Induced Spirals in Polyethylene Terephthalate Films Irradiated with Ar Ions with an Energy of 70 MeV

This paper presents the results of a study of the ordering in polyethylene terephthalate (PET) film induced by Ar8+ ions with an irradiation fluence of 2 × 1012 ions/cm2, and of the temporal stability of the induced ordering in the irradiated sample, over a three month period. Immediately after irradiation, sharp new reflections not seen at lower fluences were observed in X-ray diffraction patterns, with angular positions of 2 θ = 9–10° and 19° and variable azimuthal intensities. X-ray reflections, previously observed at lower fluences, were also seen: at 2 θ = 26° and 23°, associated with PET crystallites, and at 2 θ = 5–12°, associated with induced ordering in the amorphous zone. Aging of the irradiated sample led to significant growth of the ordering region in the amorphous zone for angles up to 2 θ < 15°, as well as to dissipation and blurring of the new diffraction reflections at 2 θ = 9–10° and 2 θ = 19° and the formation of a new diffraction ring reflection in the range 2 θ = 11–16°. The azimuthal distribution of diffraction reflection intensities immediately after irradiation displays a clear oblique cross located predominantly along lines at angles of π/4 with respect to the direction of the texture of the PET film, indicating the formation of spiral structures based on the molecular strands of PET. Our experimental results lead us to conclude that the formation of coherent scattering areas in the amorphous region at 2 θ < 15° is due to intra-chain rotations of benzene-carboxyl subunits of repeat units of the PET chain molecules interacting with the residual electric field of a single latent track; whereas the formation of spiral structures is due to the inter-chain interaction of these preordered asymmetric subunits under the influence of the electric fields from overlapping latent tracks.

Co-writing about co-producing musical heritage: what happens when musicians and academics work together?

This chapter examines the process of researching how to transmit musical heritage through the process of co-writing. The Transmitting Musical Heritage project team involved a number of different partners, all with particularly complex sets of skills. These interrelationships embedded between the academic institution and community partners had a strong impact on the project, its processes and its destinations. It involved varied approaches to practice and research, with the team and the co-producers, at times, occupying an amorphous zone where academics were academics, academics became musicians, musicians became academics, and musicians were also musicians. This community of practice was able to uncover tacit knowledge about playing and the process of making music together, as well as to unfold narratives about which heritage was valuable and why. This enabled a shared vocabulary of practice.

Microstructure and Chemical Composition of Fe-Cr Alloy Tempered in High Temperature and Atmosphere Containing Ar-SO2

The paper presents the microstructure, chemical and phase composition of thin scale, obtained as a result of high-temperature corrosion of X20Cr13 stainless steel. Samples were exposed to gas atmosphere of the following composition: 0.25 vol.% of SO2and 99.75 vol.% of Ar at 600 °C for 5 h. As a consequence, thin compact scale was formed on steel surface. This scale consisted of three different zones. An amorphous zone was formed close to steel surface. Then, nanocrystalline zone could be observed. Finally, larger grains were formed during the corrosion process. The analysis of the chemical composition revealed higher concentration of chromium near steel surface. In contrast, to chromium, the content of iron, increased near the scale surface. It was found out that the (Cr, Mn, Fe)5O12phase appeared in the thin scale.

A poly(vinylidene fluoride-co-hexafluoro propylene) nanohybrid membrane using swift heavy ion irradiation for fuel cell applications

Through channels in thin polymer/nanohybrid films have been made by irradiating with high energy swift heavy ions (SHI) followed by selective chemical etching of the amorphous zone in the latent track created by SHI during the bombardment.

Amorphisation and Recrystallisation of Nanometre Sized Zones in Silicon

In this paper we present a detailed study in which the formation, by heavy ion impact, and thermal recrystallisation of individual amorphous zones have been studied using in-situ transmission electron microscopy. In agreement with previous work, we observe a reduction in the total volume of amorphous material contained within the amorphous zones following thermal annealing over a wide range of temperatures. When the evolution of the individual amorphous zones is followed, those with similar starting sizes are observed to recrystallise over a range of temperatures from 70 °C to 500 °C. The temperature at which an amorphous zone fully recrystallises does not appear to be correlated with initial size. In addition, zones are occasionally observed to increase in size temporarily on some isochronal annealing steps. Furthermore, observations during a ramp anneal show that many zones recrystallise in a stepwise manner separated by periods of stability. These phenomenon are discussed in terms of the I-V pair.

