     

Synthesis and properties of Fe/Ni nanotubes

Fe/Ni nanotubes were formed in pores of polyethylenterephtalate-based template matrices by electrochemical deposition. The inner diameter, wall height, and thickness of the nanostructures, as well as the elemental and phase compositions, can be controlled by varying the deposition conditions. The volume deposition rate constants have been determined for each potential difference, due to which the nanostructure growth could be controlled. An X-ray diffraction analysis of the samples obtained at a potential difference of 1-1.6 V has revealed their composition to correspond to the substitutional solid solution, with an iron atom replaced by a nickel atom and dominance of the bcc a-Fe phase. The samples obtained at a potential difference of 1.8–2 V contain the bcc a-Fe phase and fcc Ni phase; the fcc phase dominates in the sample obtained at a potential difference of 2 V, which can be related to the high Ni content in nanotubes.     

Influence of X-ray irradiation on the optical properties of chromium-doped KliSO4 crystals

The absorption and circular-dichroism spectra of chromium-activated KLiSO₄ crystals both nonirradiated and irradiated with an X-ray beam have been studied. It was established that in nonirradiated crystals chromium ions are mainly trivalent (Cr³⁺) and have octahedral coordination. In irradiated crystals, along with the centers provided by (Cr³⁺) ions, new centers are formed associated with (^Cr4+) and (^Cr5+) ions.     

Structural and physical properties of cobalt nanocluster composite glasses

Composite systems with metallic nanoparticles embedded in dielectrics present peculiar physical properties which are attractive in several application fields. In the case of transition elements, the magnetic properties of the metal clusters embedded in a dielectric matrix mainly depend on the particle size and structure. In this work, silica films containing cobalt atoms were synthesized by RF magnetron co-sputtering deposition technique, with cobalt concentration of a few atomic percent. X-ray diffraction and transmission electron microscopy showed the presence of hcp cobalt nanoclusters in the as-deposited sample with the highest cobalt concentration. After deposition, thermal treatments were performed to promote cobalt compounds or nanoparticle formation. The thermal treatments were able to change the oxidation state of cobalt atoms, as well as the structure of metallic cobalt nanoclusters (from hcp to fcc), their final size depending on both the preparation parameters and the subsequent annealing atmospheres.     

Effect of electron interactions on the electronic properties of random dimer systems

We have studied the electronic wave propagation through a one-dimensional random dimer system in the presence of non-linear interactions. By investigating the scaling dependence of the extended states bandwidth, the non-linear interaction is found to improve the electronic conduction in such systems. It is also found that the resonance energy states in these systems are shifted depending on the kind of interaction. Further investigations are provided on the localization transition around these resonances.     

XPS and nuclear analysis of compositional changes occurring in glass on electron beam irradiation

X-ray photoelectron spectrometry and nuclear microanalysis have been utilized to study the compositional changes occurring in a commercial soda-lime-silica glass after electron beam irradiation. Samples were irradiated with electron energies between 2.5 and 4.5 keV and current densities of 1.2 and 4.0 μA/cm².After electron bombardment a reduction in the Na and O surface concentration appears. Na has been observed to migrate towards the inside of the sample. It accumulates at depths comparable to the maximum electron ranges. The accumulation rate has been observed to depend on the beam power.For a beam energy of 4.5 keV the amount of Na accumulated at depth is nearly twice its surface depletion, supporting the hypothesis that the irradiation influences the glass composition at depths greater than the maximum electron ranges.     

Effect of proton irradiation on electrical properties of a-As2S3

This paper reports the effect of proton irradiation on the electrical properties of a-As₂S₃ in the temperature range of 323–418 K and frequency range 0.1–100 kHz. The variation of transport property is studied with proton irradiation dose (1 × 10¹³ ions/cm² and 1 × 10¹⁵ ions/cm²). It has been observed that proton irradiation changes the dc conductivity (σ_dc), dc activation energy (ΔE_dc) and ac conductivity (σ_ac(ω)). The σ_dc and σ_ac(ω) increases with dose of proton irradiation. The value of frequency exponent (s) decreases with the temperature and irradiation dose. These results are explained in terms of change in density of defect states in these glasses.     

Structural properties of the tungsten-lead-borate glasses before and after laser irradiation

Glasses in the xWO₃·(100 − x)[3B₂O₃·PbO] system, where 0 ≤ x ≤ 40 mol%, are obtained by conventional melting-quenching method and characterized using X-ray diffraction, FTIR spectroscopy and DFT calculations. These tungsten-lead-borate systems exhibit a photochromic effect which can be induced through laser exposures (λ = 633 nm) directly on the bulk sample. Structural investigations show that the photosensitive effect are due to a reduction of W^+ 6 to W^+ 5 and/or W^+ 4 promoted by the oxidation of Pb^+ 4 and some structural changes of the borate network. DFT calculations show higher thermodynamic stability of the [W₂O₇] and [WO₄] polyhedrons comparative with the [WO₆] polyhedron.     

Changes in surface morphology of silicate glass induced by fast electron irradiation

Binary potassium-silicate glass was irradiated with a defocused electron beam. During the irradiation the alkali ions migrate from the surface into the depth and alkali ions depleted layer is created near the surface. Such changes in the chemical composition are also accompanied with changes of the glass structure and finally result in the volume changes of the irradiated glass. This was directly studied using atomic force microscope (AFM). A series of exposures with energy of electrons of 7–50 keV and with different doses were performed. For low doses the irradiated glass is continuously depressed with the increasing dose, indicating this way the structural changes leading to the volume compaction. It is suggested the compaction is caused by the relaxation processes of the silica subnetwork. A further increase of the electron dose causes a formation of the small bump inside the center of the depression. The bump arises with the dose and finally exceeds the surrounding surface. It is suggested that the expansion is connected with the migration of alkali ions and the formation of Si–O–O–Si bonds which result in the formation of new rings with new space requirements.     

