Download or read book Synthesis and Characterization of Low and Negative Thermal Expansion Materials written by Mehmet Nuri Kutukcu and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The preparation and thermophysical properties of some In(I), Ga(I) and Ag(I) substituted NZP type materials were explored. Many compositions with the NZP framework show low and negative thermal expansion. Previously reported material, GaZr2(PO4(3, transforms from one NZP related phase into another NZP type phase due to oxidation under air above 300oC. In addition, it exhibits hysteresis under inert atmosphere; the cell parameters are different on heating and cooling cycles for a given temperature. The synthesis, and characterization of a new material, InZr2(PO4)3, is outlined. It crystallizes in space group R -3 c. In addition, as GaZr2(PO4)3, it oxidizes above 300oC under air and exhibits hysteresis under inert atmosphere. Furthermore, the synthesis of AgTixZr2-x(PO4)3 solid solution compositions, their ion exchange characteristics with Ga(I) and their thermophysical properties are described. Thermal expansion anisotropy (the difference between a and c) of the solid solutions decreases as the bigger ion, Zr4+, is substituted by the smaller one, Ti4+. Thermal expansion characteristics of GaZr2(PO4)3, InZr2(PO4)3 and AgZr2(PO4)3 are compared with MZr2(PO4)3 (M = Li, Na, K, Rb, Cs). Ionic radii for Ga(I) and In(I) in a six coordinate oxygen environment were proposed.

Download or read book Synthesis and Characterization of Some Low and Negative Thermal Expansion Materials written by Támas Varga and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The high-pressure behavior of several negative thermal expansion materials was studied by different methods. In-situ high-pressure x-ray and neutron diffraction studies on several compounds of the orthorhombic Sc2W3O12 structure revealed an unusual bulk modulus collapse at the orthorhombic to monoclinic phase transition. In some members of the A2M3O12 family, a second phase transition and/or pressure-induced amorphization were also seen at higher pressure. The mechanism for volume contraction on compression is different from that on heating. A combined in-situ high pressure x-ray diffraction and absorption spectroscopic study has been carried out for the first time. The pressure-induced amorphization in cubic ZrW2O8 and ZrMo2O8 was studied by following the changes in the local coordination environments of the metals. A significant change in the average tungsten coordination was found in ZrW2O8, and a less pronounced change in the molybdenum coordination in ZrMo2O8 on amorphization. A kinetically frustrated phase transition to a high-pressure crystalline phase or a kinetically hindered decomposition, are likely driving forces of the amorphization. A complementary ex-situ study confirmed the greater distortion of the framework tetrahedra in ZrW2O8, and revealed a similar distortion of the octahedra in both compounds. The possibility of stabilizing the low thermal expansion high-temperature structure in AM2O7 compounds to lower temperatures through stuffing of ZrP2O7 was explored. Although the phase transition temperature was suppressed in MIxZr1-xMIIIxP2O7 compositions, the chemical modification employed was not successful in stabilizing the high-temperature structure to around room temperature. An attempt has been made to control the thermal expansion properties in materials of the (MIII0.5MV0.5)P2O7-type through the choice of the metal cations and through manipulating the ordering of the cations by different heat treatment conditions. Although controlled heat treatment resulted in only short-range cation ordering, the choice of the MIII cation had a marked effect on the thermal expansion behavior of the materials. Different grades of fluorinert were examined as pressure-transmitting media for high-pressure diffraction studies. All of the fluorinerts studied became nonhydrostatic at relatively low pressures ( -1 GPa).

