Materials Science Laboratory Research Articles

Electron cloud in accelerators

Low energy electrons in accelerators are known to interact with the circulating beam, giving rise to the formation of a so-called e-cloud. Such e-cloud may induce detrimental effects on the accelerated beam quality and stability. Those effects have been observed in most accelerators of positively charged particles. A longstanding effort has been so far devoted to understand in detail the physical origin of such e-cloud, its build-up and its interaction with the circulating beam. We will first describe the origin and the basic features causing e-cloud formation in accelerators, then we review some of the theoretical work produced to simulate and analyze such phenomenon. In selected cases, theoretical expectations and experimental observations will be compared, to address the importance of benchmarking codes versus observations to reach the required predictive capability. To this scope, codes need realistic input parameters which correctly describe material and surface properties at the basis of such e-cloud formation and build-up. The experimental efforts, performed worldwide in many surface and material science laboratories, to measure such essential parameters will then be presented and critically reviewed. Finally, we will describe some of the e-cloud mitigation strategies adopted so far and draw some conclusions.

Modelling of Al-7%wtSi-1wt%Fe Ternary Alloy: Application to Space Experiments with a Rotating Magnetic Field

Recently several experiments on directional solidification of Al-6.5wt.Si-0.93wt.%Fe (AlSi7Fe1) alloy were performed under terrestrial conditions and onboard the International Space Station (ISS) in the Materials Science Lab (MSL) with use of electromagnetic stirring and without it. Analysis of the samples showed that stirring with a rotating magnetic field lead to the accumulation of iron-rich intermetallics in the center of the sample and influenced the primary dendrite spacing while the secondary dendrite arm spacing were not affected. In the present paper the accumulation of the intermetallics b-Al5SiFe in the center of the samples due to RMF stirring is demonstrated numerically and the evolution of primary and secondary dendrite arm spacing is discussed.

Investigation on Characteristics of PVDF/ZnO Nanocomposite Films for High-k Capacitors

Aims: To investigate the dielectric and electrical properties of nanocomposite films for their application as high-k capacitors Study Design: The ferroelectric polymer PVDF is doped with ZnO nanoparticles (ZnONP) to study the dielectric properties Place and Duration of Study: Material Science laboratories at the Department of Physics, Chemistry and Mathematics at Alabama A&M University during the months from February 2013 to December 2013 Methodology: In this work, homogeneous ceramics-polymer nanocomposites consisting of zinc oxide (ZnO) nanoparticles as fillers and poly (vinylidene fluoride) (PVDF) polymer as matrix have been prepared using a solution casting process. The temperature dependency of the dielectric permittivity of the nanocomposite films suggests that the introduced ZnO phase and interface areas contribute to the improvement of the dielectric response. Results: In comparison with pure PVDF film, dielectric permittivity of the nanocomposite with a small amount of filler volume fraction (8.6%) significantly improved by two times. Thus, it can be predictedwith higher concentrations of ZnO nanoparticles, composite films will have higher dielectric constants and warrants in applications as high-k capacitors for printed organic electronics. Review Article Physical Science International Journal, 4(5): 734-741, 2014 735 Conclusion: The nanocomposites thick films by embedding ZnO-NPs in PVDF matrix have been successfully fabricated. The nanocomposite displayed better dielectric properties than the pristine PVDF specimens did. As expected, the effective dielectric constant of PVDF increased when it was mixed with ZnO-NPs over the entire temperature range investigated. However, as the concentration of ZnO-NPs increased, the dielectric constant for the PVDF/ZnO-NPs nanocomposite doubled over that of pure PVDF. It can be concluded nanocomposites fabricated with higher concentration of ZnO-NPs have a potential to meet both present and future technological demands of high-k dielectrics and embedded capacitors/organic substrates.

