WorldWideScience

Sample records for anomalous thermal expansion

  1. Anomalous thermal expansion of Sb2Te3 topological insulator

    Science.gov (United States)

    Dutta, P.; Bhoi, D.; Midya, A.; Khan, N.; Mandal, P.; Shanmukharao Samatham, S.; Ganesan, V.

    2012-06-01

    We have investigated the temperature dependence of the linear thermal expansion along the hexagonal c axis (ΔL), in-plane resistivity (ρ), and specific heat (Cp) of the topological insulator Sb2Te3 single crystal. ΔL exhibits a clear anomaly in the temperature region 204-236 K. The coefficient of linear thermal expansion α decreases rapidly above 204 K, passes through a deep minimum at around 225 K, and then increases abruptly in the region 225-236 K. α is negative in the interval 221-228 K. The temperature dependence of both α and Cp can be described well by the Debye model from 2 to 290 K, excluding the region around the anomaly in α.

  2. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    Science.gov (United States)

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10−6 K−1, αb = 238.8 × 10−6 K−1 and αc = −290.0 × 10−6 K−1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  3. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals.

    Science.gov (United States)

    Panda, Manas K; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10(-6) K(-1), αb = 238.8 × 10(-6) K(-1) and αc = -290.0 × 10(-6) K(-1), the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  4. Phonons, nature of bonding, and their relation to anomalous thermal expansion behavior of M2O (M = Au, Ag, Cu)

    Science.gov (United States)

    Gupta, M. K.; Mittal, R.; Chaplot, S. L.; Rols, S.

    2014-03-01

    We report a comparative study of the dynamics of Cu2O, Ag2O, and Au2O (i.e., M2O with M = Au, Ag, and Cu) using first principle calculations based on the density functional theory. Here, for the first time, we show that the nature of chemical bonding and open space in the unit cell are directly related to the magnitude of thermal expansion coefficient. A good match between the calculated phonon density of states and that derived from inelastic neutron scattering measurements is obtained for Cu2O and Ag2O. The calculated thermal expansions of Ag2O and Cu2O are negative, in agreement with available experimental data, while it is found to be positive for Au2O. We identify the low energy phonon modes responsible for this anomalous thermal expansion. We further calculate the charge density in the three compounds and find that the magnitude of the ionic character of the Ag2O, Cu2O, and Au2O crystals is in decreasing order, with an Au-O bond of covalent nature strongly rigidifying the Au4O tetrahedral units. The nature of the chemical bonding is also found to be an important ingredient to understand the large shift of the phonon frequencies of these solids with pressure and temperature. In particular, the quartic component of the anharmonic term in the crystal potential is able to account for the temperature dependence of the phonon modes.

  5. Negative thermal expansion and associated anomalous physical properties: review of the lattice dynamics theoretical foundation

    Science.gov (United States)

    Dove, Martin T.; Fang, Hong

    2016-06-01

    Negative thermal expansion (NTE) is the phenomenon in which materials shrink rather than expand on heating. Although NTE had been previously observed in a few simple materials at low temperature, it was the realisation in 1996 that some materials have NTE over very wide ranges of temperature that kick-started current interest in this phenomenon. Now, nearly two decades later, a number of families of ceramic NTE materials have been identified. Increasingly quantitative studies focus on the mechanism of NTE, through techniques such as high-pressure diffraction, local structure probes, inelastic neutron scattering and atomistic simulation. In this paper we review our understanding of vibrational mechanisms of NTE for a range of materials. We identify a number of different cases, some of which involve a small number of phonons that can be described as involving rotations of rigid polyhedral groups of atoms, others where there are large bands of phonons involved, and some where the transverse acoustic modes provide the main contribution to NTE. In a few cases the elasticity of NTE materials has been studied under pressure, identifying an elastic softening under pressure. We propose that this property, called pressure-induced softening, is closely linked to NTE, which we can demonstrate using a simple model to describe NTE materials. There has also been recent interest in the role of intrinsic anharmonic interactions on NTE, particularly guided by calculations of the potential energy wells for relevant phonons. We review these effects, and show how anhamonicity affects the response of the properties of NTE materials to pressure.

  6. Isotropic Negative Thermal Expansion Metamaterials.

    Science.gov (United States)

    Wu, Lingling; Li, Bo; Zhou, Ji

    2016-07-13

    Negative thermal expansion materials are important and desirable in science and engineering applications. However, natural materials with isotropic negative thermal expansion are rare and usually unsatisfied in performance. Here, we propose a novel method to achieve two- and three-dimensional negative thermal expansion metamaterials via antichiral structures. The two-dimensional metamaterial is constructed with unit cells that combine bimaterial strips and antichiral structures, while the three-dimensional metamaterial is fabricated by a multimaterial 3D printing process. Both experimental and simulation results display isotropic negative thermal expansion property of the samples. The effective coefficient of negative thermal expansion of the proposed models is demonstrated to be dependent on the difference between the thermal expansion coefficient of the component materials, as well as on the circular node radius and the ligament length in the antichiral structures. The measured value of the linear negative thermal expansion coefficient of the three-dimensional sample is among the largest achieved in experiments to date. Our findings provide an easy and practical approach to obtaining materials with tunable negative thermal expansion on any scale.

  7. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  8. Low Thermal Expansion Glass Ceramics

    CERN Document Server

    Bach, Hans

    2005-01-01

    This book appears in the authoritative series reporting the international research and development activities conducted by the Schott group of companies. This series provides an overview of Schott's activities for scientists, engineers, and managers from all branches of industry worldwide in which glasses and glass ceramics are of interest. Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated. This new extended edition describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics. The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions. Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization. Thus g...

  9. Contribution of thermal expansion and

    Directory of Open Access Journals (Sweden)

    O.I.Pursky

    2007-01-01

    Full Text Available A theoretical model is developed to describe the experimental results obtained for the isobaric thermal conductivity of rare gas solids (RGS. The isobaric thermal conductivity of RGS has been analysed within Debye approximation with regard to the effect of thermal expansion. The suggested model takes into consideration the fact that thermal conductivity is determined by U-processes while above the phonon mobility edge it is determined by "diffusive" modes migrating randomly from site to site. The mobility edge ω0 is determined from the condition that the phonon mean-free path restricted by the U-processes cannot be smaller than half of the phonon wavelength.

  10. Thermal Expansion of Hafnium Carbide

    Science.gov (United States)

    Grisaffe, Salvatore J.

    1960-01-01

    Since hafnium carbide (HfC) has a melting point of 7029 deg. F, it may have many high-temperature applications. A literature search uncovered very little information about the properties of HfC, and so a program was initiated at the Lewis Research Center to determine some of the physical properties of this material. This note presents the results of the thermal expansion investigation. The thermal-expansion measurements were made with a Gaertner dilatation interferometer calibrated to an accuracy of +/- 1 deg. F. This device indicates expansion by the movement of fringes produced by the cancellation and reinforcement of fixed wave-length light rays which are reflected from the surfaces of two parallel quartz glass disks. The test specimens which separate these disks are three small cones, each approximately 0.20 in. high.

  11. The Thermal Expansion Of Feldspars

    Science.gov (United States)

    Hovis, G. L.; Medford, A.; Conlon, M.

    2009-12-01

    Hovis and others (1) investigated the thermal expansion of natural and synthetic AlSi3 feldspars and demonstrated that the coefficient of thermal expansion (α) decreases significantly, and linearly, with increasing room-temperature volume (VRT). In all such feldspars, therefore, chemical expansion limits thermal expansion. The scope of this work now has been broadened to include plagioclase and Ba-K feldspar crystalline solutions. X-ray powder diffraction data have been collected between room temperature and 925 °C on six plagioclase specimens ranging in composition from anorthite to oligoclase. When combined with thermal expansion data for albite (2,3,4) a steep linear trend of α as a function of VRT emerges, reflecting how small changes in composition dramatically affect expansion behavior. The thermal expansion data for five synthetic Ba-K feldspars ranging in composition from 20 to 100 mole percent celsian, combined with data for pure K-feldspar (3,4), show α-VRT relationships similar in nature to the plagioclase series, but with a slope and intercept different from the latter. Taken as a group all Al2Si2 feldspars, including anorthite and celsian from the present study along with Sr- (5) and Pb-feldspar (6) from other workers, show very limited thermal expansion that, unlike AlSi3 feldspars, has little dependence on the divalent-ion (or M-) site occupant. This apparently is due to the necessitated alternation of Al and Si in the tetrahedral sites of these minerals (7), which in turn locks the tetrahedral framework and makes the M-site occupant nearly irrelevant to expansion behavior. Indeed, in feldspar series with coupled chemical substitution it is the change away from a 1:1 Al:Si ratio that gives feldspars greater freedom to expand. Overall, the relationships among α, chemical composition, and room-temperature volume provide useful predictive tools for estimating feldspar thermal expansion and give insight into the controls of expansion behavior in

  12. Anomalous thermal conductivity of monolayer boron nitride

    Science.gov (United States)

    Tabarraei, Alireza; Wang, Xiaonan

    2016-05-01

    In this paper, we use nonequilibrium molecular dynamics modeling to investigate the thermal properties of monolayer hexagonal boron nitride nanoribbons under uniaxial strain along their longitudinal axis. Our simulations predict that hexagonal boron nitride shows an anomalous thermal response to the applied uniaxial strain. Contrary to three dimensional materials, under uniaxial stretching, the thermal conductivity of boron nitride nanoribbons first increases rather than decreasing until it reaches its peak value and then starts decreasing. Under compressive strain, the thermal conductivity of monolayer boron nitride ribbons monolithically reduces rather than increasing. We use phonon spectrum and dispersion curves to investigate the mechanism responsible for the unexpected behavior. Our molecular dynamics modeling and density functional theory results show that application of longitudinal tensile strain leads to the reduction of the group velocities of longitudinal and transverse acoustic modes. Such a phonon softening mechanism acts to reduce the thermal conductivity of the nanoribbons. On the other hand, a significant increase in the group velocity (stiffening) of the flexural acoustic modes is observed, which counteracts the phonon softening effects of the longitudinal and transverse modes. The total thermal conductivity of the ribbons is a result of competition between these two mechanisms. At low tensile strain, the stiffening mechanism overcomes the softening mechanism which leads to an increase in the thermal conductivity. At higher tensile strain, the softening mechanism supersedes the stiffening and the thermal conductivity slightly reduces. Our simulations show that the decrease in the thermal conductivity under compressive strain is attributed to the formation of buckling defects which reduces the phonon mean free path.

  13. Novel thermal expansion of lead titanate

    Institute of Scientific and Technical Information of China (English)

    XING Xianran; DENG Jinxia; CHEN Jun; LIU Guirong

    2003-01-01

    Lattice parameters of lead titanate were precisely re-determined in the ternperature range of-150-950℃ by high precision XRPD measurements. It was clarified that there was no any evidence for a new phase transition at low temperatures. Tetragonal distortion strain decreases with temperature increasing. A novel thermal expansion was observed, positive thermal expansion from-150℃ to room temperature (RT) and above 490℃, and the negative thermal expansion in the temperature range of RT-490℃. A big jump of thermal expansion coefficient is attributed to the tetragonal-cubic phase transition. A rationalization for the negative thermal expansion of PbTiO3 is due to the decrease of anion-anion repulsion as polyhedra become more regular at heating. The mechanisms of positive and negative thermal expansions were elucidated as the same nature in the homogenous tetragonal phase at present case.

  14. Structure and thermal expansion of liquid bismuth

    Directory of Open Access Journals (Sweden)

    Mudry S.

    2015-12-01

    Full Text Available Experimental structural data for liquid Bi were used for estimation of the main structure parameters as well as the thermal expansion coefficient both in supercooled and superheated temperature ranges. It was shown that the equilibrium melt had a positive thermal expansion coefficient within a temperature range upon melting and a negative one at higher temperatures. The former was related to structure changes upon melting, whereas the latter with topologic disordering upon further heating. It was found that the superheated melt had a negative thermal expansion coefficient. The results obtained from structural data were compared with the thermal expansion coefficient calculated from the data of density for liquid Bi.

  15. Anomalous lattice expansion in yttria stabilized zirconia under simultaneous applied electric and thermal fields: A time-resolved in situ energy dispersive x-ray diffractometry study with an ultrahigh energy synchrotron probe

    Energy Technology Data Exchange (ETDEWEB)

    Akdogan, E. K.; Savkl Latin-Small-Letter-Dotless-I y Latin-Small-Letter-Dotless-I ld Latin-Small-Letter-Dotless-I z, I.; Bicer, H.; Paxton, W.; Toksoy, F.; Tsakalakos, T. [Department of Materials Science and Engineering, Rutgers University, Piscataway, New Jersey 08854-8065 (United States); Zhong, Z. [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2013-06-21

    Nonisothermal densification in 8% yttria doped zirconia (8YSZ) particulate matter of 250 nm median particle size was studied under 215 V/cm dc electric field and 9 Degree-Sign C/min heating rate, using time-resolved in-situ high temperature energy dispersive x-ray diffractometry with a polychromatic 200 keV synchrotron probe. Densification occurred in the 876-905 Degree-Sign C range, which resulted in 97% of the theoretical density. No local melting at particle-particle contacts was observed in scanning electron micrographs, implying densification was due to solid state mass transport processes. The maximum current draw at 905 Degree-Sign C was 3 A, corresponding to instantaneous absorbed power density of 570 W/cm{sup 3}. Densification of 8YSZ was accompanied by anomalous elastic volume expansions of the unit cell by 0.45% and 2.80% at 847 Degree-Sign C and 905 Degree-Sign C, respectively. The anomalous expansion at 905 Degree-Sign C at which maximum densification was observed is characterized by three stages: (I) linear stage, (II) anomalous stage, and (III) anelastic recovery stage. The densification in stage I (184 s) and II (15 s) was completed in 199 s, while anelastic relaxation in stage III lasted 130 s. The residual strains ({epsilon}) at room temperature, as computed from tetragonal (112) and (211) reflections, are {epsilon}{sub (112)} = 0.05% and {epsilon}{sub (211)} = 0.13%, respectively. Time dependence of (211) and (112) peak widths ({beta}) show a decrease with both exhibiting a singularity at 905 Degree-Sign C. An anisotropy in (112) and (211) peak widths of {l_brace} {beta}{sub (112)}/{beta}{sub (211)}{r_brace} = (3:1) magnitude was observed. No phase transformation occurred at 905 Degree-Sign C as verified from diffraction spectra on both sides of the singularity, i.e., the unit cell symmetry remains tetragonal. We attribute the reduction in densification temperature and time to ultrafast ambipolar diffusion of species arising from the

  16. Negative thermal expansion materials: technological key for control of thermal expansion

    OpenAIRE

    Koshi Takenaka

    2012-01-01

    Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining pra...

  17. Thermal Expansion Coefficients of Thin Crystal Films

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

  18. Thermal expansion coefficient of binary semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, V.; Sastry, B.S.R. [Indian School of Mines, Dhanbad (India). Dept. of Electronics and Instrumentation

    2001-07-01

    The linear thermal expansion coefficient of tetrahedrally coordinated A{sup II}B{sup VI} and A{sup III}B{sup V} semiconductors has been calculated using plasmon energy data. A simple relation between the bond length and plasmon energy has been derived. The calculated values of thermal expansion coefficient and bond length have been compared with the experimental values and the values reported by different workers. An excellent experiment has been obtained between them. (orig.)

  19. Thermal expansion of doped lanthanum gallates

    Indian Academy of Sciences (India)

    K T Jacob; S Jain; V S Saji; P V K Srikanth

    2010-08-01

    Thermal expansion of several compositions of Sr and Mg-doped LaGaO3 including an -site deficient composition (La0.9Sr0.1)0.98(Ga0.8Mg0.2)O2.821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of the perovskite structure (either or ), while keeping the composition at the other site invariant. Thermal expansion varied nonlinearly with temperature and exhibited an inflexion between 550 and 620 K, probably related to the change in crystal structure from orthorhombic to rhombohedral. The dependence of average thermal expansion coefficient (av) on the dopant concentration on either or site of the perovskite structure was found to be linear, when the composition at the other site was kept constant. Mg doping on the -site had a greater effect on the average thermal expansion coefficient than Sr doping on the -site. Cation deficiency at the -site decreases thermal expansion when compositions at both sites are held constant.

  20. Negative thermal expansion materials: technological key for control of thermal expansion

    Directory of Open Access Journals (Sweden)

    Koshi Takenaka

    2012-01-01

    Full Text Available Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.

  1. Fuel Thermal Expansion (FTHEXP). [BWR; PWR

    Energy Technology Data Exchange (ETDEWEB)

    Reymann, G. A.

    1978-07-01

    A model is presented which deals with dimensional changes in LWR fuel pellets caused by changes in temperature. It is capable of dealing with any combination of UO/sub 2/ and PuO/sub 2/ in solid, liquid or mixed phase states, and includes expansion due to the solid-liquid phase change. The function FTHEXP models fuel thermal expansion as a function of temperature, fraction of PuO/sub 2/, and the fraction of fuel which is molten.

  2. Anomalous Thermal Transport in Quantum Wires

    OpenAIRE

    Fazio, Rosario; Hekking, F. W. J.; Khmelnitskii, D. E.

    1997-01-01

    We study thermal transport in a one-dimensional quantum wire, connected to reservoirs. Despite of the absence of electron backscattering, interactions in the wire strongly influence thermal transport. Electrons propagate with unitary transmission through the wire and electric conductance is not affected. Energy, however, is carried by bosonic excitations (plasmons) which suffer from scattering even on scales much larger than the Fermi wavelength. If the electron density varies randomly, plasm...

  3. Thermal expansion of Neapolitan Yellow Tuff

    Science.gov (United States)

    Aversa, S.; Evangelista, A.

    1993-10-01

    In saturated rocks and soils it is possible to define different coefficients of thermal expansion depending on the drainage conditions. This topic is first examined from the theoretical point of view with regard to an ideal isotropic thermo-elastic porous medium. Some special features of the behaviour of natural soils and rocks during thermal expansion tests are subsequently discussed. An experimental evaluation of some of these coefficients is presented in the second part of the paper. The material investigated is a pyroclastic rock, the so-called Neapolitan Yellow Tuff. Thermal expansion coefficient in drairend conditions has been evaluated, when this material is saturated with water. The e pressure increase induced by heating has been measured in undrained tes temperatures investigated range between room temperature up to 225°C. Different types of apparatus have been used and, when possible, a comparison between the results has been proposed. The results obtained in undrained thermal expansion tests are in agreement with theoretical predictions. This research is part of an on-going study of the complex phenomena known as Bradyseism, which is occurring in a volcanic area a few kilometers from Naples (Italy). Some considerations on this phenomenon are drawn in the last paragraph of the paper.

  4. Plastic Sealed Thermal Expansion Packer for Thermal Recovery

    Institute of Scientific and Technical Information of China (English)

    Liu Li; Jiang Hua

    1995-01-01

    @@ According to the requirements of wellbore heatinsulation technique and selective zonal steaminjection technique in heavy-oil steam-injection recovery process, the Oil Recovery Technique Department of Liaohe Petroleum Exploration and Production Bureau and Shuguang Oil Recovery Plant have cooperatively designed and developed a plastic sealed thermal expansion packer for thermal recovery.

  5. Principles of Thermal Expansion in Feldspars

    Science.gov (United States)

    Hovis, Guy; Medford, Aaron; Conlon, Maricate; Tether, Allison; Romanoski, Anthony

    2010-05-01

    Following the recent thermal expansion work of Hovis et al. (1) on AlSi3 feldspars, we have investigated the thermal expansion of plagioclase, Ba-K, and Ca-K feldspar crystalline solutions. X-ray powder diffraction data were collected between room temperature and 925 °C on six natural plagioclase specimens ranging in composition from anorthite to oligoclase, the K-exchanged equivalents of these plagioclase specimens, and five synthetic Ba-K feldspars with compositions ranging from 25 to 99 mol % BaAl2Si2O8. The resulting thermal expansion coefficients (α) for volume have been combined with earlier results for end-member Na- and K-feldspars (2,3). Unlike AlSi3 feldspars, Al2Si2 feldspars, including anorthite and celsian from the present study plus Sr- and Pb-feldspar from other workers (4,5), show essentially constant and very limited thermal expansion, regardless of divalent cation size. In the context of structures where the Lowenstein rule (6) requires Al and Si to alternate among tetrahedra, the proximity of bridging Al-O-Si oxygen ions to divalent neighbors (ranging from 0 to 2) produces short Ca-O (or Ba-O) bonds (7,8) that apparently are the result of local charge-balance requirements (9). Gibbs et al. (10) suggest that short bonds such as these have a partially covalent character. This in turn stiffens the structure. Thus, for feldspar series with coupled substitution the change away from a purely divalent M-site occupant gives the substituting (less strongly bonded) monovalent cations increasingly greater influence on thermal expansion. Overall, then, thermal expansion in the feldspar system is well represented on a plot of α against room-temperature volume, where one sees a quadrilateral bounded by data for (A) AlSi3 feldspars whose expansion behavior is controlled largely by the size of the monovalent alkali-site occupant, (B) Al2Si2 feldspars whose expansion is uniformly limited by partially-covalent bonds between divalent M-site occupants and

  6. Preliminary thermal expansion screening data for tuffs

    Energy Technology Data Exchange (ETDEWEB)

    Lappin, A.R.

    1980-03-01

    A major variable in evaluating the potential of silicic tuffs for use in geologic disposal of heat-producing nuclear wastes is thermal expansion. Results of ambient-pressure linear expansion measurements on a group of tuffs that vary treatly in porosity and mineralogy are presente here. Thermal expansion of devitrified welded tuffs is generally linear with increasing temperature and independent of both porosity and heating rate. Mineralogic factors affecting behavior of these tuffs are limited to the presence or absence of cristobalite and altered biotite. The presence of cristobalite results in markedly nonlinear expansion above 200{sup 0}C. If biotite in biotite-hearing rocks alters even slightly to expandable clays, the behavior of these tuffs near the boiling point of water can be dominated by contraction of the expandable phase. Expansion of both high- and low-porosity tuffs containing hydrated silicic glass and/or expandable clays is complex. The behavior of these rocks appears to be completely dominated by dehydration of hydrous phases and, hence, should be critically dependent on fluid pressure. Valid extrapolation of the ambient-pressure results presented here to depths of interest for construction of a nuclear-waste repository will depend on a good understanding of the interaction of dehydration rates and fluid pressures, and of the effects of both micro- and macrofractures on the response of tuff masss.

  7. Thermal expansion in lead zirconate titanate

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The volume anomalies with temperature variations in tin-modified lead zirconate titanate ceramics are investigated. Experimental results show that the volume changes are related to the phase transitions induced with temperature. The magnitude and orientation of crystal volume changes are dependent on the particular phase transition. When antiferroelectrics is transformed to ferroelectrics or paraelectrics the volume expands. Oppositely when ferroelectrics is transformed to antiferroelectrics or paraelectrics the volume contracts. In the transition of antiferroelectric orthorhombic structure to tetragonal structure or ferroelectric low-temperature rhombohedral structure to high-tem- perature rhombohedral structure, there are also revealed apparent anomalies in the curves of thermal expansion. Among them, the volume strain caused by the transition between antiferroelectrics and ferroelectrics is the biggest in magnitude, and the linear expansion dL/L0 and the expansion coefficient (dL/L0)/dT can reach 2.810?3 and 7.5 × 10?4 K?1 respectively.

  8. Graphite thermal expansion reference for high temperature

    Science.gov (United States)

    Gaal, P. S.

    1974-01-01

    The design requirements of the aerospace and high-temperature nuclear reactor industries necessitate reliable thermal expansion data for graphite and other carbonaceous materials. The feasibility of an acceptable reference for calibration of expansion measuring systems that operate in carbon-rich atmospheres at temperatures ranging to 2500 C is the prime subject of this work. Present-day graphite technology provides acceptable materials for stable, reproducible references, as reflected by some of the candidate materials. The repeatability for a single specimen in a given expansion measuring system was found to be plus or minus 1%, while the combined results of several tests made on a number of samples fell within a plus or minus 2.5% band.

  9. Negative thermal expansion in framework compounds

    Indian Academy of Sciences (India)

    R Mittal

    2008-10-01

    We have studied negative thermal expansion (NTE) compounds with chemi- cal compositions of NX2O8 and NX2O7 (N=Zr, Hf and X=W, Mo, V) and M2O (M=Cu, Ag) using the techniques of inelastic neutron scattering and lattice dynamics. There is a large variation in the negative thermal expansion coefficients of these compounds. The inelastic neutron scattering experiments have been carried out using polycrystalline and single crystal samples at ambient pressure as well as at high pressures. Experimental data are useful to confirm the predictions made from our lattice dynamical calculations as well as to check the quality of the interatomic potentials developed by us. We have been able to successfully model the NTE behaviour of these compounds. Our studies show that unusual phonon softening of low energy modes is able to account for NTE in these compounds.

  10. Frequency dependent thermal expansion in binary viscoelasticcomposites

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, James G.

    2007-12-01

    The effective thermal expansion coefficient beta* of abinary viscoelastic composite is shown to be frequency dependent even ifthe thermal expansion coefficients beta A and beta B of both constituentsare themselves frequency independent. Exact calculations for binaryviscoelastic systems show that beta* is related to constituent valuesbeta A, beta B, volume fractions, and bulk moduli KA, KB, as well as tothe overall bulk modulus K* of the composite system. Then, beta* isdetermined for isotropic systems by first bounding (or measuring) K* andtherefore beta*. For anisotropic systems with hexagonal symmetry, theprincipal values of the thermal expansion beta*perp and beta*para can bedetermined exactly when the constituents form a layered system. In allthe examples studied, it is shown explicitly that the eigenvectors of thethermoviscoelastic system possess non-negative dissipation -- despite thecomplicated analytical behavior of the frequency dependent thermalexpansivities themselves. Methods presented have a variety ofapplications from fluid-fluid mixtures to fluid-solid suspensions, andfrom fluid-saturated porous media to viscoelastic solid-solidcomposites.

  11. 6th International Symposium on Thermal Expansion

    CERN Document Server

    1978-01-01

    This 6th International Symposium on Thermal Expansion, the first outside the USA, was held on August 29-31, 1977 at the Gull Harbour Resort on Hecla Island, Manitoba, Canada. Symposium Chairman was Ian D. Peggs, Atomic Energy of Canada Limited, and our continuing sponsor was CINDAS/Purdue University. We made considerable efforts to broaden the base this year to include more users of expansion data but with little success. We were successful, however, in establishing a session on liquids, an area which is receiving more attention as a logical extension to the high-speed thermophysical property measurements on materials at temperatures close to their melting points. The Symposium had good international representation but the overall attendance was, disappointingly, relatively low. Neverthe­ less, this enhanced the informal atmosphere throughout the meeting with a resultant frank exchange of information and ideas which all attendees appreciated. A totally new item this year was the presentation of a bursary to ...

  12. Estimation of thermal expansion properties of quasicrystalline alloys

    Institute of Scientific and Technical Information of China (English)

    齐育红; 张占平; 黑祖昆

    2004-01-01

    By investigating the thermal expansion properties of three quasicrystalline alloys Al65 Cu20 Cr15 quenched,Al65Cu20Cr15 cast and Al65Cu20Fe15 cast particles reinforced Al matrix composites from 25 ℃ to 500 ℃, the thermal expansion coefficients of three quasicrystalline alloys were theoretically estimated. The results show that the thermal expansion coefficients of the composites are much lower than that of pure Al, and the thermal expansion coefficients of the composites reinforced by Al-Cu-Cr quasicrystalline particles are lower than those of the composites reinforced by Al-Cu-Fe quasicrystalline particles. According to estimating, quasicrystalline alloys have negative thermal expansion coefficients, and the thermal expansion coefficients of Al-Cu-Cr quasicrystalline alloys are lower than those of Al-Cu-Fe quasicrystalline alloys. In the alloys, the more the qusicrystalline content, the lower the thermal expansion coefficient.

  13. Anomalous Expansion of Coronal Mass Ejections During Solar Cycle 24 and Its Space Weather Implications

    Science.gov (United States)

    Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong; Makela, Pertti; Michalek, Grzegorz

    2014-01-01

    The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due to the weak solar activity. The total pressure in the heliosphere (magnetic + plasma) is reduced by approximately 40%, which leads to the anomalous expansion of CMEs explaining the increased slope. The excess CME expansion contributes to the diminished effectiveness of CMEs in producing magnetic storms during cycle 24, both because the magnetic content of the CMEs is diluted and also because of the weaker ambient fields. The reduced magnetic field in the heliosphere may contribute to the lack of solar energetic particles accelerated to very high energies during this cycle.

  14. Anomalous Expansion of Coronal Mass Ejections during Solar Cycle 24 and its Space Weather Implications

    CERN Document Server

    Gopalswamy, Nat; Yashiro, Seiji; Xie, Hong; Mäkelä, Pertti; Michalek, Grzegorz

    2014-01-01

    The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due to the weak solar activity. The total pressure in the heliosphere (magnetic + plasma) is reduced by ~40%, which leads to the anomalous expansion of CMEs explaining the increased slope. The excess CME expansion contributes to the diminished effectiveness of CMEs in producing magnetic storms during cycle 24, both because the magnetic content of the CMEs is diluted and also because of the weaker ambient fields. The reduced magnetic field in the heliosphere may contribute to the lack of solar energetic particles accelerated to very high energies during this cycle.

  15. Thermal expansion of molten uranium dioxide

    International Nuclear Information System (INIS)

    The density and thermal expansion of molten UO2 were measured from 3120 to 32500K using the gamma attenuation technique. The density-temperature relation for molten UO2 was found to be rho(T) = (8.86 +- 0.06) - (9.16 +- 0.43) x 10-4 x (T - 31200K) for rho in g/cm3 and T in 0K. The results agreed within experimental error with the single previous measurement. However, the value of the first derivative of density in the molten phase with respect to temperature was found to be approximately 50% higher than the value recommended in a review of properties for reactor safety analysis. 4 figures

  16. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization.

    Science.gov (United States)

    Salim, Michael A; Willow, Soohaeng Yoo; Hirata, So

    2016-05-28

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  17. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization

    Science.gov (United States)

    Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So

    2016-05-01

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  18. Micro-architected Composite Lattices with Tunable Negative Thermal Expansions

    Science.gov (United States)

    Wang, Qiming

    Solid materials with minimum or negative thermal expansion (NTE) have broad applications, from dental fillings to thermal-sensitive precision instruments. Previous studies on NTE structures were mostly focused on theoretically design and 2D experimental demonstrations. Here, aided with multimaterial projection micro-stereolithography, we experimentally fabricate multi-material composite lattices that exhibit significant negative thermal expansion in three directions and over a large range of temperature variations. The negative thermal expansion is induced by the structural interaction of material components with distinct thermal expansion coefficients. The NTE performance can be tuned over a large range by varying the thermal expansion coefficient difference between constituent beams and geometrical arrangement. Our experimental results match qualitatively with a simple scaling law and quantitatively consistently with computational models.

  19. Thermal expansion accompanying the glass-liquid transition and crystallization

    Directory of Open Access Journals (Sweden)

    M. Q. Jiang

    2015-12-01

    Full Text Available We report the linear thermal expansion behaviors of a Zr-based (Vitreloy 1 bulk metallic glass in its as-cast, annealed and crystallized states. Accompanying the glass-liquid transition, the as-cast Vitreloy 1 shows a continuous decrease in the thermal expansivity, whereas the annealed glass shows a sudden increase. The crystallized Vitreloy 1 exhibits an almost unchanged thermal expansivity prior to its melting. Furthermore, it is demonstrated that the nucleation of crystalline phases can induce a significant thermal shrinkage of the supercooled liquid, but with the growth of these nuclei, the thermal expansion again dominates. These results are explained in the framework of the potential energy landscape, advocating that the configurational and vibrational contributions to the thermal expansion of the glass depend on both, structure and temperature.

  20. Anisotropic expansion of a thermal dipolar Bose gas

    CERN Document Server

    Tang, Yijun; Burdick, Nathaniel Q; DiSciacca, Jack M; Petrov, Dmitry S; Lev, Benjamin L

    2016-01-01

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the post-expansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases, reducing error in expansion thermometry from tens of percent to only a few percent. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.

  1. Thermal and Hygric Expansion of High Performance Concrete

    Directory of Open Access Journals (Sweden)

    J. Toman

    2001-01-01

    Full Text Available The linear thermal expansion coefficient of two types of high performance concrete was measured in the temperature range from 20 °C to 1000 °C, and the linear hygric expansion coefficient was determined in the moisture range from dry material to saturation water content. Comparative methods were applied for measurements of both coefficients. The experimental results show that both the effect of temperature on the values of linear thermal expansion coefficients and the effect of moisture on the values of linear hygric expansion coefficients are very significant and cannot be neglected in practical applications.

  2. Impact of size and temperature on thermal expansion of nanomaterials

    Indian Academy of Sciences (India)

    Madan Singh; Mahipal Singh

    2015-04-01

    A theoretical method has been discussed to study the size dependency of thermal expansion of nanomaterials at higher temperature by considering the surface effect. A thermodynamical analysis of the equation of state (EoS) is studied from the knowledge of thermal expansion of nano-materials based on theoretical thermodynamical relations. It is observed that thermal expansion coefficient increases with decrease in grain size whereas, /0 increases with increase in temperature for nanomaterials of different grain sizes. We have studied the size and temperature dependence of thermal expansion of Cu, Ag, Ni, Sn, Se and Zn nanomaterials in different shapes (spherical, nanowire and nanofilm). The available experimental data confirm these theoretical predictions that demonstrate the validity of our work.

  3. Seal assembly for materials with different coefficients of thermal expansion

    Science.gov (United States)

    Minford, Eric

    2009-09-01

    Seal assembly comprising (a) two or more seal elements, each element having having a coefficient of thermal expansion; and (b) a clamping element having a first segment, a second segment, and a connecting segment between and attached to the first and second segments, wherein the two or more seal elements are disposed between the first and second segments of the clamping element. The connecting segment has a central portion extending between the first segment of the clamping element and the second segment of the clamping element, and the connecting segment is made of a material having a coefficient of thermal expansion. The coefficient of thermal expansion of the material of the connecting segment is intermediate the largest and smallest of the coefficients of thermal expansion of the materials of the two or more seal elements.

  4. The current status of controlled thermal expansion superalloys

    Science.gov (United States)

    Wanner, E. A.; Deantonio, D. A.; Smith, D. F.; Smith, J. S.

    1991-03-01

    Controlled thermal expansion superalloys, used primarily in aerospace applications at temperatures up to 649°C, provide coefficients of thermal expansion approximately 40 percent less than those of conventional superalloys. Since their first introduction in the early 1970s, continued progress has increased the capability of these materials. Various alterations in alloying elements were found to have a profound effect on the properties of the materials; ongoing work is aimed at extending the progress.

  5. Thermal expansion of spinel-type Si3N4

    DEFF Research Database (Denmark)

    Paszkowics, W.; Minkikayev, R.; Piszora, P.;

    2004-01-01

    The lattice parameter and thermal expansion coefficient (TEC) for the spinel-type Si3N4 phase prepared under high-pressure and high-temperature conditions are determined for 14 K......The lattice parameter and thermal expansion coefficient (TEC) for the spinel-type Si3N4 phase prepared under high-pressure and high-temperature conditions are determined for 14 K...

  6. Anomalous thermal contraction of the first coordination shell in metallic alloy liquids.

    Science.gov (United States)

    Gangopadhyay, A K; Blodgett, M E; Johnson, M L; McKnight, J; Wessels, V; Vogt, A J; Mauro, N A; Bendert, J C; Soklaski, R; Yang, L; Kelton, K F

    2014-01-28

    Except for a few anomalous solids and liquids, materials expand upon heating. For liquids, this should be reflected as a shift in the peak positions in the pair correlation function, g(r), to higher r. Here, we present the results of a detailed study of the volume thermal expansion coefficients and the temperature dependences of g(r) for a large number of binary, ternary, and quaternary liquids in the equilibrium and supercooled (metastable liquid below the liquidus temperature) states. The data were obtained from x-ray scattering and volume measurements on levitated liquids using the electrostatic levitation technique. Although the volumes of all liquids expand with increasing temperature, the peak positions in g(r) for the first coordination shells contract for the majority of alloy liquids studied. The second and third peaks in g(r) expand, but at rates different from those expected from the volume expansion. This behavior is explained qualitatively in terms of changes in the coordination numbers and bond-lengths as clusters in liquids break up with increasing temperature. PMID:25669553

  7. Method of minimizing liner expansion issues in horizontal thermal applications

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, R.; Cavender, T. [Halliburton, Houston, TX (United States)

    2009-07-01

    This study reviewed well casing and liner applications used in a variety of thermal recovery operations such as steam-assisted gravity drainage (SAGD), cyclic steam stimulation (CSS), steam flooding, multilateral injection, and steam enhanced oil recovery (EOR) in depleted cold heavy-oil production with sand (CHOPS) recovery methods. Completion casing and liners are typically deployed at relatively low downhole temperature conditions. Subsequent steam injection then causes downhole temperatures to increase, causing thermal expansion in downhole tubulars and other components. The thermal stresses can result in tubular buckling and parting. Providing room for expansion when downhole components are heated can reduce the risk of failures. This study discussed a temperature-activated travel joint designed to function as a static pup joint or casing collar. The device transmits full torque and tensile strength when temperatures remain below a predetermined value. When steam or other thermal fluids are introduced into the well, thermal expansion devices are activated in order to allow the thermal expansion of adjacent components without associated thermal expansion-related stresses. Tests conducted to validate the design showed that the technology can be used with slotted liner and sand screen applications as well as with concentric tubing configurations. 9 refs., 14 figs.

  8. Anisotropic Expansion of a Thermal Dipolar Bose Gas

    Science.gov (United States)

    Tang, Y.; Sykes, A. G.; Burdick, N. Q.; DiSciacca, J. M.; Petrov, D. S.; Lev, B. L.

    2016-10-01

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the postexpansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.

  9. Strong anisotropic thermal expansion in cristobalite-type BPO 4

    Science.gov (United States)

    Achary, S. N.; Tyagi, A. K.

    2004-11-01

    In this communication, the thermal expansion behavior of cristobalite-type BPO 4, determined from high-temperature X-ray diffraction studies, is being reported. BPO 4 crystallizes in tetragonal lattice, with space group I-4 (No. 82) at room temperature, with unit cell parameters: a=4.3447(2), c=6.6415(5) Å and V=125.37(1) Å 3. The tetragonal unit cell parameters at 900 °C are: a=4.3939(2), c=6.6539(6) Å and V=128.46(1) Å 3. The results show a very strong anisotropic expansion in the lattice, with the typical thermal expansion coefficients along a- and c-axis 12.9×10 -6 and 2.1×10 -6/°C, respectively. The volume thermal expansion coefficient of the lattice is 28.2×10 -6/°C in the temperature range of 25-900 °C. The variation of the crystal structure with temperature and the thermal expansion behavior are explained in this manuscript. The role of inter-polyhedral angle on the thermal expansion behavior has also been established.

  10. Thermal expansion of solid solutions in apatite binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Alexander V.; Bulanov, Evgeny N., E-mail: bulanoven@gmail.com; Korokin, Vitaly Zh.

    2015-01-15

    Graphical abstract: Thermal dependencies of volume thermal expansion parameter for with thermal expansion diagrams for Pb{sub 5}(PO{sub 4}){sub 3}F{sub x}Cl{sub 1−x}. - Highlights: • Solid solutions in three apatitic binary systems were investigated via HT-XRD. • Thermal expansion coefficients of solid solutions in the systems were calculated. • Features of the thermal deformation of the apatites were described. • Termoroentgenography is a sensitive method for the investigation of isomorphism. - Abstract: High-temperature insitu X-ray diffraction was used to investigate isomorphism and the thermal expansion of apatite-structured compounds in three binary systems in the entire temperature range of the existence of its hexagonal modifications. Most of the studied compounds are highly expandable (α{sub l} > 8 × 10{sup 6} (K{sup −1})). In Pb{sub 5}(PO{sub 4}){sub 3}F–Pb{sub 5}(PO{sub 4}){sub 3}Cl system, volume thermal expansion coefficient is independence from the composition at 573 K. In Pb{sub 5}(PO{sub 4}){sub 3}Cl–Pb{sub 5}(VO{sub 4}){sub 3}Cl, the compound with equimolar ratio of substituted atoms has constant volume thermal expansion coefficient in temperature range 298–973 K. Ca{sub 5}(PO{sub 4}){sub 3}Cl–Pb{sub 5}(PO{sub 4}){sub 3}Cl system is characterized by the most thermal sensitive composition, in which there is an equal ratio of isomorphic substituted atoms.

  11. Ab-initio study of thermal expansion in pure graphene

    Science.gov (United States)

    Mann, Sarita; Rani, Pooja; Kumar, Ranjan; Jindal, V. K.

    2016-05-01

    Graphene is a zero band gap semiconductor with exceptionally high thermal conductivity. The electronic properties having been studied, therole of phonon in contributing to thermal expansion, thermal conductivity and other thermodynamic properties, is required to be investigated. This paper focuses more on thermal expansion. Some others results like phonon dispersion, Grüneisenparameters and bulk modulus,which are essential to estimation of thermal expansion, are also presented. The dynamical matrix was calculated using VASP code using both DFT and DFPTand the phonon frequencies were calculated using phonopy code under harmonic approximation. The linear thermal expansion coefficient of graphene is found to be strongly dependent on temperature but remains negative upto 470 K and positive thereafter, with a room temperature value of -1.44×10-6. The negative expansion coefficient is very interesting and is found to be in conformity with experimental as well as with recent theoretical estimates. There is only qualitative agreement of our results with experimental data and motivates further investigation, primarily on the high negative values of Grüneisen parameters.

  12. Thermal Expansion Behavior of Hot-Pressed Engineered Matrices

    Science.gov (United States)

    Raj, S. V.

    2016-01-01

    Advanced engineered matrix composites (EMCs) require that the coefficient of thermal expansion (CTE) of the engineered matrix (EM) matches those of the fiber reinforcements as closely as possible in order to reduce thermal compatibility strains during heating and cooling of the composites. The present paper proposes a general concept for designing suitable matrices for long fiber reinforced composites using a rule of mixtures (ROM) approach to minimize the global differences in the thermal expansion mismatches between the fibers and the engineered matrix. Proof-of-concept studies were conducted to demonstrate the validity of the concept.

  13. Zirconium titanate: stability and thermal expansion; Titanato de circonio: estabilidad termodinamica y expansion termica

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Lopez, E.; Moreno, R.; Baudin, C.

    2011-07-01

    Zirconium titanate is a well known compound in the field of electro ceramics, although it has also been used in catalyst and sensors applications. The crystallographic thermal expansion anisotropy of this compound makes it a potential candidate as constituent of structural components. In general, to assure the structural integrity and microstructural homogeneity of a ceramic piece, relatively low cooling rates from the fabrication temperature are required. This requirement is essential for zirconium titanate because thermal expansion as well as phase distribution is affected by small variations in the composition and cooling rate. This work reviews the available data on the phase equilibrium relationships in the systems ZrO{sub 2}-TiO{sub 2} and ZrO{sub 2}-TiO{sub 2}-Y{sub 2}O{sub 3}. The main discrepancies as well as the possible origins of them are discussed. Additionally, the crystallographic thermal expansion data in the current literature are reviewed. (Author) 56 refs.

  14. Elastic and thermal expansion asymmetry in dense molecular materials

    Science.gov (United States)

    Burg, Joseph A.; Dauskardt, Reinhold H.

    2016-09-01

    The elastic modulus and coefficient of thermal expansion are fundamental properties of elastically stiff molecular materials and are assumed to be the same (symmetric) under both tension and compression loading. We show that molecular materials can have a marked asymmetric elastic modulus and coefficient of thermal expansion that are inherently related to terminal chemical groups that limit molecular network connectivity. In compression, terminal groups sterically interact to stiffen the network, whereas in tension they interact less and disconnect the network. The existence of asymmetric elastic and thermal expansion behaviour has fundamental implications for computational approaches to molecular materials modelling and practical implications on the thermomechanical strains and associated elastic stresses. We develop a design space to control the degree of elastic asymmetry in molecular materials, a vital step towards understanding their integration into device technologies.

  15. Design of materials with extreme thermal expansion using a three-phase topology optimization method

    DEFF Research Database (Denmark)

    Sigmund, Ole; Torquato, S.

    1997-01-01

    We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum thermal...... expansion, zero thermal expansion, and negative thermal expansion. Assuming linear elasticity, it is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion coefficients and void. We also show...... that there is no mechanistic relationship between negative thermal expansion and negative Poisson's ratio....

  16. Thermal expansion model for multiphase electronic packaging materials

    International Nuclear Information System (INIS)

    Control of thermal expansion is often necessary in the design and selection of electronic packages. In some instances, it is desirable to have a coefficient of thermal expansion intermediate between values readily attainable with single or two phase materials. The addition of a third phase in the form of fillers, whiskers, or fibers can be used to attain intermediate expansions. To help design the thermal expansion of multiphase materials for specific applications, a closed form model has been developed that accurately predicts the effective elastic properties of isotropic filled materials and transversely isotropic lamina. Properties of filled matrix materials are used as inputs to the lamina model to obtain the composite elastic properties as a function of the volume fraction of each phase. Hybrid composites with two or more fiber types are easily handled with this model. This paper reports that results for glass, quartz, and Kevlar fibers with beta-eucryptite filled polymer matrices show good agreement with experimental results for X, Y, and Z thermal expansion coefficients

  17. Thermal expansion behaviour of barium and strontium zirconium phosphates

    Indian Academy of Sciences (India)

    P Srikari Tantri; K Geetha; A M Umarji; Sheela K Ramasesha

    2000-12-01

    Ba1.5–SrZr4P5SiO24 compounds with = 0, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5, belonging to the low thermal expansion NZP family were synthesized by the solid state reaction method. The XRD pattern could be completely indexed with respect to R$\\bar{3}$ space group indicating the ordering of vacancy at the divalent cation octahedral sites. The microstructure and bulk thermal expansion coefficient from room temperature to 800°C of the sintered samples have been studied. All the samples show very low coefficient of thermal expansion (CTE), with = 0 samples showing negative expansion. A small substitution of strontium in the pure barium compound changes the sign of CTE. Similarly, = 1.5 sample (pure strontium) shows a positive CTE and a small substitution of barium changes its sign. = 1.0 and 1.25 samples have almost constant CTE over the entire temperature range. The low thermal expansion of these samples can be attributed to the ordering of the ions in the crystal structure of these materials.

  18. Uncertainty Analysis for a Simple Thermal Expansion Experiment

    CERN Document Server

    Dounas-Frazer, Dimitri R; Gandhi, Punit R

    2012-01-01

    We describe a simple experiment for measuring the thermal expansion coefficient of a metal wire and discuss how the experiment can be used as a tool for exploring the interplay of measurement uncertainty and scientific models. In particular, we probe the regimes of applicability of three models of the wire: stiff and massless, elastic and massless, and elastic and massive. Using both analytical and empirical techniques, we present the conditions under which the wire's mass and elasticity can be neglected. By accounting for these effects, we measure nichrome's thermal expansion coefficient to be 17.1(5) ppm/K, which is consistent with the accepted value at the 1% level.

  19. Thermal expansion measurement under pressure on SmS

    International Nuclear Information System (INIS)

    We measured the thermal expansion of a single-crystalline SmS sample under pressure along direction from 4.2 K to room temperature. We have found that the thermal expansion coefficient α shows a broad minimum in the so-called golden phase and can be described by a Schottky-type anomaly with an energy gap Δ. We have revealed that Δ decreases with increasing pressure and possibly disappears around PM∼20 kbar, above which the system is evidently in the metal phase

  20. Low temperature thermal expansion measurements on optical materials.

    Science.gov (United States)

    Browder, J S; Ballard, S S

    1969-04-01

    A three-terminal capacitance type dilatometer has been developed for investigating the thermal expansion of optical materials at low temperatures. The method is applicable when only small sample lengths (13 mm or less) are available. The thermal expansion coefficients of six polycrystalline materials (the Irtrans) and of one nonoxide glass have been determined in the range from room temperature down to about 60 K. Minute changes of the length of a sample produce a change of the spacing of a parallel plate capacitor with guard ring; the resulting change of capacitance is measured on a highly sensitive bridge. The expansion coefficients are then determined by relating the change of capacitance to the change of dimensions of the sample.

  1. Measurement of thermal expansion coefficient of nonuniform temperature specimen

    Institute of Scientific and Technical Information of China (English)

    Jingmin Dai; Chunsuo Kin; Xiaowa He

    2008-01-01

    A new technique is developed to measure the longitudinal thermal expansion coefficient of C/C composite material at high temperature. The measuring principle and components of the apparatus are described in detail. The calculation method is derived from the temperature dependence of the thermal expansion coefficient. The apparatus mainly consists of a high temperature environmental chamber, a power circuit of heating, two high-speed pyrometers, and a laser scanning system. A long solid specimen is resistively heated to a steady high-temperature state by a steady electrical current. The temperature profile of the specimen surface is not uniform because of the thermal conduction and radiation. The temperature profile and the total expansion are measured with a high-speed scanning pyrometer and a laser slit scanning measuring system, respectively. The thermal expansion coefficient in a wide temperature range (1000 - 3800 K) of the specimen can therefore be obtained. The perfect consistency between the present and previous results justifies the validity of this technique.

  2. COMPACT ATHERMAL OPTICAL WAVEGUIDE USING THERMAL EXPANSION AMPLIFICATION

    DEFF Research Database (Denmark)

    2001-01-01

    A method of temperature stabilising optical waveguides having positive thermal optical path length expansion, in particular fiber Bragg gratings or optical fiber DFB lasers or optical fiber DBR lasers, comprising affixing the optical waveguide to at least two points of a negative expanding fixture...

  3. Determination of effective thermal expansion coefficients of unidirectional fibrous nanocomposites

    Science.gov (United States)

    Dai, Ming; Schiavone, Peter; Gao, Cun-Fa

    2016-10-01

    We present an efficient numerical scheme (based on complex variable techniques) to calculate the effective thermal expansion coefficients of a composite containing unidirectional periodic fibers. Moreover, the mechanical behavior of the fibers incorporates interface effects allowing the ensuing analytical model of the composite to accommodate deformations at the nanoscale. The resulting `nanocomposite' is subjected to a uniform temperature variation which leads to periodic deformations within the plane perpendicular to the fibers and uniform deformations along the direction of the fibers. These deformation fields are determined by analyzing a representative unit cell of the composite subsequently leading to the corresponding effective thermal expansion coefficients. Numerical results are illustrated via several physical examples. We find that the influence of interface effects on the effective thermal expansion coefficients (in particular that corresponding to the transverse direction in the plane perpendicular to the fibers) decays rapidly as the fibers become harder. In addition, by comparing the results obtained here with those from effective medium theories, we show that the latter may induce significant errors in the determination of the effective transverse thermal expansion coefficient when the fibers are much softer than the matrix and the fiber volume fraction is relatively high.

  4. Thermal expansion in CuAlTe2 compounds

    International Nuclear Information System (INIS)

    The lattice parameters a and c as well as the axial thermal expansion coefficients α perpendicular and α parallel in CuAlTe2 chalcopyrite-type compounds are determined as a function of temperature in the range from 80 to 650 K by a X-ray diffractometry technique. The data obtained are used to evaluate the axial ratio c/a, the tetragonal distortion δ = 2 - c/a, the interatomic distances for Cu-Te and Al-Te bonds and their temperature coefficients. It is found that the thermal expansion behaviour of CuAlTe2 is similar to that of other CuBIIIC2VI compounds in having a relatively small expansivity along the c-axis and a large one in the perpendicular direction. When comparing the results for a series of the CuBIIIC2VI compounds (B-Al, Ga, In; C-S, Se, Te) it is shown that the correlations between the thermal expansion coefficients αperpendicular, αparallel, αm, dδ/dT and the tetragonal distortion δ, as well as the molar mass of the compound take place. (author)

  5. Compressibility and thermal expansion of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lindelov, H.; Gerward, Leif;

    2002-01-01

    The compressibility and thermal expansion of the cubic silicon nitride (c-Si3N4) phase have been investigated by performing in situ x-ray powder-diffraction measurements using synchrotron radiation, complemented with computer simulations by means of first-principles calculations. The bulk...... compressibility of the c-Si3N4 phase originates from the average of both Si-N tetrahedral and octahedral compressibilities where the octahedral polyhedra are less compressible than the tetrahedral ones. The origin of the unit cell expansion is revealed to be due to the increase of the octahedral Si-N and N-N bond...

  6. Landau Theory of Trifluoride Negative Thermal Expansion Materials

    Science.gov (United States)

    Guzman-Verri, Gian; Brierley, Richard; Littlewood, Peter

    Negative thermal expansion (NTE) is a desirable property in designing materials that are dimensionally stable and resistant to thermal shocks. Transition metal trifluorides (MF3, M=Al, Cr, Fe, Ga, In, Ti, V) are a class of materials with ReO3 structure that exhibit large, isotropic, and tunable NTE over a wide temperature range, which makes them attractive material candidates. They exhibit large coefficients of thermal expansion near their cubic-to-rhombohedral structural phase change, which can be thermally or pressure induced. Though they have recently been the subject of intense experimental research, little work has been done on the theory side and it has almost exclusively focused on zero temperature properties. In this talk, we construct a simple Landau theory of trifluorides and use it to calculate the temperature dependence of the elastic constants, soft phonon frequencies, and volume expansion near their structural transition. We compare our results to existing experimental data on trifluorides. Work at the U of Costa Rica is supported by the Vicerrectoria de Investigacion under Project No. B5220. Work at Argonne Natl Lab is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.

  7. DSLM Instructional Approach to Conceptual Change Involving Thermal Expansion

    Science.gov (United States)

    She, Hsiao-Ching

    2003-01-01

    This article examines the process of students' conceptual change involving thermal expansion as a result of employing the Dual Situated Learning Model (DSLM) (She, 2001, 2002) as a classroom instructional approach. The dual situated learning events of this model are designed according to the students' ontological viewpoint of the science concepts as well as the nature of these concepts. Moreover, these events serve two functions in creating dissonance with the pre-existing knowledge and providing new schema for constructing a more scientific view of the concept. DSLM has been shown to promote students' conceptual change using one-to-one instructional procedure (She, 2002). This study further demonstrates that DSLM holds great potential to facilitate the conceptual change process involving thermal expansion through classroom instruction, even the difficult concept or higher hierarchical level one.

  8. Measurement of Thermal Expansion Coefficients with Holographic Technique

    Institute of Scientific and Technical Information of China (English)

    ZhifengZhang

    1995-01-01

    A simplified mathematical model was created for measurement of thermal expansion coefficients of thin sheet materials with holographic technique.Experimental set-ups corresponding to the mathematical model were designed and built for both tests above room temperature and at low temperatures.A fringe control technique was introduced for low temperature measurements to compensate rigid body movement,THin sheet specimens of silicon and aluminum alloy(7075) were tested with the developed technique.The tested results are in good agreement with reported data and thus verify the validity of the developed technique.The Thermal expansion coefficients of the tested materials ranged from 2.5×10-60C-1 to 23.6×10-6oC-1.

  9. Network and guest dependent thermal stability and thermal expansion in a trigonal host

    Indian Academy of Sciences (India)

    Viswanadha G Saraswatula; Mukhtar Ahmad Bhat; Suman Bhattacharya; Binoy K Saha

    2014-09-01

    Thermal stability and thermal expansion of bromo trimer synthon mediated hexagonal inclusion compounds of 2,4,6-tris(4-bromophenoxy)-1,3,5-triazine (BrPOT) with dichloromethane (DCM), tetrahydrofuran (THF) and hexamethyl benzene (HMB) and also the guest-free form of BrPOT are reported. Each of these three guests produced two concomitant inclusion compounds with BrPOT. The thermal stability of the solvate lattice increases with decreasing cavity size. The channel network of the DCM inclusion compound is stable only for a few seconds at room temperature outside the mother liquor, whereas the cage network of the DCM solvate is stable for months under similar conditions. Thermal expansions of the lattices depend upon the network, guest content as well as the type of guest molecules. The guest-free form exhibits the least thermal expansion in this series of systems.

  10. Lunar Eclipse Observations Reveal Anomalous Thermal Performance of Apollo Reflectors

    CERN Document Server

    Murphy, T W; Johnson, N H; Goodrow, S D

    2013-01-01

    Laser ranging measurements during the total lunar eclipse on 2010 December 21 verify previously suspected thermal lensing in the retroreflectors left on the lunar surface by the Apollo astronauts. Signal levels during the eclipse far exceeded those historically seen at full moon, and varied over an order of magnitude as the eclipse progressed. These variations can be understood via a straightforward thermal scenario involving solar absorption by a ~50% covering of dust that has accumulated on the front surfaces of the reflectors. The same mechanism can explain the long-term degradation of signal from the reflectors as well as the acute signal deficit observed near full moon.

  11. On thermal expansion over the last hundred years

    OpenAIRE

    De Wolde, J. R.; Bintanja, R.; Oerlemans, J.

    1995-01-01

    Estimates of sea level rise during the period 1856-1991 due to thermal expansion are presented. The estimates are based on an ocean model that consists of three zonally averaged ocean basins representing the Atlantic, Pacific, and Indian Oceans. These basins are connected by a circumpolar basin that represents the Southern Ocean. The ocean circulation in the model was prescribed. Surface ocean forcing was calculated from observed sea surface temperatures. Global mean forcing and regionally va...

