Characterization Of Advanced Materials Research Articles

Light Weight High Performance Thermal Management With Advanced Heat Sinks and Extended Surfaces

Thermal management is a critical and essential component of maintaining high efficiency and reliability of electronic components. Adequate cooling must be provided while meeting the weight and volumetric requirements, especially for passive air-cooling solutions in avionics applications where space and weight are at a premium. It should be noted that there are electronic systems where thermal solution contributes 95% or more to the total weight of the system. With recent advancements in material science and increase in demand for more aggressive cooling solutions, it has become critical to invent, manufacture, characterize, and implement advanced thermal materials for the design of compact and low weight systems. However, because of the complexity due to anisotropic properties of these materials, their thermal performances and reliability are yet to be fully understood. The present paper aims at characterization of advanced thermal materials in passive air-cooling applications. A combined computational and experimental investigation is performed on various advanced heat sink materials and manufactured prototypes. Results are compared with the traditionally used aluminum heat sink and showed that significant weight savings can potentially be achieved. A composite figure of merit is proposed for measuring mass effective cooling capabilities of heat sinks. It is defined as the cooling performance per unit mass of heat sink and shown that advanced materials can perform as much as ten times better than conventional aluminum heat sinks.

Reliability Assessment of Advanced Materials and Structures

This paper discusses the reliability assessment of advanced structures such as micro/nano structures, electronics packaging for modern electronic devices, high temperature structures such as nuclear power plants, rocket engines for space application. Characterization of advanced materials includes free-standing electrodeposited nano-crystalline nickel thin film, polysilicon, and piezoelectric thin film for MEMS/nano structures. Lead-free solders under pseudo-power cyclic thermal loading, impact loading and mechanical bending loading were evaluated for reliability assessment of the advanced electronic packaging. Reliability assessment of Cu/SnAg double bump structures was performed for the 150µm pitch flip chip electronic packaging application. The 316L austenitic stainless steel for high-temperature components application such as in the primary side of liquid metal cooled fast breeder reactor (LMFBR) was tested under various temperatures where dynamic strain ageing occurs. The effects of dynamic strain ageing on the tensile behavior and fatigue behavior of 316L stainless steel have been identified.

Numerical computation in the viscoelastoplastic continuum damage of hot mix asphalt concrete

ABSTRACTThe objective of this paper is to develop an accurate and advanced material characterization of hot mix asphalt concrete using an existing viscoelastoplastic constitutive model that accounts for rate of loading, temperature and stress state with growing damage. The modelling strategy of viscoelastoplastic continuum damage is based on modelling strain components separately and then combining the resulting models to obtain a final integrated viscoelastoplastic model. According to this model, the initial‐boundary value problem is numerically solved using the constitutive relationship expressed in the convolution integral form. The model is successful in predicting responses up to localization when microcracks start to coalesce.

Preface: Phys. Status Solidi C 6/9

AbstractIn the last two decades research in the area of the lattice dynamics of solids has developed important methods of investigation, playing a pivotal role in the characterization of advanced materials at various dimensional and temporal scales. The growing interest and high technological relevance of vibrational spectra research have been justified by the use of new experimental instruments such as those for Fourier spectroscopy and new light sources in the infrared region such as the synchrotron radiation sources opened in several great facilities both in Europe and worldwide.This E‐MRS Symposium J – New Opportunities and Challenges in Material Research using Phonon and Vibrational Spectra – was intended to:– give an overview of the current status of optical metrology in the far‐infrared region for materials characterization and quality assurance of monocrystals and layer‐structured materials as well as of one‐dimensional nanomaterials, with a particular emphasis on state‐of‐the‐art metrology for the detection of defects and impurities using vibrational spectra; and– promote and encourage the interaction between academic and industrial research (instrument manufacture, the IC and optoelectronics industry and materials suppliers) to address scientific and technological challenges associated with the improvement of standard analytical methods and qualification of newer techniques.Firstly, we highlight the trends and advances in the techniques of optical metrology in the far‐infrared region for monocrystals (mainly solid solutions), thin‐film materials, nanowires and nanotubes; secondly, we address the application of such techniques to the study of real local crystalline structure (character of basic cell distribution in lattices and quantitative analyses of defects and impurities) in these materials.It is imperative to employ in situ new metrology as manufacturing processes become more complicated; this is particularly true in the microelectronics and microsystems industry, such as compound semiconductor electronics, phononics, MEMS and sensors.The current trends in optical metrology mainly concern Fourier spectroscopy and Raman spectroscopy applied to micro‐ and nanostructures: infrared microscopy and Raman microscopy. Both related techniques (Fourier and Raman) have attracted considerable interest in the last decade and are currently involved in the characterization of nanomaterials. In the symposium, these methods were discussed with particular attention paid to their application, as well as their limitations and complementarities.In the material presented here of the E‐MRS Fall Meeting 2009 Symposium J, there is reflected the main trends mentioned above in the area of lattice dynamic research: the general problems of the far‐infrared spectroscopy of solids – use of synchrotron radiation (is begun by the paper of A. Marcelli et al.); the theoretical questions in the spectroscopy of quantum dots – phonon‐assisted Kondo tunneling (is begun by the paper of K. Kikoin); experimental research of quantum dots and nanoparticles (is begun by the paper of A. Milekhin); Raman spectroscopy of quantum wires and nanotubes (is begun by the paper of W. Szuszkiewich); and next questions – electron–phonon interactions and pononics (Y. Pennec). Unfortunately, in these proceedings some important topics considered during the work of Symposium J, such as the application of Raman microscopy to MBE growth or acoustic solitons, are not found. The organizers express the opinion that at the time of the next similar symposium, all important issues related to modern vibrational and phonon spectra research will be represented in accompanying proceedings.