Catalytic Reduction of Hexavalent Chromium Using Palladium Nanoparticles: An Undergraduate Nanotechnology Laboratory

Nanotechnology, the science and art of manipulating matter at the atomic and molecular level, is increasingly playing an important role in the undergraduate curriculum, but there are few laboratory exercises that emphasize the connection between fundamental nanoscience and larger societal issues with practical applications. A laboratory experiment is described in which students synthesized palladium nanoparticles (PdNPs) and utilized the particles for catalytic reduction of Cr(VI) to Cr(III) in the presence of formic acid. This experiment requires two 3-h laboratory periods and can be adapted for upper-division undergraduate students in instrumental analysis, materials science, or physical chemistry laboratories. During the first laboratory period, students synthesized and characterized PdNPs using TEM and UV–vis spectroscopy. During the second lab period, they utilized the nanoparticles for the catalytic reduction of Cr(VI) to Cr(III) using environmental NIST standard reference soil matrices. Students (98%) successfully prepared the black palladium nanoparticles within the first 3-h period. The students’ results yielded 93.30 ± 4.11% conversion of Cr(VI) to Cr(III) using PdNPs and formic acid, compared to <15% when formic acid was used alone. This experiment introduces students to the practical applications of nanotechnology while reinforcing basic chemical principles and instrumental techniques.

Twenty-five years of ultrafine-grained materials: Achieving exceptional properties through grain refinement

Twenty-five years ago, in 1988, there appeared a classic description of the application of severe plastic deformation (SPD) to bulk solids in order to achieve exceptional grain refinement to the submicrometer level. This report and later publications initiated considerable interest in materials science laboratories around the world and many experiments were subsequently performed to evaluate the principles and practice of SPD processing. The present report provides an overview of the more recent developments in this field, with special emphasis on the opportunities for achieving homogeneity in the as-processed materials and on the general characteristics of the mechanical properties achieved after SPD processing. For simplicity, special emphasis is placed on the two techniques of equal-channel angular pressing and high-pressure torsion as these are currently the most popular procedures for applying SPD processing.

An Advanced Experiment for Studying Electron Transfer and Charge Storage on Surfaces Modified with Metallic Complexes

Data-storage devices can be fabricated by modifying different surfaces with metallic complexes. The required time to write information and the time that information remains is crucial for the performance of the electronic device. We illustrate this technological application of molecules by adsorbing a polyoxometalate on graphite and characterization by ac voltammetry and open circuit potential amperometry. A charge-transfer constant from the surface to the electrode of 118 s–1 and a charge-storage half-life of 42 s were calculated by these methodologies. This laboratory can be easily performed and adapted in any advanced electrochemistry or materials science laboratory.

Status of the Linac based positron source at Saclay

Low energy positron beams are of major interest for fundamental science and materials science. IRFU has developed and built a slow positron source based on a compact, low energy (4.3 MeV) electron linac. The linac-based source will provide positrons for a magnetic storage trap and represents the first step of the GBAR experiment (Gravitational Behavior of Antimatter in Rest) recently approved by CERN for an installation in the Antiproton Decelerator hall. The installation built in Saclay will be described with its main characteristics. The ultimate target of the GBAR experiment will be briefly presented as well as the foreseen development of an industrial positron source dedicated for materials science laboratories.

Development of a $\hbox{Nb}_{3}\hbox{Al}$ and $\hbox{Nb}_{3}\hbox{Sn}$ Subscale Magnet

A 13 T class Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Al and Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn subscale magnet has been in development at the High Energy Accelerator Research Organization (KEK) to establish technology for a high-field accelerator magnet. The magnet was designed to generate a high magnetic field efficiently in a minimum-gap, common coil configuration with 200-mm-long racetrack coils. Two of the five coils in the magnet are Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn-produced by Lawrence Berkeley National Laboratory. The other three coils are Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Al -produced by KEK. The Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Al Rutherford cables are comprised of 28 RHQ-Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Al wires and were developed at KEK in collaboration with National Institute for Materials Science and Fermi National Accelerator Laboratory. Presently, the fabrication of two double pancake Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Al coils with the same configuration of 13 turns per layer was completed using the wind and react method. The magnet assembly and the preparations for excitation tests are currently in progress.

Новые предложения компании STRUERS для материаловедческих лабораторий

Новые предложения компании STRUERS для материаловедческих лабораторий

Reaction kinetics in the plasma membrane

A great puzzle in science is establishing a bottom up understanding of life by revealing how a collection of molecules gives rise to a living cell that can survive, communicate, and reproduce. In the confines of physics, chemistry, or material science laboratories where it possible to study complex interactions between molecules in a well-defined environment, our understanding of collective behavior is substantially developed. However, the environment in which molecules of a biological cell perform their functions is far from ideal or controllable. The environment inside cellular regions such as the plasma membrane is heterogeneous and dynamic, and functional molecules such as proteins are both dynamic and promiscuous, as they interact with countless other molecules. This makes it extremely challenging to grasp the inner mechanism of the cells, both experimentally and theoretically. On the bright side, this presents scientists with a colorful playground that waits to be explored: the mesoscopic world inside the cell. This review covers some of the recent experimental and theoretical developments in the study of molecular interactions in the plasma membrane, viewed as a heterogeneous medium where the number of reactants can be small, sometimes countable, and its implications for biological function.