  12. Phonon anharmonicity and negative thermal expansion in SnSe

    Science.gov (United States)

    Bansal, Dipanshu; Hong, Jiawang; Li, Chen W.; May, Andrew F.; Porter, Wallace; Hu, Michael Y.; Abernathy, Douglas L.; Delaire, Olivier

    2016-08-01

    The anharmonic phonon properties of SnSe in the P n m a phase were investigated with a combination of experiments and first-principles simulations. Using inelastic neutron scattering (INS) and nuclear resonant inelastic X-ray scattering (NRIXS), we have measured the phonon dispersions and density of states (DOS) and their temperature dependence, which revealed a strong, inhomogeneous shift and broadening of the spectrum on warming. First-principles simulations were performed to rationalize these measurements, and to explain the previously reported anisotropic thermal expansion, in particular the negative thermal expansion within the Sn-Se bilayers. Including the anisotropic strain dependence of the phonon free energy, in addition to the electronic ground state energy, is essential to reproduce the negative thermal expansion. From the phonon DOS obtained with INS and additional calorimetry measurements, we quantify the harmonic, dilational, and anharmonic components of the phonon entropy, heat capacity, and free energy. The origin of the anharmonic phonon thermodynamics is linked to the electronic structure.

  13. The spectrum of the anomalous dimensions of the composite operators in the $\\varepsilon$- expansion in the scalar $\\phi^{4}$ - field theory

    CERN Document Server

    Derkachov, S E

    1995-01-01

    The spectrum of the anomalous dimensions of the composite operators (with arbitrary number of fields n and derivatives l) in the scalar \\phi^4 - theory in the first order of the \\epsilon -expansion is investigated. The exact solution for the operators with number of fields \\leq 4 is presented. The behaviour of the anomalous dimensions in the large l limit has been analyzed. It is given the qualitative description of the structure of the spectrum for the arbitrary n.

  14. Studies on thermal expansion and neutron irradiation effect of polycrystalline graphites

    International Nuclear Information System (INIS)

    For thermal expansion and neutron irradiation effect, thermal expansion coefficients and physical properties were measured of polycrystalline graphites, neutron irradiated, unirradiated, and compressively pre-stressed at room temperature, respectively. Factors involved in the thermal expansion were thus clarified. Relationship between thermal expansion coefficient and dimensional changes of graphites irradiated at high temperatures was studied. Thermal expansion and physical properties were measured of the irradiated graphites and subsequently after their thermal annealing at elevated temperatures. Behavior of the irradiation-induced defects is discussed. (author)

  15. Widespread range expansions shape latitudinal variation in insect thermal limits

    Science.gov (United States)

    Lancaster, Lesley T.

    2016-06-01

    Current anthropogenic impacts, including habitat modification and climate change, may contribute to a sixth mass extinction. To mitigate these impacts and slow further losses of biodiversity, we need to understand which species are most at risk and identify the factors contributing to current and future declines. Such information is often obtained through large-scale, comparative and biogeographic analysis of lineages or traits that are potentially sensitive to ongoing anthropogenic change--for instance to predict which regions are most susceptible to climate change-induced biodiversity loss. However, for this approach to be generally successful, the underlying causes of identified geographical trends need to be carefully considered. Here, I augment and reanalyse a global data set of insect thermal tolerances, evaluating the contribution of recent and contemporary range expansions to latitudinal variation in thermal niche breadth. Previous indications that high-latitude ectotherms exhibit broad thermal niches and high warming tolerances held only for species undergoing range expansions or invasions. In contrast, species with stable or declining geographic ranges exhibit latitudinally decreasing absolute thermal tolerances and no latitudinal variation in tolerance breadths. Thus, non-range-expanding species, particularly insular or endemic species, which are often of highest conservation priority, are unlikely to tolerate future climatic warming at high latitudes.

  16. Thermal expansion and magnetostriction studies on iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liran

    2010-09-19

    In this work, a 3-terminal capacitance dilatometer was set up and used for measurements of the thermal expansion and magnetostriction of novel superconducting iron pinictides and related materials. In particular, RFeAsO with R = La, Ce, Pr, Sm, Gd, LaFeASO{sub 1-x}F{sub x} and Ca(F{sub 1-c}Co{sub x}){sub 2}As{sub 2} have been investigated. The data on polycrystalline LaFeAsO{sub 1-x} are the first published thermal expansion data on this material. The lattice effects at the structural and the magnetic phase transition have been investigated and the phase diagram upon F-doping has been studied. A main result is the observation of a previously unknown fluctuation regime for the doping level x ≤ 0.04 over a large T range above the structural transition temperature T{sub S}. The absence of any structural anomalies in the normal state of the superconducting LaFeAlO{sub 1-x}F{sub x} samples with x ≥ 0.05 corroborates the discontinuous character of the phase boundary not only for the magnetism but also for the structural degrees of freedom. Similarly, the presence of high-temperature fluctuations is found for all RFeAsO undoped materials under study. The discussion of the probable origin of the fluctuations as well as the definition of the structural transition temperature T{sub S} are done. The low temperature features shown by the thermal expansion data for RFeAsO are caused by the onset of long range magnetic order of the 4f-moments and their different configurations. In particular, PrFeAsO, which has a very pronounced anomaly associated with Pr-ordering exhibits a large magnetostriction at low temperatures. By discussing this effect along with the magnetization, resistivity and other measurements, it is found that this large magneto-elastic effect may originate from the correlations between the momentum from Fe{sup 3+} and Pr{sup 3+}. Last, the thermal expansion of Ca(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} 122 single crystals is investigated. Ca(Fe{sub 1-x}Co{sub x

  17. Linear thermal expansion, thermal diffusivity and melting temperature of Am-MOX and Np-MOX

    Energy Technology Data Exchange (ETDEWEB)

    Prieur, D., E-mail: damien.prieur@ec.europa.eu [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, 76125 Karlsruhe (Germany); Belin, R.C. [CEA, DEN, DEC/SPUA/LMPC, F-13108 Saint-Paul-lez Durance (France); Manara, D.; Staicu, D. [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, 76125 Karlsruhe (Germany); Richaud, J.-C. [CEA, DEN, DEC/SPUA/LMPC, F-13108 Saint-Paul-lez Durance (France); Vigier, J.-F. [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, 76125 Karlsruhe (Germany); Scheinost, A.C. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, D-01314 Dresden (Germany); Somers, J. [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, 76125 Karlsruhe (Germany); Martin, P. [CEA, DEN, DEC/SESC/LLCC, 13108 Saint-Paul-lez-Durance cedex (France)

    2015-07-15

    Highlights: • The thermal properties of Np- and Am-MOX solid solutions were investigated. • Np- and Am-MOX solid solutions exhibit the same linear thermal expansion. • The thermal conductivity of Am-MOX is about 10% higher than that of Np-MOX. • The melting temperatures of Np-MOX and Am-MOX are 3020 ± 30 K and 3005 ± 30 K, respectively. - Abstract: The thermal properties of Np- and Am-MOX solid solution materials were investigated. Their linear thermal expansion, determined using high temperature X-ray diffraction from room temperature to 1973 K showed no significant difference between the Np and the Am doped MOX. The thermal conductivity of the Am-MOX is about 10% higher than that of Np-MOX. The melting temperatures of Np-MOX and Am-MOX, measured using a laser heating self crucible arrangement were 3020 ± 30 K and 3005 ± 30 K, respectively.

  18. Technique for predicting the thermal expansion coefficients of cryogenic metallic alloys

    Science.gov (United States)

    Clark, A. F.

    1969-01-01

    Series of measurements on the thermal expansion coefficients of several aerospace alloys and standard materials establish relationships between related alloys that would aid in predicting their thermal expansion reliability. Thermal expansion data are also necessary for the reduction of electrical resistivity measurements of those same materials.

  19. The Effect of Homogenization Heat Treatment on Thermal Expansion Coefficient and Dimensional Stability of Low Thermal Expansion Cast Irons

    Science.gov (United States)

    Chen, Li-Hao; Liu, Zong-Pei; Pan, Yung-Ning

    2016-05-01

    In this paper, the effect of homogenization heat treatment on α value [coefficient of thermal expansion (10-6 K-1)] of low thermal expansion cast irons was studied. In addition, constrained thermal cyclic tests were conducted to evaluate the dimensional stability of the low thermal expansion cast irons with various heat treatment conditions. The results indicate that when the alloys were homogenized at a relatively low temperature, e.g., 1023 K (750 °C), the elimination of Ni segregation was not very effective, but the C concentration in the matrix was moderately reduced. On the other hand, if the alloys were homogenized at a relatively high temperature, e.g., 1473 K (1200 °C), opposite results were obtained. Consequently, not much improvement (reduction) in α value was achieved in both cases. Therefore, a compound homogenization heat treatment procedure was designed, namely 1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ, in which a relatively high homogenization temperature of 1473 K (1200 °C) can effectively eliminate the Ni segregation, and a subsequent holding stage at 1023.15 K (750 °C) can reduce the C content in the matrix. As a result, very low α values of around (1 to 2) × 10-6 K-1 were obtained. Regarding the constrained thermal cyclic testing in 303 K to 473 K (30 °C to 200 °C), the results indicate that regardless of heat treatment condition, low thermal expansion cast irons exhibit exceedingly higher dimensional stability than either the regular ductile cast iron or the 304 stainless steel. Furthermore, positive correlation exists between the α 303.15 K to 473.15 K value and the amount of shape change after the thermal cyclic testing. Among the alloys investigated, Heat I-T3B (1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ) exhibits the lowest α 303 K to 473 K value (1.72 × 10-6 K-1), and hence has the least shape change (7.41 μm) or the best dimensional stability.

  20. The Effect of Homogenization Heat Treatment on Thermal Expansion Coefficient and Dimensional Stability of Low Thermal Expansion Cast Irons

    Science.gov (United States)

    Chen, Li-Hao; Liu, Zong-Pei; Pan, Yung-Ning

    2016-08-01

    In this paper, the effect of homogenization heat treatment on α value [coefficient of thermal expansion (10-6 K-1)] of low thermal expansion cast irons was studied. In addition, constrained thermal cyclic tests were conducted to evaluate the dimensional stability of the low thermal expansion cast irons with various heat treatment conditions. The results indicate that when the alloys were homogenized at a relatively low temperature, e.g., 1023 K (750 °C), the elimination of Ni segregation was not very effective, but the C concentration in the matrix was moderately reduced. On the other hand, if the alloys were homogenized at a relatively high temperature, e.g., 1473 K (1200 °C), opposite results were obtained. Consequently, not much improvement (reduction) in α value was achieved in both cases. Therefore, a compound homogenization heat treatment procedure was designed, namely 1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ, in which a relatively high homogenization temperature of 1473 K (1200 °C) can effectively eliminate the Ni segregation, and a subsequent holding stage at 1023.15 K (750 °C) can reduce the C content in the matrix. As a result, very low α values of around (1 to 2) × 10-6 K-1 were obtained. Regarding the constrained thermal cyclic testing in 303 K to 473 K (30 °C to 200 °C), the results indicate that regardless of heat treatment condition, low thermal expansion cast irons exhibit exceedingly higher dimensional stability than either the regular ductile cast iron or the 304 stainless steel. Furthermore, positive correlation exists between the α 303.15 K to 473.15 K value and the amount of shape change after the thermal cyclic testing. Among the alloys investigated, Heat I-T3B (1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ) exhibits the lowest α 303 K to 473 K value (1.72 × 10-6 K-1), and hence has the least shape change (7.41 μm) or the best dimensional stability.

  1. Thermal expansion behavior of fluor-chlorapatite crystalline solutions

    Science.gov (United States)

    Hovis, G.; Harlov, D.; Gottschalk, M.; Hudacek, W.; Wildermuth, S.

    2009-04-01

    Apatite Ca5(PO4)3(F,Cl,OH,CO3) occurs widely as an accessory mineral in many igneous and metamorphic rocks and in nature displays a wide range of F-Cl-OH-CO3 mixtures (e.g., O'Reilly and Griffin, 2000) that have been used to interpret the role of fluids, e.g. Cl, F, and OH activities, during metamorphic and igneous processes (e.g., Harlov and Förster, 2002). It is important, therefore, to understand the thermodynamic behavior of these solid solutions, including their thermal expansion properties. Fluorapatite - chlorapatite samples were synthesized at the GFZ-Potsdam (Hovis, Harlov, Hahn and Steigert, 2007) using an adaptation of the molten flux method of Cherniak (2000). Dry CaF2 and CaCl2 (0.1 mole total) were mixed with Ca3(PO4)2 (0.03 moles), placed in a Pt crucible, equilibrated for 15 hours at 1375 °C, cooled to 1220 °C at 3 °C/hour, removed from the oven and cooled in air. Crystals were separated from the flux by boiling the quenched product in water. F:Cl fractions for each sample were determined via Rietveld refinement of X-ray powder diffraction data. Chemical homogeneity was confirmed by Rietveld refinement and high-contrast back-scattered electron imaging. Room-temperature unit-cell volumes were determined at the GFZ-Potsdam through Rietveld analysis of X-ray powder diffraction data and also at Lafayette College by standard unit-cell refinement techniques (Holland and Redfern, 1997) using NBS/NIST 640a Si as an internal standard. High-temperature unit-cell dimensions were calculated from X-ray powder diffraction data collected at Cambridge University from room temperature to 1000 °C on a Bruker D8 X-ray diffractometer. NBS Si again was utilized as an internal standard; high-temperature Si peak positions were taken from Parrish (1953). Results indicate that despite the considerable size difference between fluorine and chlorine ions, reflected by substantially different unit-cell sizes at room temperature, the coefficient of thermal expansion across

  2. Nanoscale Electromechanics To Measure Thermal Conductivity, Expansion, and Interfacial Losses.

    Science.gov (United States)

    Mathew, John P; Patel, Raj; Borah, Abhinandan; Maliakkal, Carina B; Abhilash, T S; Deshmukh, Mandar M

    2015-11-11

    We study the effect of localized Joule heating on the mechanical properties of doubly clamped nanowires under tensile stress. Local heating results in systematic variation of the resonant frequency; these frequency changes result from thermal stresses that depend on temperature dependent thermal conductivity and expansion coefficient. The change in sign of the linear expansion coefficient of InAs is reflected in the resonant response of the system near a bath temperature of 20 K. Using finite element simulations to model the experimentally observed frequency shifts, we show that the thermal conductivity of a nanowire can be approximated in the 10-60 K temperature range by the empirical form κ = bT W/mK, where the value of b for a nanowire was found to be b = 0.035 W/mK(2), significantly lower than bulk values. Also, local heating allows us to independently vary the temperature of the nanowire relative to the clamping points pinned to the bath temperature. We suggest a loss mechanism (dissipation ~10(-4)-10(-5)) originating from the interfacial clamping losses between the metal and the semiconductor nanostructure. PMID:26479952

  3. Structurally Efficient Three-dimensional Metamaterials with Controllable Thermal Expansion

    Science.gov (United States)

    Xu, Hang; Pasini, Damiano

    2016-10-01

    The coefficient of thermal expansion (CTE) of architected materials, as opposed to that of conventional solids, can be tuned to zero by intentionally altering the geometry of their structural layout. Existing material architectures, however, achieve CTE tunability only with a sacrifice in structural efficiency, i.e. a drop in both their stiffness to mass ratio and strength to mass ratio. In this work, we elucidate how to resolve the trade-off between CTE tunability and structural efficiency and present a lightweight bi-material architecture that not only is stiffer and stronger than other 3D architected materials, but also has a highly tunable CTE. Via a combination of physical experiments on 3D fabricated prototypes and numeric simulations, we demonstrate how two distinct mechanisms of thermal expansion appearing in a tetrahedron, can be exploited in an Octet lattice to generate a large range of CTE values, including negative, zero, or positive, with no loss in structural efficiency. The novelty and simplicity of the proposed design as well as the ease in fabrication, make this bi-material architecture well-suited for a wide range of applications, including satellite antennas, space optical systems, precision instruments, thermal actuators, and MEMS.

  4. Structurally Efficient Three-dimensional Metamaterials with Controllable Thermal Expansion

    Science.gov (United States)

    Xu, Hang; Pasini, Damiano

    2016-01-01

    The coefficient of thermal expansion (CTE) of architected materials, as opposed to that of conventional solids, can be tuned to zero by intentionally altering the geometry of their structural layout. Existing material architectures, however, achieve CTE tunability only with a sacrifice in structural efficiency, i.e. a drop in both their stiffness to mass ratio and strength to mass ratio. In this work, we elucidate how to resolve the trade-off between CTE tunability and structural efficiency and present a lightweight bi-material architecture that not only is stiffer and stronger than other 3D architected materials, but also has a highly tunable CTE. Via a combination of physical experiments on 3D fabricated prototypes and numeric simulations, we demonstrate how two distinct mechanisms of thermal expansion appearing in a tetrahedron, can be exploited in an Octet lattice to generate a large range of CTE values, including negative, zero, or positive, with no loss in structural efficiency. The novelty and simplicity of the proposed design as well as the ease in fabrication, make this bi-material architecture well-suited for a wide range of applications, including satellite antennas, space optical systems, precision instruments, thermal actuators, and MEMS. PMID:27721437

  5. Modulus of Elasticity and Thermal Expansion Coefficient of ITO Film

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Austin D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elhadj, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-06-24

    The purpose of this experiment was to determine the modulus of elasticity (E) and thermal expansion coefficient (α) of RF sputtered Indium Tin Oxide (ITO) as a function of temperature (T), and to collect ITO film stress data. In order to accomplish that goal, the Toho FLX-2320-S thin film stress measurement machine was used to collect both single stress and stress-temperature data for ITO coated fused silica and sapphire substrates. The stress measurement function of the FLX-2320-S cannot be used to calculate the elastic modulus of the film because the Stoney formula incorporates the elastic modulus of the substrate, rather than of the film itself.

  6. Coefficient of thermal expansion of stressed thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-dao; JIANG Shao-qing

    2006-01-01

    A new technique was proposed to determine the coefficient of thermal expansion (CTE) of thin films at low temperature. Different pre-stress could be applied and the elastic modulus of materials at different temperatures was measured with CTE simultaneously to eliminate the influence of mechanical deformation caused by the pre-stress. By using this technique,the CTEs of polyimide/silica nanocomposite films with different silica doping levels were experimentally studied at temperature from 77 K to 287 K,and some characteristics related to this new technique were discussed.

  7. Low coefficient of thermal expansion polyimides containing metal ion additives

    Science.gov (United States)

    Stoakley, D. M.; St. Clair, A. K.

    1992-01-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The incorporation of metal ion-containing additives into polyimides, resulting in significantly lowered CTE's, has been studied. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12 percent to over 100 percent depending on the choice of additive and its concentration.

  8. Negative thermal expansion and its relation to high pressures

    Science.gov (United States)

    Sikka, S. K.

    2004-04-01

    Most materials expand when heated. However, many exceptions are now known. Recently, interest in this has been revived with the discovery of isotropic negative thermal expansion (NTE) in ZrW2O8. From equation of state considerations, one can relate NTE to negative Grüneisen parameters (thermal or electronic). Under pressure, these lead to equation of state anomalies with the pressure derivative of the bulk modules being small or negative. Many of these materials undergo pressure-induced amorphization. This in some of them can be understood on the steric constraint model. It is also argued that NTE in most materials may be understood from the fact that these materials have two degenerate or nearly degenerate energy states. On increase of temperature, the material then samples the lower volume state, leading to NTE.

  9. Negative thermal expansion and its relation to high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, S K [Office of the Principal Scientific Adviser to the Government of India, 324-A, Vigyan Bhawan Annexe, Maulana Azad Road, New Delhi 110011 (India)

    2004-04-14

    Most materials expand when heated. However, many exceptions are now known. Recently, interest in this has been revived with the discovery of isotropic negative thermal expansion (NTE) in ZrW{sub 2}O{sub 8}. From equation of state considerations, one can relate NTE to negative Grueneisen parameters (thermal or electronic). Under pressure, these lead to equation of state anomalies with the pressure derivative of the bulk modules being small or negative. Many of these materials undergo pressure-induced amorphization. This in some of them can be understood on the steric constraint model. It is also argued that NTE in most materials may be understood from the fact that these materials have two degenerate or nearly degenerate energy states. On increase of temperature, the material then samples the lower volume state, leading to NTE.

  10. Series expansion of the photon self-energy in QED and the photon anomalous magnetic moment

    CERN Document Server

    Rojas, H Perez; Chavez, S Villalba

    2008-01-01

    We start from the analytical expression of the eigenvalues $\\kappa^{(i)}$ of the photon self-energy tensor in an external constant magnetic field $B$ calculated by Batalin Shabad in the Furry representation, and in the one-loop approximation. We expand in power series of the external field and in terms of the squared photon transverse momentum $z_2$ and (minus) transverse energy $z_1=k^2-z_2$, in terms of which are expressed $\\kappa^{(i)}$. A general expression is given for the photon anomalous magnetic moment $\\mu_{\\gamma}>0$ in the region of transparency, below the first threshold for pair creation, and it is shown that it is positive, i.e. paramagnetic. The results of the numerical calculation for $\\mu_{\\gamma}>0$ are displayed in a region close to the threshold.

  11. Thermal expansion of CaFe2As2: effect of cobalt doping and post-growth thermal treatment

    OpenAIRE

    Bud'ko, Sergey L.; Ran, Sheng; Canfield, Paul C.

    2013-01-01

    We report thermal expansion measurements on Ca(Fe_(1-x)Co_x)_2As_2 single crystals with different thermal treatment, with samples chosen to represent four different ground states observed in this family. For all samples thermal expansion is anisotropic with different signs of the in-plane and c-axis thermal expansion coefficients in the high temperature, tetragonal phase. The features in thermal expansion associated with the phase transitions are of opposite signs as well, pointing to a diffe...

  12. Thermal expansion investigation of tourmaline-group minerals

    Science.gov (United States)

    Hovis, G.; Scott, B.; Altomare, C.; Tomaino, G.

    2012-04-01

    In recent years one aim of this laboratory has been the characterization of thermal expansion in various mineral groups with an eye toward evaluation of the extent to which chemical composition affects expansion behaviour. We have undertaken studies on various mineral series including alkali feldspar, plagioclase, Ba/K-feldspar, Rb/K feldspar, nepheline/kalsilite minerals of various excess Si contents, and F/Cl/OH apatite. We turn our attention now to the tourmaline mineral system, which is of interest because of its wide variation in chemical composition, as well as its structural complexity. We have obtained multiple chemically-characterized tourmaline specimens from the U.S. National Museum of Natural History and also from George Rossman. Six specimens have been investigated so far, including elbaite, rossmanite, uvite, buergerite, schorl, and foitite. High-temperature X-ray powder diffraction measurements have been made from room temperature to 1000 °C at 75° intervals. X-ray peak positions were corrected utilizing NIST SRM 640a silicon as an internal standard. Peaks were indexed manually based on data in the literature; unit-cell dimensions were computed utilizing the software of Holland and Redfern (1997, Mineralogical Magazine). V-T relationships are generally linear, or close to it, up to the breakdown temperatures of all specimens. Coefficients of thermal expansion have been computed as (ΔV/ΔT)*(1/V0C), where V0C is the extrapolated volume intercept at 0 °C based on the various linear V-T relationships. Among the six specimens, all except foitite give thermal expansion coefficients between 23 and 26 x 10-6 deg-1. Foitite has a flatter V-T slope and thus expands less, giving a thermal expansion coefficient of 18 x 10-6. Based on the initial data, the relative uniformity of expansion behaviour in this system implies that any volumes of mixing in this system will be essentially constant with temperature, recognizing that this conclusion is based on the

  13. Thermal expansion investigation on EuB6

    International Nuclear Information System (INIS)

    EuB6 is a semimetallic correlated electron system, which exhibits a complex sequence of electronic and magnetic phase transitions at ∝15.5 K (T1) and 12.5 K (T2). The material also shows a colossal magnetoresistance effect which is largest at T1. The paramagnetic to ferromagnetic transition in this system is suggested to take place via the formation of magnetic polarons. In this work, we investigate by means of thermal expansion and magnetostriction measurements to which extent lattice degrees of freedom are involved in these phase transitions. We find two corresponding anomalies in the thermal expansion, the one occurring at T2 being much larger than that at T1. The anomalies are very sensitive to magnetic fields. By applying a small magnetic field of less than 50 mT the anomaly at T1 is fully suppressed, while the lower-temperature anomaly at T2 shifts to higher temperature as the field is increased and finally fades out at a field B>5 T. These measurements are complemented by measurements of the magnetostriction at various temperatures from below T2 to above T1 which highlight the extraordinarily large magnetoelastic effects in this material.

  14. Thermal expansion investigation on EuB{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Manna, Rudra Sekhar; Schnelle, Frank; Souza, Mariano de; Lang, Michael; Das, Pintu; Amyan, Adham; Mueller, Jens [Physics Institute, Goethe-University Frankfurt (M), SFB/TR 49, D-60438 Frankfurt am Main (Germany); Molnar, Stephan von; Xiong, Peng [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Fisk, Zachary [Dept. of Physics, University of California, Irvine, California 92697 (United States)

    2012-07-01

    EuB{sub 6} is a semimetallic correlated electron system, which exhibits a complex sequence of electronic and magnetic phase transitions at {proportional_to}15.5 K (T{sub 1}) and 12.5 K (T{sub 2}). The material also shows a colossal magnetoresistance effect which is largest at T{sub 1}. The paramagnetic to ferromagnetic transition in this system is suggested to take place via the formation of magnetic polarons. In this work, we investigate by means of thermal expansion and magnetostriction measurements to which extent lattice degrees of freedom are involved in these phase transitions. We find two corresponding anomalies in the thermal expansion, the one occurring at T{sub 2} being much larger than that at T{sub 1}. The anomalies are very sensitive to magnetic fields. By applying a small magnetic field of less than 50 mT the anomaly at T{sub 1} is fully suppressed, while the lower-temperature anomaly at T{sub 2} shifts to higher temperature as the field is increased and finally fades out at a field B>5 T. These measurements are complemented by measurements of the magnetostriction at various temperatures from below T{sub 2} to above T{sub 1} which highlight the extraordinarily large magnetoelastic effects in this material.

  15. Pressure-induced reversal between thermal contraction and expansion in ferroelectric PbTiO3

    OpenAIRE

    Jinlong Zhu; Jianzhong Zhang; Hongwu Xu; Vogel, Sven C.; Changqing Jin; Johannes Frantti; Yusheng Zhao

    2014-01-01

    Materials with zero/near zero thermal expansion coefficients are technologically important for applications in thermal management and engineering. To date, this class of materials can only be produced by chemical routes, either by changing chemical compositions or by composting materials with positive and negative thermal expansion. Here, we report for the first time a physical route to achieve near zero thermal expansion through application of pressure. In the stability field of tetragonal P...

  16. Study on the Thermal Expansion and Thermal Cycling of AlNp/Al Composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The AIN particle reinforced aluminum matrix composites with 50% volume fraction were fabricated by squeeze-castingtechnology. The thermal expansion behavior and its response to thermal cycling were studied between 20C and400C. Compared with four theoretical models, the measured CTEs of the composite lie within the elastic boundsat lower temperature and elevated temperature, respectively. Strain hysteresis was observed between heating andcooling curves during cycling. This was attributed primarily to the anelastic behavior of the matrix induced by matrixresidual stresses.

  17. Thermal expansion behavior of a β-LiA1SiO4/Cu composite

    Institute of Scientific and Technical Information of China (English)

    WANG Lidong; XUE Zongwei; LIU Zhe; FEI Weidong

    2009-01-01

    A copper matrix composite reinforced by β-LiAlSiO4 with negative thermal expansion coefficient was fabricated using vacuum hot-pressed sintering technique. The thermal expansion behavior of the composite was investigated, and the average residual stress in the matrix was analyzed by a simple model. The results indicate that the residual stress in the matrix affects the thermal expansion properties. After heat treatment, the coefficient of thermal expansion (CTE) of the composite decreases greatly. The CTE of the composite after thermal cycling between 50-350℃ is the lowest.

  18. High-pressure compressibility and thermal expansion of aragonite

    Science.gov (United States)

    Palaich, S.; Heffern, R. A.; Kavner, A.; Manning, C. E.; Merlini, M.; Hanfland, M.

    2015-12-01

    An important component of Earth's deep carbon cycle is the return of surficial carbon to the planet's interior. Most recycled carbon is bound in CaCO3 minerals, of which aragonite is the most significant at upper mantle pressures. It is therefore essential to understand the phase stability and compressibility of aragonite at high pressures and temperatures. Aragonite has an orthorhombic 2/m 2/m 2/m structure and a Z of 4. The high-pressure behavior of aragonite has been studied under dynamic and static compression using both X-ray diffraction and spectroscopic techniques, but these results have been contradictory and inconclusive. To address these issues, a single-crystal synchrotron X-ray diffraction study of aragonite under hydrostatic compression was performed to 40 GPa in a diamond anvil cell at ambient temperature. To supplement the compressional experiment, thermal expansion was also measured via powder X-ray diffraction at ambient pressure between 298-673 K. Ambient-pressure single-crystal measurements confirm the orthorhombic 2/m 2/m 2/m structure and yield a unit cell volume of 226.932(5) Å3. At room temperature, aragonite is stable in the orthorhombic structure to 40 GPa, with an isothermal bulk modulus of 66.5(7) GPa and K' = 5.0(1). The a-axis is most compressible and the c-axis is the least compressible. The b-axis is intermediate, but starts to decrease in compressibility at ~15 GPa. Between 25-30 GPa the aragonite unit cell distorts due to the stiffening of the b-axis, which is controlled by the orientation and distortion of the carbonate groups, layered in the aragonite structure parallel to the a-axis. The carbonate groups elongate and deform from equilateral to isosceles between 15 and 30 GPa, thus influencing the compressibility of the b-axis. The thermal expansion measurements yield expansion coefficients a0 = 4.9(2) x 10-5 and a1 =3.7(5) x 10-8, in agreement with previous data. The combination of the isothermal and isobaric studies allows the

  19. First-principles study of negative thermal expansion in zinc oxide

    Science.gov (United States)

    Wang, Zhanyu; Wang, Fei; Wang, Lei; Jia, Yu; Sun, Qiang

    2013-08-01

    We present the first-principles calculations of vibrational and thermal properties for wurtzite and zinc-blende zinc oxide (ZnO) within DFT and quasi-harmonic approximation, especially for their negative thermal expansion (NTE) behavior. For the wurtzite and zinc-blende phases, negative thermal expansions are obtained at T ZnO is dominated by the tension effect.

  20. Prediction of coefficients of thermal expansion for unidirectional composites

    Science.gov (United States)

    Bowles, David E.; Tompkins, Stephen S.

    1989-01-01

    Several analyses for predicting the longitudinal, alpha(1), and transverse, alpha(2), coefficients of thermal expansion of unidirectional composites were compared with each other, and with experimental data on different graphite fiber reinforced resin, metal, and ceramic matrix composites. Analytical and numerical analyses that accurately accounted for Poisson restraining effects in the transverse direction were in consistently better agreement with experimental data for alpha(2), than the less rigorous analyses. All of the analyses predicted similar values of alpha(1), and were in good agreement with the experimental data. A sensitivity analysis was conducted to determine the relative influence of constituent properties on the predicted values of alpha(1), and alpha(2). As would be expected, the prediction of alpha(1) was most sensitive to longitudinal fiber properties and the prediction of alpha(2) was most sensitive to matrix properties.

  1. Thermal expansion and lattice misfit in two-phase superalloys

    Science.gov (United States)

    Gornostyrev, Yu. N.; Kontsevoi, O. Yu.; Freeman, A. J.; Khromov, K. Yu.; Maksyutov, A. F.; Trefilov, A. V.; Katsnelson, M. I.; Lichtenstein, A. I.

    2004-03-01

    The magnitude of the lattice misfit between the γ and γ' phases is one of the key parameters determining the mechanical behavior, microstructure morphology and stability of γ/γ' high temperature superalloys. For the first time, the γ and γ' thermal expansion coefficients α(T) and the temperature dependence of the unconstrained lattice misfit parameter δ (T) for Ni-, Ir-, and Pt-based superalloys is obtained by means of ab initio full-potential electron and phonon spectrum calculations. We demonstrate that, in contrast with traditional beliefs, the electronic contribution to the misfit parameter dominates due to the strong compensation of the phonon contributions to α(T) from γ and γ'. The calculated results are in a good agreement with available experimental data for temperatures up to 0.8T_melt; at higher temperatures the effect of the redistribution of alloying elements between the γ, and γ' phases on δ (T) becomes essential.

  2. Thermal field theory to all orders in gradient expansion

    CERN Document Server

    Millington, Peter

    2013-01-01

    We present a new perturbative formulation of non-equilibrium thermal field theory, based upon non-homogeneous free propagators and time-dependent vertices. The resulting time-dependent diagrammatic perturbation series are free of pinch singularities without the need for quasi-particle approximation or effective resummation of finite widths. After arriving at a physically meaningful definition of particle number densities, we derive master time evolution equations for statistical distribution functions, which are valid to all orders in perturbation theory and all orders in a gradient expansion. For a scalar model, we make a loopwise truncation of these evolution equations, whilst still capturing fast transient behaviour, which is found to be dominated by energy-violating processes, leading to non-Markovian evolution of memory effects.

  3. Glass-ceramic hermetic seals to high thermal expansion metals

    Science.gov (United States)

    Kramer, D.P.; Massey, R.T.

    1987-04-28

    A process for forming glass-ceramic materials from an alkaline silica-lithia glass composition comprising 60-72 mole-% SiO/sub 2/, 18-27 mole-% Li/sub 2/O, 0-5 mole-% Al/sub 2/O/sub 3/, 0-6 mole-% K/sub 2/O, 0-3 mole-% B/sub 2/O/sub 3/, and 0.5-2.5 mole-% P/sub 2/O/sub 5/, which comprises heating said glass composition at a first temperature within the 950-1050/degree/C range for 5-60 minutes, and then at a devitrification temperature within the 700-900/degree/C range for about 5-300 minutes to obtain a glass-ceramic having a thermal expansion coefficient of up to 210 x 10/sup /minus/7///degree/C. These ceramics form strong, hermetic seals with high expansion metals such as stainless steel alloys. An intermediate nucleation heating step conducted at a temperature within the range of 675-750/degree/C for 10-120 minutes may be employed between the first stage and the devitrification stage. 1 fig., 2 tabs.

  4. Thermal Expansion Studies of Selected High-Temperature Thermoelectric Materials

    Science.gov (United States)

    Ravi, Vilupanur; Firdosy, Samad; Caillat, Thierry; Brandon, Erik; van der Walde, Keith; Maricic, Lina; Sayir, Ali

    2009-07-01

    Radioisotope thermoelectric generators (RTGs) generate electrical power by converting the heat released from the nuclear decay of radioactive isotopes (typically plutonium-238) into electricity using a thermoelectric converter. RTGs have been successfully used to power a number of space missions and have demonstrated their reliability over an extended period of time (tens of years) and are compact, rugged, radiation resistant, scalable, and produce no noise, vibration or torque during operation. System conversion efficiency for state-of-practice RTGs is about 6% and specific power ≤5.1 W/kg. A higher specific power would result in more onboard power for the same RTG mass, or less RTG mass for the same onboard power. The Jet Propulsion Laboratory has been leading, under the advanced thermoelectric converter (ATEC) project, the development of new high-temperature thermoelectric materials and components for integration into advanced, more efficient RTGs. Thermoelectric materials investigated to date include skutterudites, the Yb14MnSb11 compound, and SiGe alloys. The development of long-lived thermoelectric couples based on some of these materials has been initiated and is assisted by a thermomechanical stress analysis to ensure that all stresses under both fabrication and operation conditions will be within yield limits for those materials. Several physical parameters are needed as input to this analysis. Among those parameters, the coefficient of thermal expansion (CTE) is critically important. Thermal expansion coefficient measurements of several thermoelectric materials under consideration for ATEC are described in this paper. The stress response at the interfaces in material stacks subjected to changes in temperature is discussed, drawing on work from the literature and project-specific tools developed here. The degree of CTE mismatch and the associated effect on the formation of stress is highlighted.

  5. Thermal Expansion Studies of Selected High Temperature Thermoelectric Materials

    Science.gov (United States)

    Ravi, Vilupanur; Firdosy, Samad; Caillat, Thierry; Brandon, Erik; Van Der Walde, Keith; Maricic, Lina; Sayir, Ali

    2008-01-01

    Radioisotope thermoelectric generators (RTGs) generate electrical power by converting the heat released from the nuclear decay of radioactive isotopes (typically plutonium-238) into electricity using a thermoelectric converter. RTGs have been successfully used to power a number of space missions and have demonstrated their reliability over an extended period of time (tens of years) and are compact, rugged, radiation resistant, scalable, and produce no noise, vibration or torque during operation. System conversion efficiency for state-of-practice RTGs is about 6% and specific power less than or equal to 5.1 W/kg. Higher specific power would result in more on-board power for the same RTG mass, or less RTG mass for the same on-board power. The Jet Propulsion Laboratory has been leading, under the advanced thermoelectric converter (ATEC) project, the development of new high-temperature thermoelectric materials and components for integration into advanced, more efficient RTGs. Thermoelectric materials investigated to date include skutterudites, the Yb14MnSb11 compound, and SiGe alloys. The development of long-lived thermoelectric couples based on some of these materials has been initiated and is assisted by a thermo-mechanical stress analysis to ensure that all stresses under both fabrication and operation conditions will be within yield limits for those materials. Several physical parameters are needed as input to this analysis. Among those parameters, the coefficient of thermal expansion (CTE) is critically important. Thermal expansion coefficient measurements of several thermoelectric materials under consideration for ATEC are described in this paper. The stress response at the interfaces in material stacks subjected to changes in temperature is discussed, drawing on work from the literature and project-specific tools developed here. The degree of CTE mismatch and the associated effect on the formation of stress is highlighted.

  6. Strongly anomalous non-thermal fixed point in a quenched two-dimensional Bose gas

    CERN Document Server

    Karl, Markus

    2016-01-01

    Universal scaling behavior in the relaxation dynamics of an isolated two-dimensional Bose gas is studied by means of semi-classical stochastic simulations of the Gross-Pitaevskii model. The system is quenched far out of equilibrium by imprinting vortex defects into an otherwise phase-coherent condensate. A strongly anomalous non-thermal fixed point is identified, associated with a slowed decay of the defects in the case that the dissipative coupling to the thermal background noise is suppressed. At this fixed point, a large anomalous exponent $\\eta \\simeq -3$ and, related to this, a large dynamical exponent $z \\simeq 5$ are identified. The corresponding power-law decay is found to be consistent with three-vortex-collision induced loss. The article discusses these aspects of non-thermal fixed points in the context of phase-ordering kinetics and coarsening dynamics, thus relating phenomenological and analytical approaches to classifying far-from-equilibrium scaling dynamics with each other. In particular, a clo...

  7. Elastic cell membranes induce long-lived anomalous thermal diffusion on nearby particles

    CERN Document Server

    Daddi-Moussa-Ider, Abdallah; Gekle, Stephan

    2016-01-01

    The physical approach of a small particle (virus, medical drug) to the cell membrane represents the crucial first step before active internalization and is governed by thermal diffusion. Using a fully analytical theory we show that the stretching and bending of the elastic membrane by the approaching particle induces a memory in the system which leads to anomalous diffusion, even though the particle is immersed in a purely Newtonian liquid. For typical cell membranes the transient subdiffusive regime extends beyond 10ms and can enhance residence times and binding rates up to 50\\%. Our analytical predictions are validated by numerical simulations.

  8. Long-lived anomalous thermal diffusion induced by elastic cell membranes on nearby particles

    Science.gov (United States)

    Daddi-Moussa-Ider, Abdallah; Guckenberger, Achim; Gekle, Stephan

    2016-01-01

    The physical approach of a small particle (virus, medical drug) to the cell membrane represents the crucial first step before active internalization and is governed by thermal diffusion. Using a fully analytical theory we show that the stretching and bending of the elastic membrane by the approaching particle induces a memory in the system, which leads to anomalous diffusion, even though the particle is immersed in a purely Newtonian liquid. For typical cell membranes the transient subdiffusive regime extends beyond 10 ms and can enhance residence times and possibly binding rates up to 50%. Our analytical predictions are validated by numerical simulations.

  9. Magnetoelastic anomalies of thermal expansion of rare earth vanadates RVO4

    International Nuclear Information System (INIS)

    Systematic experimental and theoretic investigations into thermal expansion of rare earth (RE) vanadates RVO4 (R = Gd-Tm) are conducted. A substantial magnetoelastic contribution of RE ions to thermal expansion of the vanadates investigated as well as different degree of this contribution for vanadates and phosphates are detected. It is shown that RVO4 thermal expansion anomalies are well described by temperature dependence of RE ion quadrupole moments. 16 refs., 4 figs

  10. PREPARATION OF HIGH THERMAL EXPANSION COEFFICIENT PORCELAINS FUSED TO METALS

    Institute of Scientific and Technical Information of China (English)

    J.P. Yang; J.Q. Wu

    2003-01-01

    Usually the thermal expansion coefficients (TEC) of metals are higher than that of porcelains. In order to match the TECs in the case of coating porcelains on metals, high TEC porcelains are needed. In this research, the high TEC phase leucite(KAlSi2 O6) in the high TEC porcelain was prepared by sol-gel method. The crystal size of leucite made by sol-gel is about 77nm through controlling the process parameters. The process from xerogel to leucite was investigated by means of DSC (differential scanning calorimetry), TG (thermogravimetry), XRD ( X-ray diffraction) and IR(infrared absorption spectrum). Leucite had been detected after the gel was treated at 900°C, this formation temperature is about 250°C lower than that of melting method.The porcelain made from 50% of the leucite powder and 50%o of low fused temperature frit has an average TEC of 19.2× 10-6/° C from room temperature to 450°C, which is much higher than the common porcelains.

  11. Thermal expansion properties of Lu2-x FexMo3O12

    Institute of Scientific and Technical Information of China (English)

    Wu Mei-Mei; Peng Jie; Zu Yong; Liu Rong-Deng; Hu Zhong-Bo; Liu Yun-Tao; Chen Dong-Feng

    2012-01-01

    The structures and thermal expansion properties of Lu2-xFex Mo3O12 have been investigated by X-ray diffraction (XRD).XRD patterns at room temperature indicate that componnds Lu2 xFexMo3O12 with x ≤ 1.3 exhibit an orthorhombic structure with space group Pnca;compounds with x =1.5 and 1.7 have a monoclinic structure with space group P21/a.Studies on thermal expansion properties show that the linear thermal expansion coefficients of orthorhombic phase vary from negative to positive with increasing Fe content.Attempts to make zero thermal expansion materials indicate that zero thermal expansion can be observed in Lu1.3Feo.7Mo3O12 in the temperature range of 200-400°C.

  12. Thermal expansion studies on Inconel-600[reg] by high temperature X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Raju, S. E-mail: sraju@igcar.ernet.in; Sivasubramanian, K.; Divakar, R.; Panneerselvam, G.; Banerjee, A.; Mohandas, E.; Antony, M.P

    2004-02-01

    The lattice thermal expansion characteristics of Inconel-600[reg] have been studied by high temperature X-ray diffraction (HT-XRD) technique in the temperature range 298-1200 K. Altogether four experimental runs were conducted on thin foils of about 75-100 {mu}m thickness. The diffraction profiles have been accurately calibrated to offset the shift in 2{theta} values introduced by sample buckling at elevated temperatures. The corrected lattice parameter data have been used to estimate the instantaneous and mean linear thermal expansion coefficients as a function of temperature. The thermal expansion values estimated in the present study show a fair degree of agreement with other existing dilatometer based bulk thermal expansion estimates. The lattice parameter for this alloy at 300 K is found to be 0.3549(1) nm. The mean linear thermal expansivity is found to be 11.4 x 10{sup -6} K{sup -1}.

  13. Calculation of thermal expansion coefficient of glasses based on topological constraint theory

    Science.gov (United States)

    Zeng, Huidan; Ye, Feng; Li, Xiang; Wang, Ling; Yang, Bin; Chen, Jianding; Zhang, Xianghua; Sun, Luyi

    2016-10-01

    In this work, the thermal expansion behavior and the structure configuration evolution of glasses were studied. Degree of freedom based on the topological constraint theory is correlated with configuration evolution; considering the chemical composition and the configuration change, the analytical equation for calculating the thermal expansion coefficient of glasses from degree of freedom was derived. The thermal expansion of typical silicate and chalcogenide glasses was examined by calculating their thermal expansion coefficients (TEC) using the approach stated above. The results showed that this approach was energetically favorable for glass materials and revealed the corresponding underlying essence from viewpoint of configuration entropy. This work establishes a configuration-based methodology to calculate the thermal expansion coefficient of glasses that, lack periodic order.

  14. Thermal Expansion Anomaly of Tb2Fe14Cr3 Compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; HE Xiao-Hong; AN Li-Qun; Fu Bin

    2008-01-01

    We investigate the thermal expansion property of the Tb2Fe14Cr3 compound by means of x-ray diffraction.The result shows that the Tb2Fe14Cr3 compound has a hexagonal Th2Ni17-type structure.Negative thermal expansion is found in the Tb2Fe14Cr3 compound from 296 to 493K by x-ray dilatometry.The coefficient of the average thermal expansion is (a)=-2.82×10-5 K-1.In the temperature range 493-692K,the coefficient of the average thermal expansion is (a)=1.59×10-5 K-1.The physical mechanism of thermal expansion anomaly of the Tb2Fe14Cr3 compound is discussed according to the temperature dependence of magnetization measured by a superconducting quantum interference device.

  15. Anomalous thermally induced pinning of a liquid drop on a solid substrate.

    Science.gov (United States)

    Mettu, Srinivas; Kanungo, Mandakini; Law, Kock-Yee

    2013-08-27

    The effect of substrate temperature on the wetting and spreading behavior of a UV ink monomer has been studied as a surrogate for the ink on four different substrates: DTC (digital top coat)-coated BOPP (biaxial oriented polypropylene), Flexo-coated BOPP, DTC-coated SGE (semigloss elite) paper, and Flexo-coated SGE paper. Results show that the dynamic contact angles of the monomer decrease exponentially over time after contacting the surface, and the rate of spreading is consistently higher at 95 °C than at 22 °C. This observation indicates that spreading is controlled by the viscosity of the monomer as it decreases with temperature. An anomalous temperature effect is observed for the static contact angle on the DTC-coated BOPP substrate. The static contact angle at 95 °C is significantly larger than that at 22 °C (52° versus 30°). This is counterintuitive, as the surface tension of the monomer is shown to decease with increasing temperature. Microscopy (SEM and AFM) studies suggest that there is little interaction between the DTC coating solution and the BOPP substrate during the fast-drying coating process. This results in a smooth coated surface and, more importantly, voids between the BOPP nanofibers underneath the DTC coating. As the DTC-BOPP substrate is heated to 95 °C, fiber expansions occur. Microscopy results show that nanosized protrusions are formed on the DTC surface. We attribute it to fiber expansions in the vertical direction. Fiber expansions in the lateral direction causes little surface morphology change as the expanded materials only fill the voids laterally between the nanofiber network. We suggest that the protrusions on the surface create strong resistance to the wetting process and pin the monomer drop into a metastable wetting state. This interpretation is supported by the sliding angle and sessile drop height experiments. PMID:23899384

  16. Thermal expansion behaviour of Long-Period Stacking Ordered (LPSO) phase

    Energy Technology Data Exchange (ETDEWEB)

    Garces, G.; Requena, G.; Tolnai, D.; Perez, P.; Adeva, P.; Jimenez, J. A.; Stark, A.; Schell, N.

    2015-07-01

    The lineal thermal expansion coefficient of the 18R Long-Period Stacking Ordered (LPSO) structure was determined in the range between room temperature and 400 degree centigrade by dilatometry and synchrotron radiation diffraction. Results clearly show that the lineal thermal expansion coefficients for magnesium and the LPSO phase are similar and therefore no mismatch thermal stresses are generated at their interface in two-phase Mg-Y-Zn alloys containing this phase during thermomechanical processing. (Author)

  17. Investigation on the Thermal Expansion of Four Polymorphs of Crystalline CL-20

    Science.gov (United States)

    Pu, Liu; Xu, Jin-Jiang; Liu, Xiao-Feng; Sun, Jie

    2016-04-01

    The thermal expansion behaviors of α-CL-20 . 1/2H2O, anhydrous α-, β-, ε-, and γ-CL-20 crystals have been investigated by means of variable-temperature X-ray powder diffraction (XRD) together with Rietveld refinement. The results show that hexanitrohexaazaisowurtane (CL-20) with four polymorphs exhibits linear thermal expansion. The ε phase performs approximately isotropic expansion in the temperature range of 30 to 130°C, but α, β, and γ phases exhibit anisotropic expansion in the temperature ranges of 30 to 130°C, 30 to 120°C, and 30 to 180°C, respectively. The different expansion behaviors are due to the different structures of the four polymorphs. The different thermal expansion behaviors of α-CL-20 . 1/2H2O and anhydrous α are revealed in this work. The a-axis expansion of α-CL-20 . 1/2H2O exhibits a switch from positive thermal expansion (PTE) to negative thermal expansion (NTE) at 90°C, whereas the a-axis of anhydrous α is resilient to PTE. The cause is the loss of the structural water. Moreover, it is easily found that the b-axis of the γ phase shows a constriction that may be attributed to the distortion of the six-membered ring.

  18. Thermally Driven Pure Spin and Valley Currents via the Anomalous Nernst Effect in Monolayer Group-VI Dichalcogenides

    DEFF Research Database (Denmark)

    Yu, Xiao-Qin; Zhu, Zhen-Gang; Su, Gang;

    2015-01-01

    The spin and valley-dependent anomalous Nernst effects are analyzed for monolayer MoS2 and other group-VI dichalcogenides. We find that pure spin and valley currents can be generated perpendicular to the applied thermal gradient in the plane of these two-dimensional materials. This effect provides...

  19. Design of an optical reference cavity with low thermal noise and flexible thermal expansion properties

    CERN Document Server

    Zhang, J; Ouyang, B; Deng, K; Lu, Z H; Luo, J

    2012-01-01

    An ultrastable optical reference cavity with re-entrant fused silica mirrors and a ULE spacer structure is designed through finite element analysis. The designed cavity has a low thermal noise limit of $1\\times10^{-16}$ and a flexible zero crossing temperature of the effective coefficient of thermal expansion (CTE). The CTE zero crossing temperature difference between a composite cavity and a pure ULE cavity can be tuned from $-10\\ ^{\\circ}$C to $23\\ ^{\\circ}$C, which enables operation of the designed reference cavity near room temperature without worrying about the CTE zero crossing temperature of the ULE spacer. The design can be applied to cavities with different lengths. Vibration immunity of the cavity is also achieved through structure optimization.

  20. INFLUENCE OF THERMAL CYCLING ON MICROSTRUCTURE AND THERMAL EXPANSION OF CARBON FIBRES/COPPER COMPOSITES

    Directory of Open Access Journals (Sweden)

    Pavol Štefánik

    2009-06-01

    Full Text Available The preparation of copper matrix reinforced by high modulus carbon fibres (Thornel K1100 as well as the microstructure and dilatation changes during thermocycling is presented.Unidirectional composites with two types of matrix - pure copper and/or copper alloy with 0.2 wt. % of chromium - were thermally cycled between 30-600 °C three times.The composite with pure Cu exhibited larger voids and weak interfacial bonding. Due to the chemical reaction with K1100 fibres a reactive interfacial bonding has been formed. During thermocycling the hysteresis, but no large disintegration was observed. The coefficients of thermal expansion (CTEs strongly depend on fibre orientation. In direction parallel to the fibre orientation in the temperature range of 220-500°C CTEs were very low (0.7-1.0x10-6/K, but in perpendicular direction the CTEs were higher than that of pure copper.

  1. Thermal expansion of monogermanides of 3d-metals.

    Science.gov (United States)

    Valkovskiy, G A; Altynbaev, E V; Kuchugura, M D; Yashina, E G; Sukhanov, A S; Dyadkin, V A; Tsvyashchenko, A V; Sidorov, V A; Fomicheva, L N; Bykova, E; Ovsyannikov, S V; Chernyshov, D Yu; Grigoriev, S V

    2016-09-21

    Temperature dependent powder and single-crystal synchrotron diffraction, specific heat, magnetic susceptibility and small-angle neutron scattering experiments have revealed an anomalous response of MnGe. The anomaly becomes smeared out with decreasing Mn content in Mn1-x Co x Ge and Mn1-x Fe x Ge solid solutions. Mn spin state instability is discussed as a possible candidate for the observed effects. PMID:27421076

  2. Thermal expansion of monogermanides of 3d-metals

    Science.gov (United States)

    Valkovskiy, G. A.; Altynbaev, E. V.; Kuchugura, M. D.; Yashina, E. G.; Sukhanov, A. S.; Dyadkin, V. A.; Tsvyashchenko, A. V.; Sidorov, V. A.; Fomicheva, L. N.; Bykova, E.; Ovsyannikov, S. V.; Chernyshov, D. Yu; Grigoriev, S. V.

    2016-09-01

    Temperature dependent powder and single-crystal synchrotron diffraction, specific heat, magnetic susceptibility and small-angle neutron scattering experiments have revealed an anomalous response of MnGe. The anomaly becomes smeared out with decreasing Mn content in Mn1‑x Co x Ge and Mn1‑x Fe x Ge solid solutions. Mn spin state instability is discussed as a possible candidate for the observed effects.

  3. Controllable rectification of the axial expansion in the thermally driven artificial muscle

    Science.gov (United States)

    Yue, Donghua; Zhang, Xingyi; Yong, Huadong; Zhou, Jun; Zhou, You-He

    2015-09-01

    At present, the concept of artificial muscle twisted by polymers or fibers has become a hot issue in the field of intelligent material research according to its distinguishing advantages, e.g., high energy density, large-stroke, non-hysteresis, and inexpensive. The axial thermal expansion coefficient is an important parameter which can affect its demanding applications. In this letter, a device with high accuracy capacitive sensor is constructed to measure the axial thermal expansion coefficient of the twisted carbon fibers and yarns of Kevlar, and a theoretical model based on the thermal elasticity and the geometrical features of the twisted structure are also presented to predict the axial expansion coefficient. It is found that the calculated results take good agreements with the experimental data. According to the present experiment and analyses, a method to control the axial thermal expansion coefficient of artificial muscle is proposed. Moreover, the mechanism of this kind of thermally driven artificial muscle is discussed.

  4. Nonlinear temperature characteristic of thermal expansion of Grf/Mg composites

    Institute of Scientific and Technical Information of China (English)

    SONG Mei-hui; XIU Zi-yang; WU Gao-hui; CHEN Guo-qin

    2009-01-01

    Graphite fiber reinforced magnesium matrix(Grf/Mg) composites were fabricated by squeeze casting technology. M40 graphite fibers were reinforced to AZ91D and ZM6, their thermal expansion behaviors of M40/AZ91D and M40/ZM6 composites in the temperature range from 20 to 490 ℃ were investigated. The results show that the interfacial species and thermal stress have significant influence on the thermal expansion behavior of the composites. Simultaneously, the longitudinal coefficient of thermal expansion of Grf/Mg composites are affected by the thermal stress, interfacial species and yield strength of matrix alloy, it also decreases with increasing temperature and descending rate of longitudinal coefficient of thermal expansion(CTEs) of Grf/Mg composites changed in different temperature ranges. In terms of different descending rates, the curve of coefficient of thermal expansion vs temperature can be divided into three stages. The matrix alloys M40/AZ91D and M40/ZM6 yield at 170 and 155℃ in the thermal expansion, respectively.

  5. Preparation, structure and thermal expansion of CuIn3Se5

    International Nuclear Information System (INIS)

    Homogeneous monocrystals of CuIn3Se5 were growth by the method of oriented crystallization of melt. It was pointed out that monocrystals of CuIn3Se5 feature n-type conductivity, specific resistance ρ ∼ 106-107 Ohm cm (at room temperature) charge carrier concentration n ∼ 1016 cm-3 and Hall's mobility μn ∼ 120-140 cm2/(B c). It is shown that thermal expansion of the compound is anisotropic: thermal expansion coefficients along tetragonal axis are lower than those along axis a. Temperature increase from 90 to 650 K gives rise to increase in both thermal expansion coefficients

  6. Thermal expansion and thermal conductivity of CuGa1-xInxTe2 solid solutions

    International Nuclear Information System (INIS)

    The thermal expansion and thermal conductivity of the CuGa1-xInxTe2 solid solutions are studied on the crystals of the solid, obtained through the Bridgman method. It is established that the thermal expansion coefficient with the x-composition changes linearly and the thermal conductivity - with the minimum for the equimolar composition. The Debye temperatures and the root-mean-square dynamic shifts are calculated by the coefficient experimental data. It is shown that with increase of the indium atoms content in the solid solutions the Debye temperature decreases and the atoms root-mean-square dynamic shifts in the crystalline lattice increase

  7. Anomalous thermal behaviour in small electronic devices: non-uniformity and overshoot in dynamic temperature distributions

    Energy Technology Data Exchange (ETDEWEB)

    Vermeersch, B; Mey, G de [Department of Electronics and Information Systems, Ghent University, Sint Pietersnieuwstraat 41, Gent 9000 (Belgium)

    2007-04-21

    This paper presents a theoretical investigation of the temperature distributions generated by a small heat source mounted on or embedded in semiconductor material. The dynamic thermal behaviour of the structures is studied in the frequency domain using phasor notation for the temperature and heat flux fields. Both classical and hyperbolic thermal conductions are considered. The latter accounts for the finite heat propagation speed, which is necessary for accurately describing very fast transitions. Although a uniform power density is applied, the temperature distribution inside the source is spatially non-uniform. As is already well known, this even holds for steady state conditions. For high frequencies, however, the maximum magnitude (i.e. largest oscillations) of the temperature occurs near the edges and corners of the heat source, rather than in the centre where it could intuitively be expected. This anomalous behaviour is observed for a wide variety of configurations, ranging from a simple 1D analytical slab model to numerical results for a 3D multi-layered electronic package. The classical theory clearly underestimates the edge effect, particularly for submicrometre structures. The substantial deviation from the distributions obtained by non-Fourier theory illustrates that special care should be taken when analysing fast heat transfer in small electronic devices.