Introduction to the Special Issue on the Applications of Ferroelectrics

This special issue of the Transactions is a compilation of the most important papers presented at the 17th IEEE International Symposium on Applications of Ferroelectrics (ISAF). This was a joint meeting with the Electronics Division of the American Ceramics Society that was held at the Eldorado Hotel and Spa in Santa Fe, New Mexico, from February 24-27, 2008. The meeting was host to over 300 conference attendees and over 250 technical presentations. Presentations covered a wide range of technical topics, including processing, advanced characterization, theory and modeling of ferroelectrics, FERAM devices, capacitors, piezoelectrics, ultrasonics, multiferroics, and energy harvesting materials and devices.

Preface: Overview of the Forum on Functional Inorganic Materials

Inorganic Chemistry is pleased to present a Forum on Functional Inorganic Materials. A recent workshop sponsored by the National Science Foundation highlighted these materials and their technological impact (Prog. Solid State Chem. 2008, 36, 1-133). As the report makes clear, we are presently at the halfway point of the solid-state century [The Solid State Century. Sci Am. 1997, 8 (1)], in which, to date, functional inorganic materials have played profound societal and technological roles. It is without question that new functional inorganic materials will be indispensible during the second half of the solid-state century. In addition, the Department of Energy recently published their Grand Challenges for Basic Energy Sciences (http://www.science. doe.gov/bes/reports/list.html). Successfully meeting the challenges described in their report will require the synthesis and characterization of new and advanced functional inorganic materials. Rapidly changing technologies, for example, associated with cell phones, digital video devices, and computers, continue to drive the discovery of new materials. The replacement of SiO2 as a high dielectric constant (high-κ) material in transistors is crucial if additional microelectronic miniaturization is to be achieved. Currently, hafnium-based oxides and oxynitrides show promise, but it remains an ongoing challenge to discover new high-κ materials. What exactly defines an inorganic material, or for that matter any material, as functional? One broad definition would encompass materials that exhibit properties important to a new or changing technological advance. Functional inorganic materials encompass a vast and growing field, and it is not possible to present all of the ongoing research in one Forum. As part of this important multidisciplinary subject, this Forum on Functional Inorganic Materials deals mainly with oxides and other solid-state materials. Functional inorganic materials are found in batteries and fuel cells, computer memories, sensors, and thermoelectrics. In addition, microporous and open-framework materials including zeolites and metalorganic framework (MOF) compounds increasingly are used in heterogeneous catalysis and gas storage. Materials such as Nd:YAG and GaN are utilized for infrared and blue laser applications. Functional inorganic materials are not limited to nonmolecular compounds and also include numerous molecular compounds. A. F. Wells in his fifth edition of Structural Inorganic Chemistry stated that “the structural [functional] side of inorganic chemistry cannot be put on a sound basis until the knowledge gained from the study of the solid state [molecular and nonmolecular] has been incorporated into chemistry as an integral part of the subject”. A host of other attributes including the oxidation state, ion size, crystallographic order or disorder, coordination number, and symmetry, play a key role in determining the functionality of an inorganic material. The complex associations between these attributes and compound functionality must be fully understood if “rational materials design” is to be achieved.