Versatile compact X-ray radiography module for materials science under microgravity conditions

A versatile compact microfocus X-ray radiography facility is presented. The facility serves as a technology demonstrator showing the applicability of X-ray radiography to experiments in space. It has been designed as an insert fully compatible with requirements of the Materials Science Laboratory aboard the International Space Station. The facility consists of a microfocus X-ray source delivering up to 20 W X-ray power at 100kV acceleration voltage and a 49.2×49.3mm RadEye2 sensor with a Scint-X scintillator at 48μm per pixel resolution with a 14bit dynamic range. The total device weight including sample chamber is 43 kg. The facility is classified as a fully protected radiography equipment according to German radiation safety laws. The capabilities of the facility for research in materials sciences are demonstrated in ground-based experiments.

MSL compatible isothermal furnace insert for high temperature shear-cell diffusion experiments

For long-time diffusion experiments shear-cell techniques offer more favourable terms than the traditional long capillary techniques. Here, we present a further developed shear-cell that enables the measurement of diffusion coefficients up to temperatures of 1600 °C. Hence, diffusion experiments can be carried out at temperatures not accessible until now by conventional capillary or shear-cell techniques. The modified shear-cell, which can contain up to six samples of a total length of 90mm and a diameter of 1.5 mm, is built of 30 shear discs of 3mm thickness each. It is operated in an isothermal furnace insert which can be accommodated in the Materials Science Laboratory of the International Space Station. This provides the opportunity that the shear-cell can be applied to microgravity and to ground-based experiments, respectively. The heater insert with an overall length of 518mm and a diameter of 210mm consists of four heating zones with a total power of 3.5 kW. Temperature homogeneity along the graphite sample compartment is better than 2K at 1600°C. Details of the new design are discussed and results of first successfully performed heating and shearing cycles are presented.

Fluid-flow effects on phase selection and nucleation in undercooled liquid metals

Fluid flow can have a profound effect on phase selection and nucleation in undercooled liquid metals.In phase selection experiments, the sample does not solidify directly to the thermodynamically stable phase, but instead first forms a metastable phase, then transforms to the stable phase after some delay. Previous experiments and modeling on phase selection in near-eutectic Fe-Cr-Ni stainless steels have shown that the lifetime of the metastable phase is limited by the incubation time for formation of a critical nucleus of the stable phase, and that for some conditions, fluid flow can change that incubation time by an order of magnitude or more. New microgravity experiments in this area will be performed on new materials, including peritectic alloys, in the Materials Science Laboratory Electromagnetic Levitator (MSL-EML) as a part of projects PARSEC and THERMOLAB. The models that predict the effect of fluid flow on phase selection will be extended to these new experiments.In another class of experiments, nucleation in quasicrystal- and glass-forming alloys, testing a new theory on nucleation kinetics requires control of the shear rate in fluid flow to prevent interference of the solute fields around the sub-critical nuclei. These theories will be tested in microgravity using the MSL-EML under the projects ICOPROSOL and THERMOLAB.

A Review of Strain Analysis Using Electron Backscatter Diffraction

Since the automation of the electron backscatter diffraction (EBSD) technique, EBSD systems have become commonplace in microscopy facilities within materials science and geology research laboratories around the world. The acceptance of the technique is primarily due to the capability of EBSD to aid the research scientist in understanding the crystallographic aspects of microstructure. There has been considerable interest in using EBSD to quantify strain at the submicron scale. To apply EBSD to the characterization of strain, it is important to understand what is practically possible and the underlying assumptions and limitations. This work reviews the current state of technology in terms of strain analysis using EBSD. First, the effects of both elastic and plastic strain on individual EBSD patterns will be considered. Second, the use of EBSD maps for characterizing plastic strain will be explored. Both the potential of the technique and its limitations will be discussed along with the sensitivity of various calculation and mapping parameters.