Molecular-Dynamics Simulation of Displacement Cascades in Zircon (ZrSiO4)

ABSTRACTZircon (ZrSiO4) is of great interest for the nuclear industry as it is one of the new crystalline waste form considered for the disposal of actinides, for example weapons' plutonium in USA. In this study the effects of displacement cascade due to α-decay has been modelled from an atomistic point of view by molecular dynamics simulation using Born-Mayer-Huggins empirical potential. The numerical values of the parameters of this potential have been fitted on structural equilibrium properties of the crystal and on atomic arrangements.Displacement cascades are reproduced by accelerating one of the atoms of the cell, thus modelling the effect of the α-decay recoil nucleus. Kinetic energies up to 2 keV have been introduced. The unfolding of the cascades and the final structures have been studied in detail. The centre of the displacement cascade exhibits an amorphous zone where the zircon structure is completely lost. It contains an assembly of distorted SiO4 tetrahedra and disordered zirconium polyhedra. The zirconium ions (originally surrounded by 8 oxygen atoms) exhibit a decrease in their coordination number to 7 or 6 in agreement with what is observed for zirconium ions in amorphous zircon, zirconia or glasses. The size of the amorphous zone and the number of atoms displaced have been estimated for different recoil energies.The energy stored during the cascade has been calculated. It exhibits an overall good agreement with the available experimental data at complete amorphization.The existence of an amorphous track in our calculated cascades shows that the correct model for the amorphisation process should take into account the existence of a direct impact amorphous zone.

Determination of the Electron Beam-Induced Shrinkage Rates Of Isolated Amorphous Zones In Germanium

Epitaxial regrowth of isolated amorphous zones, created in Ge by implantation with 50 keV Xe+ ions, was stimulated at room temperature by using electron beams with an energy below that required to create Frenkel pairs. The process was studied by using transmission electron microscopy combined with an automatic computer image analysis program, and the regrowth was characterized by determining the shrinkage rate of the effective radius of individual zones. The effective radius decreases approximately linearly with electron dose. The regrowth rate of irregular shaped amorphous zones is fast initially and slows as the shape of the amorphous zone becomes more regular. Only one regrowth rate is found for amorphous zones with a regular shape. The regrowth rate increased with decreasing energy below the threshold displacement voltage, suggesting that electronic excitations are able to induce epitaxial growth.

Fine Structure of Sputtered Ni/Ti Multilayered Thin Films Studied by HREM

ABSTRACTNi/Ti multilayered thin films can be efficient neutron guides and are therefore of great interest in neutron optics. Ni/Ti and NiC/Ti multilayers with various layer thicknesses were fabricated by magnetron sputtering and characterized by high resolution transmission electron microscopy (TEM). The TEM studies, performed on cross-sectional specimens, revealed that both kinds of layers were textured and snowed coherence in the growth direction. The presence of a 2 nra thick amorphous zone at the Ni/Ti interface in the carbon free thin films was also confirmed. On the contrary, sharp interfaces were obtained in NiC/Ti multilayers. The fine structure of the different layers will also be reported.

Microstructural and chemical effects in Al2O3 implanted with iron at 77 K and annealed in oxidizing or reducing atmospheres

Implantation of Fe (160 keV) into α–Al2O3 at 77 K produces an amorphous surface layer for fluences in the range of 1016 to 1017 Fe/cm2. Measurements of short-range order were made by extended energy loss fine structure analysis (EXELFS). The structure of amorphous Al2O3 produced by implantation of iron at 77 K exhibits short-range order that differs from that produced by stoichiometric (Al + O) implants. This difference is manifested by changes in the Al–O near-neighbor bond length. The local environments of implanted iron were determined from conversion electron Mössbauer spectroscopy (CEMS). The iron resides in several different local environments consistent with the electronic states of Fe2+, Fe4+, and Fe0. The relative amount of each environment depends upon the concentration (fluence) of the implanted iron ions. Regrowth of the amorphous zone during annealing occurs in the sequence amorphous → γ–Al2O3 ↠ α–Al2O3. The kinetics of regrowth and phase separation vary with implanted fluence and with annealing atmosphere. The higher the concentration of implanted iron, the slower the formation of iron-aluminum oxide precipitate phases in oxidizing atmospheres and α–Fe precipitates in reducing atmospheres.