X-Ray Micro-Tomography as a Tool for Quantitative Characterization of Advanced Materials Manufacturing Processes

The potential of X-ray micro-tomography in characterizing the relevant material issues as identified during manufacturing processes was investigated. For this purpose, the 3D X-ray micro-tomography (XµRT) analysis was applied to the characterization of structural integrity of Nb3Sn superconducting wires of differing topology and the evolution of the density distribution of ceramic samples manufactured by Field Assisted Sintering Techniques (FAST). The latter technique was used to consolidate the ceramic, metal (Ni) and composite powders (MgB2). The usual scanning electron microscope (SEM) technique was enhanced by the high resolution XµRT in order to describe the volumetric density distribution before sintering and at different moments of the thermal cycle. Two types of samples sintered Ni and high density MgB2 superconductors with typical volume of 0.8÷1.5⋅10-9 m3 were sampled at space resolution around 5µm. For the sintered Ni, the 3D reconstructed volumes revealed the grain connectivity, necks formation and particle rearrangement in the densification process. The XµRT analysis was essential in explaining the differences in superconducting properties of MgB2 samples in terms of different volumetric structures. For the Nb3Sn multifilamentary wire which is at basis of many practical superconductors, the 3D tomography enabled the determination of the number of inter-filament contacts as well as the twist-pitch parameter. Advantages of our method versus the invasive etching techniques for the determination of the twist-pitch parameter were outlined.

Nanostructured electrode materials for electrochemical energy storage and conversion

Nanostructured materials play an important role in advancing the electrochemical energy storage and conversion technologies such as lithium ion batteries and fuel cells, offering great promise to address the rapidly growing environmental concerns and the increasing global demand for energy. In this review, we summarize some of the recent progress and advances in our laboratory on nanostructured electrode materials for lithium ion batteries and platinum-based and platinum-free nanoalloy electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). Materials design, novel chemical synthesis and processing, advanced materials characterization, and electrochemical evaluation data are presented.

The effect of loading time on flexible pavement dynamic response: a finite element analysis

Dynamic response of asphalt concrete (AC) pavements under moving load is a key component for accurate prediction of flexible pavement performance. The time and temperature dependency of AC materials calls for utilizing advanced material characterization and mechanistic theories, such as viscoelasticity and stress/strain analysis. In layered elastic analysis, as implemented in the new Mechanistic-Empirical Pavement Design Guide (MEPDG), the time dependency is accounted for by calculating the loading times at different AC layer depths. In this study, the time effect on pavement response was evaluated by means of the concept of “pseudo temperature.” With the pavement temperature measured from instrumented thermocouples, the time and temperature dependency of AC materials was integrated into one single factor, termed “effective temperature.” Via this effective temperature, pavement responses under a transient load were predicted through finite element analysis. In the finite element model, viscoelastic behavior of AC materials was characterized through relaxation moduli, while the layers with unbound granular material were assumed to be in an elastic mode. The analysis was conducted for two different AC mixtures in a simplified flexible pavement structure at two different seasons. Finite element analysis results reveal that the loading time has a more pronounced impact on pavement response in the summer for both asphalt types. The results indicate that for reasonable prediction of dynamic response in flexible pavements, the effect of the depth-dependent loading time on pavement temperature should be considered.

Progress and perspectives for atomic-resolution electron microscopy

The transmission electron microscope (TEM) has evolved into a highly sophisticated instrument that is ideally suited to the characterization of advanced materials. Atomic-level information is routinely accessible using both fixed-beam and scanning TEMs. This report briefly considers developments in the field of atomic-resolution electron microscopy. Recent activities include renewed attention to on-line microscope control (‘autotuning’), and assessment and correction of aberrations. Aberration-corrected electron microscopy has developed rapidly in several forms although more work needs to be done to identify standard imaging conditions and to explore novel operating modes. Preparation of samples and image interpretation have also become more demanding. Ongoing problems include discrepancies between measured and simulated image contrast, concerns about radiation damage, and inversion of electron scattering.

Effective structural unit size in titanium alloys

This paper introduces the concept of effective structural size in titanium alloys and its importance with respect to material production routes and component lifing/design. Traditionally, process route optimization has relied on optical microscopy, which may be misleading when predicting mechanical properties. Similarly, continuum mechanics and current lifing methods are based on empirical data analysis. The advent of advanced material characterization techniques, e.g. EBSD combined with crystal plasticity modelling, has the potential to provide the next generation of mechanistically sound methods that more accurately predict material behaviour in complex loading regimes. These benefits are reviewed in the context of industrial application. Crystal plasticity modelling techniques are presented and a particular structural unit - termed a rogue grain - in a model single-phase titanium alloy is considered. Cold dwell under both strain and stress control is then assessed in the structural unit.