First Experiments Using the Materials Science Laboratory on Board the International Space Station

The Materials Science Laboratory is a unique tool designed to perform high temperature experiments from various fields of physics on board the International Space Station. During the first operating phase initiated in November 2009 the directional solidification of aluminum-silicon alloys is investigated. The experiments shall elucidate the influence of fluid flow within the melt on the microstucture of the casting. In contrast to terrestrial experiments fluid flow induced by convection is virtually absent under microgravity conditions. The Materials Science Laboratory allows for solidification under both diffusive and stimulated convective conditions. After processing on orbit samples are returned to earth for detailed analyses. A short description of the experimental setup is given to familiarize with the capability of the facility. One of the experiments is specified in detail including the preparations performed on ground and the execution on orbit. Corresponding telemetry data is analyzed and first results of the metallographic examination are presented.

A Laboratory To Demonstrate the Effect of Thermal History on Semicrystalline Polymers Using Rapid Scanning Rate Differential Scanning Calorimetry

A detailed understanding of the effect of thermal history on the thermal properties of semicrystalline polymers is essential for materials scientists and engineers. In this article, we describe a materials science laboratory to demonstrate the effect of parameters such as heating rate and isothermal annealing conditions on the thermal behavior of poly(ethylene terphthalate) (PET) using a rapid heat−cool differential scanning calorimeter (RHC-DSC). The students observe the transformation of semicrystalline PET into an amorphous polymer and the occurrence of multiple melting endotherms upon subjecting the polymer to various thermal conditions. The rapid scanning rates achieved by the RHC-DSC simulate polymer-processing conditions and also facilitate the execution of more experiments in the two-hour laboratory compared to a conventional DSC.

Nanomaterials in Newfoundland: Designing a Lab Kit for Grades 9-12 to Bridge the Gap Between Science and Engineering

Innovation has its fundamental roots in engineering and entrepreneurship. This paper presents primary research gathered from high school science teachers from selected K-12 schools across Newfoundland and Labrador, Canada, addressing specifically the gaps that they have identified as being most challenging in defining what Engineering is in the realm of science curriculum in grades 9-12. This paper will also describe the development of a hands-on learning tool, a “portable materials science lab kit” that considers the input from these community educators and uses nanomaterials, to demonstrate what Engineering is and how Engineering and Innovation are relevantly applied to the important sectors of the province. The “portable lab kits” are designed for high school classrooms, in which small groups of students work through hands-on laboratory modules focusing on a specific material in a specific application. The “portable lab kits” can also be used by teachers as interactive demonstrations of specific scientific concepts in engineering applications.

Towards a Culture of Application: Science and Decision Making at the National Institute of Standards &amp; Technology

How does the research performed by a government mission agency contribute to useable technologies for its constituents? Is it possible to incorporate science policy mechanisms for increasing benefits to users in the decision process? The United States National Institute of Standards & Technology (NIST) promises research directed towards industrial application. This paper considers the processes that produce science and technology at NIST. The institute’s policies for science provide robust examples for how effective science policies can contribute to the emergence of useful technologies. To progress towards technologies that can be years away, the agency uses several means for integrating the needs of eventual information users into the prioritization process. To accomplish this, NIST units, such as the Materials Science and Engineering Laboratory, incorporate mechanisms for considering user need and project impact into different stages of its scientific decision processes. This, and other specific strategies that the agency utilizes for connecting the supply of science to information demand, provide lessons for generating useable science.

Materials solidification physics in space

The article presents a short overview on the basics solidification physics behind future experiments within the Materials Science Lab (MSL) of the International Space Station, ISS, and experimental results achieved so far in the ground based research studies as well as sounding rockets. The short paper highlights the importance of solidification research to be performed in space.

Hooke’s law and material science projects: exploring energy and entropy springs

A low-cost computer-based tensile testing apparatus is described that allows a graphicaldisplay of force–extension curves during the stretching of specimens in real time.The experiment is based on a graphics tablet combined with a force sensor. Itcan be used in a material science laboratory to investigate elastic and plasticdeformations in different materials and to model the underlying molecular mechanisms.Measurements on wires, rubber bands and spider silk are discussed in terms of energy andentropy spring models of elastic forces. Entropy springs play an important role insoft matter and underlie the intriguing mechanical properties of many biologicalmaterials.