  8. Influence of material composition on thermal expansion of graphitic materials and changes under fast neutron irradiation

    International Nuclear Information System (INIS)

    The influence of the binder coke content and graphitization temperature on thermal expansion of graphite were investigated. Property correlations such as of anisotropy with real density or coefficient of volume thermal expansion have been found. An important part of this paper deals with the irradiation induced changes of thermal expansion. Interpretations of the irradiation behaviour base on the influence of material composition and heat treatment procedure. Measurements of lattice spacings were performed using high temperature X-ray diffractometer equipment in order to calculate the lattice expansion in c-direction for an estimation of its contribution to the expansion of the bulk material. Corresponding measurements were also performed on neutron irradiated graphite specimens. (orig./GSC)

  9. Pressurized heat treatment of glass-ceramic to control thermal expansion

    Science.gov (United States)

    Kramer, Daniel P.

    1985-01-01

    A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

  10. Absolute thermal expansion of copper and aluminum between 5 K and 330 K

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, F.R. Jr.

    1976-02-01

    Theoretical and experimental results of experiments on thermal expansion of Al and Cu are presented. Experimental apparatus and procedures are described. Results are presented in graphs and plots and discussed. (JRD)

  11. Simulation of thermal and sodium expansion stress in aluminum reduction cells

    Institute of Scientific and Technical Information of China (English)

    LI Jie; WU Yu-yun; LAI Yan-qing; LIU Wei; WANG Zhi-gang; LIU Jie; LIU Ye-xiang

    2008-01-01

    Two finite element(FE) models were built up for analysis of stress field in the lining of aluminum electrolysis cells. Distribution of sodium concentration in cathode carbon blocks was calculated by one FE model of a cathode block. Thermal stress field was calculated by the other slice model of the cell at the end of the heating-up. Then stresses coupling thermal and sodium expansion were considered after 30 d start-up. The results indicate that sodium penetrates to the bottom of the cathode block after 30 d start-up. The semi-graphitic carbon block has the largest stress at the thermal stage. After 30 d start-up the anthracitic carbon has the greatest sodium expansion stress and the graphitized carbon has the lowest sodium expansion stress. Sodium penetration can cause larger deformation and stress in the cathode carbon block than thermal expansion.

  12. Sensitivity analysis of hydraulic and thermal parameters inducing anomalous heat flow in the Lower Yarmouk Gorge

    Science.gov (United States)

    Goretzki, Nora; Inbar, Nimrod; Kühn, Michael; Möller, Peter; Rosenthal, Eliyahu; Schneider, Michael; Siebert, Christian; Magri, Fabien

    2016-04-01

    The Lower Yarmouk Gorge, at the border between Israel and Jordan, is characterized by an anomalous temperature gradient of 46 °C/km. Numerical simulations of thermally-driven flow show that ascending thermal waters are the result of mixed convection, i.e. the interaction between the regional flow from the surrounding heights and buoyant flow within permeable faults [1]. Those models were calibrated against available temperature logs by running several forward problems (FP), with a classic "trial and error" method. In the present study, inverse problems (IP) are applied to find alternative parameter distributions that also lead to the observed thermal anomalies. The investigated physical parameters are hydraulic conductivity and thermal conductivity. To solve the IP, the PEST® code [2] is applied via the graphical interface FEPEST® in FEFLOW® [3]. The results show that both hydraulic and thermal conductivity are consistent with the values determined with the trial and error calibrations, which precede this study. However, the IP indicates that the hydraulic conductivity of the Senonian Paleocene aquitard can be 8.54*10-3 m/d, which is three times lower than the originally estimated value in [1]. Moreover, the IP suggests that the hydraulic conductivity in the faults can increase locally up to 0.17 m/d. These highly permeable areas can be interpreted as local damage zones at the faults/units intersections. They can act as lateral pathways in the deep aquifers that allow deep outflow of thermal water. This presentation provides an example about the application of FP and IP to infer a wide range of parameter values that reproduce observed environmental issues. [1] Magri F, Inbar N, Siebert C, Rosenthal E, Guttman J, Möller P (2015) Transient simulations of large-scale hydrogeological processes causing temperature and salinity anomalies in the Tiberias Basin. Journal of Hydrology, 520, 342-355 [2] Doherty J (2010) PEST: Model-Independent Parameter Estimation. user

  13. Using a Michelson Interferometer to Measure Coefficient of Thermal Expansion of Copper

    Science.gov (United States)

    Scholl, Ryan; Liby, Bruce W.

    2009-01-01

    When most materials are heated they expand. This concept is usually demonstrated using some type of mechanical measurement of the linear expansion of a metal rod. We have developed an alternative laboratory method for measuring thermal expansion by using a Michelson interferometer. Using the method presented, interference, interferometry, and the…

  14. Thermal Expansion and Diffusion Coefficients of Carbon Nanotube-Polymer Composites

    OpenAIRE

    Wei, Chenyu; Srivastava, Deepak; Cho, Kyeongjae

    2002-01-01

    Classical molecular dynamics (MD) simulations employing Brenner potential for intra-nanotube interactions and Van der Waals forces for polymer-nanotube interfaces are used to invetigate the thermal expansion and diffusion characteristics of carbon nanotube-polyethylene composites. Additions of carbon nanotubes to polymer matrix are found to increase the glass transition temperature Tg, and thermal expansion and diffusion coefficients in the composite above Tg. These findings could have implic...

  15. Phase Composition and Thermal Expansion of CaO Stabilised ZrO2 Refactories

    Institute of Scientific and Technical Information of China (English)

    ZHAOShike; WUJingyuan; 等

    2000-01-01

    In this,phase compsition and thermal expansion behaviour of CaO Stabilised refractories were studied,Special attention was paid to the expasion behaviour of three materials with different phase composition,The research results indicated that the expansion behaviour could be improved by modifying the stabilization of ZrO2,which thus leads to the increase in the thermal shock resistance and possibly eroion resistace of as-obtained CaO stabilised ZrO material.

  16. Effect of graphene nanoplatelets on coefficient of thermal expansion of polyetherimide composite

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huang, E-mail: huang.wu.84@gmail.com [Composite Materials and Structures Center, Michigan State University, East Lansing, MI 48864 (United States); Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI 48864 (United States); Drzal, Lawrence T. [Composite Materials and Structures Center, Michigan State University, East Lansing, MI 48864 (United States); Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI 48864 (United States)

    2014-07-01

    Thermal expansion is one of the major concerns for polymer composites. In this research, graphene nanoplatelets (GNPs) were added to polyetherimide (PEId) thermoplastic polymer in order to reduce the coefficient of thermal expansion (CTE) of the injection molded composite. First, the coefficient of linear thermal expansion (LTE) was measured in three directions in the anisotropic coupon: 0°, 90° and the out of plane Z direction. It is found that the GNP particles are very effective in terms of reducing the LTE in 0° direction due to high degree of alignment. After annealing above glass transition temperature, significant increase of 0° LTE and decrease of Z° LTE were observed. The bulk CTE was calculated by adding up the LTEs in all three directions and is found to be independent of annealing. Second, several models were applied to predict both CTE and LTE. It is found that Schapery's lower limit model fits the experimental CTE very well. Chow's model was applied for LTEs in three directions. The behavior of GNP-5/PEId composites is explained by the combination of Chow's model and morphology obtained by scanning electron microscope (SEM). - Highlights: • Coefficient of thermal expansion (CTE) of polymer composite is characterized. • Reduction of linear thermal expansion depends on filler orientation. • Filler orientation is characterized based on the location of the specimen. • Filler orientation is changed by annealing, causing subsequent change in CTE. • CTE and linear thermal expansion coefficient are modeled.

  17. Effect of graphene nanoplatelets on coefficient of thermal expansion of polyetherimide composite

    International Nuclear Information System (INIS)

    Thermal expansion is one of the major concerns for polymer composites. In this research, graphene nanoplatelets (GNPs) were added to polyetherimide (PEId) thermoplastic polymer in order to reduce the coefficient of thermal expansion (CTE) of the injection molded composite. First, the coefficient of linear thermal expansion (LTE) was measured in three directions in the anisotropic coupon: 0°, 90° and the out of plane Z direction. It is found that the GNP particles are very effective in terms of reducing the LTE in 0° direction due to high degree of alignment. After annealing above glass transition temperature, significant increase of 0° LTE and decrease of Z° LTE were observed. The bulk CTE was calculated by adding up the LTEs in all three directions and is found to be independent of annealing. Second, several models were applied to predict both CTE and LTE. It is found that Schapery's lower limit model fits the experimental CTE very well. Chow's model was applied for LTEs in three directions. The behavior of GNP-5/PEId composites is explained by the combination of Chow's model and morphology obtained by scanning electron microscope (SEM). - Highlights: • Coefficient of thermal expansion (CTE) of polymer composite is characterized. • Reduction of linear thermal expansion depends on filler orientation. • Filler orientation is characterized based on the location of the specimen. • Filler orientation is changed by annealing, causing subsequent change in CTE. • CTE and linear thermal expansion coefficient are modeled

  18. Effect of copper content on the thermal conductivity and thermal expansion of Al–Cu/diamond composites

    International Nuclear Information System (INIS)

    Highlights: ► Al–Cu/diamond composites have been produced by a squeeze casting method. ► Cu alloying is an effective approach to promoting interface bonding between metal matrix and diamond. ► Alloying Cu to Al matrix improves thermal conductivity and reduces coefficient of thermal expansion of the composites. -- Abstract: Al–Cu matrix composites reinforced with diamond particles (Al–Cu/diamond composites) have been produced by a squeeze casting method. Cu content added to Al matrix was varied from 0 to 3.0 wt.% to detect the effect on thermal conductivity and thermal expansion behavior of the resultant Al–Cu/diamond composites. The measured thermal conductivity for the Al–Cu/diamond composites increased from 210 to 330 W/m/K with increasing Cu content from 0 to 3.0 wt.%. Accordingly, the coefficient of thermal expansion (CTE) was tailored from 13 × 10−6 to 6 × 10−6/K, which is compatible with the CTE of semiconductors in electronic packaging applications. The enhanced thermal conductivity and reduced coefficient of thermal expansion were ascribed to strong interface bonding in the Al–Cu/diamond composites. Cu addition has lowered the melting point and resulted in the formation of Al2Cu phase in Al matrix. This is the underlying mechanism responsible for the strengthening of Al–Cu/diamond interface. The results show that Cu alloying is an effective approach to promoting interface bonding between Al and diamond.

  19. Anisotropic thermal expansion of a 3D metal–organic framework with hydrophilic and hydrophobic pores

    International Nuclear Information System (INIS)

    A 3D flexible metal–organic framework (MOF) with 1D hydrophilic and hydrophobic pores shows anisotropic thermal expansion with relatively large thermal expansion coefficient (αa=−21×10−6 K−1 and αc=79×10−6 K−1) between 133 K and 383 K. Temperature change gives deformation of both pores, which expand in diameter and elongate in length on cooling and vice versa. The thermally induced structural change should be derived from a unique framework topology like “lattice fence”. Silica accommodation changes not only the nature of the MOF but also thermal responsiveness of the MOF. Since the hydrophobic pores in the material are selectively blocked by the silica, the MOF with the silica is considered as a hydrophilic microporous material. Furthermore, inclusion of silica resulted in a drastic pore contraction in diameter and anisotropically changed the thermal responsiveness of the MOF. - Graphical abstract: A 3D metal–organic framework with hydrophilic and hydrophobic pores shows anisotropic thermal expansion behavior. The influence of silica filler in the hydrophobic pore was investigated. - Highlights: • Thermally induced structural change of a 3D MOF with a lattice fence topology was investigated. • The structural change was analyzed by synchrotron X-ray diffraction patterns. • Temperature change induces anisotropic thermal expansion/contraction of the MOF. • Silica inclusion anisotropically changes the thermal responsiveness of the MOF

  20. Anisotropic thermal expansion of a 3D metal–organic framework with hydrophilic and hydrophobic pores

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Atsushi, E-mail: kondoa@cc.tuat.ac.jp; Maeda, Kazuyuki

    2015-01-15

    A 3D flexible metal–organic framework (MOF) with 1D hydrophilic and hydrophobic pores shows anisotropic thermal expansion with relatively large thermal expansion coefficient (α{sub a}=−21×10{sup −6} K{sup −1} and α{sub c}=79×10{sup −6} K{sup −1}) between 133 K and 383 K. Temperature change gives deformation of both pores, which expand in diameter and elongate in length on cooling and vice versa. The thermally induced structural change should be derived from a unique framework topology like “lattice fence”. Silica accommodation changes not only the nature of the MOF but also thermal responsiveness of the MOF. Since the hydrophobic pores in the material are selectively blocked by the silica, the MOF with the silica is considered as a hydrophilic microporous material. Furthermore, inclusion of silica resulted in a drastic pore contraction in diameter and anisotropically changed the thermal responsiveness of the MOF. - Graphical abstract: A 3D metal–organic framework with hydrophilic and hydrophobic pores shows anisotropic thermal expansion behavior. The influence of silica filler in the hydrophobic pore was investigated. - Highlights: • Thermally induced structural change of a 3D MOF with a lattice fence topology was investigated. • The structural change was analyzed by synchrotron X-ray diffraction patterns. • Temperature change induces anisotropic thermal expansion/contraction of the MOF. • Silica inclusion anisotropically changes the thermal responsiveness of the MOF.

  1. Ba-filled Ni-Sb-Sn based skutterudites with anomalously high lattice thermal conductivity.

    Science.gov (United States)

    Paschinger, W; Rogl, G; Grytsiv, A; Michor, H; Heinrich, P R; Müller, H; Puchegger, S; Klobes, B; Hermann, R P; Reinecker, M; Eisenmenger-Sitter, Ch; Broz, P; Bauer, E; Giester, G; Zehetbauer, M; Rogl, P F

    2016-07-01

    Novel filled skutterudites BayNi4Sb12-xSnx (ymax = 0.93) have been prepared by arc melting followed by annealing at 250, 350 and 450 °C up to 30 days in vacuum-sealed quartz vials. Extension of the homogeneity region, solidus temperatures and structural investigations were performed for the skutterudite phase in the ternary Ni-Sn-Sb and in the quaternary Ba-Ni-Sb-Sn systems. Phase equilibria in the Ni-Sn-Sb system at 450 °C were established by means of Electron Probe Microanalysis (EPMA) and X-ray Powder Diffraction (XPD). With rather small cages Ni4(Sb,Sn)12, the Ba-Ni-Sn-Sb skutterudite system is perfectly suited to study the influence of filler atoms on the phonon thermal conductivity. Single-phase samples with the composition Ni4Sb8.2Sn3.8, Ba0.42Ni4Sb8.2Sn3.8 and Ba0.92Ni4Sb6.7Sn5.3 were used to measure their physical properties, i.e. temperature dependent electrical resistivity, Seebeck coefficient and thermal conductivity. The resistivity data demonstrate a crossover from metallic to semiconducting behaviour. The corresponding gap width was extracted from the maxima in the Seebeck coefficient data as a function of temperature. Single crystal X-ray structure analyses at 100, 200 and 300 K revealed the thermal expansion coefficients as well as Einstein and Debye temperatures for Ba0.73Ni4Sb8.1Sn3.9 and Ba0.95Ni4Sb6.1Sn5.9. These data were in accordance with the Debye temperatures obtained from the specific heat (4.4 K thermal conductivity. The elastic moduli, collected from Resonant Ultrasonic Spectroscopy ranged from 100 GPa for Ni4Sb8.2Sn3.8 to 116 GPa for Ba0.92Ni4Sb6.7Sn5.3. The thermal expansion coefficients were 11.8 × 10(-6) K(-1) for Ni4Sb8.2Sn3.8 and 13.8 × 10(-6) K(-1) for Ba0.92Ni4Sb6.7Sn5.3. The room temperature Vickers hardness values vary within the range from 2.6 GPa to 4.7 GPa. Severe plastic deformation via high-pressure torsion was used to introduce nanostructuring; however, the physical properties before and after HPT showed no

  2. Giant negative linear compression positively coupled to massive thermal expansion in a metal-organic framework.

    Science.gov (United States)

    Cai, Weizhao; Katrusiak, Andrzej

    2014-01-01

    Materials with negative linear compressibility are sought for various technological applications. Such effects were reported mainly in framework materials. When heated, they typically contract in the same direction of negative linear compression. Here we show that this common inverse relationship rule does not apply to a three-dimensional metal-organic framework crystal, [Ag(ethylenediamine)]NO3. In this material, the direction of the largest intrinsic negative linear compression yet observed in metal-organic frameworks coincides with the strongest positive thermal expansion. In the perpendicular direction, the large linear negative thermal expansion and the strongest crystal compressibility are collinear. This seemingly irrational positive relationship of temperature and pressure effects is explained and the mechanism of coupling of compressibility with expansivity is presented. The positive coupling between compression and thermal expansion in this material enhances its piezo-mechanical response in adiabatic process, which may be used for designing new artificial composites and ultrasensitive measuring devices. PMID:24993679

  3. Thermal expansion of ternary semiconductor compounds AgB3C26

    International Nuclear Information System (INIS)

    Temperature dependences of elementary cell parameters, molar volume, main and mean coefficients of thermal expansion for crystals are determined, melting temperatures are improved characteristic Debay temperatures and some thermodynamic properties of AgGaSr, AgInS2, AgGaSe2, AgInSe2, AgGaTe2, AgInTe2 compounds are calculated, effect of anion (S-Se-Te) and cation substitutions on the change of these parameters is considered, using X-ray diffraction technique. It is shown, that within 80-650 K temperature range for AgB3C26 (B-Ga, In; C-S, Se, Te) with chalcopyrite tetragonal structure the thermal expansion coefficients along the direction, parallel to tetragonal axis, are negative, while along the perpendicular direction-positive ones. With temperature increase both main coefficients of expansion increase by absolute value, coefficients, characterizing thermal expansion anisotropy, grorespectively. AgGaSe2 compound has the largest anisotropy of thermal expansion, while AgInTe2 compound has the smalest anisotropy of thermal expansion, while AgInTe2 compound has the smalest anisotropy among the considered group of A1B3C26 ternary compounds

  4. Stability and anomalous compressibility of Bose gases near resonance: The scale-dependent interactions and thermal effects

    Science.gov (United States)

    Jiang, Shao-Jian; Zhou, Fei

    2015-07-01

    The stability of Bose gases near resonance has been a puzzling problem in recent years. In this article, we demonstrate that in addition to generating thermal pressure, thermal atoms enhance the repulsiveness of the scale-dependent interactions between condensed atoms due to a renormalization effect and further stabilize the Bose gases. Consequently, we find that, as a precursor of instability, the compressibility develops an anomalous structure as a function of scattering length and is drastically reduced compared with the mean-field value. Furthermore, the density profile of a Bose gas in a harmonic trap is found to develop a flat top near the center. This is due to the anomalous behavior of compressibility and can be a potential smoking gun for probing such an effect.

  5. Unidirectional thermal expansion in KZnB3O6: role of alkali metals.

    Science.gov (United States)

    Lou, Yanfang; Li, Dandan; Li, Zhilin; Zhang, Han; Jin, Shifeng; Chen, Xiaolong

    2015-12-14

    The driving force of the unidirectional thermal expansion in KZnB3O6 has been studied experimentally and theoretically. Our results show that the low-energy vibrational modes of alkali metals play a crucial role in this unusual thermal behavior. PMID:26515521

  6. Determination of the thermal expansion and thermo-optic coefficients of a bacteriorhodopsin film

    Science.gov (United States)

    Wang Song, Q.; Zhang, Chunping; Ku, Chin-Yu; Huang, Ming-Chieh; Gross, Richard B.; Birge, Robert R.

    1995-02-01

    The linear expansion and thermo-optic coefficients of a bacteriorhodopsin film were measured by using an interferometric method. The experimental results confirm the previous suspicions that the large refractive nonlinearity which occurs at high illumination intensities arises form a thermal effect. The results also suggest a possible way to increase the usable thermal nonlinearity by four times.

  7. Growth and thermal expansion of In2S3 single crystals

    International Nuclear Information System (INIS)

    In2S3 monocrystals have been grown by the Bridgman-Stockbarger method. Their composition has been determined by electron probe X-ray microanalysis, and their phase-transition temperatures have been evaluated by differential thermal analysis. The thermal expansion coefficient of In2S3 has been determined in the range 80-1000 K by dilatometry

  8. Anomalous thermal expansion in the metallic phase of SmS under high pressure

    International Nuclear Information System (INIS)

    SmS exhibits a pressure-induced phase transition at 0.6 GPa from a semiconducting state to a rather metallic state accompanied with a change of Sm valence and volume compression. Using the X-ray diffraction technique under high pressures, we found local minima of the lattice constant of SmS in the metallic phase up to near 2 GPa. The pressure region of the volume minima coincides with that of the low-temperature increase and the humps of electrical resistivity. We succeeded in reproducing the volume minima by a phenomenological model of a Schottky-type behavior due to electronic gap suppressed by pressure

  9. Thermal expansion in the orthorhombic γ phase of ZrW2O8

    International Nuclear Information System (INIS)

    The thermal expansion of the orthorhombic γ phase of ZrW2O8 has been measured using neutron powder diffraction from 4.6 to 410 K, where it transforms to the cubic α phase. At low temperature, γ-ZrW2O8 has a negative thermal expansion, but the thermal expansion becomes less negative with increasing temperature and is slightly positive at room temperature. This behavior can be explained in terms of the contributing phonon modes: At low temperature, the vibrational modes lead to a negative thermal expansion, but additional modes that become active upon increasing temperature add positive contributions. Above room temperature, the a and b axes increase more sharply while the c axis reverses its behavior and decreases with increasing temperature. This unusual behavior can be explained in terms of a thermally activated process, presumed to result from oxygen-atom migration, that makes an additional contribution to the thermal expansion. (c) 1999 The American Physical Society

  10. Porous composite with negative thermal expansion obtained by photopolymer additive manufacturing

    Directory of Open Access Journals (Sweden)

    Akihiro Takezawa

    2015-07-01

    Full Text Available Additive manufacturing (AM could be a novel method of fabricating composite and porous materials having various effective performances based on mechanisms of their internal geometries. Materials fabricated by AM could rapidly be used in industrial application since they could easily be embedded in the target part employing the same AM process used for the bulk material. Furthermore, multi-material AM has greater potential than usual single-material AM in producing materials with effective properties. Negative thermal expansion is a representative effective material property realized by designing a composite made of two materials with different coefficients of thermal expansion. In this study, we developed a porous composite having planar negative thermal expansion by employing multi-material photopolymer AM. After measurement of the physical properties of bulk photopolymers, the internal geometry was designed by topology optimization, which is the most effective structural optimization in terms of both minimizing thermal stress and maximizing stiffness. The designed structure was converted to a three-dimensional stereolithography (STL model, which is a native digital format of AM, and assembled as a test piece. The thermal expansions of the specimens were measured using a laser scanning dilatometer. Negative thermal expansion corresponding to less than −1 × 10−4 K−1 was observed for each test piece of the N = 3 experiment.

  11. Thermal expansion of lattice parameter of (powder) silicon up to 1473 K

    Institute of Scientific and Technical Information of China (English)

    XING Xianran; CHEN Jun; DENG Jinxia; LIU Guirong

    2004-01-01

    The XRPD (X-ray powder diffractometry) patterns of silicon powder with a unit cell structure of diamond were determined from 298 to 1473 K. Lattice parameters of Si linearly increase with temperature. The thermal shifts of the positions of all reflection peaks are linearly correlated with the temperature. The coefficients of the intrinsic linear thermal expansion and volumetric thermal expansion were determined as 3.87×10-6/K and 1.16 × 10-5/K respectively. It indicates that Si is still a suitable standard in the XRPD method at high temperatures.

  12. Thermal expansion of laminated, woven, continuous ceramic fiber/chemical-vapor-infiltrated silicon carbide matrix composites

    Science.gov (United States)

    Eckel, Andrew J.; Bradt, Richard C.

    1990-01-01

    Thermal expansions of three two-dimensional laminate, continuous fiber/chemical-vapor-infiltrated silicon carbide matrix composites reinforced with either FP-Alumina (alumina), Nextel (mullite), or Nicalon (Si-C-O-N) fibers are reported. Experimental thermal expansion coefficients parallel to a primary fiber orientation were comparable to values calculated by the conventional rule-of-mixtures formula, except for the alumina fiber composite. Hysteresis effects were also observed during repeated thermal cycling of that composite. Those features were attributed to reoccurring fiber/matrix separation related to the micromechanical stresses generated during temperature changes and caused by the large thermal expansion mismatch between the alumina fibers and the silicon carbide matrix.

  13. Analysis of thermal expansivity of iron (Fe) metal at ultra high temperature and pressure

    Indian Academy of Sciences (India)

    Deepika Kandpal; B R K Gupta

    2007-01-01

    In the present investigation we have explained the thermal and compression properties of HCP iron (Fe) at high pressure with variable temperature (isobars) and at high temperature with variable pressure (isotherm). The usual Tait equation of state is modified by incorporating the effect of thermal pressure. The calculated values of pressure for different isotherms and isochors and thermal expansivity () as a function of both temperature and pressure have been compared with those values obtained by Isaak et al and Wasserman et al.

  14. Thermally stable anomalous Hall behavior in perpendicular Co/Pt multilayers sandwiched by HfO2 layers

    Science.gov (United States)

    Jiang, Shao-Long; Li, Xu-Jing; Liu, Yi-Wei; Chen, Xi; Liu, Qian-Qian; Han, Gang; Yang, Guang; Wang, Dong-Wei; Zhang, Jing-Yan; Teng, Jiao; Yu, Guang-Hua

    2016-01-01

    The effect of annealing on the anomalous Hall effect (AHE) in perpendicular Co/Pt multilayers sandwiched by HfO2 layers has been studied. It was found that thermally stable AHE features can be obtained in perpendicular Co/Pt multilayers with the introduction of two Co/HfO2 interfaces, leading to the improvement of the skew scattering contribution to the AHE after annealing. On the contrary, thermally stable AHE behavior cannot be observed in Co/Pt multilayers sandwiched by Pt layers or MgO layers because of Co-Pt interdiffusion during annealing.

  15. Thermal expansion anomaly and spontaneous magnetostriction of Gd2Fe17 compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yanming; LIANG Feifei; ZHANG Xuemin; WANG Fang; WU Yanzhao

    2011-01-01

    Materials with negative thermal expansion have many practical applications.However,these materials are known in only several oxide systems,and when the negative thermal expansion occurs,the contraction is usually small and limited to a narrow temperature range beyond room temperature.For obtaining a compound with negative thermal expansion in broad temperature range,the structural and magnetic properties of Gd2Fe17 compound were investigated by means of X-ray diffraction and magnetization measurements.The Gd2Fe17 compound annealed at 1050 ℃ had a Th2Zn17-type Structure.There existed an anisotropic strong spontaneous magnetostriction and a negative thermal expansion in Gd2Fe17 compound.The average thermal expansion coefficients was α =-7.40×10-6/K in the temperature range of 294-453 K and (α) =-1.80x 10-5/K in 453-534 K,respectively.The spontaneous rnagnetostrictive deformation ωs decreased from 4.34x10-3 to near zero with temperature increasing from 294 to 572 K.The spontaneous linear deformation λc was much larger than λa at the same temperature below about 500 K.

  16. Modeling the thermal deformation of TATB-based explosives. Part 1: Thermal expansion of “neat-pressed” polycrystalline TATB

    Energy Technology Data Exchange (ETDEWEB)

    Luscher, Darby J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-05-08

    We detail a modeling approach to simulate the anisotropic thermal expansion of polycrystalline (1,3,5-triamino-2,4,6-trinitrobenzene) TATB-based explosives that utilizes microstructural information including porosity, crystal aspect ratio, and processing-induced texture. This report, the first in a series, focuses on nonlinear thermal expansion of “neat-pressed” polycrystalline TATB specimens which do not contain any binder; additional complexities related to polymeric binder and irreversible ratcheting behavior are briefly discussed, however detailed investigation of these aspects are deferred to subsequent reports. In this work we have, for the first time, developed a mesoscale continuum model relating the thermal expansion of polycrystal TATB specimens to their microstructural characteristics. A self-consistent homogenization procedure is used to relate macroscopic thermoelastic response to the constitutive behavior of single-crystal TATB. The model includes a representation of grain aspect ratio, porosity, and crystallographic texture attributed to the consolidation process. A quantitative model is proposed to describe the evolution of preferred orientation of graphitic planes in TATB during consolidation and an algorithm constructed to develop a discrete representation of the associated orientation distribution function. Analytical and numerical solutions using this model are shown to produce textures consistent with previous measurements and characterization for isostatic and uniaxial “die-pressed” specimens. Predicted thermal strain versus temperature for textured specimens are shown to be in agreement with corresponding experimental measurements. Using the developed modeling approach, several simulations have been run to investigate the influence of microstructure on macroscopic thermal expansion behavior. Results from these simulations are used to identify qualitative trends. Implications of the identified trends are discussed in the context of

  17. Thermal Expansion of LaCoO3

    Institute of Scientific and Technical Information of China (English)

    闫柏军; 张家芸; 刘建华

    2004-01-01

    High-temperature X-ray diffraction(HTXRD)measurements of LaCoO3 powder was carried out in a temperature range from 298 to 1273 K.The experimental data obtained were adopted to evaluate the lattice parameters and cell volume.In this temperature range,the linear and volume expansion coefficients calculated using these cell parameters are 24.160~23.610×10-6·K-1 and 59.601~63.218×10-6·K-1 respectively.There is no discontinuity found in the cell parameters through the proposed first-order transition at 1210 K.

  18. Modeling of Thermal Expansion Coefficients of Ni-Based Superalloys Using Artificial Neural Network

    Science.gov (United States)

    Bano, Nafisa; Nganbe, Michel

    2013-04-01

    The objective of this work is to model the thermal expansion coefficients of various Ni-based superalloys used in gas turbine components. The thermal expansion coefficient is described as a function of temperature, chemical composition including Ni, Cr, Co, Mo, W, Ta, Nb, Al, Ti, B, Zr, and C contents as well as heat treatment including solutionizing and aging. Experimental values are well described and their relative changes well correlated by the model. Because gas turbine engine components operate under severe loading conditions and at high and varying temperatures, the prediction of their thermal expansion coefficient is crucial. The model developed in this work can be useful for design optimizations for minimizing thermo-mechanical stresses between the base alloys and potential protective coatings or adjacent components. It can substantially contribute to improve the performance and service life of gas turbine components.

  19. Anisotropic thermal expansion of Ni, Pd and Pt germanides and silicides

    Science.gov (United States)

    Geenen, F. A.; Knaepen, W.; Moens, F.; Brondeel, L.; Leenaers, A.; Van den Berghe, S.; Detavernier, C.

    2016-07-01

    Silicon or germanium-based transistors are nowadays used in direct contact with silicide or germanide crystalline alloys for semiconductor device applications. Since these compounds are formed at elevated temperatures, accurate knowledge of the thermal expansion of both substrate and the contact is important to address temperature depending effects such as thermal stress. Here we report the linear coefficients of thermal expansion of Ni-, Pd- and Pt-based mono-germanides, mono-silicides and di-metal-silicides as determined by powder-based x-ray diffraction between 300 and 1225 K. The investigated mono-metallic compounds, all sharing the MnP crystal structure, as well as Pd2Si and Pt2Si exhibit anisotropic expansion. By consequence, this anisotropic behaviour should be taken into account for evaluating the crystal unit’s cell at elevated temperatures.

  20. Thermal expansion anomaly and magnetic properties of Nd2AlFe11Mn5 compound

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Materials with negative thermal expansion have many important applications such as constituents of composite materials designed to .reduce their overall thermal expansion. The structural and magnetic properties of Nd2AlFe11Mn5 compound were investigated by means of X-ray diffraction and magnetization measurements. The result shows that the Nd2AlFe11Mn5 compound crystallizes in a rhomhedral Th2Zn17-type structure. The Curie temperature Tc is about 150 K. The negative thermal expansion coefficient of Nd2AlFe11Mn5 compound is found by X-ray diffraction in temperature range of 122-203 K. There exists an anisotropic and strong positive spontaneous magnetostriction in Nd2AlFe11Mn5 compound. The magnetostriction deformations were discussed.

  1. Thermal expansion and magnetostriction measurements using a high sensitive capacitive dilatometer at millikelvin temperatures

    International Nuclear Information System (INIS)

    We have developed a dilatometric measuring system for thermal expansion and magnetostriction, those are more singular than specific heat in approaching to a quantum critical point. With decreasing temperature, thermal expansion becomes small in proportional to the square of temperature, thus, high sensitivity and reproducibility are necessary for the dilatometric measurements in millikelvin temperatures. Our dilatometer composed of the sample and the reference capacitor provides the extremely high resolution of ΔL/L ∼ 10−10 using the ratio-transformer-based capacitance bridge. The dilatometer was installed on the 3He-4He dilution refrigerator with the 9 T superconducting magnet, and temperature was measured by the 3He melting curve thermometer. We have measured thermal expansion and magnetostriction of the typical heavy fermion compound CeRu2Si2 along a-axis at temperature down to 10 mK in magnetic fields up to 9 T

  2. About Utilization Efficiency Evaluation of Gas-Expansion and Generator Units at Thermal Power Stations

    OpenAIRE

    S. A. Kachan; A. A. Bazylenko

    2007-01-01

    The paper considers methods for determination of gas-expansion and generator unit indices when they are applied at a thermal power station. It is shown, that while relating the effect of additional power-and-heat generation output due to heat taking-off from steam turbines to gas-expansion and generator unit to the operation of this unit a specific fuel consumption of power supply from gas-expansion and generator unit can be lower than fuel equivalent of kilowatt-hour.

  3. About Utilization Efficiency Evaluation of Gas-Expansion and Generator Units at Thermal Power Stations

    Directory of Open Access Journals (Sweden)

    S. A. Kachan

    2007-01-01

    Full Text Available The paper considers methods for determination of gas-expansion and generator unit indices when they are applied at a thermal power station. It is shown, that while relating the effect of additional power-and-heat generation output due to heat taking-off from steam turbines to gas-expansion and generator unit to the operation of this unit a specific fuel consumption of power supply from gas-expansion and generator unit can be lower than fuel equivalent of kilowatt-hour.

  4. Thermal expansion and stability of cerium-doped Lu2SiO5

    International Nuclear Information System (INIS)

    In-situ X-ray diffraction, differential scanning calorimetry and dilatometry were used to measure the thermal expansion and thermal stability of cerium-doped Lu2SiO5. The thermal expansion of Lu2SiO5 was highly anisotropic, with expansion along the b- and c-axes 5-10 times greater than expansion along the a-axis. There were no measurable differences in the thermal expansion between undoped Lu2SiO5, cerium-doped Lu2SiO5 with high scintillation efficiency, cerium-doped Lu2SiO5 with low scintillation efficiency and annealed cerium-doped Lu2SiO5. Lu2SiO5 decomposed at temperatures as low as 1350 deg. C in 2, while the presence of 100-150 ppm O2 stabilized Lu2SiO5 at temperatures up to 1760 deg. C. No bulk defects were identified to account for the difference between high scintillation efficiency and low scintillation efficiency cerium-doped Lu2SiO5 samples

  5. Noninvasive temperature estimation by detecting echo-strain change including thermal expansion

    Institute of Scientific and Technical Information of China (English)

    Ma Yong; Zhang Dong; Gong Xiu-Fen; Liu Xiao-Zhou; Ma Qing-Yu; Qiu Yuan-Yuan

    2007-01-01

    This article studies the feasibility of noninvasive temperature estimation by detecting echo-strain including thermal expansion in therapeutic ultrasound treatment. This technique evaluates distributions of echo-strain and temperature inside the tissue by detecting echo signals pre- and post-heating, in combination with the temperature dependence of sound speed and thermal expansion. In the computer simulation and experimental study, echo signals pre- and postheating are acquired and then the temperature elevation is evaluated by correlation analysis. Results demonstrate that this technique can effectively extend the measured temperature range up to 75℃ with an accuracy of ±2 ℃.

  6. The JPL Cryogenic Dilatometer: Measuring the Thermal Expansion Coefficient of Aerospace Materials

    Science.gov (United States)

    Halverson, Peter G.; Dudick, Matthew J.; Karlmann, Paul; Klein, Kerry J.; Levine, Marie; Marcin, Martin; Parker, Tyler J.; Peters, Robert D.; Shaklan, Stuart; VanBuren, David

    2007-01-01

    This slide presentation details the cryogenic dilatometer, which is used by JPL to measure the thermal expansion coefficient of materials used in Aerospace. Included is a system diagram, a picture of the dilatometer chamber and the laser source, a description of the laser source, pictures of the interferometer, block diagrams of the electronics and software and a picture of the electronics, and software. Also there is a brief review of the accurace.error budget. The materials tested are also described, and the results are shown in strain curves, JPL measured strain fits are described, and the coefficient of thermal expansion (CTE) is also shown for the materials tested.

  7. Thermal Expansion and Diffusion Coefficients of Carbon Nanotube-Polymer Composites

    Science.gov (United States)

    Wei, Chengyu; Srivastava, Deepak; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Classical molecular dynamics (MD) simulations employing Brenner potential for intra-nanotube interactions and van der Waals forces for polymer-nanotube interface have been used to investigate thermal expansion and diffusion characteristics of carbon nanotube-polyethylene composites. Addition of carbon nanotubes to polymer matrix is found to significantly increase the glass transition temperature Tg, and thermal expansion and diffusion coefficients in the composite above Tg. The increase has been attributed to the temperature dependent increase of the excluded volume for the polymer chains, and the findings could have implications in the composite processing, coating and painting applications.

  8. Thermal expansion in dysprosium tungstate Dy10W2O21

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The complex oxide Dy10W2O21 was synthesized by a solid-state reaction and isolated in cubic symmetry by an X-ray diffractometry (XRD) method. Differential scanning calorimetry (DSC) measurements show that the compound is thermodynamically stable. The intrinsic thermal expansion coefficients were determined by extra-power powder Xray diffractometry from room temperature to 1000 ℃: linear coefficient α = 1.07 × 10-5 ℃-1 and bulk coefficient β=3.20 × 10-5℃-1. Dilatometry was used to measure the extrinsic thermal expansion coefficient (9.2 × 10-6℃-1).

  9. Development of Zero Coefficient of Thermal Expansion composite tubes for stable space structures

    Science.gov (United States)

    Strock, John D.

    1992-09-01

    Advanced composite materials are well suited for stable space structures due to their low Coefficient of Thermal Expansion (CTE), high stiffness and light weight. For a given design application, composite hardware can be tailored for strength, stiffness, CTE, and Coefficient of Moisture Expansion (CME). Computer modeling and laminate testing of high modulus graphite/epoxy tubes were evaluated for compressive strength, stiffness, CTE, CME and microcracking. Thermal cycling and microcracking effects on CTE were evaluated. Thin graphite/epoxy plies exhibited reduced microcracking. A zero CTE thin wall tube design resulted from the development program. Recent work on low moisture absorption resin systems is also discussed.

  10. Analysis of thermal expansion effects on leakage in self-sealed journal bearings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper, based on a simplified model, researched the problem of liquid lubricantleakage caused by thermal expansion effects in a self-sealed journal bearing, The analysis indi-cated that mismatch between thermal expansion coefficient of oil-holding-space in bearing, σT, andthat of liquid lubricant, αoi, is a subtle factor inducing leakage when bearing temperature varies.Measures like properly selecting liquid lubricant and carefully designing bearing structure could betaken to reduce the leakage by matching αT and αoil, Several such ideas concerning bearing mate-rial choosing and structure designing were presented.

  11. Fiber-content dependency of the optical transparency and thermal expansion of bacterial nanofiber reinforced composites

    Science.gov (United States)

    Nogi, Masaya; Ifuku, Shinsuke; Abe, Kentaro; Handa, Keishin; Nakagaito, Antonio Norio; Yano, Hiroyuki

    2006-03-01

    We produced transparent nanocomposite reinforced with bacterial cellulose having a wide range of fiber contents, from 7.4to66.1wt%, by the combination of heat drying and organic solvent exchange methods. The addition of only 7.4wt% of bacterial cellulose nanofibers, which deteriorated light transmittance by only 2.4%, was able to reduce the coefficient of thermal expansion of acrylic resin from 86×10-6to38×10-6K-1. As such, the nanofiber network of bacterial cellulose has an extraordinary potential as a reinforcement to obtain optically transparent and low thermal expansion materials.

  12. Thermo-optically driven adaptive mirror based on thermal expansion: preparation and resolution

    Science.gov (United States)

    Reinert, Felix; Lüthy, W.

    2005-12-01

    A thermo-optically driven adaptive mirror is presented. It is based on the thermal expansion of a thin film heated with a light pattern. We describe a procedure for the preparation of a silicon elastomer with a high-quality optical surface. This material, Sylgard 184, has a high linear thermal expansion coefficient of 3.1μ10-4 K-1. Surface modulations are recorded in an interferometer. Modulations of 350 nm result at an intensity of 370 mW/cm2. The resolution is measured with a line pattern. The contrast drops to 30 % at 1.6 line pairs per millimeter (lp/mm).

  13. Relation between thermal expansion and interstitial formation energy in pure Fe and Cr

    Energy Technology Data Exchange (ETDEWEB)

    Wallenius, Janne [Department of Nuclear and Reactor Physics, KTH, AlbaNova University Centre, Stockholm 10691 (Sweden) and Department of Neutron Research, Uppsala University, Uppsala (Sweden)]. E-mail: janne@neutron.kth.se; Olsson, Paer [Department of Neutron Research, Uppsala University, Uppsala (Sweden); Lagerstedt, Christina [Department of Nuclear and Reactor Physics, KTH, AlbaNova University Centre, Stockholm 10691 (Sweden)

    2005-01-01

    By fitting a potential of modified Finnis-Sinclair type to the thermal expansion of ferromagnetic Fe and paramagnetic Cr, stability of the <1 1 0> self-interstitial atom is obtained. The resulting potentials are relatively hard, yielding high SIA formation energies. Less hard potentials give lower interstitial formation energy, but predict too small thermal expansion. We also show that the formation energy of the <1 1 1> SIA depends on distances in-between the 2nd and 3rd neighbour. By raising the value of the pair potential in this region, the energy difference with respect to the <110> configuration calculated with VASP in the PAW approximation can be reproduced.

  14. Thermal expansion compensator having an elastic conductive element bonded to two facing surfaces

    Science.gov (United States)

    Determan, William (Inventor); Matejczyk, Daniel Edward (Inventor)

    2012-01-01

    A thermal expansion compensator is provided and includes a first electrode structure having a first surface, a second electrode structure having a second surface facing the first surface and an elastic element bonded to the first and second surfaces and including a conductive element by which the first and second electrode structures electrically and/or thermally communicate, the conductive element having a length that is not substantially longer than a distance between the first and second surfaces.

  15. Anomalously Slow Cross Symmetry Phase Relaxation, Thermalized Non-Equilibrated Matter and Quantum Computing Beyond the Quantum Chaos Border

    Directory of Open Access Journals (Sweden)

    T.H. Seligman

    2006-02-01

    Full Text Available Thermalization in highly excited quantum many-body system does not necessarily mean a complete memory loss of the way the system was formed. This effect may pave a way for a quantum computing, with a large number of qubits $nsimeq 100-1000$, far beyond the quantum chaos border. One of the manifestations of such a thermalized non-equilibrated matter is revealed by a strongasymmetry around 90$^circ $ c.m. of evaporating proton yield in the Bi($gamma$,p photonuclear reaction. The effect is described in terms of anomalously slow cross symmetry phase relaxation in highly excited quantum many-body systems withexponentially large Hilbert space dimensions. In the above reaction this phase relaxation is about eight orders of magnitude slower than energy relaxation (thermalization.

  16. Anomalously Slow Cross Symmetry Phase Relaxation, Thermalized Non-Equilibrated Matter and Quantum Computing Beyond the Quantum Chaos Border

    Science.gov (United States)

    Bienert, M.; Flores, J.; Kun, S. Yu.; Seligman, T. H.

    2006-02-01

    Thermalization in highly excited quantum many-body system does not necessarily mean a complete memory loss of the way the system was formed. This effect may pave a way for a quantum computing, with a large number of qubits n ≈ 100-1000, far beyond the quantum chaos border. One of the manifestations of such a thermalized non-equilibrated matter is revealed by a strong asymmetry around 90° c.m. of evaporating proton yield in the Bi(γ,p) photonuclear reaction. The effect is described in terms of anomalously slow cross symmetry phase relaxation in highly excited quantum many-body systems with exponentially large Hilbert space dimensions. In the above reaction this phase relaxation is about eight orders of magnitude slower than energy relaxation (thermalization).

  17. Anomalously Slow Cross Symmetry Phase Relaxation, Thermalized Non-Equilibrated Matter and Quantum Computing Beyond the Quantum Chaos Border

    CERN Document Server

    Bienert, M; Kun, S Yu; Seligman, T H

    2006-01-01

    Thermalization in highly excited quantum many-body system does not necessarily mean a complete memory loss of the way the system was formed. This effect may pave a way for a quantum computing, with a large number of qubits $n\\simeq 100$--1000, far beyond the quantum chaos border. One of the manifestations of such a thermalized non-equilibrated matter is revealed by a strong asymmetry around 90$^\\circ $ c.m. of evaporating proton yield in the Bi($\\gamma$,p) photonuclear reaction. The effect is described in terms of anomalously slow cross symmetry phase relaxation in highly excited quantum many-body systems with exponentially large Hilbert space dimensions. In the above reaction this phase relaxation is about eight orders of magnitude slower than energy relaxation (thermalization).

  18. Molecular Dynamics Study of a Thermal Expansion Coefficient: Ti Bulk with an Elastic Minimum Image Method

    Institute of Scientific and Technical Information of China (English)

    Yakup Hundur; Rainer Hippler; Ziya B. Güven(c)

    2006-01-01

    @@ Linear thermal expansion coefficient (TEC) of Ti bulk is investigated by means of molecular dynamics simulation.The elastic minimum image convention of periodic boundary conditions is introduced to allow the bulk to adjust its size according to the new fixed temperature. The TEC and the specific heat of Ti are compared to the available theoretical and experimental data.

  19. Calculation of Thermal Expansion Coefficients of Pure Elements and their Alloys

    Science.gov (United States)

    Abel, Phillip; Bozzolo, Guillermo; Huff, Dennis (Technical Monitor)

    2002-01-01

    A simple algorithm for computing the coefficient of thermal expansion of pure elements and their alloys, based on features of the binding energy curve, is introduced. The BFS method for alloys is used to determine the binding energy curves of intermetallic alloys and Ni-base superalloys.

  20. Autofrettage to Counteract Coefficient of Thermal Expansion Mismatch in Cryogenic Pressurized Pipes with Metallic Liners

    Science.gov (United States)

    Wen, Ed; Barbero, Ever; Tygielski, Phlip; Turner, James E. (Technical Monitor)

    2001-01-01

    Composite feedlines with metal liners have the potential to reduce weight/cost while providing the same level of permeation resistance and material compatibility of all-metal feedlines carrying cryogenic propellants in spacecraft. The major technical challenges are the large difference in Coefficient of Thermal Expansion between the liner and the composite, and the manufacturing method required to make a very thin liner with the required strength and dimensional tolerance. This study investigates the use of autofrettage (compressive preload) to counteract Coefficient of Thermal Expansion when pre-pressurization procedures cannot be used to solve this problem. Promising materials (aluminum 2219, Inconel 718, nickel, nickel alloy) and manufacturing techniques (chemical milling, electroplating) are evaluated to determine the best liner candidates. Robust, autofrettaged feedlines with a low Coefficient of Thermal Expansion liner (Inconel 718 or nickel alloy) are shown to successfully counteract mismatch at LOX temperature. A new concept, autofrettage by temperature, is introduced for high Coefficient of Thermal Expansion materials (aluminum and pure nickel) where pressure cannot be used to add compressive preload.

  1. Thermal expansion and isothermal compressibility of TlGaTe2

    International Nuclear Information System (INIS)

    Results of X-ray phase analysis and temperature dependencies of coefficient of thermal expansion and isothermal compression of the TlGaTe2 crystal in the 77-400 K range are performed. On the basis of these investigations they concluded that secondary recrystallization takes place in the given phase at 98.5 K

  2. Thermal expansion of the magnetorefrigerant Gd5(Si,Ge)4

    NARCIS (Netherlands)

    E.H. Brück; M. Nazih; A. de Visser; L. Zhang; O. Tegus

    2003-01-01

    We report thermal expansion measurements carried out on a single-crystal of the giant magnetocaloric effect material Gd5(Si0.43Ge0.57)4. At the magneto-structural phase transition at T0~240 K, large steps in the relative length change ÄL/L along the principle crystallographic axes are observed. The

  3. Copper-zirconium tungstate composites exhibiting low and negative thermal expansion influenced by reinforcement phase transformations

    Science.gov (United States)

    Balch, Dorian K.; Dunand, David C.

    2004-03-01

    A fully-dense Cu-75 vol pct ZrW2O8 metal matrix composite was fabricated by hot isostatic pressing of Cu-coated ZrW2O8 particles. A small amount of the high-pressure γ-ZrW2O8 phase was created during the cooldown and depressurization following densification; near complete transformation to γ-ZrW2O8 was achieved by subsequent cold isostatic pressing. The thermal expansion behavior of the composite between 25°C and 325°C was altered by the cold isostatic pressing treatment, and also depended on the length of time that had passed between thermal cycles. The measured thermal expansion coefficients within specific temperature ranges varied from -6·10-6 K-1 to far above the thermal expansion coefficient of the copper matrix. The complex temperature-dependent expansion/contraction behavior could be justified by considering the evolution of phase transformations taking place in the ZrW2O8 phase, which were observed by in-situ synchrotron X-ray diffraction measurements.

  4. How important is thermal expansion for predicting molecular crystal structures and thermochemistry at finite temperatures?

    Science.gov (United States)

    Heit, Yonaton N; Beran, Gregory J O

    2016-08-01

    Molecular crystals expand appreciably upon heating due to both zero-point and thermal vibrational motion, yet this expansion is often neglected in molecular crystal modeling studies. Here, a quasi-harmonic approximation is coupled with fragment-based hybrid many-body interaction calculations to predict thermal expansion and finite-temperature thermochemical properties in crystalline carbon dioxide, ice Ih, acetic acid and imidazole. Fragment-based second-order Möller-Plesset perturbation theory (MP2) and coupled cluster theory with singles, doubles and perturbative triples [CCSD(T)] predict the thermal expansion and the temperature dependence of the enthalpies, entropies and Gibbs free energies of sublimation in good agreement with experiment. The errors introduced by neglecting thermal expansion in the enthalpy and entropy cancel somewhat in the Gibbs free energy. The resulting ∼ 1-2 kJ mol(-1) errors in the free energy near room temperature are comparable to or smaller than the errors expected from the electronic structure treatment, but they may be sufficiently large to affect free-energy rankings among energetically close polymorphs. PMID:27484373

  5. Thermal expansion of CuAlxIn1-xSe2 chaleopyrite solid solutions

    International Nuclear Information System (INIS)

    Parameters of elementary cell and some structure features of CuAlxIn1-xSe2 solid solutions are studied within 80-650 K temperature range. It is shown that for all the specimens the factors of thermal expansion along c tetragonal axis are lower than those along a axis perpendicular to c axis

  6. Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials

    Directory of Open Access Journals (Sweden)

    Amparo Borrell, Olga García-Moreno, Ramón Torrecillas, Victoria García-Rocha and Adolfo Fernández

    2012-01-01

    Full Text Available Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (−150 to 450 °C. The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

  7. Atomistic Modeling of the Negative Thermal Expansion in δ- Plutonium  Based on the Two-State Description

    Directory of Open Access Journals (Sweden)

    Steven M. Valone

    2012-06-01

    Full Text Available The δ phase  of plutonium with the fcc structure exhibits an unusual negative thermal expansion (NTE over its narrow  temperature range of stability, 593–736 K. An accurate description  of the anomalous high-temperature volume effect of plutonium  goes beyond the current capability  of electronic-structure  calculations.  We propose an atomistic scheme to model the thermodynamic properties of δ-Pu based on the two-state model of Weiss for the Invar alloys, inspired by the simple free-energy analysis previously conducted by Lawson et al. The two-state mechanism is incorporated into the atomistic description of a many-body  interacting  system.  Two modified  embedded atom method potentials are employed to represent the binding energies of two competing  electronic  states in δ-Pu. We demonstrate how the NTE takes place in δ-Pu by means of Monte Carlo simulations implemented with the two-state mechanism.

  8. Next generation dilatometer for highest accuracy thermal expansion measurement of ZERODUR®

    Science.gov (United States)

    Jedamzik, Ralf; Engel, Axel; Kunisch, Clemens; Westenberger, Gerhard; Fischer, Peter; Westerhoff, Thomas

    2015-09-01

    In the recent years, the ever tighter tolerance for the Coefficient of thermal expansion (CTE) of IC Lithography component materials is requesting significant progress in the metrology accuracy to determine this property as requested. ZERODUR® is known for its extremely low CTE between 0°C to 50°C. The current measurement of the thermal expansion coefficient is done using push rod dilatometer measurement systems developed at SCHOTT. In recent years measurements have been published showing the excellent CTE homogeneity of ZERODUR® in the one-digit ppb/K range using these systems. The verifiable homogeneity was limited by the CTE(0°C, 50°C) measurement repeatability in the range of ± 1.2 ppb/K of the current improved push rod dilatometer setup using an optical interferometer as detector instead of an inductive coil. With ZERODUR® TAILORED, SCHOTT introduced a low thermal expansion material grade that can be adapted to individual customer application temperature profiles. The basis for this product is a model that has been developed in 2010 for better understanding of the thermal expansion behavior under given temperature versus time conditions. The CTE behavior predicted by the model has proven to be in very good alignment with the data determined in the thermal expansions measurements. The measurements to determine the data feeding the model require a dilatometer setup with excellent stability and accuracy for long measurement times of several days. In the past few years SCHOTT spent a lot of effort to drive a dilatometer measurement technology based on the push rod setup to its limit, to fulfill the continuously demand for higher CTE accuracy and deeper material knowledge of ZERODUR®. This paper reports on the status of the dilatometer technology development at SCHOTT.

  9. Carbon-based torsional and tensile artificial muscles driven by thermal expansion (presentation video)

    Science.gov (United States)

    Haines, Carter S.; Lima, Márcio D.; Li, Na; Spinks, Geoffrey M.; Foroughi, Javad; Madden, John D. W.; Kim, Shi-Hyeong; Fang, Shaoli; Jung de Andrade, Monica; Göktepe, Fatma; Göktepe, Ozer; Mirvakili, Seyed M.; Naficy, Sina; Lepró, Xavier; Oh, Jiyoung; Kozlov, Mikhail E.; Kim, Seon Jeong; Xu, Xiuru; Swedlove, Benjamin J.; Wallace, Gordon G.; Baughman, Ray H.

    2014-03-01

    High-performance artificial muscles have been produced from fibers having highly anisotropic thermal expansion. Inserting twist into these precursor fibers enables thermally-driven torsional actuation and can cause the formation of helical coils. Such coiled structures provide giant-stroke tensile actuation exceeding the 20% in-vivo contraction of natural muscles. This contraction is highly reversible, with over one million cycles demonstrated, and can occur without the hysteresis that plagues competing shape-memory and piezoelectric muscles. Several materials and composites are investigated, including low-cost, commercially-available muscle precursors, potentially facilitating thermally-responsive textiles that change porosity to provide wearer comfort.

  10. EUVL printing results of a low-thermal expansion material (LTEM) mask

    Science.gov (United States)

    Tong, William M.; Taylor, John S.; Hector, Scott D.; Shell, Melissa K.; Zhang, Guojing; Kearney, Patrick A.; Walton, Christopher C.; Larson, Cindy C.; Wasson, James R.; Mangat, Pawitter J. S.; O'Connell, Donna J.; Folk, Daniel R.

    2000-07-01

    Minimizing image placement errors due to thermal distortion of the mask is a key requirement for qualifying EUV Lithography as a Next Generation Lithography (NGL). Employing Low Thermal Expansion Materials (LTEMs) for mask substrates is a viable solution for controlling mask thermal distortion and is being investigated by a wide array of researchers, tool makers, photomask suppliers, and material manufacturers. Finite element modeling has shown that an EUVL mask with a Coefficient of Thermal Expansion (CTE) of less than 20 ppb/K will meet overlay error budgets for EQ 70 nm lithography at a throughput of 80 wafers per hour. In this paper, we describe the functional differences between today's photomask and EUVL masks; some of these differences are EUVL specific, while others are natural consequences of the shrinking critical dimension. We demonstrate that a feasible manufacturing pathway exists for Low Thermal Expansion Material (LTEM) EUVL masks by fabricating a wafer-shaped LTEM mask substrate using the same manufacturing steps as for fabricating Si wafers. The LTEM substrate was then coated with Mo/Si multilayers, patterned, and printed using the 10X Microstepper. The images were essentially indistinguishable from those images acquired from masks fabricated from high quality silicon wafers as substrates. Our observations lend further evidence that an LTEM can be used as the EUVL mask substrate material.