Download or read book Low Temperature Synthesis and Characterization of Some Low Positive and Negative Thermal Expansion Materials written by Kathleen Madara White and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low temperature synthesis and characterization of some low positive and negative thermal expansion materials Kathleen Madara White 151 pages Directed by Dr. Angus P. Wilkinson Low temperature non-hydrolytic sol-gel synthesis was used to explore the possibility of lowering the crystallization temperatures of some known AIVMV2O7 compounds. Crystallization temperatures for ZrP2O7 and ZrP2O7 were unaffected by the use of non-hydrolytic sol-gel methods; however, successful synthesis of these compounds broadens the range of materials that can be produced using this method and suggests the possibility of synthesizing solid solutions (or composites) including ZrP2O7 or ZrV2O7. This research presents for the first time the direct synthesis of ZrP2O7 from separate zirconium and phosphorus starting materials using mild autoclave methods. Characterization of some AIVMV2O7 compounds, using lab and high resolution synchrotron powder XRD, led to the assignment of a new symmetry for CeP2O7 and to the suggestion that the reported structure for PbP2O7 was inadequate. Studies using in situ high temperature lab and synchrotron powder XRD for PbP2O7 and CeP2O7 provided the opportunity to report their thermal properties for the first time, and to compare their behavior to that of some other AIVMV2O7. High pressure diffraction measurements on CeP2O7 provided data for the estimation of bulk moduli and suggested two possible pressure-induced phase transitions. A broad range of MIIIMVP4O14 compounds were prepared using low temperature hydrolytic sol-gel synthesis. Thermal studies revealed nearly linear trends in CTEs and lattice constants with respect to the sizes of MIIIMV cations. Some lower ionic radii compounds had CTEs comparable to that of ZrP2O7 at low temperature, suggesting a similar superstructure. Three compounds were found to exhibit temperature-induced phase transitions.

Download or read book Synthesis and Characterization of Solid Solutions AA Mo3O12 written by La'Nese Lovings and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expansion of solid-state materials is an important physical property that can affect the performance of many devices. When the thermal expansion coefficients of two materials that are in intimate contact in a device are mismatched, the outcome can be detrimental and lead to device failure. Negative thermal expansion (NTE) materials can be utilized to counteract the undesirable positive thermal expansion (PTE) of a material by forming a controlled expansion composite that can retain other important properties of the matrix material. Here, we study NTE materials in the A2M3O12 family (A= trivalent cation, M= Mo, W). Within this family, some materials undergo a phase transition from an orthorhombic NTE phase at high temperatures to a monoclinic PTE phase at low temperatures. Lowering of this phase transition temperature could be beneficial to achieve the largest possible temperature range with NTE. Such a suppression has been observed in AlScMo3O12, which shows a much lower transition temperature than either Al2Mo3O12 or Sc2Mo3O12. It was suggested that the large size difference between Al3+ and Sc3+ played an important role in the observed behavior. The goal of this research was to synthesize mixed A-site occupancy materials and probe their phase transition behavior as a function of composition to understand the design rules for materials in which the orthorhombic phase is stabilized. To investigate the behavior observed for AlScMo3O12 more deeply, various AlxSc2-xMo3O12 compounds were synthesized using solid-state and non-hydrolytic sol-gel (NHSG) methods (Chapter 3). Solid-state methods did not produce single-phase samples; however, NHSG methods led to single-phase samples for a wide range of compositions. Optimization was necessary for the NHSG synthesis, with solvent system, reaction temperature and synthesis duration as main variables. It was found that the stabilizing agent in the chloroform used played a key role in the production of single-phase samples. Compositions close to the parent compounds could be obtained as single-phase samples with a synthesis duration of 7 days, while a longer reaction time of 12 to 15 days was necessary near the middle of the solid solution series. To investigate a system with an even larger size difference between the A-site cations, the AlxIn2-xMo3O12 solid solution series was synthesized via solid-state and NHSG chemistry (Chapter 4). Solid-state synthesis led to high weight losses attributed to MoO3 evaporation during heating and never produced phase pure materials. Similar to the previously mentioned solid solution series, the compositions near the end members produced phase pure samples with relative ease while significant optimization was required near the middle of the solid solution, and single-phase samples could not be produced for many compositions. Increasing the temperature of synthesis in chloroform lead to improved homogeneity, while no positive effect was noted for acetonitrile samples. An increase in reaction duration improved the purity of some samples as well. It was also found that the exact heat treatment chosen could affect whether single- or multi-phase samples were obtained. A single heat treatment near the end members could produce single-phase samples, while compositions near the middle of the solid solution benefited from a lower temperature heat treatment followed by a second higher temperature heat treatment. The samples in the AlxSc2-xMo3O12 and AlxIn2-xMo3O12 solid solution series were subjected to variable temperature (VT) in-house and synchrotron PXRD studies to determine the temperatures of the phase transition (Chapter 5). Both systems showed a phase transition temperature suppression near the middle of the solid solution, with AlxSc2-xMo3O12 samples showing the largest suppression when x = 0.9 and 1. These samples showed no phase transition down to -193 °C, which was the lowest temperature measured. AlxIn2-xMo3O12 showed a phase transition suppression even for substitution levels of only 5 to 10%. During the variable temperature study, it was found that compositions that resulted in a lowering of the phase transition temperature also had a tendency to display PTE instead of NTE. A possible explanation for both effects is that the difference in A-site cation size can lead to localized strain of the system. This strain is more readily accommodated in the less dense orthorhombic phase, but also interferes with the phonon modes that cause NTE. Stress analysis of the synchrotron data showed that the compounds near the end members possessed low strain, but as the cation composition changed across the solid solution series an increase in strain was observed. A serendipitous discovery showed that raw AlxSc2-xMo3O12 samples could crystallize over an extended period of time under ambient conditions. To investigate this behavior, the effect of storage in different environments was investigated (Chapter 6). It was found that absorption of water from the atmosphere was crucial for the crystallization of the samples. To our knowledge, moisture-induced crystallization at room temperature has never been observed for any NTE materials. Typically, amorphous samples require heat treatments to 450 to 700 °C to form a crystalline product. An in-situ crystallization study was carried out using synchrotron diffraction experiments to observe the phase evolution of amorphous AlxSc2-xMo3O12 precursors during different heat treatments (Chapter 7). This study was designed to determine optimum heat treatment protocols to favor formation of single-phase samples. Surprisingly, conditions mimicking those used during ex-situ heat treatments resulted in crystallization of an MoO3 impurity at relatively low temperatures for all samples, many of which formed single-phase materials during ex situ studies. This revealed that all samples were inhomogeneous during heating. In a significant number of samples, formation of two distinct A2M3O12 phases was observed at intermediate temperatures. However, most samples were determined to be phase pure after heating to 700 °C, suggesting that these intermediate phases react during continued heating.