Low temperature electron irradiation of amorphous and crystalline FeB alloys

Three amorphous FeB based alloys and crystalline Fe₃B alloy were irradiated at a temperature of 21 K with 2.5 MeV electrons. The irradiation induced increase of electrical resistivity (Δ?) was measured during irradiation. the damage produced was analysed with the conventional production curve $\text{Δ}\text{dot}\text{?}\text{=}\text{d}\text{(Δ?)/}\text{d}\text{(?t)}$ versus Δ? where ?t is the electron dose. After irradiation, isochronal annealings were performed up to room temperature. The behaviour of the four alloys was found to be similar both during irradiation and annealing.For all the alloys: the production curve is linear at high doses; and the induced increase of electrical resistivity Δ? anneals out at low temperature following different stages. These results are interpreted in terms of the creation of well defined defects.These defects have the same nature in amorphous and crystalline alloys; i.e. probably of vacancy type.     

Electroactive influence of ferroelectric nanofillers on polyamide 11 matrix properties

Barium titanate ceramic powders have been incorporated in polyamide 11 to form homogeneous dispersion of particles in the matrix. Barium titanate/polyamide 11 nanocomposites have been synthesized using a solvent casting method with ultrasonic stirring to homogeneously disperse inclusions in the matrix. Composites with volume fraction of barium titanate ϕ ranging from 0.01 to 0.4 were elaborated. Films were fabricated using a hot press method. Only the inclusions were poled in the matrix to form a ferroelectric particles/unpoled matrix composite. Interactions between the particles and the matrix, pyroelectric and piezoelectric response were studied as a function of ϕ by dynamic dielectric spectroscopy. Composites show interesting pyro-piezoelectric activity. Pyroelectric merit factor increases linearly and it reaches a limit value of 0.3 for a volume fraction ϕ = 0.1.     

Influence of impurities,irradiation and temperature on the mechanical and electrical properties of LiF crystals

On the basis of study of the temperature dependence of mechanical and electrical properties of LiF crystals with different impurities an evident interaction between radiation defects and impurities is revealed. As a result of trapping of radiation defects (F- and H-aggregate colour centres) by impurity centres the reconstruction of impurity centres takes place, causing a change of mechanical and electrical properties.     

Effect of generated defects during plastic deformation on electron properties of silicon

Conductivity, photoconductivity and SDP of n-type silicon deformed and annealed under different thermal conditions were investigated. The conductivity was found to be dependent on the temperature of deformation and additional annealing. Recombination in deformed samples is fully controlled by paramagnetic centers localized within the charge space region around the dislocations.     

MeV electron irradiation induced crystallization in metallic glasses: Atomic structure,crystallization mechanism and stability of an amorphous phase under the irradiation

MeV electron irradiation via high voltage electron microscopy can lead to amorphous-to-crystal transition (i.e., crystallization) as well as crystal-to-amorphous transition (i.e., solid-state amorphization). Irradiation-induced crystallization can be observed in various alloy systems such as Co-, Fe-, Ni-, Pd-, and Zr-based metallic glasses, indicating that this phenomenon has wide generality in metallic materials. Irradiation-induced crystallization mechanism was discussed based on the following factors; (1) an increase in free energy for an amorphous phase, (2) the formation of crystalline clusters through modification of the atomic configuration near radiation induced defects, and (3) enhanced diffusion. The stability of an amorphous phase against irradiation-induced crystallization can be estimated from the thermal crystallization temperature (T_x), and Ni–Nb based metallic glasses have a tendency for high stability against irradiation because of high T_x.     

The influence of small amounts of crystallinity on the transport properties of metallic glasses

Small amounts of crystallinity may be present in “amorphous” alloy specimens in the form of “cast-in” crystallites or partially crystallized surfaces. in this paper the possible effects of such low-level crystallinity upon the measured electrical transport properties are considered. It is found that the observed ageing effects in the transport properties of a number of amorphous alloys may be explained as due to surface crystallization driven by selective oxidation. It is further argued that for the ferromagnetic Metglasses cast-in crystallites could have a significant effect particularly upon the thermopower, and that this is probably part of the explanation of the observed discrepancies between the different measured values. It is shown that even very small levels of crystallinity can have significant effects upon the measured transport properties and the many disagreements to be found in the published values are discussed in the light of this.     

The influence of Mg substitution for Al on the properties of SiMeRE oxynitride glasses

The thermal-mechanical properties of 60Si20Mg20RE (RE: rare earth) oxynitride glasses can be tailored by the substitution of rare earths of decreasing ionic size. The Young’s modulus, hardness, glass transition temperature and viscosity all increase with the substitution La by Gd and Gd by Lu while the thermal expansion coefficients decrease. Compared to the 55Si25Al20RE oxynitride glasses, replacement of Al by Mg lowers the glass transition temperatures and viscosities and raises the thermal expansion coefficients substantially. On the other hand, the Young’s moduli are higher in the Mg-bearing glasses. These behaviors are seen to be a result in changes in the nature of the bonding in the glass structure.