  11. Effect of high thermal expansion glass infiltration on mechanical properties of alumina–zirconia composite

    Indian Academy of Sciences (India)

    A Balakrishnan; B B Panigrahi; K P Sanosh; Min-Cheol Chu; T N Kim; Seong-Jai Cho

    2009-08-01

    This work studies the effect on the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating glass of a higher thermal expansion (soda lime glass) on the surface at high temperature. The glass improved the strength of composite at room temperature as well as at high temperature. This could be attributed to the drastic drop in the coefficient of thermal expansion due to the compositional change in the soda lime glass during infiltration. There was a significant improvement in the Weibull modulus after glass infiltration. Glass infiltrated samples showed better thermal shock resistance. The magnitude of strength increment was found to be in the order of the surface residual stress generated by thermo-elastic properties mismatch between the composite and the penetrated glass.

  12. Debye temperature, thermal expansion, and heat capacity of TcC up to 100 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Song, T., E-mail: songting@mail.lzjtu.cn [School of Mathematics and Physics, Lanzhou Jiaotong University, Lanzhou 730070 (China); School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Ma, Q. [School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Tian, J.H. [School of Mathematics and Physics, Lanzhou Jiaotong University, Lanzhou 730070 (China); Liu, X.B. [School of Physics and Information Science, Tianshui Normal University, Tianshui 741000 (China); Ouyang, Y.H.; Zhang, C.L.; Su, W.F. [School of Mathematics and Physics, Lanzhou Jiaotong University, Lanzhou 730070 (China)

    2015-01-15

    Highlights: • A number of thermodynamic properties of rocksalt TcC are investigated for the first time. • The quasi-harmonic Debye model is applied to take into account the thermal effect. • The pressure and temperature up to about 100 GPa and 3000 K, respectively. - Abstract: Debye temperature, thermal expansion coefficient, and heat capacity of ideal stoichiometric TcC in the rocksalt structure have been studied systematically by using ab initio plane-wave pseudopotential density functional theory method within the generalized gradient approximation. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of Debye temperature, thermal expansion coefficient, constant-volume heat capacity, and constant-pressure heat capacity on pressure and temperature are successfully predicted. All the thermodynamic properties of TcC with rocksalt phase have been predicted in the entire temperature range from 300 to 3000 K and pressure up to 100 GPa.

  13. Magnetization reversal and negative volume thermal expansion in Fe doped Ca2RuO4

    Science.gov (United States)

    Qi, T. F.; Yuan, S. J.; Ye, F.; Chi, S.; Terzic, J.; Zhang, H.; Zhao, Z.; Liu, X.; Parkin, S.; Mao, W. L.; Cao, G.

    We report structural, magnetic, transport and thermal properties of single-crystal Ca2Ru1-xFexO4 (0 pressure, magnetic field and temperature. The central findings of this work are a pronounced magnetization reversal and a negative thermal expansion that are induced by Fe doping. Our results including neutron diffraction data suggest that the magnetization reversal is primarily a result of different temperature dependences of two antiparallel, competing Ru and Fe sublattices and that the negative thermal expansion is achieved via magnetic and metal-insulator transitions. We will present and discuss our results with comparison drawn with relevant systems. This work was supported by the NSF via Grant No. DMR-1265162.

  14. Degradation Of Environmental Barrier Coatings (EBC) Due To Chemical and Thermal Expansion Incompatibility

    Science.gov (United States)

    Lee, Kang N.; King, Deboran (Technical Monitor)

    2001-01-01

    Current environmental barrier coatings (EBCs) consist of multiple layers, with each layer having unique properties to meet the various requirements for successful EBCs. As a result, chemical and thermal expansion compatibility between layers becomes an important issue to maintaining durability. Key constituents in current EBCs are mullite (3Al2O3-2SiO2), BSAS (BaO(1-x)-SrO(x)-Al2O3-2SiO2), and YSZ (ZrO2-8 wt.% Y2O3). The mullite-BSAS combination appears benign although significant diffusion occurs. Mullite-YSZ and BSAS-YSZ combinations do not react up to 1500 C. Thermally grown SiO2- BSAS and mullite-BSAS-YSZ combinations are most detrimental, forming low melting glasses. Thermal expansion mismatch between YSZ and mullite or BSAS causes severe cracking and delamination.

  15. Mechanical stability of the LHC dipole-dipole 50-75K thermal shield interconnect "floating" expansion joint concept

    CERN Document Server

    Skoczen, Blazej

    1998-01-01

    The LHC dipole cryostats are equipped with thermal shields carrying super-insulation. A cold helium transfer line equipped with expansion joints is integrated into the shield carrying trays (aluminium profiles supported on three composite feet). The stainless steel (316 L) expansion joints compensate for thermal contraction/expansion of the aluminium panels as well as for their misalignment. Design of the LHC thermal shield interconnect is based on the "floating" expansion joint concept (distance between the supports is of around 5 m). The present paper is dedicated to the analysis of mechanical stability of this large span system working at room and at cryogenic temperatures.

  16. EFFECTS OF HEAT TREATMENT ON THE THERMAL EXPANSION BEHAVIOR OF SiC WHISKER REINFORCED ALUMINUM COMPOSITE

    Institute of Scientific and Technical Information of China (English)

    M. Hu; W.D. Fei; W.L. Li; C.K. Yao

    2001-01-01

    The thermal expansion behaviors of SiC whisker reinforced commercially pure aluminum composites subjected to different heat treatments were studied. The results indicated that the thermal expansion behaviors were greatly affected by heat treatment.To explain the results, the microstructures and thermal mismatch stresses in the matrix of the composite were examined by the transmission electron microscope and Xray diffraction, respectively. The dislocation density and thermal mismatch stresses in the matrix of the composites water quenched from 600°C are much higher than that of the composite slowly cooled from 600°C. The analysis suggested that the coefficients of thermal expansion (CTE) are closely related to the change of thermal mismatch stresses and yield strength of the matrix of the composite. The comparison of the coefficients of thermal expansion between experiments and calculations suggested that the temperature behaviors of CTE of SiCw/Al composite agree better with those of Kerner's model within lower temperature range.

  17. Estimating the thermal expansion coefficient of graphene: the role of graphene-substrate interactions

    Science.gov (United States)

    Shaina, P. R.; George, Lijin; Yadav, Vani; Jaiswal, Manu

    2016-03-01

    The temperature-dependent thermal expansion coefficient of graphene is estimated for as-grown chemical vapor deposited graphene using temperature-dependent Raman spectroscopy. For as-grown graphene on copper, the extent of thermal expansion mismatch between substrate and the graphene layer is significant across the entire measured temperature interval, T  =  90-300 K. This mismatch induces lattice strain in graphene. However, graphene grown on copper substrates has a unique morphology in the form of quasi-periodic nanoripples. This crucially influences the profile of the strain in the graphene membrane, which is uniaxial. An estimate of the thermal expansion coefficient of graphene α (T) is obtained after consideration of this strain profile and after incorporating temperature-dependent Grüneisen parameter corrections. The value of α (T) , is found to be negative (average value, -3.75  ×  10-6 K-1) for the entire temperature range and it approaches close to zero for T  graphene wet-transferred to three kinds of substrates: copper, poly-dimethylsiloxane, and SiO2/Si, the Raman shifts can largely be modeled with lattice expansion and anharmonic contributions, and the data suggests limited interfacial interaction with the substrate.

  18. Lattice parameters and thermal expansion of delta-VNsub(1-x) from 298-1000 K

    International Nuclear Information System (INIS)

    The thermal expansion of VNsub(1-x) was determined from measurements of the lattice parameters in the temperature range of 298-1000 K and in the composition range of VNsub(0.707) - VNsub(0.996). Within the accuracy of the results the expansion of the lattice parameter with temperature is not dependent on the composition. The lattice parameter as a function of composition ([N]/[V] = 0.707-0.996) and temperature (198-1000 K) is given by a([N]/[V], T) = 0.38872+0.02488 ([N]/[V]) - (1.083+-0.021) x 10-4Tsup(1/2) + (6.2+-0.1) x 10-sup6T. The coefficient of linear thermal expansion as a function of temperature (in the same range) is given by α(T) = a([N]/[V], T)-1[(-5.04+-0.01) x 10-5Tsup(1/2) + (6.2+-0.1) x 10-6]. The average linear thermal expansion coefficient is αsub(av) = 9.70 +- 0.15 x 10-6 K-1 (298-1000 K). The data are compared with those of several fcc transition metal nitrides collected and evaluated from the literature. (Author)

  19. Isotopic composition dependences of lattice constant and thermal expansion of β-rhombohedral boron

    International Nuclear Information System (INIS)

    Boron isotope substitution in boron-containing crystalline structures is important because many properties of these materials are structure sensitive. In the present work, we studied the unit cell expansion at the fixed temperature and temperature dependence of thermal expansion for the β-rhombohedral modification of boron, when 11B is replaced by 10B isotope. Theoretical analysis of experimental results associates the observed changes in structures of the β-rhombohedral boron samples of various isotope compositions with isotope effects rather than with technologically concomitant impurities.

  20. Large anharmonic effect and thermal expansion anisotropy of metal chalcogenides: The case of antimony sulfide

    Science.gov (United States)

    Gan, Chee Kwan; Soh, Jian Rui; Liu, Yun

    2015-12-01

    We derive a compact matrix expression for the linear thermal expansion coefficients (TECs) for a general orthorhombic system which relates elastic properties and integrated quantities based on deformation and mode dependent Grüneisen parameters and mode dependent heat capacities. The density of Grüneisen parameters Γ (ν ) as a function of frequency ν , weighted by the number of phonon modes, is introduced and found to be illuminating in interpreting the TEC results. Using density functional perturbation theory and Grüneisen formalism for thermal expansion, we illustrate the general usefulness of this method by calculating the linear and volumetric TECs of a low-symmetry orthorhombic compound antimony sulfide (Sb2S3 ), which belongs to a large class of technologically and fundamentally important materials. Even though negative Grüneisen parameters are found for deformations in all three crystal directions, the Γ (ν ) data rule out the occurrences of negative TECs at all temperatures. Sb2S3 exhibits a large thermal expansion anisotropy where the TEC in the b direction can reach as high as 13 ×10-6 K-1 at high temperatures, about two and seven times larger than the TECs in the c and a direction, respectively. Our work suggests a general and practical first-principles approach to calculate the thermal properties of other complicated low-symmetry systems.

  1. Measurement of thermal expansion coefficient of graphene diaphragm using optical fiber Fabry-Perot interference

    Science.gov (United States)

    Li, Cheng; Liu, Qianwen; Peng, Xiaobin; Fan, Shangchun

    2016-07-01

    Application of the Fabry-Perot (FP) interference method for determining the coefficient of thermal expansion (CTE) of a graphene diaphragm is investigated in this paper. A miniature extrinsic FP interferometric (EFPI) sensor was fabricated by using an approximate 8-layer graphene diaphragm. The extremely thin diaphragm was transferred onto the endface of a ferrule with an inner diameter of 125 μm, and van der Waals interactions between the graphene diaphragm and its substrate created a low finesse FP interferometer with a cavity length of 36.13 μm. Double reference FP cavities using two cleaved optical fibers as reflectors were also constructed to differentially cancel the thermal expansion effects of the trapped gas and adhesive material. A temperature test demonstrated an approximate cavity length change of 166.1 nm °C-1 caused by film thermal expansion in the range of 20-60 °C. Then along with the established thermal deformation model of the suspended circular diaphragm, the calculated CTE ranging from  -9.98  ×  10-6 K-1 to  -2.09  ×  10-6 K-1 conformed well to the previously measured results. The proposed method would be applicable in other types of elastic materials as the sensitive diaphragm of an EFPI sensor over a wide temperature range.

  2. Crystal structure and thermal expansion of a CsCe2Cl7 scintillator

    International Nuclear Information System (INIS)

    We used single-crystal X-ray diffraction data to determine crystal structure of CsCe2Cl7. It crystallizes in a P1121/b space group with a=19.352(1) Å, b=19.352(1) Å, c=14.838(1) Å, γ=119.87(2)°, and V=4818.6(5) Å3. Differential scanning calorimetry measurements combined with the structural evolution of CsCe2Cl7 via X-ray diffractometry over a temperature range from room temperature to the melting point indicates no obvious intermediate solid–solid phase transitions. The anisotropy in the average linear coefficient of thermal expansion of the a axis (21.3×10–6/°C) with respect to the b and c axes (27.0×10–6/°C) was determined through lattice parameter refinement of the temperature dependent diffraction patterns. These findings suggest that the reported cracking behavior during melt growth of CsCe2Cl7 bulk crystals using conventional Bridgman and Czochralski techniques may be largely attributed to the anisotropy in thermal expansion. - Graphical abstract: Three-dimensional quadric surface of thermal expansion coefficient of CsCe2Cl7 at room temperature (sphere – isotropic) and near melting point (ellipsoid – anisotropic). - Highlights: • Crystal structure of CsCe2Cl7 was solved through X-ray diffraction. • Linear coefficients of thermal expansion were determined from in-situ XRD in 25–650 °C. • Anisotropy of the a axis with respect to b and c axes (21.3 vs 27.0×10–6/°C) was found. • No solid–solid phase transitions were observed via XRD and thermal analysis

  3. Thermal stability, thermal expansion and grain-growth in exchange-coupled Fe-Pt-Ag-B bulk nanocomposite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Nicula, R., E-mail: radu.nicula@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Advanced Materials Processing, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland); Crisan, O.; Crisan, A.D.; Mercioniu, I. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Stir, M. [University of Berne, Department of Chemistry and Biochemistry, Freiestrasse 3, CH-3012 Berne (Switzerland); Vasiliu, F. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania)

    2015-02-15

    Highlights: • Formation of the L10 FePt hard-magnetic phase (>90%) directly in the as-cast state. • Specific alternating hard/soft nanostructure is stable to 600 °C without grain growth. • Anisotropic and non-linear thermal expansion effects. • The FePtAgB alloy behaves like a single magnetic phase (full exchange coupling). - Abstract: Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studied nowadays due to their potential use in applications demanding stable high-temperature operation and corrosion resistance. In this respect, the FePt alloy system is one of the most actively addressed potential permanent magnet solutions. In FePt alloys, promising magnetic features arise from the co-existence of hard magnetic L1{sub 0} FePt and soft magnetic L1{sub 2} Fe{sub 3}Pt phases emerged from the same metastable precursor. The present work deals with an in-situ temperature-resolved synchrotron radiation study of the thermal stability, thermal expansion and microstructure evolution in exchange-coupled FePtAgB alloys. The as-cast microstructural state as well as the optimized magnetic behavior are given as reference and correlated to the observed microstructural evolution with temperature. The melt-spun Fe{sub 48}Pt{sub 28}Ag{sub 6}B{sub 18} alloy ribbons were examined in situ by synchrotron X-ray powder diffraction from ambient temperature up to 600 °C. The FePt-Fe{sub 3}Pt exchange-coupled microstructure achieved by rapid solidification is not significantly altered during the high temperature exposure. The thermal expansion of the FePt L1{sub 0} unit cell has been found to be strongly anisotropic, being essentially an in-plane expansion which may be seen as an anisotropic invar effect. For the FePt L1{sub 0} phase, a significant deviation from linear thermal expansion is observed at the Curie temperature T{sub C} = 477 °C. This non-linear behavior above T{sub C} is tentatively linked to a diffusion/segregation mechanism of Ag

  4. Electrical resistivity and thermal expansion investigation of golden SmS under pressure

    International Nuclear Information System (INIS)

    We measured the electrical resistivity and the thermal expansion of SmS at high pressures. It is known that the golden SmS undergoes an antiferromagnetic phase transition at a critical pressure (Pc2 ∼ 18 kbar). At pressures slightly below Pc2, the temperature dependence of the electrical resistivity shows a local maximum (hump). Combining the thermal expansion results showing the two-phase mixture of the paramagnetic and antiferromagnetic phase in the vicinity of Pc2, we argue that the hump in the resistivity is caused by the pressure inhomogeneity. We also argue that the inhomogeneity gives rise to a striking effect on the pressure dependence of the residual resistivity, and speculate that in the limit of hydrostatic condition, the residual resistivity may show a rapid drop when the pressure is increased across Pc2.

  5. Irradiation effects on thermal expansion of SiC/SiC composite materials

    International Nuclear Information System (INIS)

    Irradiation-induced dimensional change and thermal expansion of two kinds of composites, self-particle reinforced SiCp/SiC composites and a Hi-Nicalon SiC fiber reinforced SiCf/SiC composite, and monolithic α-SiC were measured after irradiation at 0.2 dpa with irradiation temperatures of 573, 673 and 843 K using the JMTR. From the measurement, swelling was observed for the SiCp/SiC composites and the monolithic α-SiC, on the contrary, the SiCf/SiC composites showed a shrinkage. The measured thermal expansion increased with increasing the specimen temperature below the irradiation temperature, and then rapidly decreased over the irradiation temperature. The so-called 'temperature monitor effect' of the silicon carbide was clearly observed for all specimens, the monolithic α-SiC and both composites

  6. Influence of phosphorus on oxidation behavior of low thermal expansion superalloy IN909 at 650 ℃

    Institute of Scientific and Technical Information of China (English)

    SUN Ya-ru; SUN Wen-ru; HOU Gui-chen; GUO Shou-ren; LIU Zheng; HU Zhuang-qi; N. K. PARK

    2006-01-01

    The effect of phosphorus on the oxidation resistance of low thermal expansion alloy IN909 was studied. The composition and structure of the oxidation layer were analyzed. It is found that the oxidation initiates at the grain boundaries. During the oxidation, Fe atoms diffuse toward the surface and form the outside oxidation layer as the oxide of iron. The transition oxidation layer lies between the oxidation layer and the matrix which is enriched with Nb, Ti and Si, forming FeTiO5, Nb2O5, Fe2SiO4 and TiO2. Phosphorus hardly influences the thermal expansion coefficient of IN909 alloy. However, it increases the formation of ε phase at the boundary of the transition oxidation layer and matrix. As a result, the oxidation rate is decreased efficiently because the ε phase inhibits the diffusion of the element such as iron from the matrix to the oxidation layer.

  7. Thermal expansion anomaly and spontaneous magnetostriction of Dy2AlFe14Mn2 compound

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-yun; ZHAO Miao; GAO Yan; ZHOU Yan; FU Bin; YAN Da-li

    2006-01-01

    The structure and magnetic properties of Dy2AlFe14Mn2 compound were investigated by X-ray diffractometry and magnetization measurements. Dy2AlFe14Mn2 compound has a hexagonal Th2Ni17-type structure. Zero thermal expansion and negative thermal expansion were found in Dy2AlFe14Mn2 compound in the temperature range from 184 to 264 K, and from 264 to 383 K, respectively, by X-ray dilatometry. The spontaneous magnetostrictive deformations from 104 to 400 K were calculated. The results show that the spontaneous volume magnetostrictive deformation increases firstly with increasing temperature, and then decreases with furtther increasing temperature.

  8. Removal properties of low-thermal-expansion materials with rotating-sphere elastic emission machining

    Directory of Open Access Journals (Sweden)

    Masahiko Kanaoka et al

    2007-01-01

    Full Text Available Optical mirrors used in extreme ultraviolet lithography systems require a figure accuracy and a roughness of about 0.1 nm rms. In addition, mirror substrates must be low-thermal-expansion materials. Thus, in this study, we processed two low-thermal-expansion materials, ULE [K. Hrdina, B. Hanson, P. Fenn, R. Sabia, Proc. SPIE 4688 (2002 454.] (Corning Inc. and Zerodur [I. Mitra, M.J. Davis, J. Alkemper, Rolf Müller, H. Kohlmann, L. Aschke, E. Mörsen, S. Ritter, H. Hack, W. Pannhorst, Proc. SPIE 4688 (2002 462.] (SCHOTT AG, with elastic emission machining (EEM in order to evaluate the removal properties. Consequently, we successfully calculated the respective removal rates, because removal volumes were found to be proportional to process times in EEM. Moreover, we demonstrated that the surface roughness of Zerodur is reduced to 0.1 nm rms in the spatial wavelength range from 100 μm to 1 mm.

  9. Viscosity and thermal expansion of rare earth containing soda-lime-silicate glass

    International Nuclear Information System (INIS)

    Viscosity, coefficient of thermal expansion, glass transition temperature and dilatometric softening temperature of soda-lime-silicate glass doped with rare earth oxides (La2O3, CeO2, Nd2O3) were investigated by the rotating crucible viscometer and dilatometry, the melting temperature and activation energy for viscous flow of the studied melt were derived on the basis of Arrhenius equation, in order to reveal the effects of rare earth elements on the behavior of soda-lime-silicate glass. The results show that introduction of rare earth oxides increases the coefficient of thermal expansion, decreases viscosity of soda-lime-silicate glass, and Nd2O3 is an exception in viscosity. The glass transition temperature, dilatometric softening temperature, melting temperature and activation energy for viscous flow of soda-lime-silicate glass doped with rare earth oxides increase with increasing cationic field strength of corresponding rare earth ions.

  10. Linear thermal expansion data for tuffs from the unsaturated zone at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Experiment results are presented for linear thermal expansion measurements on tuffaceous rocks from the unsaturated < one at Yucca Mountain, Nevada. Data were obtained both with and without confining pressure. The accuracy of the unconfined data collected between 50 and 250 degrees C is better than 1.8 percent, with the precision better than 4.5;percent. The accuracy of the unconfined data collected between ambient temperature and 50 degrees C and is approximately 11 percent deviation from the true value, with a precision of 12 percent of the mean value. Because of experiment design and the lack of information related calibrations, the accuracy and precision of the confined thermal expansion measurements could not be determined

  11. Preparation and Characteristic of Glass-Ceramics with Super Low Thermal Expansion Coefficient

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The preparation technics of glass-ceramics with super low coefficient of thermal expansion containing β-quartz solid solution as a main crystal phase based on the glass in the system Li2O-Al2O3-SiO2 was introduced. The composition of base glass, technics of melting and heat treatment effecting on characteristic of glass-ceramics was described. Specimens were prepared by melting, anneal and controlled two steps heat treatment. Crystal phase, microstructure and elementary distributing were studied by using XRD, SEM and EDS respectively. Prepared specimens show excellent transparency and super low thermal expansion coefficient of 2×10-8 ·K-1, which reaches international advanced level.

  12. Effects of in-plane stiffness and charge transfer on thermal expansion of monolayer transition metal dichalcogenide

    Institute of Scientific and Technical Information of China (English)

    王占雨; 周艳丽; 王雪青; 王飞; 孙强; 郭正晓; 贾瑜

    2015-01-01

    Temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconducting transition metal dichalco-genides. Unlike the corresponding bulk material, our simulations show that monolayer MX2 (M=Mo and W;X=S, Se, and Te) exhibits a negative thermal expansion at low temperatures, induced by the bending modes. Transition from con-traction to expansion at higher temperatures is observed. Interestingly, the thermal expansion can be tailored regularly by alteration of M or X atom. Detailed analysis shows that the positive thermal expansion coefficient is determined mainly by the in-plane stiffness, which can be expressed by a simple relationship. Essentially the regularity of this change can be attributed to the difference in charge transfer between the different elements. These findings should be applicable to other two-dimensional systems.

  13. Sound velocity of high-strength polymer with negative thermal expansion coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, R.; Ueno, M.; Okuda, Y.; Burmistrov, S.; Yamanaka, A

    2003-05-01

    Sound velocities of fiber reinforced plastics (FRPs) were measured along the fiber axis at temperatures between 360 and 77 K. We used two kinds of the high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which have negative thermal expansion coefficients. They also have high thermal conductivities and high resistances for flash over voltage, and are expected as new materials for coil bobbins or spacers at cryogenic temperatures. They have very large sound velocities of about 9000 (m/s) at 77 K, which are 4.5 times larger than that of the ordinary polyethylene fiber.

  14. Sound velocity of high-strength polymer with negative thermal expansion coefficient

    International Nuclear Information System (INIS)

    Sound velocities of fiber reinforced plastics (FRPs) were measured along the fiber axis at temperatures between 360 and 77 K. We used two kinds of the high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which have negative thermal expansion coefficients. They also have high thermal conductivities and high resistances for flash over voltage, and are expected as new materials for coil bobbins or spacers at cryogenic temperatures. They have very large sound velocities of about 9000 (m/s) at 77 K, which are 4.5 times larger than that of the ordinary polyethylene fiber

  15. HAYNES 244 alloy – a new 760 ∘C capable low thermal expansion alloy

    Directory of Open Access Journals (Sweden)

    Fahrmann Michael G.

    2014-01-01

    Full Text Available HAYNES® 244TM alloy is a new 760∘C capable, high strength low thermal expansion (CTE alloy. Its nominal chemical composition in weight percent is Ni – 8 Cr – 22.5 Mo – 6 W. Recently, a first mill-scale heat of 244 alloy was melted by Haynes International, and processed to various product forms such as re-forge billet, plate, and sheet. This paper presents key attributes of this new alloy (CTE, strength, low-cycle fatigue performance, oxidation resistance, thermal stability as they pertain to the intended use in rings and seals of advanced gas turbines.

  16. Damage processes in thermoviscoelastic materials with damage-dependent thermal expansion coefficients

    OpenAIRE

    Heinemann, C; Rocca, E.

    2015-01-01

    In this paper we prove existence of global in time weak solutions for a highly nonlinear PDE system arising in the context of damage phenomena in thermoviscoelastic materials. The main novelty of the present contribution with respect to the ones already present in the literature consists in the possibility of taking into account a damage-dependent thermal expansion coefficient. This term implies the presence of nonlinear couplings in the PDE system, which make the analysis more challenging.

  17. Thermal expansion study on high-pressure phases of SmS

    International Nuclear Information System (INIS)

    We have measured the thermal expansion coefficient αL(T) of SmS under pressure up to 21.6kbar. In the golden phase, an excitation gap Δ inferred from αL(T) decreases with increasing pressure. When the system enters the metallic phase from the golden phase, Δ collapses suddenly to zero, and simultaneously, a huge sharp anomaly appears in the αL(T) curve, reflecting the magnetic phase transition

  18. Temperature dependence of the coefficient of linear thermal expansion of single-crystal SmS

    International Nuclear Information System (INIS)

    The coefficient of linear thermal expansion of single-crystal SmS has been measured in the temperature range 300-850 K by dilatometry and X-ray diffraction. It is shown that the difference in the results obtained by these two methods is due to the heating-induced formation of SmS phases with small lattice parameters (5.62-5.8 A) close to that for the metallic SmS phase

  19. A noncontact measurement technique for the density and thermal expansion coefficient of solid and liquid materials

    OpenAIRE

    Chung, Sang K.; Thiessen, David B.; Rhim, Won-Kyu

    1996-01-01

    A noncontact measurement technique for the density and the thermal expansion coefficient of refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2–3 mm diam samples can be levitated, melted, and radiatively cooled in vacuum. Due to the axisymmetric nature of the molten ...

  20. Retardation of Particle Evaporation from Excited Nuclear Systems Due to Thermal Expansion

    OpenAIRE

    Tõke, J.; Pieńkowski, L.; Houck, M. de; Schröder, W. U.; Sobotka, L. G.

    2005-01-01

    Particle evaporation rates from excited nuclear systems at equilibrium matter density are studied within the Harmonic-Interaction Fermi Gas Model (HIFGM) combined with Weisskopf's detailed balance approach. It is found that thermal expansion of a hot nucleus, as described quantitatively by HIFGM, leads to a significant retardation of particle emission, greatly extending the validity of Weisskopf's approach. The decay of such highly excited nuclei is strongly influenced by surface instabilities.

  1. Retardation of particle evaporation from excited nuclear systems due to thermal expansion

    International Nuclear Information System (INIS)

    Particle evaporation rates from excited nuclear systems at equilibrium matter density are studied within the harmonic-interaction Fermi gas model (HIFGM) combined with Weisskopf's detailed balance approach. It is found that thermal expansion of a hot nucleus, as described quantitatively by HIFGM, leads to a significant retardation of particle emission, greatly extending the validity of Weisskopf's approach. The decay of such highly excited nuclei is strongly influenced by surface instabilities

  2. Thermal expansion in UO2 determined by high-energy X-ray diffraction

    Science.gov (United States)

    Guthrie, M.; Benmore, C. J.; Skinner, L. B.; Alderman, O. L. G.; Weber, J. K. R.; Parise, J. B.; Williamson, M.

    2016-10-01

    Here we present crystallographic analyses of high-energy X-ray diffraction data on polycrystalline UO2 up to the melting temperature. The Rietveld refinements of our X-ray data are in agreement with previous measurements, but are systematically located around the upper bound of their uncertainty, indicating a slightly steeper trend of thermal expansion compared to established values. This observation is consistent with recent first principles calculations.

  3. Thermal expansion and heat capacity measurement of uranium-thorium-dysprosium mixed oxides

    International Nuclear Information System (INIS)

    Dysprosium showed 40 at. % solubility in (U0.2Th0.8)O2.00 forming Face centered cubic solid solutions. XRD analysis showed that lattice parameter of mixed oxides decrease whereas average linear thermal expansion coefficients obtained using high temperature X-ray diffractometer (HTXRD) increase with increase in Dy content. Heat capacity measurements of oxides were carried out using Differential Scanning Calorimetry (DSC) in the temperature range 300-850 K. (author)

  4. A Noncontact Measurement Technique for the Density and Thermal Expansion Coefficient of Solid and Liquid Materials

    Science.gov (United States)

    Chung, Sang K.; Thiessen, David B.; Rhim, Won-Kyu

    1996-01-01

    A noncontact measurement technique for the density and the thermal expansion refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2-3 mm diameter samples can be levitated, melted, and radiatively cooled in a vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045-1565 C. The result for the liquid phase density can be expressed by p = 8.848 + (6.730 x 10(exp -4)) x T (degC) g/cu cm within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by Beta=(9.419 x 10(exp -5)) - (7.165 x 10(exp -9) x T (degC)/K within 0.2% accuracy.

  5. First-principles study on negative thermal expansion of PbTiO3

    International Nuclear Information System (INIS)

    It is well known that perovskite-type PbTiO3 behaves negative thermal expansion in a wide temperature range from room temperature to Curie temperature (763 K). The present study reports the first-principles study of the anisotropic thermal expansion of PbTiO3, in the framework of the density-functional theory and the density-functional perturbation theory. The curve of temperature dependence of the unit cell volume is presented from 20 to 520 K through the calculation of the minimum of total free energy at each temperature point. The negative thermal expansion of PbTiO3 is calculated without empirical parameters. Furthermore, the distinctive thermodynamic act of PbTiO3 from expanding to contracting at tetragonal phase is reproduced. The ab-initio calculations reveal that this unique appearance depends on the phonon vibration. The dynamical contributions of various atoms are also calculated to account for the disparate role of Pb-O and Ti-O bond

  6. Thermal expansion measurement of (U,Pu)O2-x in oxygen partial pressure-controlled atmosphere

    Science.gov (United States)

    Kato, Masato; Ikusawa, Yoshihisa; Sunaoshi, Takeo; Nelson, Andrew T.; McClellan, Kenneth J.

    2016-02-01

    Thermal expansion of U0.7Pu0.3O2-x (x = 0, 0.01, 0.02, 0.03) and U0.52Pu0.48O2.00 was investigated by a unique dilatometry which measured in an oxygen partial pressure-controlled atmosphere. The oxygen partial pressure was controlled to hold a constant oxygen-to-metal ratio in the (U,Pu)O2-x during the measurement. Thermal expansion slightly increased with the decrease in oxygen-to-metal ratio. We proposed a relationship to describe thermal expansion as a function of temperature, O/M and Pu content.

  7. Gene expression under thermal stress varies across a geographical range expansion front.

    Science.gov (United States)

    Lancaster, Lesley T; Dudaniec, Rachael Y; Chauhan, Pallavi; Wellenreuther, Maren; Svensson, Erik I; Hansson, Bengt

    2016-03-01

    Many ectothermic species are currently expanding their distributions polewards due to anthropogenic global warming. Molecular genetic mechanisms facilitating range expansion under these conditions are largely unknown, but understanding these could help mitigate expanding pests and disease vectors, or help explain why some species fail to track changing climates. Here, using RNA-seq data, we examine genomewide changes in gene expression under heat and cold stress in the range-expanding damselfly Ischnura elegans in northern Europe. We find that both the number of genes involved and levels of gene expression under heat stress have become attenuated during the expansion, consistent with a previously reported release from selection on heat tolerances as species move polewards. Genes upregulated under cold stress differed between core and edge populations, corroborating previously reported rapid adaptation to cooler climates at the expansion front. Expression of sixty-nine genes exhibited a region x treatment effect; these were primarily upregulated in response to heat stress in core populations but in response to cold stress at the range edge, suggesting that some cellular responses originally adapted to heat stress may switch to cold-stress functionality upon encountering novel thermal selection regimes during range expansion. Transcriptional responses to thermal stress involving heat-shock and neural function genes were largely geographically conserved, while retrotransposon, regulatory, muscle function and defence gene expression patterns were more variable. Flexible mechanisms of cold-stress response and the ability of some genes to shift their function between heat and cold stress might be key mechanisms facilitating rapid poleward expansion in insects. PMID:26821170

  8. Thermal effects in Jaynes-Cummings model derived with low-temperature expansion

    CERN Document Server

    Azuma, Hiroo

    2011-01-01

    In this paper, we investigate thermal effects of the Jaynes-Cummings model (JCM) at finite temperature with a perturbative approach. We assume a single two-level atom and a single cavity mode to be initially in the thermal equilibrium state and the thermal coherent state respectively at a certain finite low temperature. Describing this system with Thermo Field Dynamics (TFD) formalism, we obtain a low-temperature expansion of the atomic population inversion in a systematic manner. Letting the system evolve in time with the JCM Hamiltonian, we examine thermal effects of the collapse and the revival of the Rabi oscillations by means of the third-order perturbation theory under the low-temperature limit, that is to say, using the low-temperature expansion up to the third order terms. From an intuitive discussion, we can expect that the period of the revival of the Rabi oscillations becomes longer as the temperature rises. Numerical results obtained with the perturbation theory reproduce well this temperature dep...

  9. Cold Thermal Anomalous Structure within Lower Mantle and Its Geodynamic Implications

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The lateral temperature anomalous structure of the lower mantle is reconstructed from the seismic tomographical model and high temperature and high pressure laboratory results. A significant correlation between the distribution of the cold anomaly and the location of past subduction belts shows that the shallower anomaly corresponds to the younger subduction sites, while the deeper anomaly to the older ones. This correlation also suggests that the cold anomaly may have come from the subduction slabs and the scale of mantle convection may have been completed. The coldest and largest anomaly is concentrated near the core-mantle boundary (CMB). Few cold anomalies float in the shallower and middle parts of the lower mantle, suggesting that the downward migration of the subduction slabs, discontinuous and step-like, may be divided into the following three stages: subduction, stagnation at the 670 km discontinuity due to the phase transition, and disintegration when the size exceeds the critical point.

  10. CP: AN INVESTIGATION OF COEFFICIENT OF THERMAL EXPANSION, DECOMPOSITION KINETICS, AND REACTION TO VARIOUS STIMULI

    Energy Technology Data Exchange (ETDEWEB)

    Weese, R K; Burnham, A K; Fontes, A T

    2005-03-23

    The properties of pentaamine (5-cyano-2H-tetrazolato-N2) cobalt (III) perchlorate (CP), which was first synthesized in 1968, continues to be of interest for predicting behavior in handling, shipping, aging, and thermal cook-off situations. We report coefficient of thermal expansion (CTE) values over four specific temperature ranges, decomposition kinetics using linear heating rates, and the reaction to three different types of stimuli: impact, spark, and friction. The CTE was measured using a Thermal Mechanical Analyzer (TMA) for samples that were uniaxially compressed at 10,000 psi and analyzed over a dynamic temperature range of -20 C to 70 C. Using differential scanning calorimetry, DSC, CP was decomposed at linear heating rates of 1, 3, and 7 C/min and the kinetic triplet calculated using the LLNL code Kinetics05. Values are also reported for spark, friction, and impact sensitivity.

  11. Polyglutamine expansion in Drosophila: thermal stress and Hsp70 as selective agents

    Indian Academy of Sciences (India)

    Brian R Bettencourt; Catherine C Hogan; Mario Nimali

    2007-04-01

    Repetitive DNA sequences that encode polyglutamine tracts are prone to expansion and cause highly deleterious phenotypes of neurodegeneration. Despite this tendency, polyglutamine tracts (``polyQs”) are conserved features of eukaryotic genomes. PolyQs are the most frequent protein-coding homotypic repeat in insect genomes, and are found predominantly in genes encoding transcription factors conserved from Drosophila through human. Although highly conserved across species, polyQ lengths vary widely within species. In D. melanogaster, polyQs in 25 genes have more alleles and higher heterozygosity than all other poly-amino acid tracts. The heat shock protein Hsp70 is a principal suppressor of polyQ expansions and may play a key role in modulating the phenotypes of the alleles that encode them. Hsp70 also promotes tolerance of natural thermal stress in Drosophila and diverse organisms, a role which may deplete the chaperone from buffering against polyQ toxicity. Thus in stressful environments, natural selection against long polyQ alleles more prone to expansion and deleterious phenotypes may be more effective. This hypothesis can be tested by measuring the phenotypic interactions between Hsp70 and polyQ transgenes in D. melanogaster undergoing natural thermal stress, an approach which integrates comparative genomics with experimental and ecological genetics.

  12. Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

    Institute of Scientific and Technical Information of China (English)

    HUO Kaicheng; SHUI Zhonghe; LI Yue

    2006-01-01

    By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved: temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolution process should be taken into consideration in the same time. Proper chemical admixtures and mineral compositions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

  13. Crystallographic Observation of Dynamic Gas Adsorption Sites and Thermal Expansion in a Breathable Fluorous Metal?Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chi [University of North Texas; Wang, Xiaoping [ORNL; Omary, Mohammad A [University of North Texas

    2009-01-01

    Playing accordion: Cooling a single crystal of a microporous fluorous metal-organic framework under ambient atmosphere leads to very large breathing upon gas adsorption, during which multiple N2 molecules are filled into channels and cages (see picture). While the framework exhibits remarkable positive thermal expansion under vacuum, a gigantic apparent negative thermal expansion takes place when the crystal is exposed to N2 at ambient pressure.

  14. Zirconium tungstate/epoxy nanocomposites: effect of nanoparticle morphology and negative thermal expansivity.

    Science.gov (United States)

    Wu, Hongchao; Rogalski, Mark; Kessler, Michael R

    2013-10-01

    The ability to tailor the coefficient of thermal expansion (CTE) of a polymer is essential for mitigating thermal residual stress and reducing microcracks caused by CTE mismatch of different components in electronic applications. This work studies the effect of morphology and thermal expansivity of zirconium tungstate nanoparticles on the rheological, thermo-mechanical, dynamic-mechanical, and dielectric properties of ZrW2O8/epoxy nanocomposites. Three types of ZrW2O8 nanoparticles were synthesized under different hydrothermal conditions and their distinct properties were characterized, including morphology, particle size, aspect ratio, surface area, and CTE. Nanoparticles with a smaller particle size and larger surface area led to a more significant reduction in gel-time and glass transition temperature of the epoxy nanocomposites, while a higher initial viscosity and significant shear thinning behavior was found in prepolymer suspensions containing ZrW2O8 with larger particle sizes and aspect ratios. The thermo- and dynamic-mechanical properties of epoxy-based nanocomposites improved with increasing loadings of the three types of ZrW2O8 nanoparticles. In addition, the introduced ZrW2O8 nanoparticles did not negatively affect the dielectric constant or the breakdown strength of the epoxy resin, suggesting potential applications of ZrW2O8/epoxy nanocomposites in the microelectronic insulation industry.

  15. Determination of the coefficient of thermal expansion with embedded long-gauge fiber optic sensors

    International Nuclear Information System (INIS)

    A novel methodology for the determination of the coefficient of thermal expansion (CTE) is proposed by using long-gauge fiber optic sensors. Current approaches either neglect the shear-lag effects or do not compensate for the thermo-optic effects in optical fibers leading to precision errors. The embedded long-gauge sensor measures not only the thermo-optic effect due to temperature fluctuations, but also the strain-optic effect created by thermal stresses. However, it is difficult to directly separate these two effects in the measurements. Given that only the strain-optic effect correlates to the CTE of a host material, it is necessary to compensate for the thermo-optic effect. An additional error is attributed to the fact that the shear-lag effect is ignored, i.e. assumption is made that the strain distribution in the optical fiber is the same as that in the host material. This study reports on the development of a methodology for the computation of the coefficient of thermal expansion in structural materials using long-gauge fiber optic sensors. The proposed formulations account for both the shear-lag and thermo-optic effects

  16. Stiffness, thermal expansion, and thermal bending formulation of stiffened, fiber-reinforced composite panels

    Science.gov (United States)

    Collier, Craig S.

    1993-04-01

    A method is presented for formulating stiffness terms and thermal coefficients of stiffened, fiber-reinforced composite panels. The method is robust enough to handle panels with general cross sectional shapes, including those which are unsymmetric and/or unbalanced. Nonlinear, temperature and load dependent constitutive material data of each laminate are used to 'build-up' the stiffened panel membrane, bending, and membrane-bending coupling stiffness terms and thermal coefficients. New thermal coefficients are introduced to quantify panel response from through-the-thickness temperature gradients. A technique of implementing this capability with a single plane of shell finite elements using the MSC/NASTRAN analysis program (FEA) is revealed that provides accurate solutions of entire airframes or engines with coarsely meshed models. An example of a composite, hat-stiffened panel is included to demonstrate errors that occur when an unsymmetric panel is symmetrically formulated as traditionally done. The erroneous results and the correct ones produced from this method are compared to analysis from discretely meshed three-dimensional FEA.

  17. Stiffness, thermal expansion, and thermal bending formulation of stiffened, fiber-reinforced composite panels

    Energy Technology Data Exchange (ETDEWEB)

    Collier, C.S.

    1993-01-01

    A method is presented for formulating stiffness terms and thermal coefficients of stiffened, fiber-reinforced composite panels. The method is robust enough to handle panels with general cross sectional shapes, including those which are unsymmetric and/or unbalanced. Nonlinear, temperature and load dependent constitutive material data of each laminate are used to 'build-up' the stiffened panel membrane, bending, and membrane-bending coupling stiffness terms and thermal coefficients. New thermal coefficients are introduced to quantify panel response from through-the-thickness temperature gradients. A technique of implementing this capability with a single plane of shell finite elements using the MSC/NASTRAN analysis program (FEA) is revealed that provides accurate solutions of entire airframes or engines with coarsely meshed models. An example of a composite, hat-stiffened panel is included to demonstrate errors that occur when an unsymmetric panel is symmetrically formulated as traditionally done. The erroneous results and the correct ones produced from this method are compared to analysis from discretely meshed three-dimensional FEA. 14 refs.

  18. Stiffness, thermal expansion, and thermal bending formulation of stiffened, fiber-reinforced composite panels

    Science.gov (United States)

    Collier, Craig S.

    1993-01-01

    A method is presented for formulating stiffness terms and thermal coefficients of stiffened, fiber-reinforced composite panels. The method is robust enough to handle panels with general cross sectional shapes, including those which are unsymmetric and/or unbalanced. Nonlinear, temperature and load dependent constitutive material data of each laminate are used to 'build-up' the stiffened panel membrane, bending, and membrane-bending coupling stiffness terms and thermal coefficients. New thermal coefficients are introduced to quantify panel response from through-the-thickness temperature gradients. A technique of implementing this capability with a single plane of shell finite elements using the MSC/NASTRAN analysis program (FEA) is revealed that provides accurate solutions of entire airframes or engines with coarsely meshed models. An example of a composite, hat-stiffened panel is included to demonstrate errors that occur when an unsymmetric panel is symmetrically formulated as traditionally done. The erroneous results and the correct ones produced from this method are compared to analysis from discretely meshed three-dimensional FEA.

  19. Thermal vacancy behavior analysis through thermal expansion, lattice parameter and elastic modulus measurements of B2-type FeAl

    International Nuclear Information System (INIS)

    Thermal vacancy behavior in B2-type FeAl was analyzed through thermal expansion, lattice parameter, and elastic modulus measurements. High-temperature X-ray diffractometry (HT-XRD) was conducted to determine the lattice parameter at elevated temperatures, and the electromagnetic acoustic resonance method was applied to investigate the temperature dependence of the elastic moduli in B2-type FeAl. Using a series of in situ high-temperature techniques such as HT-XRD and dilatometry, the thermal vacancy concentration at elevated temperatures was estimated from the divergence between the changes in the sample length and the lattice parameter with temperature, giving a vacancy formation enthalpy of ∼0.7 and 0.6 eV for Fe–40Al and Fe–43Al (at.%), respectively. The long-range order parameter was found to increase with temperature in a high-temperature range, indicating that the Fe-atom recovery process occurs in this temperature range. The in situ high-temperature measurements suggest that at elevated temperatures, thermal vacancies have no significant influence on the lattice parameter and elastic moduli of B2-type FeAl

  20. Utilizing thermal isostasy to estimate sub-lithospheric heat flow and anomalous crustal radioactivity

    Science.gov (United States)

    Hasterok, D.; Gard, M.

    2016-09-01

    While surface heat flow relates to the heat loss through the lithosphere, it can be difficult to quantify and separate the heat produced internally through radiogenic decay from the heat transferred across the base of the lithosphere by mantle convection. In this study, we apply a thermo-isostatic analysis to Australia and estimate the sub-lithospheric and radiogenic heat flow components by employing a simple 1-D conservation of energy model. We estimate an anomalous radiogenic heat production across much of eastern Australia generally accounting for >50 mW m-2, while western Australia appears to have high crustal compositionally corrected elevation, possibly related to chemical buoyancy of the mantle lithosphere. A moderately high sub-lithospheric heat flow (∼40 mW m-2) along the eastern and southeastern coast, including Tasmania, is coincident with locations of Cenozoic volcanism and supports an edge-driven convection hypothesis. However, the pattern of sub-lithospheric heat flow along the margin does not support the existence of hotspot tracks. Thermo-isostatic models such as these improve our ability to identify and quantify crustal from mantle sources of heat loss and add valuable constraints on tectonic and geodynamic models of the continental lithosphere's physical state and evolution.

  1. Characterization and thermal expansion of Sr2Fe Mo2−O6 double perovskites

    Indian Academy of Sciences (India)

    Y Markandeya; Y Suresh Reddy; Shashidhar Bale; C Vishnuvardhan Reddy; G Bhikshamaiah

    2015-10-01

    Double perovskite oxides Sr2FeMo2−O6 ( = 0.8, 1.0, 1.2, 1.3 and 1.4) (SFMO) of different compositions were prepared by sol–gel growth followed by annealing under reducing atmosphere conditions of H2/Ar flow. X-ray powder diffraction studies revealed that the crystal structure of the samples changes from tetragonal to cubic at around = 1.2. Lattice parameters and unit cell volume of these samples found to decrease with the increase in Fe content. The characteristics absorption bands observed in the range 400–1000 cm−1 of Fourier transform infrared spectra indicate the presence of FeO6 and MoO6 octahedra and confirm the formation of double perovskite phase. The value of g ∼ 2.00 obtained from electron spin resonance studies indicates that Fe is in 3+ ionic state in the SFMO samples. Dilatometric studies of these samples reveal that the average value of coefficient of thermal expansion ($\\overline{\\alpha}$) increases with the increase in temperature or Fe content in SFMO samples. The low value of coefficient of thermal expansion 1.31 × 10−6°C−1 obtained for Sr2Fe0.8Mo1.2O6 in the present study in the temperature range of 40–100°C makes it useful as anode material in fuel cells. The coefficient of thermal expansion ($\\overline{\\alpha}$) and the unit cell volume () of SFMO samples vary inversely with composition in agreement with Grüneisen relation.

  2. Models for mean bonding length, melting point and lattice thermal expansion of nanoparticle materials

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.com [Department of Physics, College of Science, University of Salahaddin-Erbil, Arbil, Kurdistan (Iraq)

    2012-11-15

    Graphical abstract: Three models are derived to explain the nanoparticles size dependence of mean bonding length, melting temperature and lattice thermal expansion applied on Sn, Si and Au. The following figures are shown as an example for Sn nanoparticles indicates hilly applicable models for nanoparticles radius larger than 3 nm. Highlights: ► A model for a size dependent mean bonding length is derived. ► The size dependent melting point of nanoparticles is modified. ► The bulk model for lattice thermal expansion is successfully used on nanoparticles. -- Abstract: A model, based on the ratio number of surface atoms to that of its internal, is derived to calculate the size dependence of lattice volume of nanoscaled materials. The model is applied to Si, Sn and Au nanoparticles. For Si, that the lattice volume is increases from 20 Å{sup 3} for bulk to 57 Å{sup 3} for a 2 nm size nanocrystals. A model, for calculating melting point of nanoscaled materials, is modified by considering the effect of lattice volume. A good approach of calculating size-dependent melting point begins from the bulk state down to about 2 nm diameter nanoparticle. Both values of lattice volume and melting point obtained for nanosized materials are used to calculate lattice thermal expansion by using a formula applicable for tetrahedral semiconductors. Results for Si, change from 3.7 × 10{sup −6} K{sup −1} for a bulk crystal down to a minimum value of 0.1 × 10{sup −6} K{sup −1} for a 6 nm diameter nanoparticle.

  3. Effects of Chemical Treatments on Thermal Expansion Properties of Cordierite Ceramics

    Institute of Scientific and Technical Information of China (English)

    BAI Jiahai; GUO Lucun

    2006-01-01

    Cordierite honeycomb ceramics was treated with 1.5 M HNO3, followed with 1.5 M NaOH at 93 ℃. The combination of acid treatment with alkali treatment significantly diminished the rebounding of coefficient of thermal expansion (CTE)caused by heat treatment, a phenomenon observed in samples treated solely with acid. Inductively coupled plasma (ICP) analysis results reveal that the alkali treatment preferentially dissolved "free" SiO2 left in the acid-treated samples, which is considered to be a key factor responsible for the CTE rebounding.

  4. Size- and Temperature-Dependent Thermal Expansion Coefficient of a Nanofilm

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li-Jun; GUO Jian-Gang; ZHAO Ya-Pu

    2009-01-01

    The thermal expansion coefficient (TEC) of an ideal crystal is derived by using a method of Boltzmann statistics.The Morse potential energy function is adopted to show the dependence of the TEC on the temperature.By taking the effects of the surface relaxation and the surface energy into consideration,the dimensionless TEC of a nanofilm is derived.It is shown that with decreasing thickness,the TEC can increase or decrease,depending on the surface relaxation of the nanofilm.

  5. Crystal structure and thermal expansion of perovskites containing uranium (VI) and rare-earth elements

    Institute of Scientific and Technical Information of China (English)

    Aleksandr; Anna Ershova; Nikolai Chernorukov

    2009-01-01

    By the method of high-temperature reactions in solid phase, compounds with the general formula MII(AIII2/3U1/3)O3 (MII=Sr, AIII=Sc, In; MII=Ba, AIII=Sc, In, Y, Nd-Lu) were synthesized. Their structures (space groups Fmm and Pnma) were refined by the Rietveld method and morphotropic transition in Ba(Ln2/3U1/3)O3 on the border of Gd-Tb was discovered. By means of high-temperature X-ray diffraction, phase transitions were studied and thermal expansion coefficients were determined.

  6. DyVO4 thermal expansion anomalies caused by quadrupole ordering

    International Nuclear Information System (INIS)

    The experimental and theoretical studies on anomalies of the DyVO4 crystals thermal expansion, conditioned by ordering the Q2 quadrupole moments of the Dy3+ ion, are presented. The calculated curves sufficiently well describe the experiment both in the tetragonal and rhombic phases. The values of the complete quadrupole constant and magnetoelastic contribution to it are obtained for the DyVO4. It is noted, that the DyVO4 is the only crystal in the zircons family, for which the γ-symmetry quadrupole ordering is realized

  7. Correlation dependence of the volumetric thermal expansion coefficient of metallic aluminum on its heat capacity

    Science.gov (United States)

    Bodryakov, V. Yu.; Bykov, A. A.

    2016-05-01

    The correlation between the volumetric thermal expansion coefficient β( T) and the heat capacity C( T) of aluminum is considered in detail. It is shown that a clear correlation is observed in a significantly wider temperature range, up to the melting temperature of the metal, along with the low-temperature range where it is linear. The significant deviation of dependence β( C) from the low-temperature linear behavior is observed up to the point where the heat capacity achieves the classical Dulong-Petit limit of 3 R ( R is the universal gas constant).

  8. Thermal expansion coefficient of glass and melts of Te-I system

    International Nuclear Information System (INIS)

    Volumetric thermal expansion coefficient (VTEC) was studied in glasses and melts of (TeI)1-x (T2I)x system in the range 293-773 K. During heating to glass transition temperature VTEC of all studied glasses don't depend on temperature. VTEC for melts don't depend on temperature. This points to more high rigidity of structure as compared with Te-Cl and Te-Br systems. More significant rigidity of structure in studied system is conditioned by strengthening of intermolecular interaction increasing density of chain cross-linking. VTEC of glasses in given system are close to corresponding values of chain polymers

  9. Design of materials with extreme thermal expansion using a three-phase topology optimization method

    DEFF Research Database (Denmark)

    Sigmund, Ole; Torquato, S.

    1997-01-01

    Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases...... on a finite-element discretization of the base cell. The optimization problem is solved using sequential linear programming. To benchmark the design method we first consider two-phase designs. Our optimal two-phase microstructures are in fine agreement with rigorous bounds and the so-called Vigdergauz...

  10. Control of biaxial strain in single-layer Molybdenite using local thermal expansion of the substrate

    OpenAIRE

    Plechinger, G.; Castellanos-Gomez, A.; Buscema, M.; van der Zant, H. S. J.; Steele, G. A.; Kuc, A.; Heine, T.; Schüller, C; Korn, T.

    2015-01-01

    Single-layer MoS2 is a direct-gap semiconductor whose electronic band structure strongly depends on the strain applied to its crystal lattice. While uniaxial strain can be easily applied in a controlled way, e.g., by bending of a flexible substrate with the atomically thin MoS2 layer on top, experimental realization of biaxial strain is more challenging. Here, we exploit the large mismatch between the thermal expansion coefficients of MoS2 and a silicone-based substrate to apply a controllabl...

  11. Materials Selection in Gas Turbine Engine Design and the Role of Low Thermal Expansion Materials

    Science.gov (United States)

    Lagow, Benjamin W.

    2016-08-01

    Materials selection criteria in gas turbine engine design are reviewed, and several design challenges are introduced where selection of low coefficient of thermal expansion (CTE) materials can help improve engine performance and operability. This is followed by a review of the types of low CTE materials that are suitable for gas turbine engine applications, and discussion of their advantages and disadvantages. The primary limitation of low CTE materials is their maximum use temperature; if higher temperature materials could be developed, this could result in novel turbine system designs for gas turbine engines.

  12. Negative Thermal Expansion in Zincblende Structure: an EXAFS study of CdTe

    OpenAIRE

    Abd El All, Naglaa Fathy

    2010-01-01

    To gain a deeper insight on the local origin of NTE in zincblende crystals, EXAFS measurements have been performed on CdTe, which has NTE properties intermediate between Ge and CuCl. In this work an accurate evaluation of the bond thermal expansion, parallel and perpendicular MSRDs and distribution asymmetry of the first shell of CdTe has been made, obtaining a good agreement between two different procedures of the data analysis (i) ratio method (ii) FEFF6-FEFFIT method. The values of the rel...

  13. Fiber-content dependency of the optical transparency and thermal expansion of bacterial nanofiber reinforced composites

    OpenAIRE

    Nogi, Masaya; Ifuku, Shinsuke; Abe, Kentaro; Handa, Keishin; Nakagaito, Antonio Norio; Yano, Hiroyuki

    2006-01-01

    We produced transparent nanocomposite reinforced with bacterial cellulose having a wide range of fiber contents, from 7.4 to 66.1 wt %, by the combination of heat drying and organic solvent exchange methods. The addition of only 7.4 wt % of bacterial cellulose nanofibers, which deteriorated light transmittance by only 2.4%, was able to reduce the coefficient of thermal expansion of acrylic resin from 86×10–6 to 38×10–6 K–1. As such, the nanofiber network of bacterial cellulose has an extraord...

  14. Novel Materials through Non-Hydrolytic Sol-Gel Processing: Negative Thermal Expansion Oxides and Beyond

    Directory of Open Access Journals (Sweden)

    Cora Lind

    2010-04-01

    Full Text Available Low temperature methods have been applied to the synthesis of many advanced materials. Non-hydrolytic sol-gel (NHSG processes offer an elegant route to stable and metastable phases at low temperatures. Excellent atomic level homogeneity gives access to polymorphs that are difficult or impossible to obtain by other methods. The NHSG approach is most commonly applied to the preparation of metal oxides, but can be easily extended to metal sulfides. Exploration of experimental variables allows control over product stoichiometry and crystal structure. This paper reviews the application of NHSG chemistry to the synthesis of negative thermal expansion oxides and selected metal sulfides.