Download or read book Negative Thermal Expansion Materials written by D.J. Fisher and published by Materials Research Forum LLC. This book was released on 2018-01-15 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: In everyday life, minute thermally-induced elongations are essentially invisible to the naked eye; but even minute expansions can fatally degrade device processing and performance in – for example – the semiconductor industry. Materials which, astonishingly, contract upon heating offer the great advantage of being able to tune the overall thermal expansion of composite materials or to act as thermal-expansion compensators. The development of these negative thermal expansion materials has advanced rapidly during the past fifteen years, and a wide variety of materials of differing types has now been identified, as well as a number of intriguing mechanisms which help to avoid the apparent inviolable tendency of size to increase with temperature. The present work is the most up-to-date summary of the current range of negative thermal expansion materials and of the associated mechanisms. Negative Thermal Expansion Materials, Thermomiotic Behavior, Thermal Stress-Fracture, Thermal Expansion of Composites, Thin-Film Design, Metamaterials

Download or read book Non hydrolytic Sol gel Synthesis and Characterization of Materials of the Type AA M3O12 written by Tamam Issa Baiz and published by . This book was released on 2010 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been an increased interest in negative thermal expansion (NTE) materials, which contract upon heating. Materials exhibiting this property have the potential for achieving better control of thermal expansion through the synthesis of composite materials with more desirable expansion coefficients. By introducing NTE materials into these composites, it is possible to offset the positive thermal expansion of other components in the composite. As a result, these NTE materials can find use in a wide range of applications such as optics, electronics, tooth fillings and any other area where exact positioning of parts over a wide range of temperatures is crucial. A family of materials that has been known to show NTE are A2M3O12 compounds, where A can be a variety of trivalent cations and M can be Mo or W. Previous work on this system has shown that the thermal expansion is highly dependent on the type of trivalent cation employed. However, in spite of the interest in these 2M3O12 compounds, little research has been dedicated to synthesizing materials containing two aliovalent cations instead of just one or two trivalent cations. In fact, the first example of a heterosystem with +2 and +4 cations was not reported until 2004. This dissertation presents results of investigation and characterization of these mixed cation systems, and the change in the thermal expansion properties. The first goal of the research presented herein was to synthesize mixed cation systems using a lower temperature route, and then compare the materials synthesized using low temperature methods with those synthesized using the ball-milling method. This will ensure the validity of applying a lower temperature method to these mixed cation systems. A non-hydrolytic sol-gel (NHSG) method was used, which is based on the reaction of metal alkoxides with metal halides to form M-O-M linkages, with alkyl halides as byproducts. With this method, MgHfW3O12 and MgZrW3O12 were successfully synthesized. When compared to samples prepared by the ball-milling method, many distinct differences were observed. The first was that unlike with the ball-milling method where the desired materials required extended heat treatments at high temperatures (1050-1100 °C, 17-24 h), the NHSG method allowed the synthesis of these compounds after reacting at 130 °C for as little as 3 d and subsequent heat treatment to temperatures as low as 540 °C for as little as 2 h. Furthermore, SEM showed that with the NHSG method, micronsized particles with defined morphology were formed, instead of the large, chunky particles observed when ball-milling was used. This significant change in particle size and morphology is very important for potential applications since it leads to better homogeneity of the components in a composite. Once these results were obtained, the same NHSG method was applied to other combinations of 2+ and 4+ cations. The second goal of the project was to extend the use of the NHSG method to materials of the type A2M3O12 where A is a trivalent method. These types of materials have been previously made using traditional solid state methods. However, previous research in our group has shown that it is possible to access new metastable phases when using lower temperature routes. With the NHSG method, MgZrMo3O12 was made for the first time, as well as a new polymorph of Y2W3O12. Materials made were then characterized using a variety of analytical techniques. These included thermograviometric-differential thermal analysis, powder X-ray diffraction, variable temperature powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and synchrotron experiments. High pressure studies were also carried out in an attempt to study how the synthesized materials behave when subjected to pressure.