Characterization of Hydrogen Storage Capabilities in Advanced Battery Materials

Hydrogen storage capabilities in LaNi5 intermetallic compounds have been investigated utilizing the combination of thermoelectric power, Leco hydrogen determination, and Magnetic susceptibility measurements. Thermoelectric power has demonstrated a rapid hydrogen assessment capability and can achieve the equivalent of the pressure-composition-temperature (activity) diagram. Effective use of hydrogen storage materials occurs in the (alpha + beta)-phase plateau region of the PCT diagram. A thorough assessment of the content of each phase in this two-phase region to optimize performance of the hydrogen storage materials has been described. Electron concentration changes with variations in stored hydrogen content, thus altering the filling of the electronic d-band and slope of the plot of the paramagnetic susceptibility as a function of the thermoelectric power coefficient. Practices using the combination of these analytical techniques for rapid characterization of advanced hydrogen storage materials have been discussed. These methods also provide an opportunity for sensor development to monitor the hydrogen content in different materials.

Improving surface‐analysis methods for characterization of advanced materials by development of standards, reference data, and interlaboratory comparisons

AbstractThis paper summarizes the results of two surveys examining current needs for improved analyses of surfaces. Surfaces and interfaces are increasingly important to science and technologies associated with nanoparticles, nano‐structured materials and other complex materials including those associated with information systems and medical or biological applications. Adequate characterization of advanced materials frequently requires application of more than one analysis method along with the need to analyze data in increasingly sophisticated and sometimes interrelated ways. It is useful for both new and experienced analysts to have ready access to best practices for obtaining accurate and useful information from a variety of different analysis tools. The International Organization for Standardization (ISO) Committee TC 201 on surface chemical analysis and the ASTM Committee E‐42 on surface analysis are working to address these needs by assembling guides and standards reflecting the collective experience and wisdom of experts in this community. Published in 2007 by John Wiley & Sons, Ltd

Multi-paradigm multi-scale simulations for fuel cell catalysts and membranes

Dramatically improving the performance of fuel cell systems with their complex heterogeneous structures involving electrocatalysts, proton conducting membrane, reactant, and interfaces between them requires understanding the fundamental chemical, electrochemical, and physical phenomena at the heart of these complex materials and relating these fundamentals to the properties and performance of the membrane–electrode assembly. Our goal is to develop a predictive model that can be used to estimate the changes in performance upon changes in the design and which can be used to monitor performance of working fuel cells. Our strategy is to start with first principles quantum mechanics (QM) and to develop overlapping simulation methodologies in which QM is used to train a reactive force field that can be applied for large-scale (millions of atom) molecular dynamics simulations while retaining the accuracy of QM. The results of molecular dynamics are used to extract a coarse grain or mesoscale description useful in modeling properties at much larger scales. This model would enable the conception, synthesis, fabrication, characterization, and development of advanced materials and structures for fuel cells and for the associated hydrocarbon fuel reformers in an overall fuel cell system. We illustrate here some of the progress toward this goal.

Editorial: 40 years Crystal Research and Technology

AbstractOur journal, “Crystal Research and Technology” , will celebrate a jubilee this year – its 40th anniversary. On the one hand, this milestone gives us a good opportunity to remember the early days of the journal, and on the other hand it allows us to reflect on future developments.The journal was founded as “Kristall und Technik” by Professors Will Kleber and Hermann Neels in 1966 at a time when the eastern part of Germany was effectively isolated from the West as a result of the Cold War. Since 1953, Prof Will Kleber (1906 – 1970) has been the director of the Institute for Mineralogy of the Humboldt University of Berlin. Under his directorship, this institute was transformed into a modern institute for crystallographic research at the Humboldt University. Prof Hermann Neels (1913 – 2002) acted as the director of the Institute of Mineralogy at the University of Leipzig until his retirement in 1978. The Kleber institute of the Humboldt University in Berlin and the Neels institute in Leipzig were individual centres of crystallography in the former GDR. Therefore, it was a logical consequence that the scientific leaders of these centres were the first editors of “Kristall und Technik” . The tremendous demands associated with editing a journal were taken on solely by Hermann Neels after the unexpected early death of Will Kleber in 1970. Since that time, Prof Neels continued to serve as the Editor‐in‐Chief until 1996.The founders of the journal adhered strictly to the principle of unity of basic and applied research, while including industrial applications. Therefore, the foundation of a journal of experimental and industrial crystallography, which sought to close the gap between the already‐existing international journals of crystallography, was the logical consequence. The first issue of “Kristall und Technik” (subtitle: Zeitschrift für experimentelle und technische Kristallographie) contained 19 original papers (18 written in German, one in Russian) and one short note. After some years, the transformation from a German journal to an international one was inevitable. The cover of the earlier issues displayed the name of the journal in German and English. Starting in 1981 the transformation to “Crystal Research and Technology” as a fully international journal was performed.A great number of members of the Editorial Board as well as of the Advisory Board have accompanied and supported the editors during the four decades of Editorship.In the first preface of “Kristall und Technik” , the editors claimed that a journal of experimental and technical crystallography should find a vibrant response. This claim is more true now than ever before. The intent of “Crystal Research and Technology” is to examine the main aspects of experimental and industrial crystallography. The preferential consideration of these aspects does not exclude theoretical crystallography as a basis for a thorough understanding of practical crystallography.Nowadays, our journal covers the relevant aspects of modern crystal growth phenomena. The main field of preparation and characterisation of advanced crystalline materials, e.g., smart materials, artificial and natural nano‐structured materials like semiconductor quantum structures and nano‐tubes, will also be published in “Crystal Research and Technology” . Particular emphasis is given to the large field of industrial crystallisation. A major part of the contribution submitted is directly related to the application of modern crystalline materials in materials science, optics and electronics. New developments in crystal growth, including the field of biological crystallography, will also be covered. All in all, “Crystal Research and Technology” takes into consideration the actual developments in the field of crystallographic research.The future of our journal will find its place in fully electronic publishing. Thus, the information exchange between the editors, the referees and the authors will be easier and faster.We encourage all readers to submit novel and original contributions in the various fields of crystallographic research and thus contribute to providing the building blocks for a successful international crystallographic journal. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Progress and Perspectives for Atomic-Resolution Electron Microscopy