  15. Thermal Expansion Behavior of La1-xSrxMn1-yCoyO3-δ Perovskites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The thermal expansion behavior of La1-xSrxMn1-yCoyO3-δ (x=0.2~0.4, y=0.1~0.3) perovskites in air has been investigated. The average linear thermal expansion coefficients increased with increasing Sr content up to 40 mole fraction or Co content up to 30 mole fraction. The expansion is generally attributed to an increase in the average cation radius as some of the cations in the perovskite are reduced in valence when oxygen ions are removed from the structure.

  16. Cryogenic Refractive Index and Coefficient of Thermal Expansion for the S-TIH1 Glass

    Science.gov (United States)

    Quijada, Manuel A.; Leviton, Douglas; Content, David

    2013-01-01

    Using the CHARMS facility at NASA GSFC, we have measured the cryogenic refractive index of the Ohara S-TIH1 glass from 0.40 to 2.53 micrometers and from 120 to 300 K. We have also examined the spectral dispersion and thermo-optic coefficients (dn/dT). We also derived temperature-dependent Sellmeier models from which refractive index may be calculated for any wavelength and temperature within the stated ranges of each model. The S-TIH1 glass we tested exhibited unusual behavior in the thermo-optic coefficient. We found that for delta coefficient of thermal expansion (CTE) for the similar batch of S-TIH1 glass in order to understand its thermal properties. The CTE showed a monotonic change with a decrease in temperature.

  17. Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements.

    Science.gov (United States)

    Bansal, Dipanshu; Aref, Amjad; Dargush, Gary; Delaire, Olivier

    2016-09-28

    Based on thermodynamic principles, we derive expressions quantifying the non-harmonic vibrational behavior of materials, which are rigorous yet easily evaluated from experimentally available data for the thermal expansion coefficient and the phonon density of states. These experimentally-derived quantities are valuable to benchmark first-principles theoretical predictions of harmonic and non-harmonic thermal behaviors using perturbation theory, ab initio molecular-dynamics, or Monte-Carlo simulations. We illustrate this analysis by computing the harmonic, dilational, and anharmonic contributions to the entropy, internal energy, and free energy of elemental aluminum and the ordered compound [Formula: see text] over a wide range of temperature. Results agree well with previous data in the literature and provide an efficient approach to estimate anharmonic effects in materials. PMID:27438881

  18. Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements

    Science.gov (United States)

    Bansal, Dipanshu; Aref, Amjad; Dargush, Gary; Delaire, Olivier

    2016-09-01

    Based on thermodynamic principles, we derive expressions quantifying the non-harmonic vibrational behavior of materials, which are rigorous yet easily evaluated from experimentally available data for the thermal expansion coefficient and the phonon density of states. These experimentally-derived quantities are valuable to benchmark first-principles theoretical predictions of harmonic and non-harmonic thermal behaviors using perturbation theory, ab initio molecular-dynamics, or Monte-Carlo simulations. We illustrate this analysis by computing the harmonic, dilational, and anharmonic contributions to the entropy, internal energy, and free energy of elemental aluminum and the ordered compound \\text{FeSi} over a wide range of temperature. Results agree well with previous data in the literature and provide an efficient approach to estimate anharmonic effects in materials.

  19. Characterization of the negative thermal expansion material Zr1-xHfxW2O8

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The oxide ZrW2Osdisplays unusual property of isotropic negative thermal expansion in a large wide temperaturerange, which makes it have a number of important potential applications. The cubic Zrl-xHfxW2O8 (x = 0, 0.3, 0.5, 0.7, and1.0) weresynthesized by standard solid state reaction technique. The high and low temperature X-ray diffraction analysisindicate that the substitution of the Hf4+ for Zr4+ only leads to reducing the lattice constants, and the changes of negativethermal expansion coefficients are not obvious. The linear expansion coefficients of Zrl-xHfxW2O8 (x = 0, 0.3, 0.5, 0.7, and1.0) are about -6 × 10-6 K-1 in the temperature range of 298 to 973 K, while that of Zr0.5Hf0.5W2O8 is -9.6 × 10-6 K-1 from83 to 298 K. The phase transition temperatures from α-ZrW2O8 to β-ZrW2O8 structure were also determined by X-ray dif-fraction method. Thermogravimetric analysis (TGA) exhibits that Zrl-xHfxW2O8 is not hygroscopic in air.

  20. The effect of contained fluids during rocksalt heating: insights from thermal expansion experiments on halite single crystals.

    Science.gov (United States)

    Speranza, Giulio; Vona, Alessandro; Di Genova, Danilo; Romano, Claudia

    2015-04-01

    Rocksalt overall characteristics and peculiarity are well known and have made rocksalt bodies one of the most favorable choice for nuclear waste storage purposes. Low to medium temperature effects related to nuclear waste heat generation have been studied by several authors. However, high temperature related salt behavior has been poorly investigated as well as studies focused on the effect of temperature increase on fluids contained in halite. Here we present the results of thermal expansion experiments in the range 50 - 700°C made on halite single crystals with different fluid contents. Our results show that thermally unaltered halite is subjected, upon heating, to thermal instability around 300 - 450°C, with sudden increase in expansivity, sample cracking and fluids emission. Moreover, thermal expansion results higher for fluid-rich salts. In contrast, thermally altered halite, lacks the instability occurrence, showing a constant linear thermal expansion regardless its fluid contents. Rocksalt thermal instability, that is likely to be due to fluids overpressure development upon heating, lead also to a bulk density reduction. Thus, unaltered salt heated to temperature around 300°C or more could cause damage, fluids emission and density drop, increasing the salt mobility. For this reason, a detailed and quantitative study of fluid type, abundance and arrangement within crystals, as well as their response to stress and thermal changes is fundamental for both scientific and applicative purposes regarding halite.

  1. Internal Thermal Control System Hose Heat Transfer Fluid Thermal Expansion Evaluation Test Report

    Science.gov (United States)

    Wieland, P. O.; Hawk, H. D.

    2001-01-01

    During assembly of the International Space Station, the Internal Thermal Control Systems in adjacent modules are connected by jumper hoses referred to as integrated hose assemblies (IHAs). A test of an IHA has been performed at the Marshall Space Flight Center to determine whether the pressure in an IHA filled with heat transfer fluid would exceed the maximum design pressure when subjected to elevated temperatures (up to 60 C (140 F)) that may be experienced during storage or transportation. The results of the test show that the pressure in the IHA remains below 227 kPa (33 psia) (well below the 689 kPa (100 psia) maximum design pressure) even at a temperature of 71 C (160 F), with no indication of leakage or damage to the hose. Therefore, based on the results of this test, the IHA can safely be filled with coolant prior to launch. The test and results are documented in this Technical Memorandum.

  2. Anomalous subsurface thermal behavior in tissue mimics upon near infrared irradiation mediated photothermal therapy.

    Science.gov (United States)

    Ghosh, Soham; Sahoo, Nilamani; Sajanlal, P R; Sarangi, Nirod Kumar; Ramesh, Nivarthi; Panda, Tapobrata; Pradeep, T; Das, Sarit Kumar

    2014-03-01

    Photothermal therapy using (Near Infrared) NIR region of EM spectrum is a fast emerging technology for cancer therapy. Different types of nanoparticles may be used for enhancing the treatment. Though the treatment protocols are developed based on experience driven estimated temperature increase in the tissue, it is not really known what spatiotemporal thermal behavior in the tissue is. In this work, this thermal behavior of tissue models is investigated with and without using nanoparticles. An increased temperature inside tissue compared to surface is observed which is counter intuitive from the present state of knowledge. It is shown from fiber level microstructure that this increased temperature leads to enhanced damage at the deeper parts of biomaterials. Nanoparticles can be utilized to control this temperature increase spatially. A multiple scattering based physical model is proposed to explain this counterintuitive temperature rise inside tissue. The results show promising future for better understanding and standardizing the protocols for photothermal therapy.

  3. Anomalous thermal dynamics of Bragg gratings inscribed in germanosilicate optical fiber

    OpenAIRE

    Rahman, A.; Madhav, Venu K; B. Srinivasan; S. Asokan

    2009-01-01

    An interesting, periodic appearance of a new peak has been observed in the reflected spectrum of a Fiber Bragg Grating (FBG) inscribed in a germanosilicate fiber during thermal treatment. The new peak occurs on the longer wavelength side of the spectrum during heating and on the shorter wavelength side during cooling, following an identical reverse dynamics. Comparison with a commercial grating with 99.9% reflectivity shows a similar decay dynamics. It is proposed that the distortion due to s...

  4. Synthesis, characterization and thermal expansion measurements on uranium-cerium mixed oxides

    Science.gov (United States)

    Venkata Krishnan, R.; Panneerselvam, G.; Singh, Brij Mohan; Kothandaraman, B.; Jogeswararao, G.; Antony, M. P.; Nagarajan, K.

    2011-07-01

    Uranium-cerium mixed oxides (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) were prepared by combustion synthesis using citric acid as the fuel. Sintering of the solid solutions was carried out at 1873 K under reduced atmosphere. From the room temperature XRD patterns of the sintered samples it was found that the solid solutions form single phase fluorite structure. The room temperature lattice parameters of (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) are 0.5458, 0.5446, 0.5434 and 0.5422 nm respectively. Thermal expansion of (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) in the temperature range 298-1973 K was measured by high temperature X-ray diffraction (HTXRD). The coefficients of thermal expansion increase with increase in CeO 2 content in the sample and the measured data in the temperature range 298-1973 K, for (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) are 18.23, 19.91, 21.59, 23.29 × 10 -6 K -1, respectively.

  5. TEV—A Program for the Determination of the Thermal Expansion Tensor from Diffraction Data

    Directory of Open Access Journals (Sweden)

    Thomas Langreiter

    2015-02-01

    Full Text Available TEV (Thermal Expansion Visualizing is a user-friendly program for the calculation of the thermal expansion tensor αij from diffraction data. Unit cell parameters determined from temperature dependent data collections can be provided as input. An intuitive graphical user interface enables fitting of the evolution of individual lattice parameters to polynomials up to fifth order. Alternatively, polynomial representations obtained from other fitting programs or from the literature can be entered. The polynomials and their derivatives are employed for the calculation of the tensor components of αij in the infinitesimal limit. The tensor components, eigenvalues, eigenvectors and their angles with the crystallographic axes can be evaluated for individual temperatures or for temperature ranges. Values of the tensor in directions parallel to either [uvw]’s of the crystal lattice or vectors (hkl of reciprocal space can be calculated. Finally, the 3-D representation surface for the second rank tensor and pre- or user-defined 2-D sections can be plotted and saved in a bitmap format. TEV is written in JAVA. The distribution contains an EXE-file for Windows users and a system independent JAR-file for running the software under Linux and Mac OS X. The program can be downloaded from the following link: http://www.uibk.ac.at/mineralogie/downloads/TEV.html (Institute of Mineralogy and Petrography, University of Innsbruck, Innsbruck, Austria

  6. Thermal expansion of Y0.8U0.2Pd3

    International Nuclear Information System (INIS)

    We have measured the linear thermal expansion coefficient α(T) of polycrystalline Y1-xUxPd3 in the temperature range 0.4-30 K for x=0.2 and from 4.2 to 36 K for x=0.4. For Y0.8U0.2Pd3, α(T)/T versus T shows a -ln T dependence between 2 and 14 K, consistent with non-Fermi liquid behaviour related to a two-channel quadrupolar Kondo effect, as previously reported [1, 2]. At lower temperatures, the thermal expansion deviates from this temperature dependence, finally becoming negative below T=0.8 K. For Y0.6U0.4Pd3, spin-glass freezing has been reported below TSG∼10 K [1]. Close to this temperature we observe only a deviation of α(T)/T from its high temperature behaviour: α(T) becomes small in magnitude, changing sign around 5 K, and not showing -ln T dependence. We discuss these experimental results in terms of the two-channel quadrupolar Kondo effect. ((orig.))

  7. Thermal expansion and decomposition of jarosite: a high-temperature neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory; Zhao, Yusheng [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory; Hickmott, Donald D [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

    2009-01-01

    The structure of deuterated jarosite, KFe{sub 3}(SO{sub 4}){sub 2}(OD){sub 6}, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate {approx}10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH){sub 6}] octahedra and [SO{sub 4}] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, a = a{sub 0} + a{sub 1} T, where a{sub 0} = 1.01 x 10{sup -4} K{sup -1} and a{sub 1} = -1.15 x 10{sup -7} K{sup -2}. On heating, the hydrogen bonds, O1{hor_ellipsis}D-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D{hor_ellipsis}O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

  8. Thermal expansion anomaly and spontaneous magnetostriction of Tb2Fe15Cr2 compound

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The structural and magnetic properties of Tb2Fe15Cr2 compound were investigated by means of X-ray diffraction and magnetization measurements. Tb2Fe15Cr2 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Tb2Fe15Cr2 compound from 372 to 452 K by X-ray dilatometry. The coefficient of the average thermal expansion is α =-3.14×10-5 K-1. The magnetostrictive deformations from 292 to 450 K were calculated. The result showed that the spontaneous volume magnetostrictive deformation ωs remains nearly constant with increasing temperature up to 360 K, but decreases with the further increase of temperature. The spontaneous linear magnetostrictive deformation λc along the c axis decreases with increasing temperature. The spontaneous linear magnetostrictive deformation, λa, in the basal-plane increases with increasing temperature up to 360 K, but decreases with further increasing temperature.

  9. Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y2Fe14Al3Compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; ZHANG Yan-Yan; JIANG Xin-Yuan; GAO Chun-Jing; WU Yan-Zhao

    2009-01-01

    The structure and magnetic properties of Y2Fe14Al3 compound are investigated by means of x-ray diffraction and magnetization measurements. The Y2Fe14.Al3 compound has a hexagonal Th2Ni17-type structure. Nega-tive thermal expansion is found in Y2Fe14Al3 compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is α = -2.54 × 10-5 K-1. The spontaneous mag-netostrictive deformations from 283 to 470 K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs decreases from 5.74 × 10-3 to nearly zero with temperature increasing from 283 to 470K, the spontaneous linear magnetostrictive deformation λc along the c-axis is larger than the spontaneous linear magnetostrictive deformation λα in basal-plane in the same temperature below 350K.

  10. Modeling of thermal expansion coefficient of perovskite oxide for solid oxide fuel cell cathode

    Science.gov (United States)

    Heydari, F.; Maghsoudipour, A.; Alizadeh, M.; Khakpour, Z.; Javaheri, M.

    2015-09-01

    Artificial intelligence models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the material science. This study investigates the applicability of adaptive neuro-fuzzy inference system (ANFIS) approach for modeling the performance parameters of thermal expansion coefficient (TEC) of perovskite oxide for solid oxide fuel cell cathode. Oxides (Ln = La, Nd, Sm and M = Fe, Ni, Mn) have been prepared and characterized to study the influence of the different cations on TEC. Experimental results have shown TEC decreases favorably with substitution of Nd3+ and Mn3+ ions in the lattice. Structural parameters of compounds have been determined by X-ray diffraction, and field emission scanning electron microscopy has been used for the morphological study. Comparison results indicated that the ANFIS technique could be employed successfully in modeling thermal expansion coefficient of perovskite oxide for solid oxide fuel cell cathode, and considerable savings in terms of cost and time could be obtained by using ANFIS technique.

  11. Zero-Thermal Expansion and Heat Capacity of Zirconium Pyrovanadate Doped with Zirconia and Vanadium (V) Oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dominant phase ZrV2O7 material, doped with zirconia and vanadium (V) oxide, was synthesized by solid state reaction and sol-gel methods. X-ray power diffraction patterns show that it is cubic structure. Thermal mechanic analysis measurements exhibit a zero-thermal expansion of this material above 150 ℃. Meanwhile, the heat capacity dependent on temperature, determined by differential scanning calorimetry, keeps in constant almost in the same temperature range. The relationship between unusual thermal expansion and abnormal heat capacity is discussed with Gr€黱eisen parameter.

  12. Matrix-filler interfaces and physical properties of metal matrix composites with negative thermal expansion manganese nitride

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Koshi, E-mail: takenaka@nuap.nagoya-u.ac.jp [Department of Applied Physics, Nagoya University, Nagoya 464-8603 (Japan); Department of Crystalline Materials Science, Nagoya University, Nagoya 464-8603 (Japan); Kuzuoka, Kota [Department of Applied Physics, Nagoya University, Nagoya 464-8603 (Japan); Sugimoto, Norihiro [Department of Crystalline Materials Science, Nagoya University, Nagoya 464-8603 (Japan)

    2015-08-28

    Copper matrix composites containing antiperovskite manganese nitrides with negative thermal expansion (NTE) were formed using pulsed electric current sintering. Energy dispersive X-ray spectroscopy revealed that the chemically reacted region extends over 10 μm around the matrix–filler interfaces. The small-size filler was chemically deteriorated during formation of composites and it lost the NTE property. Therefore, we produced the composites using only the nitride particles having diameter larger than 50 μm. The large-size filler effectively suppressed the thermal expansion of copper and improved the conductivity of the composites to the level of pure aluminum. The present composites, having high thermal conductivity and low thermal expansion, are suitable for practical applications such as a heat radiation substrate for semiconductor devices.

  13. Matrix-filler interfaces and physical properties of metal matrix composites with negative thermal expansion manganese nitride

    Science.gov (United States)

    Takenaka, Koshi; Kuzuoka, Kota; Sugimoto, Norihiro

    2015-08-01

    Copper matrix composites containing antiperovskite manganese nitrides with negative thermal expansion (NTE) were formed using pulsed electric current sintering. Energy dispersive X-ray spectroscopy revealed that the chemically reacted region extends over 10 μm around the matrix-filler interfaces. The small-size filler was chemically deteriorated during formation of composites and it lost the NTE property. Therefore, we produced the composites using only the nitride particles having diameter larger than 50 μm. The large-size filler effectively suppressed the thermal expansion of copper and improved the conductivity of the composites to the level of pure aluminum. The present composites, having high thermal conductivity and low thermal expansion, are suitable for practical applications such as a heat radiation substrate for semiconductor devices.

  14. Extreme variation in basal thermal conditions of the central Greenland Ice Sheet due to anomalous lithosphere structure

    Science.gov (United States)

    Rogozhina, Irina; Petrunin, Alexey; Vaughan, Alan P. M.; Kukkonen, Ilmo T.; Kaban, Mikhail K.; Koulakov, Ivan; Thomas, Maik

    2013-04-01

    At the Earth's surface, heat fluxes from the interior are generally insignificant when compared with fluxes from the sun and atmosphere; however, in areas permanently blanketed by ice these become very important. Modelling studies show that they are key to understanding the internal thermal structure of ice sheets and the distribution of melt water at their bases, information which is crucial for planning deep ice drilling campaigns and climate reconstructions. Unfortunately, the challenging conditions in ice-covered regions make measurement difficult in exactly the places where it is needed most. Until now, proxy methodologies have been considered best for determining geothermal heat flux (GHF) beneath ice sheets. Our method is to use a novel interdisciplinary approach, integrating a time-evolved climate-ice-lithosphere coupled model with a wide range of data such as direct ice-core measurements, past climate reconstructions and indirect estimates of the lithospheric thermal state. Here we show that the oldest (and thickest) part of the Greenland Ice Sheet (GIS) is strongly thermally influenced by both GHF increasing from west to east and glaciation-induced perturbations of the thermal structure of the upper crust. A pronounced lateral gradient in GHF across the Summit region of the GIS is due to anomalously thin lithosphere, which has only about 25 to 66% of the thickness typical for Archaean to early Proterozoic areas. Our findings suggest that the thermal basal conditions of the present-day central GIS are characterized by surprising rapid lateral variations in ice temperatures of up to 12°C along relatively small distances of 100 to 150 km. We reveal two areas of rapid basal melt in central Greenland, only one of which was previously predicted by ice-penetrating radar measurements and age-depth relations from internal layering (Fahnestock et al. [2001]). The endothermic phase transition associated with rapid basal ice melt is found to increase subglacial heat

  15. Anomalous Thermal Diffusivity in Underdoped YBa$_2$Cu$_3$O$_{6+x}$

    CERN Document Server

    Zhang, J -C; Ramshaw, B J; Bonn, D A; Liang, R; Hardy, W N; Hartnoll, S A; Kapitulnik, A

    2016-01-01

    We present local optical measurements of thermal diffusivity in the $ab$ plane of underdoped YBCO crystals. We find that the diffusivity anisotropy is comparable to reported values of the electrical resistivity anisotropy, suggesting that the anisotropies have the same origin. The anisotropy drops sharply below the charge order transition. We interpret our results through a strong electron-phonon scattering picture and find that both electronic and phononic contributions to the diffusivity saturate a proposed bound. Our results suggest that neither well-defined electron nor phonon quasiparticles are present in this material.

  16. The anomalous low temperature resistivity of thermally evaporated alpha-Mn thin film

    Energy Technology Data Exchange (ETDEWEB)

    Ampong, F.K., E-mail: kampxx@yahoo.co [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Boakye, F.; Nkum, R.K. [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana)

    2010-08-15

    Electrical resistivity measurements have been carried out on thermally evaporated alpha-Mn thin film between 300 and 1.4 K using the van der Pauw four probe technique. The film was grown on a glass substrate held at a temperature of 373 K, in an ambient pressure of 5x10{sup -6} Torr. The results show a resistance minimum, a notable characteristic of alpha-Mn but at a (rather high) temperature of 194+-1 K. Below the resistivity maximum which corresponds to 70 K, the resistivity drops by only 0.02 muOMEGAm indicating a rather short range magnetic ordering. The low temperature results show a tendency towards saturation of the resistivity as the temperature approaches zero suggesting a Kondo scattering.

  17. The Thermal Expansion of Ring Particles and the Secular Orbital Evolution of Rings Around Planets and Asteroids

    Science.gov (United States)

    Rubincam, David P.

    2013-01-01

    The thermal expansion and contraction of ring particles orbiting a planet or asteroid can cause secular orbit evolution. This effect, called here the thermal expansion effect, depends on ring particles entering and exiting the shadow of the body they orbit. A particle cools off in the shadow and heats up again in the sunshine, suffering thermal contraction and expansion. The changing cross-section it presents to solar radiation pressure plus time lags due to thermal inertia lead to a net along-track force. The effect causes outward drift for rocky particles. For the equatorial orbits considered here, the thermal expansion effect is larger than Poynting-Robertson drag in the inner solar system for particles in the size range approx. 0.001 - 0.02 m. This leads to a net increase in the semimajor axis from the two opposing effects at rates ranging from approx. 0.1 R per million years for Mars to approx. 1 R per million years for Mercury, for distances approx. 2R from the body, where R is the body's radius. Asteroid 243 Ida has approx. 10 R per million years, while a hypothetical Near-Earth Asteroid (NEA) can have faster rates of approx. 0.5 R per thousand years, due chiefly to its small radius compared to the planets. The thermal expansion effect weakens greatly at Jupiter and is overwhelmed by Poynting-Robertson for icy particles orbiting Saturn. Meteoroids in eccentric orbits about the Sun also suffer the thermal expansion effect, but with only approx. 0.0003e2 AU change in semimajor axis over a million years for a 2 m meteoroid orbiting between Mercury and Earth.

  18. PROPERTIES OF CP: COEFFICIENT OF THERMAL EXPANSION, DECOMPOSITION KINETICS, AND REACTION TO SPARK, FRICTION AND IMPACT

    Energy Technology Data Exchange (ETDEWEB)

    Weese, R K; Burnham, A K

    2005-09-28

    The properties of pentaamine (5-cyano-2H-tetrazolato-N2) cobalt (III) perchlorate (CP), which was first synthesized in 1968, continues to be of interest for predicting behavior in handling, shipping, aging, and thermal cook-off situations. We report coefficient of thermal expansion (CTE) values over four specific temperature ranges, decomposition kinetics using linear and isothermal heating, and the reaction to three different types of stimuli: impact, spark, and friction. The CTE was measured using a Thermal Mechanical Analyzer (TMA) for samples that were uniaxially compressed at 10,000 psi and analyzed over a dynamic temperature range of -20 C to 70 C. Differential scanning calorimetry, DSC, was used to monitor CP decomposition at linear heating rates of 1-7 C min{sup -1} in perforated pans and of 0.1-1.0 C min{sup -1} in sealed pans. The kinetic triplet was calculated using the LLNL code Kinetics05, and predictions for 210 and 240 C are compared to isothermal thermogravimetric analysis (TGA) experiments. Values are also reported for spark, friction, and impact sensitivity.

  19. Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target

    Science.gov (United States)

    Dubey, P. K.; Kumar, Yudhisther; Gupta, Reeta; Jain, Anshul; Gohiya, Chandrashekhar

    2014-05-01

    The Radiation Force Balance (RFB) technique is well established and most widely used for the measurement of total ultrasonic power radiated by ultrasonic transducer. The technique is used as a primary standard for calibration of ultrasonic transducers with relatively fair uncertainty in the low power (below 1 W) regime. In this technique, uncertainty comparatively increases in the range of few watts wherein the effects such as thermal heating of the target, cavitations, and acoustic streaming dominate. In addition, error in the measurement of ultrasonic power is also caused due to movement of absorber at relatively high radiated force which occurs at high power level. In this article a new technique is proposed which does not measure the balance output during transducer energized state as done in RFB. It utilizes the change in buoyancy of the absorbing target due to local thermal heating. The linear thermal expansion of the target changes the apparent mass in water due to buoyancy change. This forms the basis for the measurement of ultrasonic power particularly in watts range. The proposed method comparatively reduces uncertainty caused by various ultrasonic effects that occur at high power such as overshoot due to momentum of target at higher radiated force. The functionality of the technique has been tested and compared with the existing internationally recommended RFB technique.

  20. Composite Laminate With Coefficient of Thermal Expansion Matching D263 Glass

    Science.gov (United States)

    Robinson, David; Rodini, Benjamin

    2012-01-01

    The International X-ray Observatory project seeks to make an X-ray telescope assembly with 14,000 flexible glass segments. The glass used is commercially available SCHOTT D263 glass. Thermal expansion causes the mirror to distort out of alignment. A housing material is needed that has a matching coefficient of thermal expansion (CTE) so that when temperatures change in the X-ray mirror assembly, the glass and housing pieces expand equally, thus reducing or eliminating distortion. Desirable characteristics of this material include a high stiffness/weight ratio, and low density. Some metal alloys show promise in matching the CTE of D263 glass, but their density is high compared to aluminum, and their stiffness/weight ratio is not favorable. A laminate made from carbon fiber reinforced plastic (CFRP) should provide more favorable characteristics, but there has not been any made with the CTE matching D263 Glass. It is common to create CFRP laminates of various CTEs by stacking layers of prepreg material at various angles. However, the CTE of D263 glass is 6.3 ppm/ C at 20 C, which is quite high, and actually unachievable solely with carbon fiber and resin. A composite laminate has been developed that has a coefficient of thermal expansion identical to that of SCHOTT D263 glass. The laminate is made of a combination of T300 carbon fiber, Eglass, and RS3C resin. The laminate has 50% uni-T300 plies and 50% uni-E-glass plies, with each fiber-layer type laid up in a quasi-isotropic laminate for a total of 16 plies. The fiber volume (percent of fiber compared to the resin) controls the CTE to a great extent. Tests have confirmed that a fiber volume around 48% gives a CTE of 6.3 ppm/ C. This is a fairly simple composite laminate, following well established industry procedures. The unique feature of this laminate is a somewhat unusual combination of carbon fiber with E-glass (fiberglass). The advantage is that the resulting CTE comes out to 6.3 ppm/ C at 20 C, which matches D

  1. Generalized Grüneisen parameters and low temperature limit of lattice thermal expansion of cadmium and zirconium

    Indian Academy of Sciences (India)

    S Sindhu; C S Menon

    2006-09-01

    The generalized Grüneisen parameters ($_{j}^{'}$) and ($_{j}^{''}$) for cadmium and zirconium were calculated from the second- and third-order elastic constants to determine the low temperature limit of the volume thermal expansion of these metals of hexagonal symmetry. The low temperature limit of cadmium and zirconium was calculated to be positive values indicating a positive volume expansion down to 0 K even though many Grüneisen gammas were found to be negative.

  2. Anomalous ion thermal transport in hot ion plasmas by the ion temperature gradient mode

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.Y.; Horton, W. (Texas Univ., Austin, TX (United States). Inst. for Fusion Studies); Coppi, B. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Research Lab. of Electronics)

    1992-01-01

    Experiments show that the observed radial profiles of the ion thermal conductivity {chi}{sub i} have the opposite shapes with those obtained from the ion temperature gradient mode ({eta}{sub i} mode) turbulence model by the traditional mixing length estimate. In this work, this radial profile problem is reconsidered with an electromagnetic study of the linear stability of the toroidal {eta}{sub i} mode and a new rule for choosing the mixing length. It is first shown that the electromagnetic effect gives a significant stabilizing effect on the toroidal {eta}{sub i} mode, and that the observed reduction of {chi}{sub i}(r) in the core region can be explained by this electromagnetic effect. Secondly, in view of earlier numerical simulations showing the transfer of fluctuation energy to larger scales that those for the fastest growth rate, as well as fluctuation measurements indicating longer radial correlation lengths, a new mixing length formula is proposed to explain the radial increase of the {chi}{sub i}. It is shown the new formula fits well the observed {chi}{sub i}(r) profiles in two TFTR supershot discharges and also gives the scaling law in the current and the magnetic field which agrees better with experiment than the conventional formula.

  3. Anomalous ion thermal transport in hot ion plasmas by the ion temperature gradient mode

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.Y.; Horton, W. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Coppi, B. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Research Lab. of Electronics

    1992-08-01

    Experiments show that the observed radial profiles of the ion thermal conductivity {chi}{sub i} have the opposite shapes with those obtained from the ion temperature gradient mode ({eta}{sub i} mode) turbulence model by the traditional mixing length estimate. In this work, this radial profile problem is reconsidered with an electromagnetic study of the linear stability of the toroidal {eta}{sub i} mode and a new rule for choosing the mixing length. It is first shown that the electromagnetic effect gives a significant stabilizing effect on the toroidal {eta}{sub i} mode, and that the observed reduction of {chi}{sub i}(r) in the core region can be explained by this electromagnetic effect. Secondly, in view of earlier numerical simulations showing the transfer of fluctuation energy to larger scales that those for the fastest growth rate, as well as fluctuation measurements indicating longer radial correlation lengths, a new mixing length formula is proposed to explain the radial increase of the {chi}{sub i}. It is shown the new formula fits well the observed {chi}{sub i}(r) profiles in two TFTR supershot discharges and also gives the scaling law in the current and the magnetic field which agrees better with experiment than the conventional formula.

  4. Anomalous dielectric and thermal properties of Ba-doped PbZrO3 ceramics

    Science.gov (United States)

    Pirc, R.; Rožič, B.; Koruza, J.; Cordoyiannis, G.; Malič, B.; Kutnjak, Z.

    2015-11-01

    The dielectric and thermal properties of an antiferroelectric (AFE) material characterised by an intermediate ferroelectric (FE) phase between the AFE and paraelectric phase in zero field are studied by means of a generalised Landau-Kittel model of AFEs. A temperature-dependent coupling of the two sublattices is introduced in accordance with the Rae-Dove (RD) model of re-entrant phase transitions. The sublattice polarisation components are calculated as functions of temperature and the applied electric field by minimising numerically the free energy. The calculated dielectric susceptibility shows anomalies at the boundaries of the intermediate FE phase, characteristic for first-order phase transitions. It is shown that this behaviour is in qualitative agreement with the measured dielectric constant in Ba-doped PbZrO3 ceramics. The model also predicts a negative adiabatic electrocaloric temperature change Δ T in a broad temperature range in the AFE phase, in qualitative agreement with experiments. The dipolar heat capacity is also predicted to be negative in the intermediate phase in zero field, in analogy with the results of the RD model.

  5. Anomalous ion thermal transport in hot ion plasmas by the ion temperature gradient mode

    International Nuclear Information System (INIS)

    Experiments show that the observed radial profiles of the ion thermal conductivity χi have the opposite shapes with those obtained from the ion temperature gradient mode (ηi mode) turbulence model by the traditional mixing length estimate. In this work, this radial profile problem is reconsidered with an electromagnetic study of the linear stability of the toroidal ηi mode and a new rule for choosing the mixing length. It is first shown that the electromagnetic effect gives a significant stabilizing effect on the toroidal ηi mode, and that the observed reduction of χi(r) in the core region can be explained by this electromagnetic effect. Secondly, in view of earlier numerical simulations showing the transfer of fluctuation energy to larger scales that those for the fastest growth rate, as well as fluctuation measurements indicating longer radial correlation lengths, a new mixing length formula is proposed to explain the radial increase of the χi. It is shown the new formula fits well the observed χi(r) profiles in two TFTR supershot discharges and also gives the scaling law in the current and the magnetic field which agrees better with experiment than the conventional formula

  6. Phonon and thermal expansion properties in Weyl semimetals MX (M = Nb, Ta; X = P, As): ab initio studies.

    Science.gov (United States)

    Chang, Dahu; Liu, Yaming; Rao, Fengfei; Wang, Fei; Sun, Qiang; Jia, Yu

    2016-06-01

    Weyl semimetal (WSM) is a new type of topological quantum material for future spintronic devices. Using the first-principles density functional theory, we systematically investigated the thermal expansion properties, and the temperature dependence of isovolume heat capacity and bulk modulus in WSMs MX (M = Nb, Ta; X = P, As). We also presented the phonon dispersion curves and its variation under stress in MX and the anisotropic thermal expansion properties due to the anisotropic crystal structure in WSMs have been predicted in our calculations. Intriguing, we found that the heat capacities increase more rapidly with increasing temperature in the low temperature region for all MX. Furthermore, our results showed that the thermal expansion properties are determined mainly by the isovolume heat capacity at low temperatures, while the bulk modulus has the major effect at high temperatures. These results are useful for applications of WSMs in electronic and spintronic devices. PMID:27174542

  7. Synthesis and thermal expansion hysteresis of Ca1–SrZr4P6O24

    Indian Academy of Sciences (India)

    Basavaraj Angadi; V M Jali; M T Lagare; N S Kini; A M Umarji

    2002-06-01

    The low thermal expansion ceramic system, Ca1-SrZr4P6O24, for the compositions with = 0, 0.25, 0.50, 0.75 and 1 was synthesized by solid-state reaction. The sintering characteristics were ascertained by bulk density measurements. The fracture surface microstructure examined by scanning electron microscopy showed the average grain size of 2.47 m for all the compositions. The thermal expansion data for these ceramic systems over the temperature range 25–800°C is reported. The sinterability of various solid solutions and the hysteresis in dilatometric behaviour are shown to be related to the crystallographic thermal expansion anisotropy. A steady increase in the amount of porosity and critical grain size with increase in is suggested to explain the observed decrease in the hysteresis.

  8. Study on Thermal Expansion Coefficient of Sealing Materials for Ceramic Metal Halide Lamps

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients (TECs) at different anneal time were investigated. TECs of the basic glass, which were heat-treated under different temperature, were also investigated. The result showed that TECs of the basic glass gradually approached a fixed value as the anneal time was extended, which suggested that most of the inner stress had been eliminated. After heat treatment, the contents of Dy2O3, Dy2Si2O7, and a new crystal increased up to 1200 ℃ and decreased below 1250 ℃, which was consistent with the TEC change of crystallized samples. This suggests that the crystal has a direct effect on TECs of the crystallized samples.

  9. Transverse Coefficient of Thermal Expansion Measurements of Carbon Fibers Using ESEM at High Temperatures

    Science.gov (United States)

    Ochoa, O.; Jiang, J.; Putnam, D.; Lo, Z.; Ellis, A.; Effinger, Michael

    2003-01-01

    The transverse coefficient of thermal expansion (CTE) of single IM7, T1000, and P55 carbon fibers are measured at elevated temperatures. The specimens are prepared by press-fitting fiber tows into 0.7mm-diameter cavity in a graphite disk of 5mm in diameter and 3mm high. The specimens are placed on a crucible in an ESEM, and images of the fiber cross section are taken as the fibers are heated up to 800 C. Holding time, heating and cool down cycles are also introduced. The geometrical changes are measured using a graphics tablet. The change in area/perimeter is calculated to determine the strain and transverse CTE for each fiber. In a complimentary computational effort, displacements and stresses are calculated with finite element models.

  10. Multilayer Article Characterized by Low Coefficient of Thermal Expansion Outer Layer

    Science.gov (United States)

    Lee, Kang N. (Inventor)

    2004-01-01

    A multilayer article comprises a substrate comprising a ceramic or a silicon-containing metal alloy. The ceramic is a Si-containing ceramic or an oxide ceramic with or without silicon. An outer layer overlies the substrate and at least one intermediate layer is located between the outer layer and thc substrate. An optional bond layer is disposed between thc 1 least one intermediate layer and thc substrate. The at least one intermediate layer may comprise an optional chemical barrier layer adjacent the outer layer, a mullite-containing layer and an optional chemical barrier layer adjacent to the bond layer or substrate. The outer layer comprises a compound having a low coefficient of thermal expansion selected from one of the following systems: rare earth (RE) silicates; at least one of hafnia and hafnia-containing composite oxides; zirconia-containing composite oxides and combinations thereof.

  11. Negative thermal expansion in hybrid improper ferroelectric Ruddlesden-Popper perovskites by symmetry trapping.

    Science.gov (United States)

    Senn, M S; Bombardi, A; Murray, C A; Vecchini, C; Scherillo, A; Luo, X; Cheong, S W

    2015-01-23

    We present new results on the microscopic nature of the ferroelectricity mechanisms in Ca3 Mn2O7 and Ca3Ti2O7. To the first approximation, we confirm the hybrid improper ferroelectric mechanism recently proposed by Benedek and Fennie for these Ruddlesden-Popper compounds. However, in Ca3Mn2O7 we find that there is a complex competition between lattice modes of different symmetry which leads to a phase coexistence over a large temperature range and the "symmetry trapping" of a soft mode. This trapping of the soft mode leads to a large uniaxial negative thermal expansion (NTE) reaching a maximum between 250 and 350 K (3.6×10^(-6)  K^{-1}) representing the only sizable NTE reported for these and related perovskite materials to date. Our results suggest a systematic strategy for designing and searching for ceramics with large NTE coefficients.

  12. High-resolution thermal expansion measurements under Helium-gas pressure

    CERN Document Server

    Manna, Rudra Sekhar; de Souza, Mariano; Lang, Michael; 10.1063/1.4747272

    2012-01-01

    We report on the realization of a capacitive dilatometer, designed for high-resolution measurements of length changes of a material for temperatures 1.4\\,K $\\leq T \\leq$ 300\\,K and hydrostatic pressure $P \\leq$ 250\\,MPa. Helium ($^4$He) is used as a pressure-transmitting medium, ensuring hydrostatic-pressure conditions. Special emphasis has been given to guarantee, to a good approximation, constant-pressure conditions during temperature sweeps. The performance of the dilatometer is demonstrated by measurements of the coefficient of thermal expansion at pressures $P \\simeq$ 0.1\\,MPa (ambient pressure) and 104\\,MPa on a single crystal of azurite, Cu$_3$(CO$_3$)$_2$(OH)$_2$, a quasi-one-dimensional spin S = 1/2 Heisenberg antiferromagnet. The results indicate a strong effect of pressure on the magnetic interactions in this system.

  13. Influence of microstructural features on thermal expansion coefficient in graphene/epoxy composites.

    Science.gov (United States)

    Shi, Zhan; Li, Xiao-Fei; Bai, Hua; Xu, Wei-Wei; Yang, Shui-Yuan; Lu, Yong; Han, Jia-Jia; Wang, Cui-Ping; Liu, Xing-Jun; Li, Wei-Bin

    2016-03-01

    In this paper, theoretical calculations were conducted to determine the coefficient of thermal expansion (CTE) based on the effective medium approach using Green's function method. The influences of microstructural features were investigated, including volume fraction, aspect ratio, and the orientation of graphene fillers. Calculated results demonstrated strong anisotropy of CTE when all graphene sheets in the composite were aligned in the in-plane direction due to the large difference between the elastic moduli of the graphene and epoxy. The in-plane CTE in the graphene/epoxy composite can be effectively reduced with small additions of graphene additive. Orientation dispersion among the graphene fillers significantly decreases the anisotropy of CTE. Accounting for the influences of all microstructural features, simulation results closely align with current experimental results. This work will provide a general guideline and a solid foundation for the optimal design and preparation of graphene/polymer composites. PMID:27441268

  14. Young's modulus and thermal expansion of ceramic samples made from kaolin and zeolite

    Science.gov (United States)

    Sunitrová, Ivana; Trník, Anton

    2016-07-01

    In this study we investigate the dependence of Young's modulus, mass change, and thermal expansion of ceramic samples made from a varying amount of kaolin (100 - 50 %) and zeolite (0 - 50 %) on the firing temperature. The samples are fired in a furnace at different temperatures from room temperature up to 1100 °C with a heating rate of 5°C.min-1 and 5 min soaking time at the highest temperature. Afterwards, the samples are freely cooled down and their mass, dimensions and resonant frequency are measured at room temperature. The resonant frequency (from which Young's modulus is calculated) is measured using an apparatus based on the impulse excitation technique (IET). Young's modulus of green samples is the highest for the sample containing 10 mass% of zeolite (3.2 GPa). After sintering the sample with 50 mass% of zeolite has the highest value (11.3 GPa).

  15. A uniaxial stress capacitive dilatometer for high-resolution thermal expansion and magnetostriction under multiextreme conditions

    Science.gov (United States)

    Küchler, R.; Stingl, C.; Gegenwart, P.

    2016-07-01

    Thermal expansion and magnetostriction are directional dependent thermodynamic quantities. For the characterization of novel quantum phases of matter, it is required to study materials under multi-extreme conditions, in particular, down to very low temperatures, in very high magnetic fields or under high pressure. We developed a miniaturized capacitive dilatometer suitable for temperatures down to 20 mK and usage in high magnetic fields, which exerts a large spring force between 40 to 75 N on the sample. This corresponds to a uniaxial stress up to 3 kbar for a sample with cross section of (0.5 mm)2. We describe design and performance test of the dilatometer which resolves length changes with high resolution of 0.02 Å at low temperatures. The miniaturized device can be utilized in any standard cryostat, including dilution refrigerators or the commercial physical property measurement system.

  16. Thermal expansion of mantle and core materials at very high pressures

    OpenAIRE

    Duffy, Thomas S.; Ahrens, Thomas J.

    1993-01-01

    The thermal expansivities (α) of MgO and high-pressure phases of CaO, CaMgSi_2O_6, and Fe at ultrahigh pressure are obtained by comparing existing shock compression and temperature measurements to 300 K compression curves constructed from ultrasonic elasticity and static compression data. For MgO, α can be represented by: α = ρ_oγ_oC_V(ρ_o/ρ)^(0.5±0.5)/K_T where γ is the Grüneisen parameter, C_V is the constant volume specific heat, K_T is the isothermal bulk modulus, and ρ is the density. Us...

  17. Thermal conductivity, thermoelectric power, and thermal expansion of CuInS/sub 2x/Se/sub 2(1-x)/

    International Nuclear Information System (INIS)

    The thermal conductivity, the thermoelectric power, and the thermal expansion of CuInS/sub 2x/Se/sub 2(1-x)/ solid solutions are investigated by different methods. The temperature dependence of thermal conductivity of CuInS2, CuInSe2, CuInS/sub 0.8/Se/sub 1.2/ and CuInS/sub 0.4/Se/sub 1.6/ has been measured in the range of 300 to 560 K. The composition dependence of the thermal conductivity (at 293 K) and of the thermal expansion coefficients (at 77, 293, and 873 K) of CuInS/sub 2x/Se/sub 2(1-x)/ solid solutions are given

  18. Electrical Transport and Thermal Expansion in van der Waals Materials: Graphene and Topological Insulator

    Science.gov (United States)

    Jing, Lei

    Novel two-dimensional materials with weak interlayer Van der Waals interaction are fantastic platforms to study novel physical phenomena. This thesis describes our investigation on two different Van der Waals materials: graphene and bismuth selenide with calcium doping (CaxBi 2-xSe3, x as the doping level) in the topological insulator family. Firstly, we characterize the electrical transport behaviors of high-quality substrate-supported bilayer graphene devices with suspended metal gates. The device exhibits a transport gap induced by external electric field with an on/off ratio of 20,000, which could be explained by variable range hoping between localized states or disordered charge puddles. At large magnetic field, the device presents quantum Hall plateau at fractional values of conductance quantum, which arises from the equilibration of edge states between differentially doped regions. Secondly, we present our study on the electronic transport of CaxBi 2-xSe3 thin films, which are three-dimensional topological insulators and coupled with superconducting leads. In these novel Josephson transistors, we observe different characteristic features by energy dispersion spectrum (EDS) and Raman spectroscopy, and the weak suppression in the critical current Ic. Thirdly, we explore the thermal expansion of suspended graphene. By in-situ scanning electron microscope (SEM), we measure the thickness-dependence of graphene's negative thermal expansion coefficient (TEC). We propose that there is a competitive relation between the intrinsic TEC and the friction from the substrate and the graphene. Lastly, in collaboration with Dr. Nikolai Kalugin from New Mexico Tech., we explore the graphene's application as a quantum Hall effect infrared photodetector. This graphene-based detector can be operated at higher temperature (liquid nitrogen) and wider frequency than the previous implementations of quantum Hall detector.

  19. Thermal expansion characteristics of a titanium modified austenitic stainless steel: measurement by high-temperature X-ray diffraction and modelling using Grueneisen formalism

    Energy Technology Data Exchange (ETDEWEB)

    Jose, R.; Raju, S. E-mail: sraju@igcar.ernet.in; Divakar, R.; Mohandas, E.; Panneerselvam, G.; Antony, M.P.; Sivasubramanian, K

    2003-04-01

    The thermal expansion of a titanium modified, swelling resistant austenitic stainless steel designated as D9 is studied by measuring the lattice parameter as a function of temperature in the range 300-1300 K by high-temperature X-ray diffraction technique. The thermal expansion data thus obtained is in reasonable agreement with the typical thermal expansion values reported for similar nuclear grade austenitic stainless steels. However, at temperatures exceeding 900 K, the measured thermal expansivity exhibits a pronounced non-linear increase due partly to the precipitation of complex carbide and intermetallic phases. The high-temperature thermal expansion data obtained in the present study are augmented by modelling the low-temperature thermal expansion behaviour by Grueneisen formalism.

  20. Anomalous magnetic moment with heavy virtual leptons

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Alexander [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Liu, Tao; Steinhauser, Matthias [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2013-11-15

    We compute the contributions to the electron and muon anomalous magnetic moment induced by heavy leptons up to four-loop order. Asymptotic expansion is applied to obtain three analytic expansion terms which show rapid convergence.

  1. Role of acoustic phonons in the negative thermal expansion of layered structures and nanotubes based on them

    Science.gov (United States)

    Eremenko, V. V.; Sirenko, A. F.; Sirenko, V. A.; Dolbin, A. V.; Gospodarev, I. A.; Syrkin, E. S.; Feodosyev, S. B.; Bondar, I. S.; Minakova, K. A.

    2016-05-01

    Calculations on a microscopic level are used to explain the experimentally observed negative linear thermal expansion along some directions in a number of crystalline compounds with complicated lattices and anisotropic interactions between atoms. Anomalies in the temperature dependence of the coefficient of linear thermal expansion are analyzed in layered crystals made up of monatomic layers (graphite and graphene nanofilms) and multilayer "sandwiches" (transition metal dichalcogenides), in multilayered crystal structures such as high-temperature superconductors where the anisotropy of the interatomic interactions is not conserved in the long-range order, and in graphene nanotubes. The theoretical calculations are compared with data from x-ray, neutron diffraction, and dilatometric measurements.

  2. Technique for reduction of mechanical losses in AC superconducting coils due to thermal expansion properties of various FRP bobbins

    Energy Technology Data Exchange (ETDEWEB)

    Sekine, N. [Tsukamoto Laboratory, Faculty of Engineering, Yokohama National University, 79-5, Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)]. E-mail: n-sekine@tsukalab.dnj.ynu.ac.jp; Tada, S. [Sophia University, 7-1, Kioicho, Chiyoda-ku, Tokyo 102-8554 (Japan); Higuchi, T. [Sophia University, 7-1, Kioicho, Chiyoda-ku, Tokyo 102-8554 (Japan); Furumura, Y. [Sophia University, 7-1, Kioicho, Chiyoda-ku, Tokyo 102-8554 (Japan); Takao, T. [Sophia University, 7-1, Kioicho, Chiyoda-ku, Tokyo 102-8554 (Japan); Yamanaka, A. [Research Center, Toyobo, Co., Ltd, 2-1-1, Katata, Otsu, Shiga 520-0292 (Japan)

    2005-10-01

    We reported about reduction of mechanical losses in AC superconducting coils. The method is the use of FRP bobbins fabricated with special fibers. Since their FRPs have negative thermal expansion coefficient to the fiber direction, the FRP bobbins expand to the circumferential direction during cooling down. In case of the superconducting coils with such FRP bobbins, the winding tensions do not decrease during cooling down. Therefore, the mechanical losses are reduced by the suppression of wire's vibration. Their special FRPs are a Dyneema[reg] fiber reinforced plastic (DFRP), a Dyneema and glass fiber reinforced plastic (DGFRP), and a Zylon[reg] fiber reinforced plastic (ZFRP). These materials have negative thermal expansion coefficient to the fiber direction, however, the amplitudes of thermal expansion are various by the quantity or quality of the fiber. In this paper, the values of thermal expansion were actually measured, and it was discussed about the influence on the mechanical losses. At the experimental results, the mechanical loss was small, so that the thermal strain to the circumferential direction on the coil was large. Moreover, in case of the coils with sufficiently strong winding tensions at coil-operating temperature, the mechanical losses vanished.

  3. Technique for reduction of mechanical losses in AC superconducting coils due to thermal expansion properties of various FRP bobbins

    Science.gov (United States)

    Sekine, N.; Tada, S.; Higuchi, T.; Furumura, Y.; Takao, T.; Yamanaka, A.

    2005-10-01

    We reported about reduction of mechanical losses in AC superconducting coils. The method is the use of FRP bobbins fabricated with special fibers. Since their FRPs have negative thermal expansion coefficient to the fiber direction, the FRP bobbins expand to the circumferential direction during cooling down. In case of the superconducting coils with such FRP bobbins, the winding tensions do not decrease during cooling down. Therefore, the mechanical losses are reduced by the suppression of wire's vibration. Their special FRPs are a Dyneema® fiber reinforced plastic (DFRP), a Dyneema and glass fiber reinforced plastic (DGFRP), and a Zylon® fiber reinforced plastic (ZFRP). These materials have negative thermal expansion coefficient to the fiber direction, however, the amplitudes of thermal expansion are various by the quantity or quality of the fiber. In this paper, the values of thermal expansion were actually measured, and it was discussed about the influence on the mechanical losses. At the experimental results, the mechanical loss was small, so that the thermal strain to the circumferential direction on the coil was large. Moreover, in case of the coils with sufficiently strong winding tensions at coil-operating temperature, the mechanical losses vanished.

  4. Technique for reduction of mechanical losses in AC superconducting coils due to thermal expansion properties of various FRP bobbins

    International Nuclear Information System (INIS)

    We reported about reduction of mechanical losses in AC superconducting coils. The method is the use of FRP bobbins fabricated with special fibers. Since their FRPs have negative thermal expansion coefficient to the fiber direction, the FRP bobbins expand to the circumferential direction during cooling down. In case of the superconducting coils with such FRP bobbins, the winding tensions do not decrease during cooling down. Therefore, the mechanical losses are reduced by the suppression of wire's vibration. Their special FRPs are a Dyneema[reg] fiber reinforced plastic (DFRP), a Dyneema and glass fiber reinforced plastic (DGFRP), and a Zylon[reg] fiber reinforced plastic (ZFRP). These materials have negative thermal expansion coefficient to the fiber direction, however, the amplitudes of thermal expansion are various by the quantity or quality of the fiber. In this paper, the values of thermal expansion were actually measured, and it was discussed about the influence on the mechanical losses. At the experimental results, the mechanical loss was small, so that the thermal strain to the circumferential direction on the coil was large. Moreover, in case of the coils with sufficiently strong winding tensions at coil-operating temperature, the mechanical losses vanished

  5. Universality of anomalous conductivities in theories with higher-derivative holographic duals

    CERN Document Server

    Grozdanov, Sašo

    2016-01-01

    Anomalous chiral conductivities in theories with global anomalies are independent of whether they are computed in a weakly coupled quantum (or thermal) field theory, hydrodynamics, or at infinite coupling from holography. While the presence of dynamical gauge fields and mixed, gauge-global anomalies can destroy this universality, in their absence, the non-renormalisation of anomalous Ward identities is expected to be obeyed at all intermediate coupling strengths. In holography, bulk theories with higher-derivative corrections incorporate coupling constant corrections to the boundary theory observables in an expansion around infinite coupling. In this work, we investigate the coupling constant dependence and universality of anomalous conductivities (and thus of the anomalous Ward identities) in general, four-dimensional systems that possess asymptotically anti-de Sitter holographic duals with a non-extremal black brane in five dimensions, and anomalous transport introduced into the boundary theory via the bulk...

  6. Tunable Negative Thermal Expansion in Layered Perovskites from Quasi-Two-Dimensional Vibrations

    Science.gov (United States)

    Huang, Liang-Feng; Lu, Xue-Zeng; Rondinelli, James M.

    2016-09-01

    We identify a quasi-two-dimensional (quasi-2D) phonon mode in the layered-perovskite Ca3Ti2O7, which exhibits an acoustic branch with quadratic dispersion. Using first-principles methods, we show this mode exhibits atomic displacements perpendicular to the layered [CaTiO3]2 blocks comprising the structure and a negative Grüneisen parameter. Owing to these quasi-2D structural and dynamical features, we find that the mode can be utilized to realize unusual membrane effects, including a tunable negative thermal expansion (NTE) and a rare pressure-independent thermal softening of the bulk modulus. Detailed microscopic analysis shows that the NTE relies on strong intralayer Ti—O covalent bonding and weaker interlayer interactions, which is in contrast to conventional NTE mechanisms for perovskites, such as rigid-unit modes, structural transitions, and electronic or magnetic ordering. The general application of the quasi-2D lattice dynamics opens exciting avenues for the control of lattice dynamical and thermodynamic responses of other complex layered compounds through rational chemical substitution, as we show in A3Zr2O7 (A =Ca , Sr), and by heterostructuring.

  7. Measuring the thermal expansion coefficient of tubular steel specimens with digital image correlation techniques

    Science.gov (United States)

    De Strycker, M.; Schueremans, L.; Van Paepegem, W.; Debruyne, D.

    2010-10-01

    In this contribution it is investigated whether it is possible to measure the coefficient of thermal expansion (CTE) of steel with the aid of the digital image correlation (DIC) technique. DIC is first used to obtain reference values of the CTE of well-known steels (S235 and SS304) on simple geometries (rectangular blocks) within a low temperature interval (up to 120 °C). Although the strains that occur in this process are small, the CTE can be determined with good accuracy if enough images are available. The influence of the different parameters that control the correlation process showed no influence on the results. The values for the CTE are compared to available literature references and strain gauge measurements. The technique is extended to measure within a higher temperature interval (up to 600 °C), three-dimensional geometries (tubular samples), and a third material (SS409). It is shown that also in these cases, the results obtained are reliable. This contribution is part of a larger research effort predicting the residual stress in tubes coming from the welding process with finite element (FE) simulation. The goal of this research is therefore twofold: firstly obtaining the CTE in function of temperature, which can be used as input for the FE simulations; and secondly exploring the possibilities of measuring small thermal strains with DIC.

  8. Effect of Microstructure on Thermal Expansion Coefficient of 7A09 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    Hongzhi Ji; Lin Yuan; Debin Shan

    2011-01-01

    The relationship between microstructure evolution and coefficient of thermal expansion (CTE) of 7A09 aluminum alloy was investigated in this paper. Differential scanning calorimetry (DSC) was combined with transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) to investigate microstructure evolution taking place in 7A09 aluminum alloy during heating and cooling process. The corresponding CTE curves of the 7A0g alloy were recorded by thermal dilatometer. Results indicated that GPII zones and Ur phase were main precipitates in the highest strength tempered (T6) 7A09 alloy. The r/phase was the main participate in 7A09 alloy during the cooling process. The nonlinear dependency existed between CTE and temperature in both changing temperature processes. During the heating process, obvious additional contraction of alloy volume was directly caused by phase transition, such as dissolution of η' phase, transition from η' to η phase and dissolution of η phase. The additional contraction could slow down the increase of CTE greatly and be expressed in the nonlinearity of CTE curve. Volume and energy changes of alloy system influenced the variation trend of CTE directly, which was caused by the precipitation of U phase during the cooling process. These effects were revealed by the corresponding nonlinear change of CTE.

  9. Antiferromagnetic spin structure and negative thermal expansion of Li2Ni (WO4)2

    Science.gov (United States)

    Karna, Sunil K.; Wang, C. W.; Sankar, R.; Avdeev, M.; Singh, A.; Panneer Muthuselvam, I.; Singh, V. N.; Guo, G. Y.; Chou, F. C.