Download or read book Synthesis and Characterization of A2Mo3O12 Materials written by Lindsay Kay Young and published by . This book was released on 2015 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Negative thermal expansion (NTE) materials have attracted considerable research interest in recent decades. These unique materials shrink when heated, offering a potential means to control the overall thermal expansion of composites. Several families of materials display this behavior, the largest of which is the A2Mo3O12 family (also called the scandium tungstate family), in which A is a trivalent cation and M is molybdenum or tungsten. These materials show NTE in an orthorhombic structure, but many members transform to a monoclinic structure with positive expansion at low temperatures. Many properties of these materials are dependent on their elemental composition, especially the identity of the A3+ cation. This includes the magnitude of NTE, as well as the phase transition behavior as a function of temperature and pressure. It is also possible to create "mixed site" cation A2Mo3O12 materials, in which the A site is occupied by two different cations. These are described as AxA'2-xM3O12 materials, as the composition A:A' can vary. Creating these new compositions may result in different phase transition properties or the ability to tune the NTE properties of these materials. In this work, the focus was on synthesis and characterization of indium gallium molybdate (InxGa2-xM3O12). The non-hydrolytic sol-gel (NHSG) method was used to synthesize indium gallium molybdate while exploring a variety of reaction parameters. While the goal was to create stoichiometric, homogenous materials, it was found that this could not be accomplished using easily accessible parameters during NHSG reactions. However, it was discovered that certain conditions allowed unusually low temperature (230 °C) crystallization of these materials. Similar conditions were explored for single cation A2Mo3O12 materials, and it was determined that crystallization of indium molybdate, iron molybdate, and scandium molybdate was possible at temperatures of 230 or 300 °C. This extremely low temperature crystallization may provide the opportunity for exploring the in situ synthesis of polymer composites containing these materials, as the crystallization temperatures are compatible with many polymer systems. In the second part of this thesis, the high pressure behavior of a number of A2Mo3O12 and AA'Mo3O12 materials was studied. The open frameworks of NTE compounds are generally prone to pressure induced phase transitions. NTE materials may have to withstand high pressures during production or regular use of composites, thus understanding the high pressure behavior of these materials is necessary for effective application. Irreversible transitions to new phases or amorphization at high pressures could lead to failure of composites, as these phases are not expected to exhibit any NTE properties. Studies were carried out at the Advanced Photon Source at Argonne National Laboratory at pressures up to 5-7 GPa using a diamond anvil cell. The materials investigated could be divided into three groups based on distinct types of high pressure behavior. The room temperature monoclinic Group1 compounds (A2 = Al2, Fe2, FeAl, AlGa) underwent a similar sequence of reversible subtle phase transitions before undergoing a major structural transition to a common high pressure structure. The unit cell of this high pressure phase was successfully indexed, and the transition was found to be reversible upon decompression. Phase transition pressures increased with decreasing A-site cation radius. In contrast, Group2 materials (A = Cr, Y) retained their low temperature monoclinic structures up to the highest pressures investigated. The remaining materials (A2 = In2, InGa) underwent a different sequence of subtle transitions followed by an irreversible transition at higher pressures. The patterns belonging to these high pressure phases are unlike those of the first group. No patterns similar to InGaMo3O12 were found in the literature, while In2Mo3O12 may transform to the same high pressure polymorph as In2W3O12. The classification of A2Mo3O12 materials into several groups with distinct high pressure behavior adds pertinent knowledge to the field that may help elucidate the structures of previously studied materials, and ultimately may help predict the behavior of compositions that have not yet been explored.