The transmission electron microscope (TEM) has evolved into a highly sophisticated instrument that is ideally suited to the characterization of advanced materials. Atomic-level information is routinely accessible using both fixed-beam and scanning TEMs. This report briefly considers developments in the field of atomic-resolution electron microscopy. Recent activities include renewed attention to on-line microscope control ('autotuning'), and assessment and correction of aberrations. Aberration-corrected electron microscopy has developed rapidly in several forms although more work needs to be done to identify standard imaging conditions and to explore novel operating modes. Preparation of samples and image interpretation have also become more demanding. Ongoing problems include discrepancies between measured and simulated image contrast, concerns about radiation damage, and inversion of electron scattering.

MSE on the Move

The new Institute for Critical Technology and Applied Science (ICTAS) will attract top faculty and stu­ dents, foster collaboration between researchers, increase research funding, and provide infrastructure and space to facilitate these aims. The ICTAS Initiative at Virginia Tech (led by the College of Engineering) will involve the construction of several new buildings comprising a multi-disciplinary research laboratory and a 15,000 ft 2 state-of-the-art Advanced Materials Characterization Facility (AMCF). The AMCF facility will be formed by a collection of new and existing tools for processing, characterizing, and testing materials at the macro, micro, and nanometer scales. Of the expected cost of $12M in equipment for the AMCF, the University has already provided $3.2M to purchase a High-Resolution Transmission Electron Microscope (HRTEM) and an ion microprobe. The equipment to be housed in the AMCF includes

Laser vibrometry of air-coupled Lamb waves

Abstract A new non-contact methodology combining air-coupled ultrasonic excitation and laser detection of the Lamb waves is developed and applied for advanced material characterization. The flexural modes are generated in a specimen at normal and slanted incidence of a focused air-coupled beam. A laser scanning vibrometer is used for dynamic visualization of the Lamb wave field. As the local flexuaral wave velocity depends on the thickness of a specimen, the meth-odology enables remote imaging and profiling of thickness at high accuracy. Direct imaging of the flexural wave-defect interaction is capable of visualizing the damaged areas in fibre-reinforced composites. The shape of the detected flexural waveforms is shown to reflect the in-plane material anisotropy. The experiments proved a high sensitivity of the technique in remote imaging and measuring of local fibre orientation in composite materials.

Characterization of advanced semiconductor materials by positron annihilation

Characterization of advanced semiconductor materials by positron annihilation

Special requirements for material characterisation regarding the simulation of solid waste material processing

Modelling and simulation has gained a high importance in the field of process engineering over recent years. As the processing technology of solid waste materials becomes more complex due to the growing requirements on the products, the need for computerised simulation technologies in this area of engineering is evident. The task that derives from the heterogeneity of the waste material to be described is vectorisation of the material flow. In order to have a cluster of parameters which is capable of describing the characteristics of the material flow, the waste material has to be categorised and structured in accordance with the key processes which are used to process the material flow. To guarantee a satisfactory material description, advanced analytical concepts have to be applied to the samples taken for characterisation. As an example, the grain-size-specific water content is analysed and implemented in the model library used for the simulation. The simulation results indicate that the advanced material characterisation is more efficient than the ordinary one.