    2015-07-01

    We report the results of a study on the crystal and magnetic structure of Li2Ni (WO4)2 with a neutron diffraction technique. The Ni2 + spins of S = 1 for NiO6 octahedra are coupled via corner-sharing, nonmagnetic double tungstate groups in a super-superexchange route. Two magnetic anomalies at TN 1˜ 18 K and TN 2˜ 13 K are revealed from the measured magnetic susceptibility χ (T), and TN 2 is confirmed to be the onset of a commensurate long-range antiferromagnetic (AF) ordering through neutron diffraction. A negative thermal expansion phenomenon is observed below TN 2, which has been interpreted as a result of competing normal thermal contraction and long-range AF spin ordering through counterbalanced WO4 and NiO6 polyhedral local distortion. The AF spin structure has been modeled and used to show that Ni spins with a saturated magnetic moment of ˜1.90 (27 )μB that lies in the a -c plane approximately 46∘(±10∘) off the a axis. The experimental results are compared and found to be consistent with theoretical calculations using density-functional theory with a generalized gradient approximation plus on-site Coulomb interaction.

  10. Measurement of the thermal expansion of space structures using fiber Bragg grating sensors and displacement measuring interferometers

    International Nuclear Information System (INIS)

    A thermal deformation measurement system, composed of fiber Bragg grating (FBG) sensors for strain measurement and a displacement measuring interferometer (DMI) system for accurate specimen expansion data acquisition, was prepared and installed in a vacuum chamber where the temperature of the test specimen can be controlled to simulate space environments. The DMI system, which consists of two heterodyne interferometers, a laser head, electronics and a thermally stable specimen base made of fused silica, was used to validate the thermal expansions of the specimens measured by the FBG sensors. We measured the average coefficient of thermal expansion (CTE) of an Invar specimen, known as a thermally stable material, using both the FBG sensors and the DMI system in vacuum conditions from 20 °C to 40 °C. The CTE results of the Invar specimen were found to be 1.226 × 10−6 K−1 and 1.298 × 10−6 K−1 based on the FBG and DMI measurements, respectively. The present results show that it is possible to precisely measure the thermal deformation of a specimen or structure in space environments using FBG sensors

  11. Supramolecular interactions induced hinge-like motion of a metal-organic framework accompanied by anisotropic thermal expansion.

    Science.gov (United States)

    Zhang, Lei; Kuang, Xiaofei; Wu, Xiaoyuan; Yang, Wenbin; Lu, Canzhong

    2014-05-21

    A novel three-dimensional metal-organic framework (MOF), Ag4(tpt)4{δ-[Mo8O26]}·1.5H2O (A) (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine), possesses a ths-type topology with the hinge deformation mode. The single-crystal X-ray diffraction study shows that A and the dehydrated phase Ag4(tpt)4{δ-[Mo8O26]} (B) display distinct anisotropic thermal expansion with expansion in the b direction but contraction in the ac plane. This rare area negative thermal expansion (NTE) behavior is attributed to the hinged structure model and the supramolecular interactions (argentophilic interaction, π-π interaction) that act as the microscopic driving forces. In addition, supramolecular interactions also play a key role in thermochromic behavior of compound A. PMID:24671278

  12. An Ag based brazing system with a tunable thermal expansion for the use as sealant for solid oxide cells

    DEFF Research Database (Denmark)

    Kiebach, Wolff-Ragnar; Engelbrecht, Kurt; Grahl-Madsen, Laila;

    2016-01-01

    as a function of the operation temperature were measured. The thermal expansion coefficient in the Ag-Al2TiO5 system can be tailored by varying the amount of the ceramic filler. The brazing process can be carried out in air, the joining partners showed a good chemical stability and sufficient low leak rates...

  13. Study on thermal expansion behavior of Dy2O3- Al2O3- SiO2 glass

    Institute of Scientific and Technical Information of China (English)

    LIU Yuzhu; GENG Zhiting; ZHUANG Weidong; HE Huaqiang

    2008-01-01

    Employing Dy2O3, Al2O3, and SiO2 as starting materials, several series of Dy2O3-Al2O3-SiO2 sealing glass were prepared. The relationship between their coefficients of thermal expansion and the contents of Dy2O3, Al2O3, and SiO2 were studied respectively. Experimental results showed that Dy2O3 and Al2O3 had a positive effect on the coefficient of thermal expansion of glass, whereas, SiO2 had a negative effect. The coefficient of thermal expansion of glass showed an apparent linear relation to the contents of these three raw materials, from which an estimation model was built, to calculate the coefficient of thermal expansion of sealing glass. Relative errors of the calculating resalts to testing results were no more than 2%, which suggested that the estimation model was reasonable. This study provides a good theory reference for the practical utilizing of this sealing material, through which a proper glass composition for good sealing could be easily found.

  14. Extrusion-formed uranium-2.4 wt. % article with decreased linear thermal expansion and method for making the same

    Science.gov (United States)

    Anderson, Robert C.; Jones, Jack M.; Kollie, Thomas G.

    1982-01-01

    The present invention is directed to the fabrication of an article of uranium-2.4 wt. % niobium alloy in which the linear thermal expansion in the direction transverse to the extrusion direction is less than about 0.98% between 22.degree. C. and 600.degree. C. which corresponds to a value greater than the 1.04% provided by previous extrusion operations over the same temperature range. The article with the improved thermal expansion possesses a yield strength at 0.2% offset of at least 400 MPa, an ultimate tensile strength of 1050 MPa, a compressive yield strength of at least 0.2% offset of at least 675 MPa, and an elongation of at least 25% over 25.4 mm/sec. To provide this article with the improved thermal expansion, the uranium alloy billet is heated to 630.degree. C. and extruded in the alpha phase through a die with a reduction ratio of at least 8.4:1 at a ram speed no greater than 6.8 mm/sec. These critical extrusion parameters provide the article with the desired decrease in the linear thermal expansion while maintaining the selected mechanical properties without encountering crystal disruption in the article.

  15. Hexakis(urea-jO)zinc(II) dinitrate at 110 and 250 K: uniaxial negative thermal expansion

    NARCIS (Netherlands)

    Smeets, S.; Lutz, M.

    2011-01-01

    The crystal structure of the title compound, [Zn{CO(NH2)2}6]- (NO3)2, has been determined at 110 and 250 K. The structure is stabilized by 12 individual hydrogen bonds, both intra- and intermolecular. Analysis of the thermal expansion tensor, based on unit cells determined over a temperature range o

  16. Thermal expansion measurements of (Cu0.25Tl0.75)-1234 added by MgO-nano particles

    International Nuclear Information System (INIS)

    The effect of nano-size MgO (40-60 nm) addition on both granular structure and volume thermal expansion measurements of polycrystalline (Cu0.25Tl0.75)-1234 was studied. The MgO-content x varied from 0.0 to 1.0 wt.% of the sample total mass. Granular investigation using scanning electron microscope revealed that both number and size of voids decreased as x increased from 0 wt.% to 0.6 wt.%. These results were supported by porosity calculation of the samples. The volume thermal expansion was calculated using X-ray powder diffraction from room temperature down to 80 K. The volume thermal expansion coefficient, at room temperature decreased, from 9.3 x 10-5 K-1 to 7.2 x 10-5 K-1 as MgO-concentration increased from 0.0 wt.% to 0.6 wt.% before it increased to 8.9 x 10-5 K-1 for MgO-concentration = 1 wt.%. The Debye temperatures, calculated from the volume thermal expansion coefficient measurements, were reported as a function of MgO-concentration and superconducting transition temperature.

  17. Negative thermal expansion and spontaneous volume magnetostriction of Tb{sub 2}Fe{sub 16}Cr compound

    Energy Technology Data Exchange (ETDEWEB)

    Hao Yanming [Department of Physics, Tianjin Normal University, Tianjin 300074 (China)]. E-mail: zhao.miao@126.com; Zhao Miao [Department of Physics, Tianjin Normal University, Tianjin 300074 (China); Zhou Yan [Department of Physics, Tianjin Normal University, Tianjin 300074 (China); Hu Jifan [Department of Physics, Shandong University, Jinan, 250100 (China)

    2005-08-15

    The compound Tb{sub 2}Fe{sub 16}Cr has a hexagonal Th{sub 2}Ni{sub 17}-type structure. Negative thermal expansion was found at 292-556 K. Magnetization measurements show that a Cr atom substituting for a Fe atom increases the Curie temperature of the Tb{sub 2}Fe{sub 17} compound.

  18. Measurements of the densities, isobaric thermal expansion coefficients and isothermal compressibilities of linear alkylbenzene in large liquid scintillator detectors

    CERN Document Server

    Zhou, Xiang; Liu, Qian; Zhang, Zhenyu; Ding, Yayun; Zhou, Li; Cao, Jun

    2014-01-01

    We report the measurements of the densities of linear alkylbenzene at three temperatures over 4 to 23 Celsius degree with pressures up to 10 MPa. The measurements have been analysed to yield the isobaric thermal expansion coefficients and, so far for the first time, isothermal compressibilities of linear alkylbenzene.

  19. Cs3W3PO13: A Tungsten Phosphate with One-Dimensional Zigzag Tunnels Exhibiting Strongly Anisotropic Thermal Expansion.

    Science.gov (United States)

    Gong, Pifu; Jiang, Xingxing; Yang, Yi; Luo, Siyang; Huang, Rongjin; Li, Laifeng; Chen, Chuangtian; Lin, Zheshuai

    2016-06-01

    A new tungsten phosphate, Cs3W3PO13, is synthesized using the high-temperature flux method. Cs3W3PO13 crystallizes in the space group Pnma and contains one-dimensional zigzag tunnels, which are found for the first time in tungsten phosphate. This highly anisotropic structural feature results in a very strong anisotropic thermal expansion, with thermal expansion coefficients of 14.15 ± 1.11 and 0.72 ± 0.22 M K(-1) along the a and b axes, respectively, over the temperature range from 13 to 270 K. In addition, thermal analysis, UV-vis-near-IR diffuse reflectance, and first-principles electronic structure calculations on Cs3W3PO13 are performed. PMID:27182930

  20. Structural investigation of the negative-thermal-expansion material ZrW2O8

    International Nuclear Information System (INIS)

    High-resolution powder diffraction data have been recorded on cubic ZrW2O8 [a = 9.18000 (3) A at 2 K] at 260 temperatures from 2 to 520 K in 2 K steps. These data have confirmed that α-ZrW2O8 has a negative coefficient of thermal expansion, α = -9.07 x 10-6 K-1 (2-350 K). A 'parametric' approach to Rietveld refinement is adopted and it is demonstrated that a full anisotropic refinement can be performed at each temperature, despite using a data collection time of only 5 min. Examination of the resulting structural parameters suggests that the origin of the contraction with increasing temperature can be traced straightforwardly to the rigid-body transverse librations of bridging O atoms, α-ZrW2O8 undergoes a phase transition from P213 to Pa anti 3 at 448 K that is associated with the onset of considerable oxygen mobility. The phase transition can be described in terms of a simple cubic three-dimensional Ising model. Unusual kinetics are associated with this phase transition. Hysteresis in the cell parameter through the phase transition is the opposite of that normally observed. (orig.)

  1. Determination of thermal expansion coefficients for unidirectional fiber-reinforced composites

    Directory of Open Access Journals (Sweden)

    Ran Zhiguo

    2014-10-01

    Full Text Available In the present work, the coefficients of thermal expansion (CTEs of unidirectional (UD fiber-reinforced composites are studied. First, an attempt is made to propose a model to predict both longitudinal and transverse CTEs of UD composites by means of thermo-elastic mechanics analysis. The proposed model is supposed to be a concentric cylinder with a transversely isotropic fiber embedded in an isotropic matrix, and it is subjected to a uniform temperature change. Then a concise and explicit formula is offered for each CTE. Finally, some finite element (FE models are created by a finite element program MSC. Patran according to different material systems and fiber volume fractions. In addition, the available experimental data and results of other analytical solutions of CTEs are presented. Comparisons are made among the results of the cylinder model, the finite element method (FEM, experiments, and other solutions, which show that the predicted CTEs by the new model are in good agreement with the experimental data. In particular, transverse CTEs generally offer better agreements than those predicted by most of other solutions.

  2. Effects of changes in composite lamina properties on laminate coefficient of thermal expansion

    Science.gov (United States)

    Tompkins, Stephen S.; Funk, Joan G.

    1992-01-01

    An analytical study of the effects of changes in composite lamina properties on the laminate coefficient of thermal expansion, CTE, has been made. Low modulus graphite/epoxy (T300/934) and high modulus graphite/epoxy (P75/934, P100/934, P120/934), graphite/aluminum (P100/Al), and graphite/glass (HMS/Gl) composite materials were considered in quasi-isotropic and near-zero CTE laminate configurations. The effects of changes in lamina properties on the laminate CTE strongly depend upon the type of composite material as well as the laminate configuration. A 10 percent change in the lamina transverse CTE resulted in changes as large as 0.22 ppm/C in the laminate CTE of a quasi-isotropic Gr/934 laminates. No significant differences were observed in the sensitivities of the laminate CTEs of the P100/934 and P120/934 composite materials due to identical changes in lamina properties. Large changes in laminate CTE can also result from measured temperature and radiation effects on lamina properties.

  3. Thermal expansion anomalies in REBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Results of theoretical and experimental study of the contribution of 4f electrons to the coefficient of linear thermal expansion αm(T) for orthorhombic REBa2Cu3O7-δ are presented. Theoretically, αm(T) is treated in terms of the electric quadrupole moments of the 4f shell of the RE3+ ions induced by the crystal field. Considering the available crystal field parameters we calculate the temperature dependence of αm for RE ions which form the REBa2Cu3O7-δ structure. Experimentally, we have studied αm(T) of polycrystalline PrBa2Cu3O7-δ using strain gauges in the temperature range 10-300 K. The latter compound was chosen with regard to its outstanding features, lack of superconductivity in particular. The anomalies on αm(T) observed for PrBa2Cu3O7-δ as well as those available for a high-Tc superconductor DyBa2Cu3O7-δ at low temperatures compare well with the prediction of the theory. (orig.)

  4. Dimensional errors in LIGA-produced metal structures due to thermal expansion and swelling of PMMA.

    Energy Technology Data Exchange (ETDEWEB)

    Kistler, Bruce L.; Dryden, Andrew S.; Crowell, Jeffrey A.W.; Griffiths, Stewart K.

    2004-04-01

    Numerical methods are used to examine dimensional errors in metal structures microfabricated by the LIGA process. These errors result from elastic displacements of the PMMA mold during electrodeposition and arise from thermal expansion of the PMMA when electroforming is performed at elevated temperatures and from PMMA swelling due to absorption of water from aqueous electrolytes. Both numerical solutions and simple analytical approximations describing PMMA displacements for idealized linear and axisymmetric geometries are presented and discussed. We find that such displacements result in tapered metal structures having sidewall slopes up to 14 {micro}m per millimeter of height for linear structures bounded by large areas of PMMA. Tapers for curved structures are of similar magnitude, but these structures are additionally skewed from the vertical. Potential remedies for reducing dimensional errors are also discussed. Here we find that auxiliary moat-like features patterned into the PMMA surrounding mold cavities can reduce taper by an order of magnitude or more. Such moats dramatically reduce tapers for all structures, but increase skew for curved structures when the radius of curvature is comparable to the structure height.

  5. Analysis of rail cooling strategies through numerical simulation with instant calculation of thermal expansion coefficient

    International Nuclear Information System (INIS)

    This article describes a new methodology to simulate the cooling process for an asymmetrical Ri60 grooved rail, designed for city tramways, in a more realistic manner than that conducted previously by other authors for long steel sections. The approach considers the phase transformation of the steel and the forced convection cooling. The process is modelled as an uncoupled thermo-mechanical problem. First, the rails temperature history is obtained from a computer fluid dynamic model and subsequently introduced in the finite element model, in order to model the stresses and displacements. This second stage involves the calculation of the thermal expansion coefficient, for each element and at each iteration. The calculation is made according to the continuous cooling transformation diagram. These results lead to the extremely reliable determination of residual stresses as proved by the comparison with experimental data obtained in the industrial plant. The methodology allows for an accurate study of two types of cooling strategies for the Ri60 and the selection of the more suitable one. (Author)

  6. Experimental Investigations of the Thermal Expansion of Solid SF6 and CHCl3

    Science.gov (United States)

    Sarwar, Ivan

    2001-10-01

    The absolute dilatometric study of the thermal expansion is carried out for the high temperature phase of solid SF6 and CHCl3 in the temperature range 85 - 170 K by the laser Michelson interferometric dilatometer. Experimental technique is described. From the comparison of results for the investigated samples and the solid xenon the quality analysis was carried out to investigate the influence of the phonon-rotational interaction in molecular crystals with different spherical symmetry to check performance of low corresponding states. Received results are in the good agreement with existing structure analysis X-ray data for SF6 [1]. It is found that with the temperature increase due to the growth of liberation amplitudes the additional effect has take place in comparison with solidified rare gases. Grunisen's constants for the solid SF6 were calculated. It is shown that these constants are the same as for solidified rare gases and weakly raise with the temperature in accordance to Max Born theory.

  7. Control of biaxial strain in single-layer molybdenite using local thermal expansion of the substrate

    Science.gov (United States)

    Plechinger, Gerd; Castellanos-Gomez, Andres; Buscema, Michele; van der Zant, Herre S. J.; Steele, Gary A.; Kuc, Agnieszka; Heine, Thomas; Schüller, Christian; Korn, Tobias

    2015-03-01

    Single-layer MoS2 is a direct-gap semiconductor whose electronic band structure strongly depends on the strain applied to its crystal lattice. While uniaxial strain can be easily applied in a controlled way, e.g., by bending of a flexible substrate with the atomically thin MoS2 layer on top, experimental realization of biaxial strain is more challenging. Here, we exploit the large mismatch between the thermal expansion coefficients of MoS2 and a silicone-based substrate to apply a controllable biaxial tensile strain by heating the substrate with a focused laser. The effect of this biaxial strain is directly observable in optical spectroscopy as a redshift of the MoS2 photoluminescence. We also demonstrate the potential of this method to engineer more complex strain patterns by employing highly absorptive features on the substrate to achieve non-uniform heat profiles. By comparison of the observed redshift to strain-dependent band structure calculations, we estimate the biaxial strain applied by the silicone-based substrate to be up to 0.2%, corresponding to a band gap modulation of 105 meV per percentage of biaxial tensile strain.

  8. Structural investigation of the negative thermal expansion in yttrium and rare earth molybdates

    Energy Technology Data Exchange (ETDEWEB)

    Guzman-Afonso, Candelaria; Torres, Manuel Eulalio; Sabalisck, Nanci; Sanchez-Fajardo, VIctor [Departamento de Fisica Basica, Universidad de La Laguna, Tenerife (Spain); Gonzalez-Silgo, Cristina; Gonzalez-Platas, Javier [Departamento de Fisica Fundamental II, Universidad de La Laguna, Tenerife (Spain); Lozano-GorrIn, Antonio Diego [Servicio Integrado de Difraccion de Rayos X, Universidad de La Laguna, Tenerife (Spain); Campo, Javier [Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza (Spain); RodrIguez-Carvajal, Juan, E-mail: csilgo@ull.es [Institut Laue-Langevin, Grenoble (France)

    2011-08-17

    The Sc{sub 2}(WO{sub 4}){sub 3}-type phase (Pbcn) of Y{sub 2}(MoO{sub 4}){sub 3}, Er{sub 2}(MoO{sub 4}){sub 3} and Lu{sub 2}(MoO{sub 4}){sub 3} has been prepared by the conventional solid-state synthesis with preheated oxides and the negative thermal expansion (NTE) has been investigated along with an exhaustive structural study, after water loss. Their crystal structures have been refined using the neutron and x-ray powder diffraction data of dehydrated samples from 150 to 400 K. The multi-pattern Rietveld method, using atomic displacements with respect to a known structure as parameters to refine, has been applied to facilitate the interpretation of the NTE behavior. Polyhedral distortions, transverse vibrations of A{center_dot}{center_dot}{center_dot}O-Mo (A = Y and rare earths) binding oxygen atoms, non-bonded distances A{center_dot}{center_dot}{center_dot}Mo and atomic displacements from the high temperature structure, have been evaluated as a function of the temperature and the ionic radii.

  9. Molar volume, thermal expansivity and isothermal compressibility of trans-decahydronaphthalene up to 200MPa and 446K

    Institute of Scientific and Technical Information of China (English)

    Zhu Hu-Gang; Liu Zhi-Hua; Tian Yi-Ling; Xue Yuan; Yin Liang

    2005-01-01

    The molar volume isotherms of trans-decahydronaphthalene (C10H18) between 293 and 446 K and at pressures from 10 to 200 MPa have been determined. A modified Tait equation of state is used to fit each experimental molar volume isotherm with a maximum average deviation of 0.029%. The thermal expansivity (cubic expansion coefficient) α and isothermal compressibility κ were determined by fitting the slopes of the isobaric curves and isotherms, respectively.The coefficients in the equation Vm = C1 + C2T + C3T2 - C4p - C5pT have been fitted with an average deviation of 1.03%.

  10. A parametric study of assembly pressure, thermal expansion, and membrane swelling in PEM fuel cells

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2016-01-01

    Full Text Available Proton Exchange membrane (PEM fuel cells are still undergoing intense development, and the combination of new and optimized materials, improved product development, novel architectures, more efficient transport processes, and design optimization and integration are expected to lead to major gains in performance, efficiency, durability, reliability, manufacturability and cost-effectiveness. PEM fuel cell assembly pressure is known to cause large strains in the cell components. All components compression occurs during the assembly process of the cell, but also during fuel cell operation due to membrane swelling when absorbs water and cell materials expansion due to heat generating in catalyst layers. Additionally, the repetitive channel-rib pattern of the bipolar plates results in a highly inhomogeneous compressive load, so that while large strains are produced under the rib, the region under the channels remains approximately at its initial uncompressed state. This leads to significant spatial variations in GDL thickness and porosity distributions, as well as in electrical and thermal bulk conductivities and contact resistances (both at the ribe-GDL and membrane-GDL interfaces. These changes affect the rates of mass, charge, and heat transport through the GDL, thus impacting fuel cell performance and lifetime. In this paper, computational fluid dynamics (CFD model of a PEM fuel cell has been developed to simulate the pressure distribution inside the cell, which are occurring during fuel cell assembly (bolt assembling, and membrane swelling and cell materials expansion during fuel cell running due to the changes of temperature and relative humidity. The PEM fuel cell model simulated includes the following components; two bi-polar plates, two GDLs, and, an MEA (membrane plus two CLs. This model is used to study and analyses the effect of assembling and operating parameters on the mechanical behaviour of PEM. The analysis helped identifying critical

  11. First-principles study of thermal expansion and thermomechanics of single-layer black and blue phosphorus

    Science.gov (United States)

    Sun, Hongyi; Liu, Gang; Li, Qingfang; Wan, X. G.

    2016-05-01

    The linear thermal expansion coefficients (LTEC) and thermomechanics of single-layer black and blue phosphorus are systematically studied using first-principles based on quasiharmonic approximation. We find the thermal expansion of black phosphorus is very anisotropic. The LTEC along zigzag direction has a turning from negative to positive at around 138 K, while the LTEC along armchair direction is positive (except below 8 K) and about 2.5 times larger than that along zigzag direction at 300 K. For blue phosphorus, the LTEC is negative in the temperature range from 0 to 350 K. In addition, we find that the Young's modulus and Poisson's ratio of black phosphorus along zigzag direction are 4 to 5 times larger than those along armchair direction within considered temperature range, showing a remarkable anisotropic in-plane thermomechanics property. The mechanisms of these peculiar thermal properties are also explored. This work provides a theoretical understanding of the thermal expansion and thermomechanics of this single layer phosphorus family, which will be useful in nanodevices.

  12. Thermal expansion of kyanite at ambient pressure: An X-ray powder diffraction study up to 1000 ℃

    Institute of Scientific and Technical Information of China (English)

    Xi Liu; Qiang He; Hejing Wang; Michael E. Fleet; Xiaomin Hu

    2010-01-01

    The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients: aa = 5.8(3) × 10-5, ab = 5.8 (1) × 10-5, ac% = 5.2(1) × 10-5, and av = 7.4(1) × 10-3 ℃-1, in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles a, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively.

  13. Phase-Transformation-Induced Extra Thermal Expansion Behavior of (SrxBa1-x)TiO3/Cu Composite.

    Science.gov (United States)

    Sheng, Jie; Wang, Lidong; Li, Shouwei; Yin, Benke; Liu, Xiangli; Fei, Wei-Dong

    2016-01-01

    The properties of metal matrix composites (MMCs) can be optimized effectively through adjusting the type or the volume fraction of reinforcement. Generally, the coefficient of thermal expansion (CTE) of MMCs can be reduced by increasing the volume fraction of the reinforcement with lower CTE than metal matrix. However, it is great challenge to fabricate low CTE MMCs with low reinforcement volume fraction because of the limitation of reinforcement CTEs. SrxBa1-xTiO3 (SBT) powder presents negative thermal expansion behavior during the phase transformation from tetragonal to cubic phase. Here, we demonstrate that the phase transformation of SBT can be utilized to reduce and design the thermal expansion properties of SBT particle-reinforced Cu (SBT/Cu) composite, and ultralow CTE can be obtained in SBT/Cu composite. The X-ray diffraction analysis on heating indicates that the temperature range of phase transformation is extended greatly, therefore, the low CTE can be achieved within wide temperature range. Landau-Devonshire theory study on the phase transformation behaviors of SBT particles in the composite indicates that thermal mismatch stress significantly affects the Curie temperature of SBT particles and the CTE of the composite. The results given in the present study provide a new approach to design the MMCs with low CTE. PMID:27255420

  14. Phase-Transformation-Induced Extra Thermal Expansion Behavior of (SrxBa1-x)TiO3/Cu Composite

    Science.gov (United States)

    Sheng, Jie; Wang, Lidong; Li, Shouwei; Yin, Benke; Liu, Xiangli; Fei, Wei-Dong

    2016-06-01

    The properties of metal matrix composites (MMCs) can be optimized effectively through adjusting the type or the volume fraction of reinforcement. Generally, the coefficient of thermal expansion (CTE) of MMCs can be reduced by increasing the volume fraction of the reinforcement with lower CTE than metal matrix. However, it is great challenge to fabricate low CTE MMCs with low reinforcement volume fraction because of the limitation of reinforcement CTEs. SrxBa1-xTiO3 (SBT) powder presents negative thermal expansion behavior during the phase transformation from tetragonal to cubic phase. Here, we demonstrate that the phase transformation of SBT can be utilized to reduce and design the thermal expansion properties of SBT particle-reinforced Cu (SBT/Cu) composite, and ultralow CTE can be obtained in SBT/Cu composite. The X-ray diffraction analysis on heating indicates that the temperature range of phase transformation is extended greatly, therefore, the low CTE can be achieved within wide temperature range. Landau-Devonshire theory study on the phase transformation behaviors of SBT particles in the composite indicates that thermal mismatch stress significantly affects the Curie temperature of SBT particles and the CTE of the composite. The results given in the present study provide a new approach to design the MMCs with low CTE.

  15. Phase-Transformation-Induced Extra Thermal Expansion Behavior of (SrxBa1-x)TiO3/Cu Composite.

    Science.gov (United States)

    Sheng, Jie; Wang, Lidong; Li, Shouwei; Yin, Benke; Liu, Xiangli; Fei, Wei-Dong

    2016-01-01

    The properties of metal matrix composites (MMCs) can be optimized effectively through adjusting the type or the volume fraction of reinforcement. Generally, the coefficient of thermal expansion (CTE) of MMCs can be reduced by increasing the volume fraction of the reinforcement with lower CTE than metal matrix. However, it is great challenge to fabricate low CTE MMCs with low reinforcement volume fraction because of the limitation of reinforcement CTEs. SrxBa1-xTiO3 (SBT) powder presents negative thermal expansion behavior during the phase transformation from tetragonal to cubic phase. Here, we demonstrate that the phase transformation of SBT can be utilized to reduce and design the thermal expansion properties of SBT particle-reinforced Cu (SBT/Cu) composite, and ultralow CTE can be obtained in SBT/Cu composite. The X-ray diffraction analysis on heating indicates that the temperature range of phase transformation is extended greatly, therefore, the low CTE can be achieved within wide temperature range. Landau-Devonshire theory study on the phase transformation behaviors of SBT particles in the composite indicates that thermal mismatch stress significantly affects the Curie temperature of SBT particles and the CTE of the composite. The results given in the present study provide a new approach to design the MMCs with low CTE.

  16. Carbon fiber-reinforced cyanate ester/nano-ZrW2O8 composites with tailored thermal expansion.

    Science.gov (United States)

    Badrinarayanan, Prashanth; Rogalski, Mark K; Kessler, Michael R

    2012-02-01

    Fiber-reinforced composites are widely used in the design and fabrication of a variety of high performance aerospace components. The mismatch in coefficient of thermal expansion (CTE) between the high CTE polymer matrix and low CTE fiber reinforcements in such composite systems can lead to dimensional instability and deterioration of material lifetimes due to development of residual thermal stresses. The magnitude of thermally induced residual stresses in fiber-reinforced composite systems can be minimized by replacement of conventional polymer matrices with a low CTE, polymer nanocomposite matrix. Zirconium tungstate (ZrW(2)O(8)) is a unique ceramic material that exhibits isotropic negative thermal expansion and has excellent potential as a filler for development of low CTE polymer nanocomposites. In this paper, we report the fabrication and thermal characterization of novel, multiscale, macro-nano hybrid composite laminates comprising bisphenol E cyanate ester (BECy)/ZrW(2)O(8) nanocomposite matrices reinforced with unidirectional carbon fibers. The results reveal that incorporation of nanoparticles facilitates a reduction in CTE of the composite systems, which in turn results in a reduction in panel warpage and curvature after the cure because of mitigation of thermally induced residual stresses.

  17. Thermal stability and thermal expansion behaviour of ZrO2/Y2O3 multilayers deposited by pulsed laser deposition technique

    International Nuclear Information System (INIS)

    Multilayers of ZrO2/Y2O3 were prepared by pulsed laser deposition technique with variation in the ZrO2 layer thickness from 5 to 30 nm keeping the Y2O3 layer thickness constant (∼10 nm). The stability, phase evolution and thermal expansion behaviour of the multilayers were analyzed by high temperature x-ray diffraction technique, in the temperature range of 300–1373 K. Unlike the single layer of ZrO2 film, which shows a mixture of tetragonal and monoclinic phase, the ZrO2 layers in multilayers show tetragonal phase in case of all the multilayers investigated in the present work. The values of coefficient of thermal expansion (CTE) decrease with increase in the ZrO2 layer thickness. The CTE of both ZrO2 and Y2O3 are found to be influenced by their mutual solubility as well as due to interdiffusion of these oxides taking place along the interfaces of the multilayers, especially during high temperature heat-treatment. - Highlights: • ZrO2/Y2O3 multilayers were deposited by pulsed laser deposition technique. • Formation of tetragonal phase of ZrO2 and cubic phase of Y2O3 were observed. • The multilayers films show good thermal stability upto temperature 1373 K. • The coefficient of thermal expansion (CTE) of t-ZrO2 decreases with increase in ZrO2 layer thickness

  18. Jupiter's Thermal Structure on the Eve of Juno's Arrival and an NEB Expansion Event

    Science.gov (United States)

    Fletcher, Leigh N.; Orton, Glenn S.; Greathouse, Thomas K.; Sinclair, James; Giles, Rohini; Irwin, Patrick; Rogers, John; Encrenaz, Therese

    2016-04-01

    regular stratospheric wave pattern in stratospheric temperatures between 20 and 30°N (i.e., above the North Tropical Zone and Temperate Belt, NTropZ and NTB, respectively), possibly associated with the northward expansion of the broad North Equatorial Belt (NEB); (ii) tropospheric thermal variability along the NEB itself with correlations between aerosol variability in the 600-mbar region (sensed at 8.6 μm) and the 2-3 bar region (sensed at 5 μm). This appears to coincide with similar NEB and NTropZ wave structure observed in reflected sunlight near 2 μm, based on images from the SpeX instrument on the IRTF. Zonal mean distributions of temperature, phosphine, ammonia, aerosols and hydrocarbons will be compared to those derived by the Cassini Composite Infrared Spectrometer (CIRS) 15 years earlier. High-resolution VLT images of the Great Red Spot will be compared between 2008 and 2016 to understand the thermochemical changes associated with its recent shrinkage. All images and maps of retrieved properties will be assembled as a database (JCliD) to aid in the interpretation of Juno data during 2016-2017.

  19. Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

    Directory of Open Access Journals (Sweden)

    Stella Crosara Lopes

    2009-04-01

    Full Text Available The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs of the metals and ceramics. Verabond (VB Ni-Cr-Be alloy, Verabond II (VB2, Ni-Cr alloy, Pors-on 4 (P, Pd-Ag alloy, and IPS (I and Duceram (D ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01 for the MCBS test results (MPa, with PI showing higher MCBS (67.72 than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1 differences were: VBI (0.54, VBD (1.33, VB2I (-0.14, VB2D (0.63, PI (1.84 and PD (2.62. Pearson's correlation test (r=0.17 was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

  20. A study of the mechanism of laser welding defects in low thermal expansion superalloy GH909

    International Nuclear Information System (INIS)

    In this paper, we describe experimental laser welding of low-thermal-expansion superalloy GH909. The main welding defects of GH909 by laser in the weld are liquation cracks and porosities, including hydrogen and carbon monoxide porosity. The forming mechanism of laser welding defects was investigated. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum, X-ray diffractometer and other methodologies. The results demonstrated that porosities appearing in the central weld were related to incomplete removal of oxide film on the surface of the welding samples. The porosities produced by these bubbles were formed as a result of residual hydrogen or oxygenium in the weld. These elements failed to escape from the weld since laser welding has both a rapid welding speed and cooling rate. The emerging crack in the heat affected zone is a liquation crack and extends along the grain boundary as a result of composition segregation. Laves–Ni2Ti phase with low melting point is a harmful phase, and the stress causes grain boundaries to liquefy, migrate and even crack. Removing the oxides on the surface of the samples before welding and carefully controlling technological parameters can reduce welding defects and improve formation of the GH909 alloy weld. - Highlights: ► It is a new process for the forming of GH909 alloy via laser welding. ► The forming mechanism of laser welding defects in GH909 has been studied. ► It may be a means to improve the efficiency of aircraft engine production

  1. Thermo-optic and thermal expansion coefficients of RTP and KTP crystals over 300-350 K

    CERN Document Server

    Smith, Arlee V; Do, Binh T

    2016-01-01

    We report new measurements of the thermal expansion and thermo-optic coefficients of RbTiOPO$_4$ (RTP) and KTiOPO$_4$ (KTP) crystals over the temperature range 300-350 K. For RTP/KTP our coefficients of linear thermal expansion at 305 K are: $\\alpha_x=9.44/7.88\\times 10^{-6}$/K, $\\alpha_y=12.49/9.48\\times 10^{-6}$/K, $\\alpha_z=-4.16/0.02\\times 10^{-6}$/K. Our normalized thermo-optic coefficients $\\beta=(1/n)dn/dT$ at 632.8 nm and 305 K are: $\\beta_x=5.39/3.78\\times 10^{-6}$/K, $\\beta_y=7.11/5.24\\times 10^{-6}$/K, $\\beta_z=12.35/9.34\\times 10^{-6}$/K.

  2. Thermal lattice expansion effect on reactive scattering of H2 from Cu(111) at T(s) = 925 K.

    Science.gov (United States)

    Mondal, Arobendo; Wijzenbroek, Mark; Bonfanti, Matteo; Díaz, Cristina; Kroes, Geert-Jan

    2013-09-12

    Surface phonons and surface temperature may have important effects on reactions of molecules at surfaces, and at present much remains unknown about these effects. A question addressed here, which has received little attention so far, is how reaction at elevated temperature is affected by thermal lattice expansion. To answer this question for the benchmark reaction of H2 and D2 with Cu(111), we have performed quantum and quasi-classical dynamics calculations. The specific reaction parameter (SRP) approach to density functional theory (DFT) has been used to compute the required six-dimensional potential energy surfaces (PES). Computed reaction probabilities and rotational quadrupole alignment parameters have been compared for surface temperatures Ts = 0 and 925 K. Surface thermal expansion of the lattice leads to a considerable decrease of reaction barrier heights and thereby to increased reaction probabilities as well as decreased rotational quadrupole alignment parameter values in associative desorption. PMID:23763274

  3. Thermo-optic and thermal expansion coefficients of RTP and KTP crystals over 300-350 K

    OpenAIRE

    Smith, Arlee V.; Smith, Jesse J.; Do, Binh T.

    2016-01-01

    We report new measurements of the thermal expansion and thermo-optic coefficients of RbTiOPO$_4$ (RTP) and KTiOPO$_4$ (KTP) crystals over the temperature range 300-350 K. For RTP/KTP our coefficients of linear thermal expansion at 305 K are: $\\alpha_x=9.44/7.88\\times 10^{-6}$/K, $\\alpha_y=12.49/9.48\\times 10^{-6}$/K, $\\alpha_z=-4.16/0.02\\times 10^{-6}$/K. Our normalized thermo-optic coefficients $\\beta=(1/n)dn/dT$ at 632.8 nm and 305 K are: $\\beta_x=5.39/3.78\\times 10^{-6}$/K, $\\beta_y=7.11/5...

  4. Linear thermal expansion data for tuffs from the unsaturated zone at Yucca Mountain, Nevada; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, B.M.; Chocas, C.S.

    1992-07-01

    Experiment results are presented for linear thermal expansion measurements on tuffaceous rocks from the unsaturated thermal expansion measurements could not be determined.

  5. Influence of Chemical Composition on Phase Transformation Temperature and Thermal Expansion Coefficient of Hot Work Die Steel

    Institute of Scientific and Technical Information of China (English)

    XIE Hao-jie; WU Xiao-chun; MIN Yong-an

    2008-01-01

    On the basis of the uniform design method,six kinds of martensitie hot work die steels were designed.The phase transformation temperatures including Ac1,Ac3,and M,were measured by DIL805A quenching dilatometer.The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis,and three corresponding equations were obtained.These equations,in which the interactions of the elements were considered,showed more effectiveness than the traditional ones.In addition,the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests.The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed;the equations obtained Were verified by using several kinds of steels.The predicted values were in accordance with the results of the experiments.

  6. Abnormal thermal expansion, multiple transitions, magnetocaloric effect, and electronic structure of Gd6Co4.85

    International Nuclear Information System (INIS)

    The structure of known Gd4Co3 compound is re-determined as Gd6Co4.85, adopting the Gd6Co1.67Si3 structure type, which is characterized by two disorder Co sites filling the Gd octahedral and a short Gd-Gd distance within the octahedra. The compound shows uniaxial negative thermal expansion in paramagnetic state, significant negative expansion in ferromagnetic state, and positive expansion below ca. 140 K. It also exhibits large magnetocaloric effect, with an entropy change of −6.4 J kg−1 K−1 at 50 kOe. In the lattice of the compound, Co atoms at different sites show different spin states. It was confirmed by the X-ray photoelectron spectra and calculation of electronic structure and shed lights on the abnormal thermal expansion. The stability of such compound and the origin of its magnetism are also discussed based on measured and calculated electronic structures

  7. Atomistic modeling of finite-temperature properties of β-SiC. I. Lattice vibrations, heat capacity, and thermal expansion

    International Nuclear Information System (INIS)

    We present a two-part theoretical study of the thermal properties of crystalline β-SiC based on an empirical interatomic potential developed by Tersoff which emphasizes the bond-order nature of covalent solids. In part I we use this description of interatomic interactions in both lattice dynamical calculations and molecular dynamics simulations with a temperature-scaling procedure to obtain reasonably accurate predictions of the heat capacity and the thermal expansion coefficient. Our results notwithstanding, improvement of the potential to include ionic interactions for the description of vibrational properties, and extension of short-range forces beyond the nearest neighbors, would be quite useful. (orig.)

  8. Thermal expansion and phase transformations of nitrogen-expanded austenite studied with in situ synchrotron X-ray diffraction

    DEFF Research Database (Denmark)

    Brink, Bastian; Ståhl, Kenny; Christiansen, Thomas Lundin;

    2014-01-01

    Nitrogen-expanded austenite, _N, with high and low nitrogen contents was produced from AISI 316 grade stainless steel powder by gaseous nitriding in ammonia/hydrogen gas mixtures. In situ synchrotron X-ray diffraction was applied to investigate the thermal expansion and thermal stability of...... expanded austenite in the temperature range 385–920 K. Evaluation of the diffractograms of the sample with a high nitrogen content, corresponding to an occupancy of the interstitial lattice of 56%, with Rietveld refinement yielded a best convergence after including the stacking fault probability as a...

  9. Dependence of Ionicity and Thermal Expansion Coefficient on Valence Electron Density in AIIBIVC2V Chalcopyrite Semiconductors

    Directory of Open Access Journals (Sweden)

    Amar BAHADUR

    2013-06-01

    Full Text Available A striking correlation has been found to exist between the free electron density parameter, average bond length, homoplar energy gap, heteropolar energy gap, ionicity and thermal expansion coefficient for AIIBIVC2V chalcopyrite semiconductors. The estimated values of these parameters are in good agreement with the available experimental values and theoretical findings. The electron density parameter data is the only one input data to estimate all above properties.

  10. Standard test method for linear thermal expansion of glaze frits and ceramic whiteware materials by the interferometric method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1995-01-01

    1.1 This test method covers the interferometric determination of linear thermal expansion of premelted glaze frits and fired ceramic whiteware materials at temperatures lower than 1000°C (1830°F). 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  11. Hybrid Composites from Wheat Straw, Inorganic Filler, and Recycled Polypropylene: Morphology and Mechanical and Thermal Expansion Performance

    OpenAIRE

    Min Yu; Runzhou Huang; Chunxia He; Qinglin Wu; Xueni Zhao

    2016-01-01

    Reinforcing effect of hybrid filler including wheat straw (WS) and inorganic filler (heavy calcium carbonate, silicon dioxide, and fly ash) in recycled polypropylene (R-PP) has been investigated. The effects of individual filler (WS) and combined fillers (WS and inorganic filler) on morphological, mechanical, and thermal expansion and water absorption properties of hybrid composites were investigated. The flexural modulus and flexural strength were both reduced when reinforced with three kind...

  12. Application of inverse models and XRD analysis to the determination of Ti-17 {beta}-phase coefficients of thermal expansion

    Energy Technology Data Exchange (ETDEWEB)

    Freour, S. [GeM, Institut de Recherche en Genie Civil et Mecanique (UMR CNRS 6183), Universite de Nantes, Ecole Centrale de Nantes, 37 Boulevard de l' Universite, BP 406, 44 602 Saint-Nazaire cedex (France)]. E-mail: freour@crttsn.univ-nantes.fr; Gloaguen, D. [GeM, Institut de Recherche en Genie Civil et Mecanique (UMR CNRS 6183), Universite de Nantes, Ecole Centrale de Nantes, 37 Boulevard de l' Universite, BP 406, 44 602 Saint-Nazaire cedex (France); Francois, M. [Laboratoire des Systemes Mecaniques et d' Ingenierie Simultanee (LASMIS FRE CNRS 2719), Universite de Technologie de Troyes, 12 Rue Marie Curie, BP 2060, 10010 Troyes (France); Guillen, R. [GeM, Institut de Recherche en Genie Civil et Mecanique (UMR CNRS 6183), Universite de Nantes, Ecole Centrale de Nantes, 37 Boulevard de l' Universite, BP 406, 44 602 Saint-Nazaire cedex (France)

    2006-04-15

    scope of this work is the determination of the coefficients of thermal expansion of the Ti-17 {beta}-phase. A rigorous inverse thermo-elastic self-consistent scale transition micro-mechanical model extended to multi-phase materials was used. The experimental data required for the application of the inverse method were obtained from both the available literature and especially dedicated X-ray diffraction lattice strain measurements performed on the studied ({alpha} + {beta}) two-phase titanium alloy.

  13. Thermal Expansion of Sintered Glass Ceramics in the System BaO-SrO-ZnO-SiO2 and Its Dependence on Particle Size.

    Science.gov (United States)

    Thieme, Christian; Schlesier, Martin; Bocker, Christian; Buzatto de Souza, Gabriel; Rüssel, Christian

    2016-08-10

    The thermal expansion behavior of sintered glass-ceramics containing high concentrations of Ba1-xSrxZn2Si2O7, a phase with very low and highly anisotropic thermal expansion behavior, was investigated. The observed phase has the crystal structure of the high-temperature phase of BaZn2Si2O7, which can be stabilized by the introduction of Sr(2+) into this phase. The high anisotropy leads to microcracking within the volume of the samples, which strongly affects the dilatometric thermal expansion. However, these cracks also have an influence on the nominal thermal expansion of the as-mentioned phase, which decreases if the cracks appear. Below a grain size of approximately 80 μm, the sintered glass-ceramics have almost no cracks and show positive thermal expansion. Hence, coefficients of thermal expansion between -5.6 and 6.5 × 10(-6) K(-1) were measured. In addition to dilatometric studies, the effect of the microstructure on the thermal expansion was also measured using in situ X-ray diffraction at temperatures up to 1000 °C. PMID:27433854

  14. Thermal Expansion of Sintered Glass Ceramics in the System BaO-SrO-ZnO-SiO2 and Its Dependence on Particle Size.

    Science.gov (United States)

    Thieme, Christian; Schlesier, Martin; Bocker, Christian; Buzatto de Souza, Gabriel; Rüssel, Christian

    2016-08-10

    The thermal expansion behavior of sintered glass-ceramics containing high concentrations of Ba1-xSrxZn2Si2O7, a phase with very low and highly anisotropic thermal expansion behavior, was investigated. The observed phase has the crystal structure of the high-temperature phase of BaZn2Si2O7, which can be stabilized by the introduction of Sr(2+) into this phase. The high anisotropy leads to microcracking within the volume of the samples, which strongly affects the dilatometric thermal expansion. However, these cracks also have an influence on the nominal thermal expansion of the as-mentioned phase, which decreases if the cracks appear. Below a grain size of approximately 80 μm, the sintered glass-ceramics have almost no cracks and show positive thermal expansion. Hence, coefficients of thermal expansion between -5.6 and 6.5 × 10(-6) K(-1) were measured. In addition to dilatometric studies, the effect of the microstructure on the thermal expansion was also measured using in situ X-ray diffraction at temperatures up to 1000 °C.

  15. Crystal structure, electrical conductivity and thermal expansion of Ni and Nb co-doped LaCoO3.

    Science.gov (United States)

    Øygarden, Vegar; Grande, Tor

    2013-02-28

    The effect of co-doping LaCoO(3) with Ni and Nb has been investigated in the two solid solution series (1 - x)LaCoO(3)-xLaNi(2/3)Nb(1/3)O(3) and (1 - y)LaCo(2/3)Ni(1/3)O(3)-yLaNi(2/3)Nb(1/3)O(3). The materials were shown to be stoichiometric with respect to oxygen. The compositional effect on the evolution of the crystal structure, thermal expansion and electrical conductivity is reported. The chemical stability of LaCoO(3) in a reducing atmosphere was improved and the thermal expansion was suppressed at higher levels of Nb-substitution. The materials with mixed oxidation states on the B-site possessed superior electrical transport properties compared to solid solutions with cations in mainly isovalent oxidation states. The evolution of the electronic conductivity, thermal expansion and crystal structural is discussed with emphasis on the oxidation states of Ni and Co, and the spin transitions of Co.

  16. Crystal structure and negative thermal expansion properties of solid solution Er_2W_(3-x)Mo_xO_(12)

    Institute of Scientific and Technical Information of China (English)

    PENG Jie; LIU Xin-zhi; GUO Fu-li; HAN Song-bai; LIU Yun-tao; CHEN Dong-feng; ZHAO Xin-hua; HU Zhong-bo

    2009-01-01

    A series of solid solutions Er_2W_(3-x)Mo_xO_(12) (0.5≤x≤2.5) were successfully synthesized by the solid state method.Their crystal structures and negative thermal expansion properties were studied by high temperature X-ray powder diffraction and the Rietveld method.All samples with rare earth tungstates and molybdates crystallize in the same orthorhombic structure with space group Pnca,and show the negative thermal expansion phenomena related to transverse vibration of bridging oxygen atoms in the structure.Thermal expansion coefficients (TECs) of Er_2W_(3-x)Mo_xO_(12) were determined as -16.2×10~(-6) K~(-1) for x=0.5 and -16.5×10~(-6) K~(-1) for x=2.5 while -20.2×10~(-6) K~(-1) and -18.4×10~(-6) K~(-1) for unsubstituted Er_2W_3O_(12) and Er_2Mo_3O_(12) in the identical temperature range of 200-800 ℃.High temperature XRD data and bond length analysis suggest that the difference between W-O and Mo-O is responsible for the change of TECs after the element substitution in the series of solid solutions.

  17. Molecular modeling of nanotube composite materials: Interface formation, interfacial strength, and thermal expansion

    Science.gov (United States)

    Marietta-Tondin, Olivier

    present in this resin system, such as molecular wrapping around the SWNTs. Second, existing MD simulation models of nanotube pullout are analyzed and modified to examine the energy of certain material systems more correctly, and to characterize interfacial shear strength in SWNT/polymer composites. The interfacial bonding and load transfer behaviors between the different SWNTs' configurations (open end, capped end, functionalized end) and three different matrices (polystyrene, polyethylene and Epon862) were examined using the modified models. The results of the modified models effectively reveal the effects of different tube configurations and resin matrices on the interfacial strength during a simulated pullout. Finally, we use MD simulation to investigate the coefficient of thermal expansion (CTE) of individual SWNTs, SWNT ropes, as well as SWNT nanocomposites. Experiments were also carried out in order to gain further insight in the results. It is found that, while the CTE of individual nanotubes is of low negative value, the CTE of the same tubes within a rope or a nanocomposite can significantly change. We also find that SWNTs can be utilized to tailor the CTE of the Epon862 resin system, depending on the functionalization of the SWNTs prior to their introduction in the resin. Finally, a new twisting vibration mode was revealed in SWNT ropes that should prove critical in further SWNT rope studies utilizing MD simulation.

  18. Anomalous law of cooling

    Science.gov (United States)

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  19. Anomalous law of cooling

    International Nuclear Information System (INIS)

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton’s law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics

  20. Anomalous law of cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lapas, Luciano C., E-mail: luciano.lapas@unila.edu.br [Universidade Federal da Integração Latino-Americana, Caixa Postal 2067, 85867-970 Foz do Iguaçu, Paraná (Brazil); Ferreira, Rogelma M. S., E-mail: rogelma.maria@gmail.com [Centro de Ciências Exatas e Tecnológicas, Universidade Federal do Recôncavo da Bahia, 44380-000 Cruz das Almas, Bahia (Brazil); Rubí, J. Miguel, E-mail: mrubi@ub.edu [Departament de Física Fonamental, Facultat de Física, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain); Oliveira, Fernando A., E-mail: fernando.oliveira@pq.cnpq.br [Instituto de Física and Centro Internacional de Física da Matéria Condensada, Universidade de Brasília, Caixa Postal 04513, 70919-970 Brasília, Distrito Federal (Brazil)

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton’s law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  1. Mechanical and thermal-expansion characteristics of Ca10(PO46(OH2-Ca3(PO42 composites

    Directory of Open Access Journals (Sweden)

    Ruseska G.

    2006-01-01

    Full Text Available Three types of composites consisting of Ca10(PO46(OH2 and Ca3(PO42 with composition: 75% (wt Ca10(PO46(OH2: 25%(wt Ca3(PO42; 50%(wt Ca10(PO46(OH2: 50%(wtCa3(PO42 and 25 %(wt Ca10(PO46(OH2: 75%(wt Ca3(PO42 were the subject of our investigation. Sintered compacts were in thermal equilibrium, which was proved by the absence of hysteresis effect of the dependence ΔL/L=f(T during heating /cooling in the temperature interval 20-1000-200C. Sintered compacts with the previously mentioned composition possess 26-50% higher values of the E-modulus, G-modulus and K-modulus indicating the presence of a synergism effect. Several proposed model equations for predicting the thermal expansion coefficient in dependence of the thermal and elastic properties of the constitutive phases and their volume fractions, given by: Turner, Kerner, Tummala and Friedberg, Thomas and Taya, were used for making correlations between mechanical and thermal-expansion characteristics of the Ca10(PO46(OH2 - Ca3(PO42 composites. Application of the previously mentioned model equations to all kinds of composites leads to the conclusion that the experimentally obtained results for the thermal expansion coefficient are in an excellent agreement with the theoretical calculated values on account of the volume fraction of each constitutive phase and with all applied model equations, with a coefficient of correlation from 98.16-99.86 %.

  2. Anomalous Magnetohydrodynamics

    OpenAIRE

    Giovannini, Massimo

    2013-01-01

    Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy with charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved co...

  3. A STUDY OF THE PROPERTIES OF CP: COEFFICIENT OF THERMAL EXPANSION, DECOMPOSITION KINETICS AND REACTION TO SPARK, FRICTION AND IMPACT

    Energy Technology Data Exchange (ETDEWEB)

    Weese, R K; Burnham, A K; Fontes, A T

    2005-03-30

    The properties of pentaamine (5-cyano-2H-tetrazolato-N2) cobalt (III) perchlorate (CP), which was first synthesized in 1968, continues to be of interest for predicting behavior in handling, shipping, aging, and thermal cook-off situations. We report coefficient of thermal expansion (CTE) values over four specific temperature ranges, decomposition kinetics using linear heating rates, and the reaction to three different types of stimuli: impact, spark, and friction. The CTE was measured using a Thermal Mechanical Analyzer (TMA) for samples that were uniaxially compressed at 10,000 psi and analyzed over a dynamic temperature range of -20 C to 70 C. Using differential scanning calorimetry, DSC, CP was decomposed at linear heating rates of 1, 3, and 7 C/min and the kinetic triplet calculated using the LLNL code Kinetics05. Values are also reported for spark, friction, and impact sensitivity.

  4. PREPARATION OF ZrWMoO8-CONTAINING COMPOSITES WITH ZERO THERMAL EXPANSION PROPERTY USING Al(NO33.9H2O AS A SINTERING AID

    Directory of Open Access Journals (Sweden)

    Qinqin Liu

    2015-12-01

    Full Text Available Mixed oxide β-ZrWMoO8-containing composites with monoclinic zirconia (m-ZrO2 were prepared in search for zero thermal expansion ceramics over a wide temperature range. Thermomechanical analyzer (TMA results indicate that the thermal expansion coefficients of the β-ZrWMoO8-containing composites decrease with increasing amount of β-ZrWMoO8 and that the composite with 50 wt. % β-ZrWMoO8 and 50 wt. % m-ZrO2 exhibits near-zero thermal expansion from 30 to about 600oC. However, its relative density is low. The addition of a small amount of Al(NO33.9H2O as a sintering aid increases the density (possibly because the Al3+ ion promotes sintering and densification while affecting the structure and thermal expansion only insignificantly.

  5. Thermal stability and thermal expansion behaviour of ZrO{sub 2}/Y{sub 2}O{sub 3} multilayers deposited by pulsed laser deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Maneesha, E-mail: pkigcar@gmail.com [Materials Synthesis and Structural Characterisation Division, Physical Metallurgy Group, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kuppusami, P. [Centre for Nanoscience and Nanotechnology, Sathyabama University, Chennai, 600119 Tamil Nadu (India); Murugesan, S.; Ghosh, Chanchal; Divakar, R.; Singh, Akash; Mohandas, E. [Materials Synthesis and Structural Characterisation Division, Physical Metallurgy Group, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2015-07-15

    Multilayers of ZrO{sub 2}/Y{sub 2}O{sub 3} were prepared by pulsed laser deposition technique with variation in the ZrO{sub 2} layer thickness from 5 to 30 nm keeping the Y{sub 2}O{sub 3} layer thickness constant (∼10 nm). The stability, phase evolution and thermal expansion behaviour of the multilayers were analyzed by high temperature x-ray diffraction technique, in the temperature range of 300–1373 K. Unlike the single layer of ZrO{sub 2} film, which shows a mixture of tetragonal and monoclinic phase, the ZrO{sub 2} layers in multilayers show tetragonal phase in case of all the multilayers investigated in the present work. The values of coefficient of thermal expansion (CTE) decrease with increase in the ZrO{sub 2} layer thickness. The CTE of both ZrO{sub 2} and Y{sub 2}O{sub 3} are found to be influenced by their mutual solubility as well as due to interdiffusion of these oxides taking place along the interfaces of the multilayers, especially during high temperature heat-treatment. - Highlights: • ZrO{sub 2}/Y{sub 2}O{sub 3} multilayers were deposited by pulsed laser deposition technique. • Formation of tetragonal phase of ZrO{sub 2} and cubic phase of Y{sub 2}O{sub 3} were observed. • The multilayers films show good thermal stability upto temperature 1373 K. • The coefficient of thermal expansion (CTE) of t-ZrO{sub 2} decreases with increase in ZrO{sub 2} layer thickness.

  6. Thermal expansivities of peptides, polypeptides and proteins as measured by pressure perturbation calorimetry.

    Science.gov (United States)

    Pandharipande, Pranav P; Makhatadze, George I

    2015-04-01

    The main goal of this work was to provide direct experimental evidence that the expansivity of peptides, polypeptides and proteins as measured by pressure perturbation calorimetry (PPC), can serve as a proxy to characterize relative compactness of proteins, especially the denatured state ensemble. This is very important as currently only small angle X-ray scattering (SAXS), intrinsic viscosity and, to a lesser degree, fluorescence resonance transfer (FRET) experiments are capable of reporting on the compactness of denatured state ensembles. We combined the expansivity measurements with other biophysical methods (far-UV circular dichroism spectroscopy, differential scanning calorimetry, and small angle X-ray scattering). Three case studies of the effects of conformational changes on the expansivity of polypeptides in solution are presented. We have shown that expansivity appears to be insensitive to the helix-coil transition, and appears to reflect the changes in hydration of the side-chains. We also observed that the expansivity is sensitive to the global conformation of the polypeptide chain and thus can be potentially used to probe hydration of different collapsed states of denatured or even intrinsically disordered proteins.