Download or read book Synthesis and Characterization of Ultralow Thermal Expansion NZP type Compounds written by Jinmin Kim and published by . This book was released on 1988 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermal Properties of Solids at Room and Cryogenic Temperatures written by Guglielmo Ventura and published by Springer. This book was released on 2014-06-23 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The minimum temperature in the natural universe is 2.7 K. Laboratory refrigerators can reach temperatures in the microkelvin range. Modern industrial refrigerators cool foods at 200 K, whereas space mission payloads must be capable of working at temperatures as low as 20 K. Superconducting magnets used for NMR work at 4.2 K. Hence the properties of materials must be accurately known also at cryogenic temperatures. This book provides a guide for engineers, physicists, chemists, technicians who wish to approach the field of low-temperature material properties. The focus is on the thermal properties and a large spectrum of experimental cases is reported. The book presents updated tables of low-temperature data on materials and a thorough bibliography supplements any further research. Key Features include: ° Detailed technical description of experiments ° Description of the newest cryogenic apparatus ° Offers data on cryogenic properties of the latest new materials ° Current reference review

Download or read book Effect of Negative Thermal Expansion Material Cubic ZrW2O8 on Polycarbonate Composites written by Xiaodong Gao and published by . This book was released on 2015 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on control of thermal expansion of polymers has attracted significant attention, since polymers exhibit excellent mechanical and electronic properties, but suffer from high thermal expansion due to the thermal motion of their long molecular chains. Such problems can be addressed through formation of composites that contain an inorganic filler material. Filler materials reduce the thermal expansion of polymers through restriction of polymer chain motion. One particular area of interest is the introduction of negative thermal expansion (NTE) materials into polymer composites. The NTE property is expected to have an additional effect on the reduction of the coefficient of thermal expansion (CTE) of the composites. Several papers have demonstrated successful reduction of the CTE of polymer composites using cubic ZrW2O8, however, it is still unclear how much of this effect is caused by the NTE behavior, and how much is due to chain stiffening. To address whether the use of expensive NTE materials is justified, this project is designed to investigate the exact effects of NTE and chain stiffening on the reduction of thermal expansion of polymer composites. This objective was achieved through the preparation and testing of two sets of composites containing isomorphic particles with opposite thermal expansion (ZrW2O8 and ZrW2O7(OH)2¿2H2O),which possess identical chain stiffening effects. The first goal of the project was to synthesize two different particles that have identical morphology but opposite thermal expansion, with cubic ZrW2O8 as the NTE material of choice. The initial idea was to use a-Al2O3 (corundum), which has a known positive CTE value, as the second material. This phase can be obtained through heat treatment of AlOOH at about 1100 °C. The synthesis of AlOOH with controlled morphologies based on choice of synthetic conditions has been reported. Attempts on the synthesis of AlOOH were made through two different routes. Neither of them delivered particles with similar size as cubic ZrW2O8. Additionally, it was found that the heat treatment at high temperature caused sintering of the particles, resulting in the formation of large particles. To circumvent this problem, the precursor of ZrW2O8, ZrW2O7(OH)2¿2H2O, was used as the counterpart for the comparison, since the topotactic transformation between the two phases results in unchanged morphology, giving rod-like shape for both materials. The synthesis of ZrW2O7(OH)2¿2H2O was optimized to prepare particles with small size, high crystallinity, and good resistance to hydration after converting to the cubic NTE phase. The effects of acid concentration and reaction time were explored. The products were examined by powder X-ray diffraction (PXRD) and scanning electron microscopy, and the hydration rates were also estimated based on the PXRD patterns. Final reaction conditions were chosen as 6 M HCl at 230 °C for 7 d. The coefficient of thermal