  7. Thermal Expansion Measurements in Fresh and Saline Ice Using Fiber Optic Strain Gauges and Multipoint Temperature Sensors Based on Bragg Gratings

    OpenAIRE

    Aleksey Marchenko; Ben Lishman; David Wrangborg; Torsten Thiel

    2016-01-01

    This paper describes the use of Fiber Bragg Grating (FBG) sensors to investigate the thermomechanical properties of saline ice. FBG sensors allowed laboratory measurements of thermal expansion of ice samples with a range of different sizes and geometries. The high sampling frequency, accuracy, and resolution of the FBG sensors provide good quality data across a temperature range from 0°C to −20°C. Negative values of the effective coefficient of thermal expansion were observed in ice samples w...

  8. Thermal expansion of CuIn5S8 single crystals and the temperature dependence of their band gap

    International Nuclear Information System (INIS)

    Single crystals of the CuIn5S8 ternary compound are grown by planar crystallization of the melt (the vertical Bridgman method). The composition and structure of the crystals are established. The specific expansion is measured by the dilatometric technique, and the coefficients of thermal expansion are calculated. From the data, the Debye temperatures (ΘD) and the root-mean-square dynamic displacements of atoms (√(u-bar2)) in the CuIn5S8 compound are calculated. From the transmittance spectra recorded in the region of the fundamental absorption edge in the temperature range 20 to 300 K, the band gap is determined and its temperature dependence is constructed.

  9. Sensitivity of the coefficients of thermal expansion of selected graphite reinforced composite laminates to lamina thermoelastic properties

    Science.gov (United States)

    Tompkins, S. S.; Funk, J. G.

    1992-01-01

    An analytical study of the sensitivity of the laminate coefficient of thermal expansion, CTE, to changes in lamina elastic properties has been made. High modulus graphite/epoxy (P75/934, P100/934, P120/934), graphite/aluminum (P100/Al), and graphite/glass (HMS/Gl) composite materials were considered in quasi-isotropic, low thermal stress, and 'near-zero' thermal expansion laminate configurations. The effects of a positive or negative 10 percent change in lamina properties on laminate CTE is strongly dependent upon both the composite material and the laminate configuration. A 10 percent change in all of the lamina properties had very little effect on the laminate CTE of the HMS/Gl composite laminates investigated. The sensitivity and direction of change in the laminate CTE of Gr/934 depended very strongly on the fiber properties. A 10 percent change in the lamina transverse CTE resulted in changes as large as 0.216 ppm/C in the laminate CTE of a quasi-isotropic Gr/934 laminate. No significant difference was observed in the sensitivity of the laminate CTE of the P100/934 and P120/934 composite materials due to changes in lamina properties. Large changes in laminate CTE can result from measured temperature and radiation effects on lamina properties.

  10. Study of non-contact measurement of the thermal expansion coefficients of materials based on laser feedback interferometry.

    Science.gov (United States)

    Zheng, Fasong; Tan, Yidong; Lin, Jing; Ding, Yingchun; Zhang, Shulian

    2015-04-01

    The noncooperative and ultrahigh sensitive length measurement approach is of great significance to the study of a high-precision thermal expansion coefficient (TEC) determination of materials at a wide temperature range. The novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry with 1064 nm wavelength, the beam frequency of which is shifted by a pair of acousto-optic modulators and then the heterodyne phase measurement technique is used. The sample is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams are perpendicular and coaxial on each surface of the sample, the configuration which can not only achieve the length measurement of sample but also eliminate the influence of the distortion of the sample supporter. The reference beams inject on the reference mirrors which are put as possible as near the holes, respectively, to eliminate the air disturbances and the influence of thermal lens effect out of the furnace chamber. For validation, the thermal expansion coefficients of aluminum and steel 45 samples are measured from room temperature to 748 K, which proved measurement repeatability of TECs is better than 0.6 × 10(-6)(K(-1)) at the range of 298 K-598 K and the high-sensitive non-contact measurement of the low reflectivity surface induced by the oxidization of the samples at the range of 598 K-748 K. PMID:25933843

  11. Linear Thermal Expansion Measurements with Sub-Atomic Resolution for the Study of Phase Transitions in Novel Condensed Matter Systems. Final Report

    International Nuclear Information System (INIS)

    This grant has involved numerous projects focusing on further development of thermal expansion measurement technology. Significant improvements to our novel quartz thermal expansion cell have been realized. We have developed an absolute method for measuring the thermal expansion of materials under consideration for use in thermal expansion cell construction. The work associated with this grant has significantly expanded the capabilities and infrastructure for the measurement of the thermal expansion of solids at Montana State University. The techniques we develop have been transferred to students and postdocs through the training they receive. The National High Magnetic Field Laboratory (NHMFL) in Los Alamos has collaborated with the PI to import our quartz thermal expansion cells for measurements in pulsed-magnetic field as part of their user program. The significant progress made with our technology is expected to impact important problems in materials physics. Collaborations with LANL, ANL, BNL and ORNL formed a significant portion of the scientific work. Numerous scientific investigations associated with this grant have already appeared in the archival literature, or have been submitted. Some other work is still in progress, and will be the subject of future grant proposals and publications.

  12. Anomalous commutator corrections to sum rules

    International Nuclear Information System (INIS)

    In this paper we consider the contributions of anomalous commutators to various QCD sum rules. Using a combination of the Bjorken-Johnson-Low limit with the operator product expansion the results are presented in terms of the vacuum condensates of gauge-invariant operators. It is demonstrated that the anomalous contributions are non-negligible and reconcile various apparently contradictory calculations

  13. Thermal expansion measurements by x-ray scattering and breakdown of Ehrenfest's relation in alloy liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, A. K.; Blodgett, M. E.; Johnson, M. L.; Vogt, A. J.; Mauro, N. A.; Kelton, K. F. [Department of Physics and Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130 (United States)

    2014-05-12

    Measurements of sharp diffraction peaks as a function of temperature are routinely used to obtain precise linear expansion coefficients of crystalline solids. In this case, the relation between temperature dependent changes in peak position in momentum transfer (q{sub 1}) and volume expansion is straightforward (Ehrenfest's relation: q{sub 1} = K(2π/d), where K is a constant and d is the interatomic spacing) and the data obtained are usually in close agreement with more direct measurements. With high intensity synchrotron x-ray and spallation neutron sources, it is also possible to accurately measure the positions of the much broader peaks for liquids and glasses. This has led to a debate on whether linear expansion coefficients derived from these data are an accurate representation of the volume expansion coefficients. We present here volume thermal expansion and x-ray diffraction data for a large number of glass-forming alloy liquids acquired in a containerless environment using the beamline electrostatic levitation technique. The data show a large difference in the values obtained from the two different techniques. Moreover, the position of the first peak (q{sub 1}) in the scattered intensity in the structure factor (S(q)) and the atomic volume v for all liquids follow a simple relationship, v∝(q{sub 1}){sup −ε}. The exponent, ε = 2.28 (±0.11), is much different from the expected value of 3 from Ehrenfest's relation and shows no temperature dependence over the temperature range of the data collected.

  14. Assessment and Accommodation of Thermal Expansion of the Internal Active Thermal Control System Coolant During Launch to On-Orbit Activation of International Space Station Elements

    Science.gov (United States)

    Edwards, Darryl; Ungar, Eugene K.; Holt, James M.

    2002-01-01

    The International Space Station (ISS) employs an Internal Active Thermal Control System (IATCS) comprised of several single-phase water coolant loops. These coolant loops are distributed throughout the ISS pressurized elements. The primary element coolant loops (i.e. U.S. Laboratory module) contain a fluid accumulator to accomodate thermal expansion of the system. Other element coolant loops are parasitic (i.e. Airlock), have no accumulator, and require an alternative approach to insure that the system maximum design pressure (MDP) is not exceeded during the Launch to Activation (LTA) phase. During this time the element loops is a stand alone closed system. The solution approach for accomodating thermal expansion was affected by interactions of system components and their particular limitations. The mathematical solution approach was challenged by the presence of certain unknown or not readily obtainable physical and thermodynamic characteristics of some system components and processes. The purpose of this paper is to provide a brief description of a few of the solutions that evolved over time, a novel mathematical solution to eliminate some of the unknowns or derive the unknowns experimentally, and the testing and methods undertaken.

  15. Thermal expansion of CaIrO3 post-perovskite determined by time-of-flight measurements

    Science.gov (United States)

    Aguado, F.; Hirai, S.; Redfern, S. A. T.; Smith, R. I.

    2014-11-01

    The thermal evolution of the CaIrO3 post-perovskite structure has been determined by neutron powder diffraction (time-of-flight) measurements in a wide temperature range, from 1.8K to 550K. The linear expansion is similar to that found in previous x-ray diffraction studies, being αb > αc > αa,. However, the difference in relative lattice parameters is less pronounced in the present case, suggesting a more isotropic evolution under temperature. Other structural differences found at low and high temperatures through several X-ray and neutron diffraction studies have been also analysed.

  16. The effect of bromination of carbon fibers on the coefficient of thermal expansion of graphite fiber-epoxy composites

    Science.gov (United States)

    Jaworske, D. A.; Maciag, C.

    1987-01-01

    To examine the effect of bromination of carbon fibers on the coefficient of thermal expansion (CTE) of carbon fiber epoxy composites, several pristine and brominated carbon fiber-epoxy composite samples were subjected to thermomechanical analysis. The CTE's of these samples were measured in the uniaxial and transverse directions. The CTE was dominated by the fibers in the uniaxial direction, while it was dominated by the matrix in the transverse directions. Bromination had no effect on the CTE of any of the composites. In addition, the CTE of fiber tow was measured in the absence of a polymer matrix, using an extension probe. The results from this technique were inconclusive.

  17. The pseudogap and anisotropic thermal expansion in RMn(4)Al(8) (R = La,Y,Lu and Sc).

    Science.gov (United States)

    Muro, Y; Nakamura, H; Kohara, T

    2006-04-26

    The temperature dependence of the magnetic susceptibility shows a broad maximum at ∼550 and 630 K for LuMn(4)Al(8) and ScMn(4)Al(8), respectively, which can be interpreted as due to the presence of a pseudogap in the effective bands as in LaMn(4)Al(8) and YMn(4)Al(8). The anisotropic thermal expansion observed for RMn(4)Al(8) (R = La, Y, Lu and Sc) and the sensitive volume dependence of the gap width throughout the RMn(4)Al(8) system suggest dominant magnetic coupling in Mn spin chains along the c axis.

  18. Phonons and Colossal Thermal Expansion Behavior of Ag3Co(CN)6 and Ag3Fe(CN)6

    OpenAIRE

    Mittal, R.; Zbiri, M.; Schober, H.; Achary, S. N.; Tyagi, A. K.; Chaplot, S. L.

    2012-01-01

    Recently colossal positive volume thermal expansion has been found in the framework compounds Ag3Co(CN)6 and Ag3Fe(CN)6. Phonon spectra have been measured using the inelastic neutron scattering technique as a function of temperature and pressure. The data has been analyzed using ab-initio calculations. We find that the bonding is very similar in both compounds. At ambient pressure modes in the intermediate frequency part of the vibrational spectra in the Co compound are shifted to slightly hi...

  19. High-resolution thermal expansion of isovalently substituted BaFe2(As1−xPx)2

    International Nuclear Information System (INIS)

    We have investigated the isovalently substituted system BaFe2(As1−xPx)2 by high-resolution thermal expansion using a home-built capacitive dilatometer. Accurate measurements succeeded despite the very small size of the available single crystals (∼ 500 × 500 × 100μm3). Information on the uniaxial pressure derivatives of the transition temperatures is obtained using thermodynamic relations. In-plane and out-of-plane pressure derivatives have opposite sign, which demonstrates the sensitivity of the compound to uniaxial pressure. The structural and the superconducting transition always respond oppositely to uniaxial pressure, which signals their coupling and competition.

  20. Isobaric Thermal Expansion and Isothermal Compression of Powdered NiFe Based Alloys Studied by In-Situ EDXRD

    OpenAIRE

    Olekšáková, D.; J. Füzer; Kollár, P.; Bednarčík, J.; Lathe, C.

    2014-01-01

    The aim of the present work was to study the isothermal compression and isobaric thermal expansion behaviour of ball-milled NiFe (81 wt.% of Ni) and NiFeMo (79 wt.% of Ni, 16 wt.% of Fe) alloy and follow its phase evolution when exposed to high pressure and temperature. In-situ pressure-temperature energy dispersive X-ray (EDXRD) diffraction experiments were performed at the MAX80 instrument (beamline F2.1). The compressibility of NiFe alloy at 400 °C was evaluated for pressure values of up t...

  1. Study of Thermal Expansion of Al2O3—MgO—C Bricks Used in Ladles

    Institute of Scientific and Technical Information of China (English)

    WEILingxuan; HANXiuyue; 等

    1997-01-01

    The reason that Al2O3-MgO-C bricks and Al2O3-Spinel-C bricks excesively expand when used in ladles at high temperature has been analysed,and the effects of spinels aadding amount and their chemical constituents on ther-mal expanion have been studied ,It is pointed out that adding amount of spinels and their chemical contents are the key factors to bring the excessive expansion of above-mentioned bricks at high temperature under control.

  2. Anomalous magnetic moment of anyons

    CERN Document Server

    Gat, G; Gat, Gil; Ray, Rashmi

    1994-01-01

    The anomalous magnetic moment of anyons is calculated to leading order in a 1/N expansion. It is shown that the gyromagnetic ratio g remains 2 to the leading order in 1/N. This result strongly supports that obtained in \\cite{poly}, namely that g=2 is in fact exact.

  3. Anomalous law of cooling

    OpenAIRE

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Oliveira, Fernando A.; Rubí, J. Miguel

    2014-01-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergo a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature ma...

  4. Thermally induced changes in the focal distance of composite mirrors - Composites with a zero coefficient of thermal expansion of the radius of curvature

    Science.gov (United States)

    Dolgin, Benjamin P.

    1992-01-01

    Calculations are presented of the coefficient of thermal expansion (CTE) of the radius of curvature of the reflector face sheets made of a quasi-isotropic composite. It is shown that, upon cooling, the change of the CTE of the focal distance of the mirror is equal to that of the radius of the curvature of the reflector face sheet. The CTE of the radius of the curvature of a quasi-isotropic composite face sheet depends on both the in-plane and the out-of-plane CTEs. The zero in-plane CTE of a face sheet does not guarantee mirrors with no focal length changes.

  5. Thermoacoustic Effects at a Solid-Fluid Boundary: The Role of a Second-Order Thermal Expansion Coefficient

    Science.gov (United States)

    Gopinath, Ashok

    1996-01-01

    Analytical and numerical studies are to be carried out to examine time-averaged thermal effects which are induced by the interaction of strong acoustic fields with a rigid boundary (thermoacoustic streaming). Also of interest is the significance of a second-order thermal expansion coefficient that emerges from this analysis. The model problem to be considered is that of a sphere that is acoustically levitated such that it is effectively isolated in a high-intensity standing acoustic field. The solution technique involves matched asymptotic analysis along with numerical solution of the boundary layer equations. The objective of this study is to predict the thermoacoustic streaming behavior and fully understand the role of the associated second-order thermodynamic modulus.

  6. The equilibrium response to idealized thermal forcings in a comprehensive GCM: implications for recent tropical expansion

    Directory of Open Access Journals (Sweden)

    R. J. Allen

    2011-12-01

    Full Text Available Several recent studies have shown the width of the tropical belt has increased over the last several decades. The mechanisms driving tropical expansion are not well known and the recent expansion is underpredicted by state-of-the art GCMs. We use the CAM3 GCM to investigate how tropical width responds to idealized atmospheric heat sources, focusing on zonal displacement of the tropospheric jets (TJ. The heat sources include global and zonally restricted lower-tropospheric warmings and stratospheric coolings, which coarsely represent possible impacts of ozone or aerosol changes. Similar to prior studies with simplified GCMs, we find that stratospheric cooling-particularly at high-latitudes-shifts jets poleward and excites Northern and Southern Annular Mode (NAM/SAM-type responses. We also find, however, that modest heating of the midlatitude boundary layer drives a similar response; heating at high latitudes provokes a weaker, equatorward shift and tropical heating produces no shift. Responses to stratospheric cooling are consistent with a wave-mean flow interaction involving increased wave refraction, and downward propagation of the stratospheric wind anomaly. Over 70% of the variance in annual mean jet displacements across 27 experiments, however, is accounted for by a newly proposed "Expansion Index", which compares mid-latitude tropospheric warming to that at other latitudes. We find that previously proposed factors, including tropopause height and tropospheric stability, do not fully explain the results. Results suggest recently observed tropical expansion could have been driven not only by stratospheric cooling, but also by mid-latitude heating sources due for example to ozone or aerosol changes.

  7. The Dependence of the Change in the Coefficient of Thermal Expansion of Graphite Fiber Reinforced Polyimide IM7-K3B on Microcracking due to Thermal Cycling

    Science.gov (United States)

    Stewart, Melissa C.

    1995-01-01

    Composite IM7-K3B was subjected to a simulated high speed aircraft thermal environment to determine the effects of microcracking on the change in CTE. IM7-K3B is a graphite fiber reinforced polyimide laminate, manufactured by Dupont. The lay-up for the material was (0.90((Sub 3)(Sub s))). The specimens were placed in a laser-interferometric dilatometer to obtain thermal expansion measurements and were then repeatedly cycled between -65 F and 350 F up to 1000 cycles. After cycling they were scanned for microcracks at a magnification of 400x. The material was expected not to crack and to have a near zero CTE. Some microcracking did occur in all specimens and extensive microcracking occurred in one specimen. Further testing is required to determine how closely the CTE and microcracking are related.

  8. Thermal Expansion Behavior of Precursor-Derived Amorphous Si-C-N and Si-B-C-N Ceramics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Thermal expansion behaviors of some precursor-derived amorphous Si-C-N and Si-B-C-N ceramics, which were shaped by plastic forming after crosslink, were studied. To complete the shrinkage and densification, after thermolysis specimens were heat treated at a temperature of 1400℃ for 10 h in nitrogen atmosphere. The thermal expansion coefficient of VT50-derived amorphous Si-C-N ceramic increases from 1.98×10-6/K at 400℃ to 3.09×10-6/K at 1000℃, of NCP200-derived amorphous Si-C-N ceramic increases from 2.35× 10-6/K at 400℃ to 3.45×10-6/K at1000℃, and of T2-1-derived amorphous Si-B-C-N ceramic increases from 2.08×10-6/K at 400℃ to 3.18×10-6/K at 1000℃. No glass transition for these amorphous ceramic materials was detected, indicating that as-thermolyzed precursor-derived Si-(B-)C-N ceramic materials are amorphous solids, but not glasses.

  9. Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

    Institute of Scientific and Technical Information of China (English)

    Hemant Pal; Vimal Sharma

    2014-01-01

    The mechanical, electrical, and thermal expansion properties of carbon nanotube (CNT)-based silver and silver–palladium (10:1, w/w) alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified mo-lecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, em-bedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young’s modulus along with concomitant decreases in the electrical con-ductivity and the coefficient of thermal expansion (CTE). The hardness and Young’s modulus of the nanocomposites were increased by 30%-40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical proper-ties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying ele-ment.

  10. Application of Mythen detector: In-situ XRD study on the thermal expansion behavior of metal indium

    Science.gov (United States)

    Du, Rong; Chen, ZhongJun; Cai, Quan; Fu, JianLong; Gong, Yu; Wu, ZhongHua

    2016-07-01

    A Mythen detector has been equipped at the beamline 4B9A of Beijing Synchrotron Radiation Facility (BSRF), which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction (XRD) full-profiles. In this paper, the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector. The indium was heated from 303 to 433 K with a heating rate of 2 K/min. The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds. Rietveld refinement was used to extract the structural parameters. The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis. The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point (429.65 K). The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature, while the c-axis contracts with a cubic dependency on temperature. By the time-resolved XRD measurements, it was observed that the [200] preferred orientation can maintain to about 403.15 K. While (110) is the last and detectable crystal plane just before melting of the polycrystalline indium foil. This study is not only beneficial to the application of metal indium, but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.

  11. The P-T conditions of garnet inclusion formation in diamond: thermal expansion of synthetic end-member pyrope

    Science.gov (United States)

    Milani, Sula; Mazzucchelli, Matteo; Nestola, Fabrizio; Alvaro, Matteo; Angel, Ross J.; Geiger, Charles A.; Domeneghetti, Chiara

    2013-04-01

    Pyrope, Mg3Al2Si3O12, due to the abundance of garnet in Earths's upper mantle, has been studied many times. A number of different investigations have measured its physical and thermodynamic properties at high temperature or pressure and, even more recently, under simultaneous high P-T conditions (e.g. Zou et al., 2012). This abstract reports thermal expansion results on pyrope, as part of a much wider project on the determination of the physical properties of garnet, in order to obtain geobarometric information on the formation conditions of its inclusion in diamond. Our experimental approach is based on the elastic method (e.g. Izraeli et al., 1999; Howell et al., 2010; Nestola et al., 2011; Howell et al., 2012), which takes into account the thermoelastic properties of both diamond and any tiny solid phase inclusion within it. The method requires accurate and precise knowledge of thermal expansion and compressibility behavior in order to calculate precisely the pressure and temperature formation conditions of the diamond-inclusion pair. Thus, in order to do this, we measured the thermal expansion of an end-member synthetic single crystal of pyrope up to 1100 K at 52 different temperatures. This was done by measuring the ao unit-cell edge with high precision and accuracy under heating and cooling conditions. This allows excellent experimental reproducibility, which is also checked by monitoring any diffraction peak broadening over the entire range of temperatures. Fitting the temperature-volume data to the thermal expansion equation of Berman (1988), we obtained a room temperature volume-thermal expansion coefficient equal to 2.72(2)×10-5K-1. Using the same pyrope crystal, in situ high-pressure measurements are now in progress in order to determine its isothermal bulk modulus. The use of our results, along with the dK/dT data of Zou et al ( 2012), we plan to calculate the pressure of formation of diamonds containing pyrope-rich garnet inclusions. References Berman

  12. Anomalous thermodynamic behaviour of novel compounds: inelastic neutron scattering and lattice dynamics studies

    International Nuclear Information System (INIS)

    The understanding of the thermodynamic properties of solids has important applications in diverse areas like condensed matter physics, materials science, mineralogy, geophysics, etc. We have been extensively investigating anomalous thermodynamic properties of compounds using the techniques of lattice dynamics, inelastic neutron scattering, inelastic x-ray scattering and synchrotron x-ray diffraction. Here we present some of the results from our recent studies. Studies of materials exhibiting anomalous thermal expansion are of interest due to their fundamental scientific importance and potential applications in ceramic, optical and electronic industry etc. We have studied the thermodynamic properties of negative thermal expansion (NTE) compounds ZrWO8, HfW2O8, ZrMO2O8, Zn(CN)2, Cu2O, Ag2O; Ag3Co(CN)6 and Ag3Fe(CN)6. Our calculations predicted that large softening of the phonon spectrum involving librational and translational modes below 10 MeV would be responsible for anomalous thermal expansion behaviour. High pressure inelastic neutron scattering experiments carried by us on cubic ZrW2O8, ZrMo2O8 and Zn(CN)2 confirmed the phonon softening. The thermal expansion as derived from the phonon measurements is in good agreement with that obtained from diffraction data. This indicates that unusual phonon softening of low energy modes is able to account for the thermal expansion behaviour in these compounds. Superionic conduction in fluorite-structured (anti-fluorite, Li2O) oxides and LiMPO4 (M=Fe, Mn) have applications in energy storage, conversion and nuclear industry. Fast ion conductors exhibit high ionic conductivity, which allow macroscopic movement of ions through their structure. The possible role of phonon in initiation of diffusion has been studied in Li2O and LiMPO4 (M=Fe, Mn). The simulations play a pivotal role in understanding the conduction processes at high temperatures in these compounds. (author)

  13. Thermal expansion of liquid Ti–6Al–4V measured by electrostatic levitation

    OpenAIRE

    John J. Z. Li; Johnson, William L.; Rhim, Won-Kyu

    2006-01-01

    The liquid density of Ti–6Al–4V was measured over a temperature range from 1661 to 1997 K that included undercooling by as much as 280 K. The sample was levitated in an electrostatic levitator and video imaging technique was used to capture the volume changes as a function of temperature. Over the temperature range the liquid density can be expressed by rholiq(T)=4123–0.254 (T–Tm) kg/m^3, where the melting temperature Tm is 1943 K. The corresponding volume expansion coefficient is alphaliq=6...

  14. Inverse correlation between cohesive energy and thermal expansion coefficient in liquid transition metal alloys.

    Science.gov (United States)

    Gangopadhyay, A K; Bendert, J C; Mauro, N A; Kelton, K F

    2012-09-19

    The volume expansion coefficients (α) of twenty-five glass-forming transition metal alloy liquids, measured using the electrostatic levitation technique, are reported. An inverse correlation between α and the cohesive energy is found. The predicted values of α from this relationship agree reasonably well with the published data for thirty other transition metal and alloy liquids; some disagreement was found for a few alloys containing significant amounts of group III and IV elements. A theoretical argument for this empirical relationship is presented. PMID:22842287

  15. Inverse correlation between cohesive energy and thermal expansion coefficient in liquid transition metal alloys

    International Nuclear Information System (INIS)

    The volume expansion coefficients (α) of twenty-five glass-forming transition metal alloy liquids, measured using the electrostatic levitation technique, are reported. An inverse correlation between α and the cohesive energy is found. The predicted values of α from this relationship agree reasonably well with the published data for thirty other transition metal and alloy liquids; some disagreement was found for a few alloys containing significant amounts of group III and IV elements. A theoretical argument for this empirical relationship is presented. (paper)

  16. Thermal expansion behaviour and phase stability of AFe$_2$As$_2$ (A=Ca, Sr and Eu) using powder diffraction technique

    Indian Academy of Sciences (India)

    MISHRA S K; MITTAL R; KRISHNA P S R; SASTRY P U; CHAPLOT S L; BABU P D; MATSUISHI S; HOSONO H

    2016-06-01

    The thermal expansibilities and phase stabilities of AFe$_2$As$_2$ (A = Ca, Sr and Eu) have been investigated by powder diffraction techniques in the temperature range 5–600 K.We found the anisotropic thermal expansivities with temperature for all the compounds. The lattice parameter in the tetragonal phase (AT) of CaFe$_2$As$_2$ contracts with increasing temperature, whereas CT expands. The rate of contraction in AT is lower than the rate of expansion in CT. Other compounds show normal thermal expansion behaviour along both a- and c-axes. In-plane expansion (i.e., along the a-axis) is found to be the smallest for EuFe$_2$As$_2$ and the highest for BaFe$_2$As$_2$. However, therate of change of thermal expansivities along out-of-plane (i.e., along the c-axis) is higher as we go from Ba, Sr, Eu and Ca, respectively. Above 600 K, we notice the appearance/disappearance of certain reflections which suggest that tetragonal phase is not stable above this temperature for these compounds.

  17. Giant Phonon Anharmonicity and Anomalous Pressure Dependence of Lattice Thermal Conductivity in Y2Si2O7 silicate

    Science.gov (United States)

    Luo, Yixiu; Wang, Jiemin; Li, Yiran; Wang, Jingyang

    2016-07-01

    Modification of lattice thermal conductivity (κL) of a solid by means of hydrostatic pressure (P) has been a crucially interesting approach that targets a broad range of advanced materials from thermoelectrics and thermal insulators to minerals in mantle. Although it is well documented knowledge that thermal conductivity of bulk materials normally increase upon hydrostatic pressure, such positive relationship is seriously challenged when it comes to ceramics with complex crystal structure and heterogeneous chemical bonds. In this paper, we predict an abnormally negative trend dκL/dP functional theoretical calculations. The mechanism is disclosed as combined effects of slightly decreased group velocity and significantly augmented scattering of heat-carrying acoustic phonons in pressured lattice, which is originated from pressure-induced downward shift of low-lying optic and acoustic phonons. The structural origin of low-lying optic phonons as well as the induced phonon anharmonicity is also qualitatively elucidated with respect to intrinsic bonding heterogeneity of Y2Si2O7. The present results are expected to bring deeper insights for phonon engineering and modulation of thermal conductivity in complex solids with diverging structural flexibility, enormous bonding heterogeneity, and giant phonon anharmonicity.

  18. 用热弯实验方法决定导电薄膜的热膨胀系数%DETERMINING THERMAL EXPANSION COEFFICIENT OF CONDUCTIVE THIN FILM BY THERMAL BEND TEST

    Institute of Scientific and Technical Information of China (English)

    沈为; 彭立华; 李伟; 邓泽贤

    2001-01-01

    研究了热-力载荷下薄膜/基板复合梁的弯曲问题,导出了薄膜的热膨胀系数与试样表面的温度和变形之间的关系式;提出一种测量导电薄膜的热膨胀系数的方法,并用热弯实验测SnO2膜的热膨胀系数.%The bending problem of thin film/substrate composite subjected to thermal load is studied. The relation between the thermal expansion coefficient of conductive thin films, temperature and deformation of specimen surfaces is derived in this paper. Based on the findings, a method for measuring the thermal expansion coefficient of conductive thin films is developed. The thermal expansion coefficient of conductive thin films has been measured by applying the method in a thermal bend test.

  19. Thermal expansion in the garnet-type solid electrolyte (Li7−xAlx/3)La3Zr2O12 as a function of Al content

    International Nuclear Information System (INIS)

    Highlights: • Thermal expansion (TE) coefficients of LLZ found up to 700°. • The aluminum content of LLZ has a small impact on the thermal expansion. • Typical thermal expansion values were around, 16 × 10−6 K−1. • The TE is approximately double other garnet-type structures. - Abstract: The thermal expansion (TE) coefficients of the lithium-stable lithium-ion conducting garnet lithium lanthanum zirconium oxide (LLZ) and the effect of aluminum substitution were measured from room temperature up to 700 °C by a synchrotron-based X-ray diffraction. The typical TE value measured for the most reported composition (LLZ doped with 0.3 wt.% or 0.093 mol% aluminum) was 15.498 × 10−6 K−1, which is approximately twice the value reported for other garnet-type structures. As the Al(III) concentration has been observed to strongly affect the structure observed and the ionic conductivity, we also assessed its role on thermal expansion and noted only a small variation with increasing dopant concentration. The materials implications for using LLZ in a solid state battery are discussed

  20. Oxidation resistant and low coefficient of thermal expansion Nia1-CoCrAly alloy

    Science.gov (United States)

    Hebsur, Mohan G. (Inventor)

    2004-01-01

    A bond coat composition for use in thermal barrier coatings comprises a NiAl--CoCrAlY matrix containing particles of AlN dispersed therein. The bond coat composition is prepared by croymilling NiAl and CoCrAlY in liquid nitrogen.

  1. Electrical conductivity and thermal expansion behavior of MMoO{sub 4} (M = Ca, Sr and Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Maji, Binoy Kumar; Jena, Hrudananda, E-mail: hruda66@yahoo.co.in; Asuvathraman, R.; Kutty, K.V. Govindan

    2015-08-15

    Highlights: • CaMoO{sub 4}, SrMoO{sub 4} and BaMoO{sub 4} are scheelite type oxides exhibit electrical conduction. • These are the interaction products of radio-nuclides in the nuclear fuel cycle. • Decrease in thermal expansion shows decrease in bond strength from CaMoO{sub 4} to BaMoO{sub 4}. • Decrease in σ from CaMoO{sub 4} to BaMoO{sub 4} is due to decrease in electropositive character. • Diffusion coefficient (D) of oxide ion conduction decreases from CaMoO{sub 4} to BaMoO{sub 4}. - Abstract: Alkaline earth (Ca, Sr, Ba) molybdates were synthesized by solid state reaction route. The compounds were characterized by powder-XRD, TG–DTA techniques. The electrical conductivities of these compounds were measured by AC-impedance technique at 673–1073 K. The activation energies of electrical conduction of CaMoO{sub 4}, SrMoO{sub 4} and BaMoO{sub 4} were found to be 1.29 ± 0.01 eV, 1.33 ± 0.01 eV and 1.31 ± 0.01 eV respectively. The linear thermal expansion of these molybdates was measured by dilatometry. The mean coefficients (α{sub m}) of thermal expansion for these compounds were found to be in the range of 9.38 ± 0.18 × 10{sup −6}–12.96 ± 0.25 × 10{sup −6} K{sup −1} at 305–1005 K temperature range. The diffusion coefficient (D) values of oxide ion conduction for these molybdates were determined and found to be in the range of 9.48 ± 0.02 × 10{sup −14}–3.32 ± 0.01 × 10{sup −10} for CaMoO{sub 4}, 5.86 ± 0.02 × 10{sup −14}–2.50 ± 0.01 × 10{sup −10} for SrMoO{sub 4} and 3.46 ± 0.02 × 10{sup −14}–1.22 ± 0.01 × 10{sup −10} cm{sup 2} s{sup −1} for BaMoO{sub 4} at 673–1073 K range of temperature.

  2. A model for thermal oxidation of Si and SiC including material expansion

    Energy Technology Data Exchange (ETDEWEB)

    Christen, T., E-mail: thomas.christen@ch.abb.com; Ioannidis, A. [ABB Corporate Research, Segelhofstrasse 1K, CH-5405 Baden (Switzerland); Winkelmann, C. [ETH Zürich, Seminar for Applied Mathematics, Rämistrasse 101, CH-8092 Zürich (Switzerland)

    2015-02-28

    A model based on drift-diffusion-reaction kinetics for Si and SiC oxidation is discussed, which takes the material expansion into account with an additional convection term. The associated velocity field is determined self-consistently from the local reaction rate. The approach allows a calculation of the densities of volatile species in an nm-resolution at the oxidation front. The model is illustrated with simulation results for the growth and impurity redistribution during Si oxidation and for carbon and silicon emission during SiC oxidation. The approach can be useful for the prediction of Si and/or C interstitial distribution, which is particularly relevant for the quality of metal-oxide-semiconductor electronic devices.

  3. A study on the thermal expansion characteristics of Inconel-82 filler wire by high temperature X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Panneerselvam, G.; Antony, M.P. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102 (India); Raju, S.; Jose, R.; Divakar, R.; Mohandas, E. [Materials Characterization Group, Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102 (India); Sivasubramanian, K. [Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102 (India)

    2004-01-01

    The lattice parameter (a) change with respect to temperature (T) has been measured by high temperature X-ray diffraction (HT-XRD) technique for Inconel-82 filler wire used in the TIG welding of a dissimilar joint involving Inconel-600 and commercially pure iron. By taking proper precautions to minimise the temperature gradient across the sample thickness, and by suitably calibrating the shift in 2{theta} produced as a result of sample buckling at high temperatures, we could obtain fairly reliable estimates of lattice parameter in the temperature range 300-1200 K. The lattice parameter and the coefficient of mean linear thermal expansion at 300 K, have been found to be 3.546(2)x10{sup -10} m and 11.03x10{sup -6} K{sup -1}, respectively.

  4. Phase-matched second-harmonic generation due to thermal expansion of TlGaSe2 layered crystal

    International Nuclear Information System (INIS)

    Second-harmonic generation effects have been investigated in TlGaSe2 layered crystal over a temperature range where ferroelectric phase exists. Pronounced periodical changes of the second-harmonic signal with temperature have been discovered. The observed effect is explained within the phase synchronism condition which changes with the temperature. The main mechanism of the thermal expansion of the sample in the observed phenomenon is explained. -- Highlights: ► Second-harmonic generation was investigated in TlGaSe2 layered crystal. ► Periodical changes of the SH signal with temperature are found for the first time. ► Conditions for temperature phase-matched SHG were proposed.

  5. Development of low coefficient of thermal expansion (CTE) nickel alloys for potential use as interconnects in SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Alman, David E.; Jablonski, Paul D.

    2004-11-01

    This paper deals with the development of low coefficient of thermal expansion (CTE) nickel-base superalloys for potential use as interconnects for SOFC. Ni-Mo-Cr alloys were formulated with CTE on the order of 12.5 to 13.5 x10-6/°C. The alloys were vacuum induction melted and reduced to sheet via a combination of hot and cold working. Dilatometry was used to measure CTE of the alloys. Oxidation behavior of the alloys at 800°C in dry and moist air is reported. The results are compared to results for Haynes 230 (a commercial Ni-base superalloy) and for Crofer 22APU (a commercial ferritic stainless steel designed specifically for use as an SOFC interconnect).

  6. On the sensitivity of projected oceanic thermal expansion to the parameterisation of sub-grid scale ocean mixing

    Science.gov (United States)

    Weaver, Andrew J.; Wiebe, Edward C.

    A coupled model of intermediate complexity is used to examine the importance of the parameterisation of sub-grid scale ocean mixing on the global mean steric sea level rise in global warming simulations. It is shown that when mixing associated with mesoscale eddies is treated in a more physically realistic way than the commonly used horizontal/vertical scheme, quasi-equilibrium projected steric sea level rise is more than two times lower in both 2 × CO2 and 4 × CO2 climates. This occurs despite the invariance of the coupled model climate sensitivity to the particular sub-grid scale mixing scheme employed. During the early phase of the transient integrations thermal expansion differences are smaller, although experiments using the Gent and McWilliams parameterisation for mixing associated with mesoscale eddies approach equilibrium more rapidly once the radiative forcing is held fixed. This reduced expansion commitment reflects a greater decoupling of the surface ocean from the deep ocean, due to a reduction in spurious high latitude convection that occurs when a horizontal/vertical mixing scheme is used.

  7. Thermal Expansion and Second Harmonic Generation Response of the Tungsten Bronze Pb2AgNb5O15.

    Science.gov (United States)

    Lin, Kun; Gong, Pifu; Sun, Jing; Ma, Hongqiang; Wang, You; You, Li; Deng, Jinxia; Chen, Jun; Lin, Zheshuai; Kato, Kenichi; Wu, Hui; Huang, Qingzhen; Xing, Xianran

    2016-03-21

    The incorporation of transition metal element Ag was performed to explore negative thermal expansion (NTE) materials with tetragonal tungsten bronze (TTB) structures. In this study, the structure and thermal expansion behaviors of a polar TTB oxide, Pb2AgNb5O15 (PAN), were systematically investigated by high-resolution synchrotron powder diffraction, high-resolution neutron powder diffraction, transmission electron microscope (TEM), and high-temperature X-ray diffractions. The TEM and Rietveld refinements revealed that the compound PAN displays (√2a(TTB), √2b(TTB), 2c(TTB))-type superstructure. This superstructure within the a-b plane is caused by the ordering of A-site cations, while the doubling of the c axis is mainly induced by a slight tilt distortion of the NbO6 octahedra. The transition metal Ag has larger spontaneous polarization displacements than Pb, but the Pb-O covalence seems to be weakened compared to the potassium counterpart Pb2KNb5O15 (PKN), which may account for the similar Curie temperature and uniaxial NTE behavior for PAN and PKN. Powder second harmonic generation (SHG) measurement indicates that PAN displays a moderate SHG response of ∼0.2 × LiNbO3 (or ∼100 × α-SiO2) under 1064 nm laser radiation. The magnitudes of the local dipole moments in NbO6 and PbOx polyhedra were quantified using bond-valence approach. We show that the SHG response stems from the superposition of dipole moments of both the PbO(x) and NbO6 polyhedra. PMID:26928907

  8. Synthesis, Structures, and Thermal Expansion of the La 2W 2- xMo xO 9 Series

    Science.gov (United States)

    Collado, J. A.; Aranda, M. A. G.; Cabeza, A.; Olivera-Pastor, P.; Bruque, S.

    2002-08-01

    The La 2W 2- xMo xO 9 series has been synthesized by the ceramic method. An alternative synthesis using microwave radiation is also reported. La 2W 2O 9 has two polymorphs and the low-temperature phase ( α) transforms to the high-temperature form ( β) at 1077°C. The influence of the W/Mo substitution in this phase transition has been investigated by DTA. The β structure for x≥0.7 compositions can be prepared as single phase at any cooling rate. The β phase for 0.3≤ x≤0.7 compounds can be prepared as single phase by quenching, whereas a mixture of α and β phases is obtained by slow cooling. The W/Mo ratio in both coexisting phases is different with the β-phase having a higher Mo content. The x=0.1 and 0.2 compounds have been prepared as mixtures of phases. The room temperature structure of β-La 2W 1.7Mo 0.3O 9 has been analyzed by the Rietveld method in P2 13 space group. The final R-factors were RWP=9.0% and RF=5.6% with a structure similar to that of β-La 2Mo 2O 9. Finally, the thermal expansion of both types of structures has been determined from a thermodiffractometric study. The thermal expansion coefficients were 2.9×10 -6 and 9.7×10 -6°C -1 for α-La 2W 2O 9 and β-La 2W 1.2Mo 0.8O 9, respectively.

  9. Large Scale Solar Thermal Systems for the Solution of Europe`S Expansion Of Energy Demand

    Directory of Open Access Journals (Sweden)

    Erdogan Guk

    2014-04-01

    Full Text Available This paper describes solar thermal technologies for the solution of long term Europe`s energy problem with better reliability.\tA\tshort\toverview\tabout\tsolar\tenergy\tis\texplained with\ta\tbasic\tenergy\tanalysis.\tThis\treport\talso\tincludes\tsome evaluations and discussions of solar energy systems in the following pages. The general purpose of the article is to understand\thow\tefficiently\tsolar\tthermal\tsystems\tgenerates\tenergy,\tand\tsolve\tthe\tEurope`s\tincreasing\tenergy\tdemand in\tour\tcentury.

  10. Thermal expansion and the Grueneisen parameter near the magnetic instability in Ce sub 1 sub - sub x La sub x Ru sub 2 Si sub 2

    CERN Document Server

    Kambe, S; Lejay, P; Haen, P; Visser, A D

    1997-01-01

    The low-temperature thermal expansion of the heavy-fermion system with the formula Ce sub 1 sub - sub x La sub x Ru sub 2 Si sub 2 (x=0 and x=0.05) close to the magnetic instability is analysed in terms of the renormalization group and self-consistent renormalized spin-fluctuation models. The Grueneisen parameter calculated using the renormalized Fermi temperature is compared with the effective one which is determined from thermal expansion measurements and previously obtained specific heat data. (author)

  11. Exploring the charge-ordering transition in (TMTTF){sub 2}X via thermal expansion measurements

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Mariano de, E-mail: mariano@physik.uni-frankfurt.d [Physikalisches Institut, Goethe-Universitaet Frankfurt, SFB/TRR 49, D-60438 Frankfurt am Main (Germany); Hofmann, Daniel [Physikalisches Institut, Goethe-Universitaet Frankfurt, SFB/TRR 49, D-60438 Frankfurt am Main (Germany); Foury-Leylekian, Pascale; Moradpour, Alec; Pouget, Jean-Paul [Laboratoire de Physique des Solides, Universite Paris Sud, CNRS UMR 8502, 91405 Orsay (France); Lang, Michael [Physikalisches Institut, Goethe-Universitaet Frankfurt, SFB/TRR 49, D-60438 Frankfurt am Main (Germany)

    2010-06-01

    We report results of high-resolution measurements of the c{sup *}-axis expansivity ({alpha}{sub c}{sup *}) at the charge-ordering (CO) transition for the quasi-1D (TMTTF){sub 2}X compounds with X=SbF{sub 6} and Br and make a comparison with previous results for the X=PF{sub 6} and AsF{sub 6} salts. For X=SbF{sub 6}, due to the screening of the long-range Coulomb forces, a sharp {lambda}-type anomaly is observed at T{sub CO}, which contrasts with the step-like mean-field anomaly at T{sub CO} for PF{sub 6} and AsF{sub 6}, where CO occurs in the Mott-Hubbard charge-localized regime. For the latter two salts, a negative contribution to {alpha}{sub c}{sup *} is observed above T{sub CO}. This feature is assigned to the anions' rigid-unit modes, which become inactive for T

  12. Thermal expansion, thermal conductivity, and heat capacity measurements for boreholes UE25 NRG-4, UE25 NRG-5, USW NRG-6, and USW NRG-7/7A

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, N.S.; Riggins, M. [Sandia National Labs., Albuquerque, NM (United States); Connolly, J. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology and Inst. of Meteoritics; Ricci, P. [Holometrix, Inc., Bedford, MA (United States)

    1997-09-01

    Specimens were tested from four thermal-mechanical units, namely Tiva Canyon (TCw), Paintbrush Tuff (PTn), and two Topopah Spring units (TSw1 and TSw2), and from two lithologies, i.e., welded devitrified (TCw, TSw1, TSw2) and nonwelded vitric tuff (PTn). Thermal conductivities in W(mk){sup {minus}1} averaged over all boreholes, ranged (depending upon temperature and saturation state) from 1.2 to 1.9 for TCw, from 0.4 to 0.9 for PTn, from 1.0 to 1.7 for TSw1, and from 1.5 to 2.3 for TSw2. Mean coefficients of thermal expansion were highly temperature dependent and values, averaged over all boreholes, ranged (depending upon temperature and saturation state) from 6.6 {times} 10{sup {minus}6} to 49 {times} 10{sup {minus}6} C{sup {minus}1} for TCw, from the negative range to 16 {times} 10{sup {minus}6} {center_dot} {degree}C{sup {minus}1} for PTn, from 6.3 {times} 10{sup {minus}6} to 44 {times} 10{sup {minus}6} C{sup {minus}1} for TSw1, and from 6.7 {times} 10{sup {minus}6} to 37 {times} 10{sup {minus}6} {center_dot} {degree}C{sup {minus}1} for TSw2. Mean values of thermal capacitance in J/cm{sup 3}K (averaged overall specimens) ranged from 1.6 J to 2.1 for TSw1 and from 1.8 to 2.5 for TSw2. In general, the lithostratigraphic classifications of rock assigned by the USGS are consistent with the mineralogical data presented in this report.

  13. Compressibility and thermal expansion of hydrous ringwoodite with 2.5(3) wt% H[subscript 2]O

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Yu; Brown, David A.; Smyth, Joseph R.; Panero, Wendy R.; Jacobsen, Steven D.; Chang, Yun-Yuan; Townsend, Joshua P.; Thomas, Sylvia-Monique; Hauri, Erik H.; Dera, Przemyslaw; Frost, Daniel J. (Bayreuth); (Colorado); (CIW); (UC); (NWU); (OSU)

    2016-07-29

    Ringwoodite ({gamma}-Mg{sub 2}SiO{sub 4}) is the stable polymorph of olivine in the transition zone between 525-660 km depth, and can incorporate weight percent amounts of H{sub 2}O as hydroxyl, with charge compensated mainly by Mg vacancies (Mg{sup 2+} = 2H{sup +}), but also possibly as (Si{sup 4+} = 4H{sup +} and Mg{sup 2+} + 2H{sup +} = Si{sup 4+}). We synthesized pure Mg ringwoodite containing 2.5(3) wt% H{sub 2}O, measured by secondary ion mass spectrometry (SIMS), and determined its compressibility at 300 K by single-crystal and powder X-ray diffraction (XRD), as well as its thermal expansion behavior between 140 and 740 K at room pressure. A third-order Birch-Murnaghan equation of state (BM3 EOS) fits values of the isothermal bulk modulus K{sub T0} = 159(7) GPa and (dK{sub T}/dP){sub P = 0} = K' = 6.7(7) for single-crystal XRD; K{sub T0} = 161(4) GPa and K' = 5.4(6) for powder XRD, with K{sub T0} = 160(2) GPa and K' = 6.2(3) for the combined data sets. At room pressure, hydrous ringwoodite breaks down by an irreversible unit-cell expansion above 586 K, which may be related to dehydration and changes in the disorder mechanisms. Single-crystal intensity data were collected at various temperatures up to 736 K, and show that the cell volume V(cell) has a mean thermal expansion coefficient {alpha}{sub V0} of 40(4) x 10{sup -6}/K (143-736 K), and 29(2) x 10{sup -6}/K (143-586 K before irreversible expansion). V(Mg) have {alpha}{sub 0} values of 41(3) x 10{sup -6}/K (143-736 K), and V(Si) has {alpha}{sub 0} values of 20(3) x 10{sup -6}/K (143-586 K) and 132(4) x 10{sup -6}K (586-736 K). Based on the experimental data and previous work from {sup 29}Si NMR, we propose that during the irreversible expansion, a small amount of H{sup +} cations in Mg sites transfer to Si sites without changing the cubic spinel structure of ringwoodite, and the substituted Si{sup 4+} cations move to the normally vacant octahedral site at (1/2, 1/2, 0). Including new SIMS

  14. Effects of thermal expansion of the crystal lattice on x-ray crystal spectrometers used for fusion research

    International Nuclear Information System (INIS)

    X-ray imaging crystal spectrometers with high spectral and spatial resolution are currently being used on magnetically confined fusion devices to infer the time history profiles of ion and electron temperatures as well as plasma flow velocities. The absolute measurement of flow velocities is important for optimizing various discharge scenarios and evaluating the radial electric field in tokamak and stellarator plasmas. Recent studies indicate that the crystal temperature must be kept constant to within a fraction of a degree to avoid changes of the interplanar 2d-spacing by thermal expansion that cause changes in the Bragg angle, which could be misinterpreted as Doppler shifts. For the instrumental parameters of the x-ray crystal spectrometer on Alcator C-Mod, where those thermal effects were investigated, a change of the crystal temperature by 1 °C causes a change of the lattice spacing of the order of Δd = 1 × 10−5 Å introducing a fictitious velocity drift of the order of ∼3 km s−1. This effect must be considered for x-ray imaging crystals spectrometers installed on LHD, KSTAR, EAST, J-TEXT, NSTX and, in the future, W7-X and ITER. (paper)

  15. New Family of Materials with Negative Coefficients of Thermal Expansion: The Effect of MgO, CoO, MnO, NiO, or CuO on the Phase Stability and Thermal Expansion of Solid Solution Phases Derived from BaZn2Si2O7.

    Science.gov (United States)

    Thieme, Christian; Waurischk, Tina; Heitmann, Stephan; Rüssel, Christian

    2016-05-01

    Recently, a silicate with the composition SrxBa1-xZn2Si2O7 was reported, which exhibits a negative coefficient of thermal expansion. The compound BaZn2Si2O7 shows a highly positive coefficient of thermal expansion up to a temperature of 280 °C and then transfers to a high temperature phase, which exhibits a coefficient of thermal expansion near zero or negative over a limited temperature range up to around 500 °C. This high temperature modification can be stabilized to room temperature if Ba(2+) is replaced by Sr(2+). In the solid solution SrxBa1-xZn2Si2O7, also Zn(2+) can be replaced in a wide concentration range by other cations with the respective valency. In the present study, Zn was partially or completely replaced by Mg, Co, Mn, Ni, or Cu. If the high temperature phase is stable at room temperature, the thermal expansion is negative, and if the partial substitution exceeds a certain concentration threshold, the low temperature phase with the crystal structure of BaZn2Si2O7 and highly positive thermal expansion is formed. The lowest mean coefficients of thermal expansion were measured for the composition Ba0.5Sr0.5Zn1.4Co0.6Si2O7 with a value of -2.9 × 10(-6) K(-1). In general, a lower Zn-concentration leads to a higher anisotropy and a lower mean coefficient of thermal expansion. PMID:27062972

  16. New Family of Materials with Negative Coefficients of Thermal Expansion: The Effect of MgO, CoO, MnO, NiO, or CuO on the Phase Stability and Thermal Expansion of Solid Solution Phases Derived from BaZn2Si2O7.

    Science.gov (United States)

    Thieme, Christian; Waurischk, Tina; Heitmann, Stephan; Rüssel, Christian

    2016-05-01

    Recently, a silicate with the composition SrxBa1-xZn2Si2O7 was reported, which exhibits a negative coefficient of thermal expansion. The compound BaZn2Si2O7 shows a highly positive coefficient of thermal expansion up to a temperature of 280 °C and then transfers to a high temperature phase, which exhibits a coefficient of thermal expansion near zero or negative over a limited temperature range up to around 500 °C. This high temperature modification can be stabilized to room temperature if Ba(2+) is replaced by Sr(2+). In the solid solution SrxBa1-xZn2Si2O7, also Zn(2+) can be replaced in a wide concentration range by other cations with the respective valency. In the present study, Zn was partially or completely replaced by Mg, Co, Mn, Ni, or Cu. If the high temperature phase is stable at room temperature, the thermal expansion is negative, and if the partial substitution exceeds a certain concentration threshold, the low temperature phase with the crystal structure of BaZn2Si2O7 and highly positive thermal expansion is formed. The lowest mean coefficients of thermal expansion were measured for the composition Ba0.5Sr0.5Zn1.4Co0.6Si2O7 with a value of -2.9 × 10(-6) K(-1). In general, a lower Zn-concentration leads to a higher anisotropy and a lower mean coefficient of thermal expansion.

  17. Determination of isobaric thermal expansivity of organic compounds from 0.1 to 30 MPa at 30 degrees C with an isothermal pressure scanning microcalorimeter

    DEFF Research Database (Denmark)

    Verdier, Sylvain Charles Roland; Andersen, Simon Ivar

    2003-01-01

    This paper describes a simple high-pressure mercury-free microcalorimetric technique that enables the compression of a fluid from 0.1 to 30 MPa. Thermal expansivities of several compounds were calculated (n-hexane, cyclohexane, heptane, and toluene) with the pressure. scanning transitiometry meth...

  18. Predictions of thermal expansion coefficients of rare-earth zirconate pyrochlores: A quasi-harmonic approximation based on stable phonon modes

    Science.gov (United States)

    Lan, Guoqiang; Ouyang, Bin; Xu, Yushuai; Song, Jun; Jiang, Yong

    2016-06-01

    Rare-earth (RE) pyrochlores are considered as promising candidate materials for the thermal barrier coating. In this study, we performed first-principles calculations, augmented by quasi-harmonic phonon calculations, to investigate the thermal expansion behaviors of several RE2Zr2O7 (RE = La, Nd, Sm, Gd) pyrochlores. Our findings show that RE2Zr2O7 pyrochlores exhibit low-lying optical phonon frequencies that correspond to RE-cation rattling vibrational modes. These frequencies become imaginary upon volume expansion, preventing correct determination of the free energy versus volume relation and thereby quantification of thermal expansion using QH phonon calculations. To address this challenge, we proposed a QH approximation approach based on stable phonon modes where the RE-cation rattling modes were systematically eliminated. This approach is shown to provide accurate predictions of the coefficients of thermal expansion (CTEs) of RE2Zr2O7 pyrochlores, in good agreement with experimental measurements and data from first-principles molecular dynamics simulations. In addition, we showed that the QH Debye model considerably overestimates the magnitudes and wrongly predicts the trend for the CTEs of RE2Zr2O7 pyrochlores.

  19. Near-zero thermal expansion of In2(1-x)(HfMg) x Mo3O12 with tailored phase transition

    Science.gov (United States)

    Cheng, Yong-Guang; Mao, Yan-Chao; Liu, Xain-Sheng; Yuan, Bao-He; Chao, Ming-Ju; Liang, Er-Jun

    2016-08-01

    Solid solutions of In2(1-x)(HfMg) x Mo3O12 are synthesized by solid state reaction with the aim to reduce the phase transition temperature of In2Mo3O12 and improve its thermal expansion property. The effects of (HfMg)6+ incorporation on the phase transition and thermal expansion are investigated. It is shown that the monoclinic-to-orthorhombic phase transition temperature obviously decreases and the coefficient of thermal expansion (CTE) of the orthorhombic becomes less negative and approaches to zero with increasing the content of (HfMg)6+. A near zero thermal expansion covering the case at room temperature (RT) is achieved for the solid solutions with x ≥ 0.85, implying potential applications of this material in many fields. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574276, 51302249, and 51503185) and the Doctoral Fund of the Ministry of Education of China (Grant No. 20114101110003).

  20. Extrusion-formed uranium-2. 4 wt % article with decreased linear thermal expansion and method for making the same. [Patent application

    Science.gov (United States)

    Anderson, R.C.; Jones, J.M.; Kollie, T.G.

    1982-05-24

    The present invention is directed to the fabrication of an article of uranium-2.4 wt % niobium alloy in which the linear thermal expansion in the direction transverse to the extrusion direction is less than about 0.98% between 22 and 600/sup 0/C which corresponds to a value greater than the 1.04% provided by previous extrusion operations over the same temperature range. The article with the improved thermal expansion possesses a yield strength at 0.2% offset of at least 400 MPa, an ultimate tensile strength of 1050 MPa, a compressive yield strength of at least 0.2% offset of at least 675 MPa, and an elongation of at least 25% over 25.4 mm/s. To provide this article with the improved thermal expansion, the uranium alloy billet is heated to 630/sup 0/C and extruded in the alpha phase through a die with a reduction ratio of at least 8.4:1 at a ram speed no greater than 6.8 mm/s. These critical extrusion parameters provide the article with a desired decrease in the linear thermal expansion while maintaining the selected mechanical properties without encountering crystal disruption in the article.

  1. Sodium Borohydride Reduction of Aqueous Silver-Iron-Nickel Solutions: a Chemical Route to Synthesis of Low Thermal Expansion-High Conductivity Ag-Invar Alloys

    Science.gov (United States)

    Sterling, E. A.; Stolk, J.; Hafford, L.; Gross, M.