expansion was determined for ZrW2O7(OH)2¿2H2O using Pawley refinements of variable temperature PXRD data, and values of ¿a = 11 × 10-6 ± 1 × 10-6 K-1 and ¿c = 2.6 × 10-6 ± 0.3 × 10-6 K-1, respectively, were found. Rietveld refinements were carried out on PXRD patterns of both types of particles mixed with silicon to estimate their amorphous content. Results indicated that both particles were close to fully crystalline. To improve the interaction between the particles and polymer, surface modification was carried out via in-situ polymerization in the presence of the particles using triphosgene and bisphenol A as monomers. Soxhlet extraction was used to purify the recovered particles. Thermogravimetric analysis was used to determine the surface coverage of the products and the presence of unbound polymer, and the required time for extraction was revealed to be 96 h based on the TGA results. Infrared spectroscopy was also used to examine the modified particles, which confirmed the presence of surface bound oligomers. Optimization of synthetic conditions, including monomers ratio, reaction time and amount of particles, was carried out to obtain the highest possible coverage. It was found that the optimum ratio for the monomers is between 2.2 : 1 and 1.3 : 1. Leveling off was observed for the surface coverage after 21 h of reaction time. Smaller amounts of particles gave higher surface coverages, but resulted in very low quantities of recovered particles due to losses during recovery steps. To recover more particles from a single batch reaction, the particles were subjected to two consecutive modification steps, resulting in both high coverage and high recovered amounts. The precursor particles could be modified under the same optimum conditions found for NTE particles. The interaction between the particles and polymer was found to be improved after the modification. Solution casting was used to prepare the composite films. A custom made glass vessel was created to provide an inert atmosphere with reduced pressure. This can lower the moisture level and increase the evaporation rate of the casting solvent, which can prevent moisture deposition and crystallization of the polymer. The interaction between the two phases was further enhanced through reprecipitation blending. Under optimized conditions, composite films loaded with bth types of particles were prepared with weight loadings ranging from 2 wt% to 25 wt%. Films with loadings above 12 wt% showed agglomeration on optical images. The homogeneity of the particle dispersion within the films was still acceptable based on combustion analysis. Several properties of the composites were measured, including tensile properties, thermal stability, glass transition temperature and coefficient of thermal expansion. All films without agglomeration showed enhance thermal stability. On the other hand, most films with agglomeration exhibited slightly lower thermal stability. Similar trends were seen for the stress and strain at yield for both types of composites. The composites with lower thermal stability showed lower stress and strain at yield than pristine PC films, whereas the rest showed similar values for these two properties. The Young’s modulus of both types of composite films was found to slightly increase with the addition of the filler particles. All composites exhibited similar values as pristine PC. However, the local structure of the two types of the composites was revealed to be different by dynamic mechanical analysis. The films loaded with the precursor particles exhibited earlier softening than pristine PC, while a delay in softening was found for the ones loaded with NTE particles. The coefficient of thermal expansion (CTE) was measured for the film samples at the University of Mulhouse. This instrument produced faulty numbers that required corrections for instrument contributions. The correction for instrument contributions was checked by comparing the corrected values of three selected film samples to values obtained through analysis at West Kentucky University. The composites blended with NTE particles showed consistently lower CTE values than pristine PC and decreased with increased particle loading, whereas the values of the other set of composites showed no clear trends. Overall, considering the errors associated with the CTE values, the difference caused by the NTE behavior of the particles may not be very significant. Additional samples with higher loadings need to be tested to obtain a clearer picture, and data should be collected on well calibrated instruments to reduce errors.

Download or read book Activity report written by Brookhaven National Laboratory. National Synchrotron Light Source and published by . This book was released on 2005 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Capacity and Thermal Expansion at Low Temperatures written by T.H.K. Barron and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: The birth of this monograph is partly due to the persistent efforts of the General Editor, Dr. Klaus Timmerhaus, to persuade the authors that they encapsulate their forty or fifty years of struggle with the thermal properties of materials into a book before they either expired or became totally senile. We recognize his wisdom in wanting a monograph which includes the closely linked properties of heat capacity and thermal expansion, to which we have added a little 'cement' in the form of elastic moduli. There seems to be a dearth of practitioners in these areas, particularly among physics postgraduate students, sometimes temporarily alleviated when a new generation of exciting materials are found, be they heavy fermion compounds, high temperature superconductors, or fullerenes. And yet the needs of the space industry, telecommunications, energy conservation, astronomy, medical imaging, etc. , place demands for more data and understanding of these properties for all classes of materials - metals, polymers, glasses, ceramics, and mixtures thereof. There have been many useful books, including Specific Heats at Low Tempera tures by E. S. Raja Gopal (1966) in this Plenum Cryogenic Monograph Series, but few if any that covered these related topics in one book in a fashion designed to help the cryogenic engineer and cryophysicist. We hope that the introductory chapter will widen the horizons of many without a solid state background but with a general interest in physics and materials.

Download or read book A Practical Guide to Scientific Writing in Chemistry written by Andrew Terhemen Tyowua and published by CRC Press. This book was released on 2023-03-31 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Successful completion of postgraduate studies, especially PhD, and career advancement in academia strongly depend on the ability to publish scientific papers or books and attract research grants. However, many chemical scientists find preparing scientific papers and research grant and book proposals difficult; partly because of insufficient training in writing and partly because there are few practical books to enable them to learn the art. This step-by-step practical guide is intended mainly for postgraduate students and early career researchers in chemical science and the libraries that serve them but will also be useful to other scientists. Key Features: Improves the reader’s chances of getting their manuscript published in chemistry journals. Increases the likelihood of winning research grants in chemistry. Takes a “lead by the hand” approach. Contains chapters on the preparation of graphical abstracts and research highlights. Uses sketches and other illustration styles to aid mental visualization of concepts. Contains practical examples taken from published papers and successful research grant proposals.

Download or read book Low and Negative Thermal Expansion Materials written by David A. Woodcock and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polymer and Ceramic Composite Materials written by Noureddine Ramdani and published by CRC Press. This book was released on 2019-02-07 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes recent advances in the fabrication methods, properties, and applications of various ceramic-filled polymer matrix composites. Surface-modification methods and chemical functionalization of the ceramic fillers are explored in detail, and the outstanding thermal and mechanical properties of polymer–ceramic composites, the modeling of some of their thermal and mechanical parameters, and their major potential applications are discussed along with detailed examples. Aimed at researchers, industry professionals, and advanced students working in materials science and engineering, this work offering a review of a vast number of references in the polymer–ceramic field, this work helps readers easily advance their research and understanding of the field.

Download or read book Handbook of Polymer Synthesis Characterization and Processing written by Enrique Saldivar-Guerra and published by John Wiley & Sons. This book was released on 2013-02-28 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering a broad range of polymer science topics, Handbook of Polymer Synthesis, Characterization, and Processing provides polymer industry professionals and researchers in polymer science and technology with a single, comprehensive handbook summarizing all aspects involved in the polymer production chain. The handbook focuses on industrially important polymers, analytical techniques, and formulation methods, with chapters covering step-growth, radical, and co-polymerization, crosslinking and grafting, reaction engineering, advanced technology applications, including conjugated, dendritic, and nanomaterial polymers and emulsions, and characterization methods, including spectroscopy, light scattering, and microscopy.

Download or read book Synthesis Modelling and Characterization of 2D Materials and their Heterostructures written by Eui-Hyeok Yang and published by Elsevier. This book was released on 2020-06-19 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis, Modelling and Characterization of 2D Materials and Their Heterostructures provides a detailed discussion on the multiscale computational approach surrounding atomic, molecular and atomic-informed continuum models. In addition to a detailed theoretical description, this book provides example problems, sample code/script, and a discussion on how theoretical analysis provides insight into optimal experimental design. Furthermore, the book addresses the growth mechanism of these 2D materials, the formation of defects, and different lattice mismatch and interlayer interactions. Sections cover direct band gap, Raman scattering, extraordinary strong light matter interaction, layer dependent photoluminescence, and other physical properties. Explains multiscale computational techniques, from atomic to continuum scale, covering different time and length scales Provides fundamental theoretical insights, example problems, sample code and exercise problems Outlines major characterization and synthesis methods for different types of 2D materials