    2009-07-01

    Thermal management is a critical concern in the design and performance of electronics systems. If heat extraction and thermal expansion are not properly addressed, the thermal mismatch among dissimilar materials may give rise to high thermal stresses or interfacial shear strains, and ultimately to premature system failure. In this article, we present a chemical synthesis process that yields Ag-Invar (64Fe-36Ni) alloys with a range of attractive properties for thermal management applications. Sodium borohydride reduction of an aqueous Ag-Fe-Ni metal salt solution produces nanocrystalline powders, and conventional powder processing converts this powder to fine-grained alloys. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, thermomechanical analysis, and electrical conductivity measurements; thermal conductivity is estimated using the Wiedemann-Franz law. Sintering of Ag-Fe-Ni powders leads to the formation of two-phase silver-Invar alloys with low coefficients of thermal expansion (CTEs) and relatively high electrical conductivities. A sample of 50Ag-50Invar exhibits a CTE of 8.76 μm/(m· °C) and an estimated thermal conductivity of 236 W/(m·K). The Ag-Invar alloys offer thermodynamic stability and tailorable properties, and they may help address the need for improved packaging materials.

  2. Uranium hexafluoride liquid thermal expansion, elusive eutectic with hydrogen fluoride, and very first production using chlorine trifluoride

    Energy Technology Data Exchange (ETDEWEB)

    Rutledge, G.P. [Central Environmental, Inc., Anchorage, AK (United States)

    1991-12-31

    Three unusual incidents and case histories involving uranium hexafluoride in the enrichment facilities of the USA in the late 1940`s and early 1950`s are presented. The history of the measurements of the thermal expansion of liquids containing fluorine atoms within the molecule is reviewed with special emphasis upon uranium hexafluoride. A comparison is made between fluorinated esters, fluorocarbons, and uranium hexafluoride. The quantitative relationship between the thermal expansion coefficient, a, of liquids and the critical temperature, T{sub c} is presented. Uranium hexafluoride has an a that is very high in a temperature range that is used by laboratory and production workers - much higher than any other liquid measured. This physical property of UF{sub 6} has resulted in accidents involving filling the UF{sub 6} containers too full and then heating with a resulting rupture of the container. Such an incident at a uranium gaseous diffusion plant is presented. Production workers seldom {open_quotes}see{close_quotes} uranium hexafluoride. The movement of UF{sub 6} from one container to another is usually trailed by weight, not sight. Even laboratory scientists seldom {open_quotes}see{close_quotes} solid or liquid UF{sub 6} and this can be a problem at times. This inability to {open_quotes}see{close_quotes} the UF{sub 6}-HF mixtures in the 61.2{degrees}C to 101{degrees}C temperature range caused a delay in the understanding of the phase diagram of UF{sub 6}-HF which has a liquid - liquid immiscible region that made the eutectic composition somewhat elusive. Transparent fluorothene tubes solved the problem both for the UF{sub 6}-HF phase diagram as well as the UF{sub 6}-HF-CIF{sub 3} phase diagram with a miscibility gap starting at 53{degrees}C. The historical background leading to the first use of CIF{sub 3} to produce UF{sub 6} in both the laboratory and plant at K-25 is presented.

  3. Anisotropic lattice thermal expansion of PbFeBO{sub 4}: A study by X-ray and neutron diffraction, Raman spectroscopy and DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Murshed, M. Mangir, E-mail: murshed@uni-bremen.de [Chemische Kristallographie fester Stoffe, Institut für Anorganische Chemie, Universität Bremen, Leobener Straße, D-28359 Bremen (Germany); Mendive, Cecilia B.; Curti, Mariano [Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Dean Funes 3350, B7600AYL, Mar del Plata (Argentina); Nénert, Gwilherm [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Kalita, Patricia E. [Department of Physics and Astronomy and High-Pressure Science and Engineering Center, University of Nevada Las Vegas, Box 4002, Las Vegas, NV 89154-4002 (United States); Lipinska, Kris [Department of Mechanical Engineering, University of Nevada Las Vegas, 4505 Maryland Parkway, Box 454009, Las Vegas, NV 89154-4009 (United States); Cornelius, Andrew L. [Department of Physics and Astronomy and High-Pressure Science and Engineering Center, University of Nevada Las Vegas, Box 4002, Las Vegas, NV 89154-4002 (United States); Huq, Ashfia [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475 (United States); Gesing, Thorsten M. [Chemische Kristallographie fester Stoffe, Institut für Anorganische Chemie, Universität Bremen, Leobener Straße, D-28359 Bremen (Germany)

    2014-11-15

    Highlights: • Mullite-type PbFeBO{sub 4} shows uni-axial negative coefficient of thermal expansion. • Anisotropic thermal expansion of the metric parameters was modeled using modified Grüneisen approximation. • The model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy. • DFT calculation, temperature- and pressure-dependent Raman spectra help understand the phonon decay and associated anharmonicity. - Abstract: The lattice thermal expansion of mullite-type PbFeBO{sub 4} is presented in this study. The thermal expansion coefficients of the metric parameters were obtained from composite data collected from temperature-dependent neutron and X-ray powder diffraction between 10 K and 700 K. The volume thermal expansion was modeled using extended Grüneisen first-order approximation to the zero-pressure equation of state. The additive frame of the model includes harmonic, quasi-harmonic and intrinsic anharmonic potentials to describe the change of the internal energy as a function of temperature. The unit-cell volume at zero-pressure and 0 K was optimized during the DFT simulations. Harmonic frequencies of the optical Raman modes at the Γ-point of the Brillouin zone at 0 K were also calculated by DFT, which help to assign and crosscheck the experimental frequencies. The low-temperature Raman spectra showed significant anomaly in the antiferromagnetic regions, leading to softening or hardening of some phonons. Selected modes were analyzed using a modified Klemens model. The shift of the frequencies and the broadening of the line-widths helped to understand the anharmonic vibrational behaviors of the PbO{sub 4}, FeO{sub 6} and BO{sub 3} polyhedra as a function of temperature.

  4. Negative thermal expansion and broad band photoluminescence in a novel material of ZrScMo2VO12

    Science.gov (United States)

    Ge, Xianghong; Mao, Yanchao; Liu, Xiansheng; Cheng, Yongguang; Yuan, Baohe; Chao, Mingju; Liang, Erjun

    2016-04-01

    In this paper, we present a novel material with the formula of ZrScMo2VO12 for the first time. It was demonstrated that this material exhibits not only excellent negative thermal expansion (NTE) property over a wide temperature range (at least from 150 to 823 K), but also very intense photoluminescence covering the entire visible region. Structure analysis shows that ZrScMo2VO12 has an orthorhombic structure with the space group Pbcn (No. 60) at room temperature. A phase transition from monoclinic to orthorhombic structure between 70 and 90 K is also revealed. The intense white light emission is tentatively attributed to the n- and p-type like co-doping effect which creates not only the donor- and acceptor-like states in the band gap, but also donor-acceptor pairs and even bound exciton complexes. The excellent NTE property integrated with the intense white-light emission implies a potential application of this material in light emitting diode and other photoelectric devices.

  5. Giant negative thermal expansion covering room temperature in nanocrystalline GaN{sub x}Mn{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J. C.; Tong, P., E-mail: tongpeng@issp.ac.cn; Chen, L.; Guo, X. G.; Yang, C.; Song, B.; Wu, Y.; Lin, S.; Song, W. H. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zhou, X. J.; Lin, H., E-mail: linhe@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 200120 (China); Ding, Y. W.; Bai, Y. X. [Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026 (China); Sun, Y. P., E-mail: ypsun@issp.ac.cn [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China); Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-09-28

    Nanocrystalline antiperovskite GaN{sub x}Mn{sub 3} powders were prepared by mechanically milling. The micrograin GaN{sub x}Mn{sub 3} exhibits an abrupt volume contraction at the antiferromagnetic (AFM) to paramagnetic (PM) (AFM-PM) transition. The temperature window of volume contraction (ΔT) is broadened to 50 K as the average grain size (〈D〉) is reduced to ∼30 nm. The corresponding coefficient of linear thermal expansion (α) reaches ∼ −70 ppm/K, which are comparable to those of giant NTE materials. Further reducing 〈D〉 to ∼10 nm, ΔT exceeds 100 K and α remains as large as −30 ppm/K (−21 ppm/K) for x = 1.0 (x = 0.9). Excess atomic displacements together with the reduced structural coherence, revealed by high-energy X-ray pair distribution functions, are suggested to delay the AFM-PM transition. By controlling 〈D〉, giant NTE may also be achievable in other materials with large lattice contraction due to electronic or magnetic phase transitions.

  6. Effect of thermal lattice expansion on the stacking fault energies of fcc Fe and Fe75Mn25 alloy

    Science.gov (United States)

    Razumovskiy, Vsevolod I.; Reyes-Huamantinco, Andrei; Puschnig, Peter; Ruban, A. V.

    2016-02-01

    Temperature dependent stacking fault energies in fcc Fe and the Fe75Mn25 random alloy are calculated within density functional theory. The high temperature paramagnetic state of Fe is modeled by the spin wave (SW) method within a Hamiltonian formalism and by the disordered local moment (DLM) approach in the Green's function technique using the coherent potential approximation (CPA). To determine the stacking fault energy, the supercell approach is used in the case of the SW method, while the axial Ising model is used in both the SW method and CPA-DLM calculations. The SW and CPA-DLM results are in very good agreement with each other, and they also accurately reproduce the existing experimental data. In both cases, fcc Fe and the Fe75Mn25 alloy, the SFE increases with temperature. This increase is almost entirely due to thermal lattice expansion, in contrast to earlier claims connecting such a dependence with magnetic entropy. Additionally, we check the convergence of the SW method with respect to the number of spin waves in the calculations of the phonon spectrum and the vacancy formation energy of paramagnetic fcc Fe.

  7. Fuel cell integral bundle assembly including ceramic open end seal and vertical and horizontal thermal expansion control

    Science.gov (United States)

    Zafred, Paolo R.; Gillett, James E.

    2012-04-24

    A plurality of integral bundle assemblies contain a top portion with an inlet fuel plenum and a bottom portion containing a base support, the base supports a dense, ceramic air exhaust manifold having four supporting legs, the manifold is below and connects to air feed tubes located in a recuperator zone, the air feed tubes passing into the center of inverted, tubular, elongated, hollow electrically connected solid oxide fuel cells having an open end above a combustion zone into which the air feed tubes pass and a closed end near the inlet fuel plenum, where the open end of the fuel cells rest upon and within a separate combination ceramic seal and bundle support contained in a ceramic support casting, where at least one flexible cushion ceramic band seal located between the recuperator and fuel cells protects and controls horizontal thermal expansion, and where the fuel cells operate in the fuel cell mode and where the base support and bottom ceramic air exhaust manifolds carry from 85% to all of the weight of the generator.

  8. Crystal structures, thermal expansion and phase transitions of mixed Pr1-xLaxAlO3 perovskites

    International Nuclear Information System (INIS)

    The crystal structures, thermal expansion and phase transitions of mixed Pr1-xLaxAlO3 perovskites have been examined by using an in situ high resolution X-ray powder diffraction technique applying synchrotron radiation in a wide temperature range of 12-1173 K. At room temperature all samples in the PrAlO3-LaAlO3 pseudo-binary system adopt the rhombohedral perovskite-like structure. At elevated temperatures, all Pr1-xLaxAlO3compositions undergo continuous phase transitions from rhombohedral to cubic structures. The sequence of the low-temperature (LT) phase transformations R anti 3 cImmaC2/m has been observed in Pr1-xLaxAlO3 samples. Temperatures of HT and LT phase transitions in Pr1-xLaxAlO3decrease with decreasing Pr content. Crystal structure parameters for all compositions Pr1-xLaxAlO3 have been determined. Based on in situ powder diffraction and DTA/DSC data, the phase diagram of the PrAlO3-LaAlO3pseudo-binary system has been constructed. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Thermal expansivity, bulk modulus, and melting curve of H2O-ice VII to 20 GPa

    Science.gov (United States)

    Fei, Yingwei; Mao, Ho-Kwang; Hemley, Russell J.

    1993-01-01

    Equation of state properties of ice VII and fluid H2O at high pressures and temperatures have been studied experimentally from 6 to 20 GPa and 300-700 K. The techniques involve direct measurements of the unit-cell volume of the solid using synchrotron X-ray diffraction with an externally heated diamond-anvil cell. The pressure dependencies of the volume and bulk modulus of ice VII at room temperature are in good agreement with previous synchrotron X-ray studies. The thermal expansivity was determined as a function of pressure and the results fit to a newly proposed phenomenological relation and to a Mie-Gruneisen equation of state formalism. The onset of melting of ice VII was determined directly by X-ray diffraction at a series of pressures and found to be in accord with previous volumetric determinations. Thermodynamic calculations based on the new data are performed to evaluate the range of validity of previously proposed equations of state for fluid water derived from static and shock-wave compression experiments and from simulations.

  10. Thermal expansion and magnetostriction of Yb{sub 2}Fe{sub 12}P{sub 7} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Grube, Kai; Schaefer, Roland; Schweiss, Peter [Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, Karlsruhe (Germany); Zaum, Sebastian; Loehneysen, Hilbert von [Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, Karlsruhe (Germany); Karlsruher Institut fuer Technologie, Physikalisches Institut, Karlsruhe (Germany); Baumbach, R.E.; Maple, M.B. [Department of Physics, University of California, San Diego, La Jolla (United States)

    2011-07-01

    The noncentrosymmetric heavy-fermion compound Yb{sub 2}Fe{sub 12}P{sub 7} exhibits a magnetic transition at {approx}1 K. Recent resistivity measurements reveal non-Fermi-liquid behavior in an extended temperature and field range. From the unusual low-temperature behavior it was concluded that Yb{sub 2}Fe{sub 12}P{sub 7} belongs to the growing class of compounds in which the non-Fermi-liquid behavior does not conform to the standard QCP scenario which can be described by the Hertz-Millis-Moriya theory. We report on thermal expansion and magnetostriction measurements in a temperature range of 40 mK

  11. Determination of Thermal Expansion Coefficients and Locating the Temperature-Induced Phase Transition in Methylammonium Lead Perovskites Using X-ray Diffraction.

    Science.gov (United States)

    Jacobsson, T Jesper; Schwan, L Josef; Ottosson, Mikael; Hagfeldt, Anders; Edvinsson, Tomas

    2015-11-16

    Lead halogen perovskites, and particularly methylammonium lead iodine, CH3NH3PbI3, have recently attracted considerable interest as alternative solar cell materials, and record solar cell efficiencies have now surpassed 20%. Concerns have, however, been raised about the thermal stability of methylammonium lead iodine, and a phase transformation from a tetragonal to a cubic phase has been reported at elevated temperature. Here, this phase transition has been investigated in detail using temperature-dependent X-ray diffraction measurements. The phase transformation is pinpointed to 54 °C, which is well within the normal operating range of a typical solar cell. The cell parameters were extracted as a function of the temperature, from which the thermal expansion coefficient was calculated. The latter was found to be rather high (αv = 1.57 × 10(-4) K(-1)) for both the tetragonal and cubic phases. This is 6 times higher than the thermal expansion coefficient for soda lime glass and CIGS and 11 times larger than that of CdTe. This could potentially be of importance for the mechanical stability of perovskite solar cells in the temperature cycling experienced under normal day-night operation. The experimental knowledge of the thermal expansion coefficients and precise determination of the cell parameters can potentially also be valuable while conducting density functional theory simulations on these systems in order to deliver more accurate band structure calculations. PMID:26457861

  12. Research Progress of Lowing Thermal Expansion Coefficient of Thermoplastic Plastics%降低热塑性塑料热膨胀系数的研究进展

    Institute of Scientific and Technical Information of China (English)

    吴银财; 郑嘉玮; 宁冲冲; 崔益华

    2012-01-01

    综述了国内外关于降低热塑性塑料热膨胀系数的主要方法,按添加物的种类分为:一般颗粒材料填充改性、空心玻璃微珠填充改性、负热膨胀系数材料填充改性、稀土氧化物填充改性、高热稳定性材料填充改性、橡胶共混改性、多种材料混杂复合改性等.对未来降低热塑性塑料热膨胀系数的发展方向进行了展望.%Main methods of lowing the thermal expansion coefficient of thermoplastic plastics at home and abroad were summarized. According to the types of additives the methods could be divided into the following categories : general granular materials filling modification, hollow glass bead filling modification, materials with negative thermal expansion coefficient filling modification, rare earth oxide filling modification, high thermal stability materials filling modification, rubber blending modification, a variety of materials hybrid mixing modification and so on. The future development trend of lowing the thermal expansion coefficeint of thermoplastic plastics was prospected.

  13. In-situ Density and Thermal Expansion Measurements of Fe and Fe-S Alloying Liquids Under Planetary Core Conditions

    Science.gov (United States)

    Jing, Z.; Chantel, J.; Yu, T.; Sakamaki, T.; Wang, Y.

    2015-12-01

    Liquid iron is likely the dominant constituent in the cores of terrestrial planets and icy satellites such as Earth, Mars, Mercury, the Moon, Ganymede, and Io. Suggested by geophysical and geochemical observations, light elements such as S, C, Si, etc., are likely present in planetary cores. These light elements can significantly reduce the density and melting temperature of the Fe cores, and hence their abundances are crucial to our understanding of the structure and thermal history of planetary cores, as well as the generation of intrinsic magnetic fields. Knowledge on the density of Fe-light element alloying liquids at high pressures is critical to place constraints on the composition of planetary cores. However, density data on liquid Fe-light element alloys at core pressures are very limited in pressure and composition and are sometimes controversial. In this study, we extend the density dataset for Fe-rich liquids by measuring the density of Fe, Fe-10wt%S, Fe-20wt%S, Fe-27wt%S, and FeS liquids using the X-ray absorption technique in a DIA-type multianvil apparatus up to 7 GPa and 2173 K. An ion chamber (1D-detector) and a CCD camera (2D-detector) were used to measure intensities of transmitted monochromatic X-rays through molten samples, with the photon energy optimized at 40 keV. The densities were then determined from the Beer-Lambert law using the mass absorption coefficients, calibrated by solid standards using X-ray diffraction. At each pressure, density measurements were conducted at a range of temperatures above the liquidus of the samples, enabling the determination of thermal expansion. Combined with our previous results on the sound velocity of Fe and Fe-S liquids at high pressures (Jing et al., 2014, Earth Planet. Sci. Lett. 396, 78-87), these data provide tight constraints on the equation of state and thermodynamic properties such as the adiabatic temperature gradient for Fe-S liquids. We will discuss these results with implications to planetary

  14. An Ag based brazing system with a tunable thermal expansion for the use as sealant for solid oxide cells

    Science.gov (United States)

    Kiebach, Ragnar; Engelbrecht, Kurt; Grahl-Madsen, Laila; Sieborg, Bertil; Chen, Ming; Hjelm, Johan; Norrman, Kion; Chatzichristodoulou, Christodoulos; Hendriksen, Peter Vang

    2016-05-01

    An Ag-Al2TiO5 composite braze was developed and successfully tested as seal for solid oxide cells. The thermo-mechanical properties of the Ag-Al2TiO5 system and the chemical compatibility between this composite braze and relevant materials used in stacks were characterized and the leak rates as a function of the operation temperature were measured. The thermal expansion coefficient in the Ag-Al2TiO5 system can be tailored by varying the amount of the ceramic filler. The brazing process can be carried out in air, the joining partners showed a good chemical stability and sufficient low leak rates were demonstrated. Furthermore, the long-term stability of the Ag-Al2TiO5 composite braze was studied under relevant SOFC and SOEC conditions. The stability of brazed Crofer/Ag-Al2TiO5/NiO-YSZ assemblies in reducing atmosphere and in pure oxygen was investigated over 500 h at 850 °C. Additionally, a cell component test was performed to investigate the durability of the Ag-Al2TiO5 seal when exposed to dual atmosphere. The seals performed well over 900 h under electrolysis operation conditions (-0.5 A cm2, 850 °C), and no cell degradation related to the Ag-Al2TiO5 sealing was found, indicating that the developed braze system is applicable for the use in SOFC/SOEC stacks.

  15. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients.

    Science.gov (United States)

    Aktas, Guliz; Sahin, Erdal; Vallittu, Pekka; Ozcan, Mutlu; Lassila, Lippo

    2013-12-01

    This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min(-1)). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)-(39.7±4.7) and (27.4±5.6)-(35.9±4.7) MPa with and without colouring, respectively) (Pceramic covering ceramic group, veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.

  16. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients

    Institute of Scientific and Technical Information of China (English)

    Guliz Aktas; Erdal Sahin; Pekka Vallittu; Mutlu Ozcan; Lippo Lassila

    2013-01-01

    This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N5240;6 mm37 mm37 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n516) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm?min21). Neither the zirconia core material (P50.318) nor colouring (P50.188) significantly affected the results (three-way analysis of variance, Tukey’s test). But the results were significantly affected by the veneering ceramic (P50.000). Control group exhibited significantly higher mean bond strength values (45.768) MPa than all other tested groups ((27.164.1)2(39.764.7) and (27.465.6)2(35.964.7) MPa with and without colouring, respectively) (P,0.001). While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering ,1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered .1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.

  17. Direct calculation of the linear thermal expansion coefficients of MoS2 via symmetry-preserving deformations

    Science.gov (United States)

    Gan, Chee Kwan; Liu, Yu Yang Fredrik

    2016-10-01

    Using density-functional perturbation theory and the Grüneisen formalism, we directly calculate the linear thermal expansion coefficients (TECs) of a hexagonal bulk system MoS2 in the crystallographic a and c directions. The TEC calculation depends critically on the evaluation of a temperature-dependent quantity Ii(T ) , which is the integral of the product of heat capacity and Γi(ν ) , of frequency ν and strain type i , where Γi(ν ) is the phonon density of states weighted by the Grüneisen parameters. We show that to determine the linear TECs we may use minimally two uniaxial strains in the z direction and either the x or y direction. However, a uniaxial strain in either the x or y direction drastically reduces the symmetry of the crystal from a hexagonal one to a base-centered orthorhombic one. We propose to use an efficient and accurate symmetry-preserving biaxial strain in the x y plane to derive the same result for Γ (ν ) . We highlight that the Grüneisen parameter associated with a biaxial strain may not be the same as the average of Grüneisen parameters associated with two separate uniaxial strains in the x and y directions due to possible preservation of degeneracies of the phonon modes under a biaxial deformation. Large anisotropy of TECs is observed where the linear TEC in the c direction is about 1.8 times larger than that in the a or b direction at high temperatures. Our theoretical TEC results are compared with experiment. The symmetry-preserving approach adopted here may be applied to a broad class of two lattice-parameter systems such as hexagonal, trigonal, and tetragonal systems, which allows many complicated systems to be treated on a first-principles level.

  18. Densities, Excess Molar Volumes, and Thermal Expansion Coefficients of Aqueous Aminoethylethanolamine Solutions at Temperatures from 283.15 to 343.15 K.

    Science.gov (United States)

    Stec, Marcin; Tatarczuk, Adam; Spiewak, Dariusz; Wilk, Andrzej

    2014-01-01

    The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15-343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich-Kister equation. Temperature dependences of the Redlich-Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian-Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. PMID:24899753

  19. Field and concentration dependent scaling behavior of the thermal expansion near the quantum critical point of CeCu6-xAux

    International Nuclear Information System (INIS)

    The heavy-fermion system CeCu6-xAux exhibits long-range antiferromagnetic order at x>0.1. The order can be suppressed by hydrostatic or chemical pressure, through the variation of the Au content, as well as by the application of a magnetic field. The quantum critical point at the onset of antiferromagnetism leads to non-Fermi liquid behavior visible in thermodynamic and transport properties. Among these, the thermal expansion offers a particularly sensitive probe to study the quantum critical scaling behavior due to the strong pressure dependence of the Kondo effect in heavy-fermion materials. To shed light on the difference between the two control parameters, pressure and magnetic field, we studied the scaling behavior of the thermal expansion on CeCu6-xAux single crystals with varying Au content as a function of the magnetic field in the temperature range between 40 mK and 10 K.

  20. Determination of the linear coefficient of thermal expansion in polymer films at the nanoscale: influence of the composition of EVA copolymers and the molecular weight of PMMA.

    Science.gov (United States)

    González-Benito, J; Castillo, E; Cruz-Caldito, J F

    2015-07-28

    Nanothermal-expansion of poly(ethylene-co-vinylacetate), EVA, and poly(methyl methacrylate), PMMA, in the form of films was measured to finally obtain linear coefficients of thermal expansion, CTEs. The simple deflection of a cantilever in an atomic force microscope, AFM, was used to monitor thermal expansions at the nanoscale. The influences of: (a) the structure of EVA in terms of its composition (vinylacetate content) and (b) the size of PMMA chains in terms of the molecular weight were studied. To carry out this, several polymer samples were used, EVA copolymers with different weight percents of the vinylacetate comonomer (12, 18, 25 and 40%) and PMMA polymers with different weight average molecular weights (33.9, 64.8, 75.600 and 360.0 kg mol(-1)). The dependencies of the vinyl acetate weight fraction of EVA and the molecular weight of PMMA on their corresponding CTEs were analyzed to finally explain them using new, intuitive and very simple models based on the rule of mixtures. In the case of EVA copolymers a simple equation considering the weighted contributions of each comonomer was enough to estimate the final CTE above the glass transition temperature. On the other hand, when the molecular weight dependence is considered the free volume concept was used as novelty. The expansion of PMMA, at least at the nanoscale, was well and easily described by the sum of the weighted contributions of the occupied and free volumes, respectively. PMID:26108706

  1. Abnormal thermal expansion, multiple transitions, magnetocaloric effect, and electronic structure of Gd{sub 6}Co{sub 4.85}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiliang [Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong (Hong Kong); Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 (United States); Zheng, Zhigang [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Shan, Guangcun, E-mail: gshan2-c@my.cityu.edu.hk, E-mail: bobev@udel.edu, E-mail: apchshek@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong (Hong Kong); School of Instrumentation Science and Optoelectronics Engineering, Beihang University, Beijing 100191 (China); Bobev, Svilen, E-mail: gshan2-c@my.cityu.edu.hk, E-mail: bobev@udel.edu, E-mail: apchshek@cityu.edu.hk [Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 (United States); Shek, Chan Hung, E-mail: gshan2-c@my.cityu.edu.hk, E-mail: bobev@udel.edu, E-mail: apchshek@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong (Hong Kong)

    2015-10-07

    The structure of known Gd{sub 4}Co{sub 3} compound is re-determined as Gd{sub 6}Co{sub 4.85}, adopting the Gd{sub 6}Co{sub 1.67}Si{sub 3} structure type, which is characterized by two disorder Co sites filling the Gd octahedral and a short Gd-Gd distance within the octahedra. The compound shows uniaxial negative thermal expansion in paramagnetic state, significant negative expansion in ferromagnetic state, and positive expansion below ca. 140 K. It also exhibits large magnetocaloric effect, with an entropy change of −6.4 J kg{sup −1} K{sup −1} at 50 kOe. In the lattice of the compound, Co atoms at different sites show different spin states. It was confirmed by the X-ray photoelectron spectra and calculation of electronic structure and shed lights on the abnormal thermal expansion. The stability of such compound and the origin of its magnetism are also discussed based on measured and calculated electronic structures.

  2. Bootstrapping Rapidity Anomalous Dimension for Transverse-Momentum Resummation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ye [Fermilab; Zhu, Hua Xing [MIT, Cambridge, CTP

    2016-04-05

    Soft function relevant for transverse-momentum resummation for Drell-Yan or Higgs production at hadron colliders are computed through to three loops in the expansion of strong coupling, with the help of bootstrap technique and supersymmetric decomposition. The corresponding rapidity anomalous dimension is extracted. An intriguing relation between anomalous dimensions for transverse-momentum resummation and threshold resummation is found.

  3. Bootstrapping rapidity anomalous dimension for transverse-momentum resummation

    CERN Document Server

    Li, Ye

    2016-01-01

    Soft function relevant for transverse-momentum resummation for Drell-Yan or Higgs production at hadron colliders are computed through to three loops in the expansion of strong coupling, with the help of bootstrap technique and supersymmetric decomposition. The corresponding rapidity anomalous dimension is extracted. An intriguing relation between anomalous dimensions for transverse-momentum resummation and threshold resummation is found.

  4. Thermal Expansion Measurements in Fresh and Saline Ice Using Fiber Optic Strain Gauges and Multipoint Temperature Sensors Based on Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Aleksey Marchenko

    2016-01-01

    Full Text Available This paper describes the use of Fiber Bragg Grating (FBG sensors to investigate the thermomechanical properties of saline ice. FBG sensors allowed laboratory measurements of thermal expansion of ice samples with a range of different sizes and geometries. The high sampling frequency, accuracy, and resolution of the FBG sensors provide good quality data across a temperature range from 0°C to −20°C. Negative values of the effective coefficient of thermal expansion were observed in ice samples with salinities 6 ppt, 8 ppt, and 9.4 ppt. A model is formulated under which structural transformations in the ice, caused by temperature changes, can lead to brine transfer from closed pockets to permeable channels, and vice versa. This model is compared to experimental data. Further, in experiments with confined floating ice, heating as well as thermal expansion due to vertical migration of liquid brine, caused by under-ice water pressure, was observed.

  5. Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na{sub 3}OBr and Na{sub 4}OI{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yonggang, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu [High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154 (United States); Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou, Henan 450006 (China); High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Wen, Ting [Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou, Henan 450006 (China); Park, Changyong; Kenney-Benson, Curtis [High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Pravica, Michael; Zhao, Yusheng, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu [High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154 (United States); Yang, Wenge, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu [High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China)

    2016-01-14

    The structure stability under high pressure and thermal expansion behavior of Na{sub 3}OBr and Na{sub 4}OI{sub 2}, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na{sub 3}OBr and Na{sub 4}OI{sub 2}, respectively. The cubic Na{sub 3}OBr structure and tetragonal Na{sub 4}OI{sub 2} with intergrowth K{sub 2}NiF{sub 4} structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na{sub 4}OI{sub 2} exhibits nearly isotropic compressibility. Negative thermal expansion was observed at low temperature range (20–80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.

  6. Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na3OBr and Na4OI2

    Science.gov (United States)

    Wang, Yonggang; Wen, Ting; Park, Changyong; Kenney-Benson, Curtis; Pravica, Michael; Yang, Wenge; Zhao, Yusheng

    2016-01-01

    The structure stability under high pressure and thermal expansion behavior of Na3OBr and Na4OI2, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na3OBr and Na4OI2, respectively. The cubic Na3OBr structure and tetragonal Na4OI2 with intergrowth K2NiF4 structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na4OI2 exhibits nearly isotropic compressibility. Negative thermal expansion was observed at low temperature range (20-80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.

  7. Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia, Universita di Firenze, Via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it

    2009-04-03

    The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: {alpha}{sub a} = 1.5 x 10{sup -5} K{sup -1}, {alpha}{sub b} = 3.0 x 10{sup -5} K{sup -1}, {alpha}{sub c} = 2.2 x 10{sup -5} K{sup -1}, and the bulk thermal expansion coefficient {alpha}{sub V} is 5.4 x 10{sup -5} K{sup -1} for the temperature range 298-463 K.

  8. Development of Testing System on Thermal Expansion Valve Capacity%汽车空调热力膨胀阀容量测试系统的研制

    Institute of Scientific and Technical Information of China (English)

    颜吉亮; 王玉刚; 耿丽萍; 王清平

    2015-01-01

    热力膨胀阀在不同工况下的流量特性是影响制冷系统性能的重要因素,因此需要对热力膨胀阀进行制冷剂实流检测。本文研制了制冷量范围为1.7~10 kW的热力膨胀阀容量测试台。该测试台以“膨胀阀进出口的压力值”为测试条件,避免了阀前高压部分设备流动阻力的差异对测量结果的影响。系统的流量测量不确定度为0.5%,控温精度为±0.5℃。在标准工况下取额定容量5.5 kW的H型热力膨胀阀的性能进行了测试,根据温度-开度、开度-流量、温度-流量关系特性分析得到在热力膨胀阀工作区域内,其温度与流量基本成线性比例关系。根据热力膨胀阀增益和滞环的定量分析,判别热力膨胀阀的性能优劣。%Thermal expansion valve’s flow characteristic under different conditions is one of the most important factors affecting refrigera-tion system performance. So it is necessary to detect the actual refrigerant flow of thermal expansion valve. A thermal expansion valve test-bench was developed and its range of refrigerating capacity was 1. 7-10 kW. In the system, in order to avoid the influence of flow resist-ance difference of the high pressure part on the measured results, inlet pressure of expansion was treated as the testing condition. The un-certainty of flow measurement is 0. 5% and temperature control accuracy is ± 0. 5℃. Performance of a 7 kW capacity H-type thermal ex-pansion valve was tested in the standard condition, and the property of flow-opening, temperature-opening, flow-temperature was acquired and analyzed. In the thermal expansion valve’s work range, the flow increases linearly with the increase of temperature. Through the quan-titative analysis of thermal expansion valve’s gain and hysteresis, the performance of thermal expansion valve is judged.

  9. 小米淀粉热膨化条件的优化%Optimization of thermal expansion parameters of millet starch

    Institute of Scientific and Technical Information of China (English)

    梁万礼; 张建超; 朱丽丹; 马晓军

    2012-01-01

    通过单因素及正交实验以膨化率和脆度为指标确定了小米淀粉热膨化的最佳工艺条件。结果表明,对膨化效果的影响因素次序为水分含量〉膨化温度〉膨化时间,其中水分含量对膨化效果的影响高度显著(P〈0.01)。膨化的最佳条件为水分含量8%,膨化温度310℃,膨化时间50s。此条件下膨化制小米饼的膨化率和脆度分别为8.32及0.254kg·s,脆度优于市售的品牌雪饼(0.424kg·s),感官评价也得到了同样的结论。实验显示以小米为原料制作米雪饼切实可行。%The optimal condition of thermal expansion of millet starch was investigated by orthogonal array design based on single factor experiments using expansion ratio and crispness as indicators.Results showed that the primary and secondary sequence of influence factors were in the following order of moisture content 〉 expansion temperature 〉 expansion time and a significant effect of moisture content was observed ( P 〈 O.Oi ) .The optimal condition of thermal expansion was as follows.moisture content 8%, expansion temperature 310~C and expansion time 50s.A maximum expansion ratio of 8.32 and crispness of 0.254kg ~ s which was better than rice cakes on the market(0.424kg ~ s) were obtained under the optimal values of related parameters. Sensory evaluation also confirmed that the textural quality of sample was nicer than the latter.Experiments revealed that it was feasible to make rice cakes from millet.

  10. Asymptotic expansion and statistical description of turbulent systems

    International Nuclear Information System (INIS)

    A new approach to studying turbulent systems is presented in which an asymptotic expansion of the general dynamical equations is performed prior to the application of statistical methods for describing the evolution of the system. This approach has been applied to two specific systems: anomalous drift wave turbulence in plasmas and homogeneous, isotropic turbulence in fluids. For the plasma case, the time and length scales of the turbulent state result in the asymptotic expansion of the Vlasov/Poisson equations taking the form of nonlinear gyrokinetic theory. Questions regarding this theory and modern Hamiltonian perturbation methods are discussed and resolved. A new alternative Hamiltonian method is described. The Eulerian Direct Interaction Approximation (EDIA) is slightly reformulated and applied to the equations of nonlinear gyrokinetic theory. Using a similarity transformation technique, expressions for the thermal diffusivity are derived from the EDIA equations for various geometries, including a tokamak. In particular, the unique result for generalized geometry may be of use in evaluating fusion reactor designs and theories of anomalous thermal transport in tokamaks. Finally, a new and useful property of the EDIA is pointed out. For the fluid case, an asymptotic expansion is applied to the Navier-Stokes equation and the results lead to the speculation that such an approach may resolve the problem of predicting the Kolmogorov inertial range energy spectrum for homogeneous, isotropic turbulence. 45 refs., 3 figs

  11. Modeling and Thermal Performance Evaluation of Porous Curd Layers in Sub-Cooled Boiling Region of PWRs and Effects of Sub-Cooled Nucleate Boiling on Anomalous Porous Crud Deposition on Fuel Pin Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Barclay Jones

    2005-06-27

    A significant number of current PWRs around the world are experiencing anomalous crud deposition in the sub-cooled region of the core, resulting in an axial power shift or Axial Offset Anomaly (AOA), a condition that continues to elude prediction of occurrence and thermal/neutronic performance. This creates an operational difficulty of not being able to accurately determine power safety margin. In some cases this condition has required power ''down rating'' by as much as thirty percent and the concomitant considerable loss of revenue for the utility. This study examines two aspects of the issue: thermal performance of crud layer and effect of sub-cooled nucleate boiling on the solute concentration and its influence on initiation of crud deposition/formation on fuel pin surface.

  12. Calculation of the effect of alloy characteristics on the permanent expansion of cold compacted hypereutectic Al-Si-Fe-X powder after thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Timmermans, G.; Froyen, L. [Katholieke Univ. Leuven (Belgium). Dept. Metaalkunde en Toegepaste Materiaalkunde

    1999-02-19

    For the atomized powder Al-17Si-5Fe-3.5Cu-1.1Mg-0.6Zr (wt%), investigated in this work, a permanent elongation of about 0.8% of a bar shape sample of a green product (cold compacted powder) is measured by Thermo Mechanical Analysis after a first thermal cycle up to 470 C, when a heating rate of 5 C/min or 1 C/min is applied. This 0.8% is the average of 10 measurements. In subsequent cycles, there is no extra permanent expansion anymore, indicating the mainly irreversible character. The irreversible part of the expansion mainly occurs between 200 and 300 C, where Si is precipitating, as detected by X-Ray Diffractometry (XRD) and Differential Scanning Calorimetry (DSC). This Si-precipitation from supersaturated Al solid solutions is observed by many researchers, using also XRD Al line shift analysis and microscopy techniques.

  13. Thermal expansion of CuIn{sub 5}S{sub 8} single crystals and the temperature dependence of their band gap

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I. V., E-mail: chemzav@bsuir.by [Belarussian State University of Information and Radio Electronics (Belarus)

    2012-05-15

    Single crystals of the CuIn{sub 5}S{sub 8} ternary compound are grown by planar crystallization of the melt (the vertical Bridgman method). The composition and structure of the crystals are established. The specific expansion is measured by the dilatometric technique, and the coefficients of thermal expansion are calculated. From the data, the Debye temperatures ({Theta}{sub D}) and the root-mean-square dynamic displacements of atoms ({radical}(u-bar{sup 2})) in the CuIn{sub 5}S{sub 8} compound are calculated. From the transmittance spectra recorded in the region of the fundamental absorption edge in the temperature range 20 to 300 K, the band gap is determined and its temperature dependence is constructed.

  14. Undrained heating and anomalous pore-fluid pressurization of a hardened cement paste

    Science.gov (United States)

    Ghabezloo, S.; Sulem, J.; Saint-Marc, J.

    2009-04-01

    cement paste are also measured in the heating tests. The measured value of the thermal pressurization coefficient is found equal to 0.6MPa/°C and the test results unexpectedly show that it does not change with temperature between 20°C and 55°C. In most geomaterials, as shown experimentally by Ghabezloo and Sulem (2008), the temperature dependency of the thermal expansion of the pore fluid results in temperature dependency of the thermal pressurization coefficient. The observed anomalous thermal pressurization phenomenon is attributed to the anomalous thermal behaviour of cement paste pore fluid. The anomalous thermal behaviour of cement pore fluid is back analysed from the results of the undrained heating test and it is shown that the thermal expansion of the cement paste pore fluid is higher than the one of pure bulk water and is much less sensitive to temperature changes. This anomalous thermal behaviour is due to the confinement of the pore fluid in the very small pores of the microstructure of the cement paste, and also to the presence of dissolved ions in the pore fluid. References: 1.Sulem J., Lazar P., Vardoulakis I. (2007) Thermo-Poro-Mechanical Properties of Clayey Gouge and Application to Rapid Fault Shearing, Int. J. Num. Anal. Meth. Geomechanics, 31(3), 523-540 2.Ghabezloo S., Sulem J. (2008) Stress dependent thermal pressurization of a fluid-saturated rock. Rock Mechanics and Rock Engineering, in press, DOI 10.1007/s00603-008-0165-z. 3.Ghabezloo S., Sulem J., Saint-Marc, J. (2009) The effect of undrained heating on a fluid-saturated hardened cement paste. Cement and Concrete Research, 39(1), 54-64. 4.Ghabezloo S., Sulem J. (2009) Evaluation of the undrained thermo-poro-elastic parameters in a conventional triaxial cell: the effect of the dead volume of the drainage system. Submitted to Int J Rock Mech Min Sci.

  15. Low-temperature heat capacity and thermal expansion of synthetic caracolite Na{sub 3}Pb{sub 2}(SO{sub 4}){sub 3}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, A.V., E-mail: knyazevav@gmail.com; Bulanov, E.N.; Smirnova, N.N.; Korokin, V.Zh.; Shushunov, A.N.; Blokhina, A.G.

    2014-11-20

    Highlights: • Temperature dependence of heat capacity of Na{sub 3}Pb{sub 2}(SO{sub 4}){sub 3}Cl has been measured by adiabatic vacuum calorimetry. • The thermodynamic functions of the Na{sub 3}Pb{sub 2}(SO{sub 4}){sub 3}Cl have been determined for the range from T → 0–336 K. • The character of heterodynamics of structure was detected. • The high-temperature X-ray diffraction method was used for the determination of thermal expansion coefficients. - Abstract: In the present work the temperature dependences of trisodium dilead tris(sulfate(VI)) chloride heat capacity have been measured for the first time in the range from 6 to 336 K. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity C{sub p}{sup °}(T), enthalpy H°(T) − H°(0), entropy S°(T) − S°(0) and Gibbs function G°(T) − H°(0), for the range from T → 0–336 K. The differential thermal analysis was applied to measure temperature of incongruent melting of compound under study. The high-temperature X-ray diffraction was used for the determining thermal expansion coefficients.

  16. Synthesis, microstructure and thermal expansion studies on Ca0.5+/2Sr0.5+/2Zr4P6−2Si2O24 system prepared by co-precipitation method

    Indian Academy of Sciences (India)

    Basavaraj Angadi; M R Ajith; A M Umarji

    2013-02-01

    We report on the synthesis, microstructure and thermal expansion studies on Ca0.5+/2Sr0.5+/2Zr4P6−2Si2O24 ( = 0.00 to 1.00) system which belongs to NZP family of low thermal expansion ceramics. The ceramics synthesized by co-precipitation method at lower calcination and the sintering temperatures were in pure NZP phase up to = 0.37. For ≥ 0.5, in addition to NZP phase, ZrSiO4 and Ca2P2O7 form as secondary phases after sintering. The bulk thermal expansion behaviour of the members of this system was studied from 30 to 850 °C. The thermal expansion coefficient increases from a negative value to a positive value with the silicon substitution in place of phosphorous and a near zero thermal expansion was observed at = 0.75. The amount of hysteresis between heating and cooling curves increases progressively from = 0.00 to 0.37 and then decreases for ≥ 0.37. The results were analysed on the basis of formation of the silicon based glassy phase and increase in thermal expansion anisotropy with silicon substitution.

  17. Design of capacity test system for thermal expansion valve%热力膨胀阀容量测试系统的设计

    Institute of Scientific and Technical Information of China (English)

    董长盛; 郭晓铃; 彭军皓

    2014-01-01

    In order to deal with the shortcomings of the capacity detection device for thermal expan-sion valve, such as low automatic level and poor test accuracy, a capacity test system for thermal expan-sion valve is designed according to the test method which is provided by the national standard QC/T 663-2000. On the hardware design, the system consists of opening test device, refrigerant flow test device and control module. On the software design, this paper use Visual Basic 6. 0 developed a set of visual test software. The experimental results of capacity test showed that the system could well realize the ca-pacity test of the thermal expansion valve, and its test accuracy had reached 1. 0%.%针对目前热力膨胀阀容量测试设备自动化程度低、测试精度低等缺点,依据国标QC/T 663-2000的测试方法,设计了一套热力膨胀阀容量测试系统。在硬件设计上,该系统由开度测试装置、制冷剂流量测试装置和控制模块组成。在软件设计上,利用Visual Basic 6.0开发了一套可视化的测试软件。容量测试结果表明,该系统能较好地实现热力膨胀阀的容量测试,其测试精度达到了1.0%。

  18. Anomalous baryogenesis at the weak scale

    International Nuclear Information System (INIS)

    One of the fundamental constants of nature is the baryon asymmetry of the universe -- the ratio of the number of baryons to the entropy. This constant is about 10-11. In baryon- number conserving theories, this was just an initial condition. With the advent of the grand unified theories (GUTs), baryon number is no longer conserved, and this asymmetry can be generated dynamically. Unfortunately, however, there are reasons for preferring another mechanism. For example, GUTs predict proton decay which, after extensive searches, has not been found. An alternative place to look for baryogenesis is the electroweak phase transition, described by the standard model, which posses all the necessary ingredients for baryogenesis. Anomalous baryon-number violation in weak interactions becomes large at high temperatures, which offers the prospect of creating the asymmetry with the standard model or minimal extensions. This can just barely be done if certain conditions are fulfilled. CP violation must be large, which rules out the minimal standard model as the source of the asymmetry, but which is easily arranged with an extended Higgs sector. The baryon-number violating rates themselves are not exactly known, and they must be pushed to their theoretical limits. A more exact determination of these rates is needed before a definitive answer can be given. Finally, the phase transition must be at least weakly first order. Such phase transitions are accompanied by the formation and expansion of bubbles of true vacuum within the false vacuum, much like the boiling of water. As the bubbles expand, they provide a departure from thermal equilibrium, otherwise the dynamics will adjust the net baryon number to zero. The bubble expansion also provides a biasing that creates an asymmetry on the bubbles surface. Under optimal conditions, the observed asymmetry can just be produced. 31 refs., 10 figs

  19. Evidence for monoclinic crystal structure and negative thermal expansion below magnetic transition temperature in Pb(Fe_1/2Nb_1/2)O_3

    OpenAIRE

    Singh, Satendra Pal; Pandey, Dhananjai; Yoon, Songhak; Baik, Sunggi; Shin, Namsoo

    2007-01-01

    The existing controversy about the room temperature structure of multiferroic Pb(Fe_1/2Nb_1/2)O_3 is settled using synchrotron powder x-ray diffraction data. Results of Rietveld refinements in the temperature range 300 to 12K reveal that the structure remains monoclinic in the Cm space group down to 12K, but the lattice parameters show anomalies at the magnetic transition temperature (T_N) due to spin lattice coupling. The lattice volume exhibits negative thermal expansion behaviour, with Alp...

  20. Effect of Solid Solution Treatment on Microstructure of Fe-Ni Based High Strength Low Thermal Expansion Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-fu; TU Yi-fan; XU Jin; ZHANG Jian-sheng; ZHANG Jing-lin

    2008-01-01

    The influence of solid solution treatments on the dissolution of carbides precipitates, the grain size, and the hardness of high strength low expansion alloy were investigated through XRD analysis, microstructure observations, and theoretical computation. It was seen that most primary Mo2C type carbide band dissolved in a temperature range of 1 100-1 150 ℃. When the temperature was over 1 200 ℃, the grain size increased remarkably, which led to the reduction of hardness.

  1. Fracture toughness of hydroxide catalysis bonds between silicon carbide and Zerodur low thermal expansion glass-ceramic

    NARCIS (Netherlands)

    Ende, D.A. van den; Gubbels, G.H.M.

    2014-01-01

    In many optical and precision engineering applications, low thermal distortion materials need to be bonded together reliably. Since high temperature bonding process ultimately introduce stresses in the bond, rendering it dimensionally instable, room temperature or near room temperature processes are

  2. SnO{sub 2} thin films morphological and optical properties in terms of the Boubaker Polynomials Expansion Scheme BPES-related Opto-Thermal Expansivity {psi}{sub AB}

    Energy Technology Data Exchange (ETDEWEB)

    Amlouk, A.; Boubaker, K. [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Amlouk, M., E-mail: mmbb11112000@yahoo.f [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia)

    2010-02-04

    In this study, SnO{sub 2} thin films have been grown using spray pyrolysis technique on glass substrates under a substrate temperature (T{sub s} = 440 {sup o}C). The precursors were methanol CH{sub 4}O and anhydrous tin tetrachloride. XRD analyses yielded strong (1 1 0)-(1 0 1)-(2 0 0) X-ray diffraction peaks which are characteristics to tetragonal crystals. Atomic Force Microscopy (AFM) analyses showed the existence of clusters with particular pyramidal shapes. The main part of this study concerns the optical measurements of transmittance T({lambda}) and reflectance R({lambda}) spectra inside 250-1800 nm domain. Conjoint optical and thermal properties were deduced using the Amlouk-Boubaker Opto-Thermal Expansivity {psi}{sub AB}. The obtained value: {psi}{sub AB} {approx} 23.4 m{sup 3} s{sup -1} helped situating the performance of the as-grown SnO{sub 2} compound among most known PV-T oxides like ZnO and TiO{sub 2}.

  3. Thermal expansion properties and hygroscopicity of Y2-xSmxW3O12 (x = 0.0-0.4) compounds

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel class of solid solutions of Y2-xSmxW3O12 (x = 0.0-0.4) were synthesized and studied by means of powder X-ray diffraction. All samples crystallize in an orthorhombic space group Pnca. The lattice parameters a, b and c of Y2-xSmxW3O12 increase with increasing Sm content. Since the compounds of this series hydrate at room temperature, thermogravimetric (TG) analysis was carried out. The result shows that the compound stores less water with increasing Sm content. The thermal expansion properties of Y2-xSmxW3O12 (x = 0.1, 0.3 and 0.4) were investigated with high temperature X-ray diffraction. Negative thermal expansion coefficient -α becomes less negative from -6.644×10-6 to -6.211×10-6℃-1 when x changes from 0.1 to 0.4.

  4. Temperature dependence of thermal expansion coefficient of (CuInTe{sub 2}){sub 1-x}(2ZnTe){sub x} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I.V.; Chibusova, L.V. [Belarus State Univ. of Information Science and Radio Electronics, Minsk (Belarus); Korzun, B.V. [Inst. of Physics of Solids and Semiconductors, Minsk (Belarus)

    2000-06-16

    Investigations have been made for the first time of the thermal expansion of the (CuInTe{sub 2}){sub 1-x}(2ZnTe){sub x} solid solutions. It has been demonstrated that the thermal expansion coefficient {alpha}{sub L} grows considerably in the temperature range from 77 to 300 K whereas the temperature dependence above 300 K is rather weak. For the solid solutions with 0=} 0.4). The Debye temperatures {theta}{sub D} and the average quadratic dynamic displacements u{sup 2} were calculated. (orig.)

  5. New Insights into the Negative Thermal Expansion: Direct Experimental Evidence for the "Guitar-String" Effect in Cubic ScF3.

    Science.gov (United States)

    Hu, Lei; Chen, Jun; Sanson, Andrea; Wu, Hui; Guglieri Rodriguez, Clara; Olivi, Luca; Ren, Yang; Fan, Longlong; Deng, Jinxia; Xing, Xianran

    2016-07-13

    The understanding of the negative thermal expansion (NTE) mechanism remains challenging but critical for the development of NTE materials. This study sheds light on NTE of ScF3, one of the most outstanding materials with NTE. The local dynamics of ScF3 has been investigated by a combined analysis of synchrotron-based X-ray total scattering, extended X-ray absorption fine structure, and neutron powder diffraction. Very interestingly, we observe that (i) the Sc-F nearest-neighbor distance strongly expands with increasing temperature, while the Sc-Sc next-nearest-neighbor distance contracts, (ii) the thermal ellipsoids of relative vibrations between Sc-F nearest-neighbors are highly elongated in the direction perpendicular to the Sc-F bond, indicating that the Sc-F bond is much softer to bend than to stretch, and (iii) there is mainly dynamically transverse motion of fluorine atoms, rather than static shifts. These results are direct experimental evidence for the NTE mechanism, in which the rigid unit is not necessary for the occurrence of NTE, and the key role is played by the transverse thermal vibrations of fluorine atoms through the "guitar-string" effect. PMID:27336200

  6. Low-temperature negative thermal expansion behavior of LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shaopeng [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Huang, Rongjin, E-mail: huangrongjin@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); Li, Wen [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Wang, Wei [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); Zhao, Yuqiang [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Li, Laifeng, E-mail: laifengli@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China)

    2015-10-15

    The cubic NaZn{sub 13}-type LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x}(x = 0.2, 0.3, 0.4 and 0.5) compounds with different Si content were fabricated by conventional arc-melting method, the structures of which were confirmed by powder X-ray diffraction (XRD) measurement at ambient temperature. Besides, the thermal expansion and magnetic properties of these samples were also researched by means of a strain gage and a physical property measurement system (PPMS). Significantly, it was found that the negative thermal expansion (NTE) behavior have been remarkably enhanced with substituting Al with Si atoms. Furthermore, the NTE operation-temperature window concurrently shifts toward a higher temperature region. The variable temperature XRD results indicate that LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} retain cubic NaZn{sub 13}-type structure when temperature varies from 20 K to 270 K, including the temperature region where NTE occurs. The further theoretical analysis combined with magnetic characterization reveal that the improvement of NTE behavior is attributed to the enhancement of Fe–Fe magnetic exchange interactions with doping Si atoms. It is noteworthy that this study displays a new pathway to improve the NTE property of La(Fe,Al){sub 13}-based compounds at low temperature region, which highlights the potential applications of NTE materials in cryogenic engineering. - Highlights: • Negative thermal expansion of LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} was improved by introducing Si. • The structure of LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} was studied by X-ray diffraction measurement. • We analyze the mechanism of NTE in LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} by magnetic measurement.

  7. CRYSTALLIZATION AND THERMAL EXPANSION CHARACTERISTICS OF In2O3-CONTAINING LITHIUM IRON SILICATE-DIOPSIDE GLASSES

    OpenAIRE

    *S. M. Salman; S.N. Salama

    2011-01-01

    The crystallization characteristics of glasses based on lithium iron silicate (LiFeSi2O6)-diopside (CaMgSi2O6) composition with addition of Al2O3 at the expense of Fe2O3 were described. The effect of LiInSi2O6/CaMgSi2O6 replacements was also investigated. The thermal treatment, the crystal phases, and the micro-structural properties of (LiFeSi2O6–CaMgSi2O6) glasses, replacing partial Fe2O3 with Al2O3 and partial CaMgSi2O6 with LiInSi2O6, have been studied by a differential thermal analysis, a...

  8. Negative thermal expansion and magnetostriction in the frustrated spinel ZnCr2(Se1-x S x )4 (0  ≤  x  ≤  0.1).

    Science.gov (United States)

    Gu, Chuanchuan; Yang, Zhaorong; Chen, Xuliang; Pi, L I; Zhang, Yuheng

    2016-05-11

    The bond-frustrated ZnCr2Se4 displays strong spin-lattice coupling characterized by large magnetostriction and negative thermal expansion. Here, we report on systematic investigations on the magnetization, heat capacity, thermal expansion and magnetostriction of single crystalline ZnCr2(Se1-x S x )4 (0  ⩽  x  ⩽  0.1) to study the evolution of its spin-lattice coupling with sulfur substitution. We show that with increasing sulfur content, the antiferromagnetic ordering is gradually replaced by a spin-glass state, the temperature region of the negative thermal expansion expands, and the magnetostriction is gradually suppressed. These phenomena are explained qualitatively by taking into account the enhancement of the antiferromagnetic interactions and bond disorder introduced by sulfur substitution. PMID:27049604

  9. Effect of solid-solution temperature on the microstructure of Fe-Ni based high strength low thermal expansion (HSLTE) alloy

    Institute of Scientific and Technical Information of China (English)

    Yifan Tu; Jin Xu; Jianfu Zhang; Boping Zhang; Dongliang Zhao

    2007-01-01

    The influence of solid-solution temperature on the dissolution of carbide precipitates,the average grain size and the microhardness of the austenite matrix in an Fe-Ni based high strength low thermal expansion (HSLTE) alloy was investigated to obtain the proper temperature range of the solid-solution process.The XRD analysis,microstructure observations,and the theoretical calculations showed that the Mo-rich M2C-type precipitates in the Fe-Ni based HSLTE alloy dissolve completely at about 1100 ℃.The average grain size of the studied alloys increases from 14 to 46 μm in the temperature range of 1050 to 1200 ℃.The microhardness of the matrix decreases first for the sake of solid-solution treatment,but then increases later with increasing solution temperature because of the solution strengthening effect.

  10. Thermal expansion of the high-7c superconductors REBa2Cu3O7 (RE = Y, Dy) revisited at low temperatures

    Science.gov (United States)

    Lahoubi, M.

    2014-05-01

    The linear thermal expansion coefficient α(T) of two high-Tc superconductors, YBa2Cu3O7 and DyBa2Cu3O7 has been revisited in the 4.5-80K temperature range. The X-ray diffraction analysis and microstructural characterization using scanning electron microscopy confirm an orthorhombic single phase with an average of the grain size of about 20 μm for both polycrystalline samples. In the case of the Dy compound, a small magnetic excess superimposed to the high phonon contribution is observed in the T3 term, whereas no anomaly is detected below 40K. The deduced magnetic contribution αm(T) which increases monotonically with rising temperature is attributed to the CF interactions induced by the 4f electric quadrupole moment of the Dy Kramers ions. A discussion and a comparison with respect to the previous experimental and theoretical works are presented.

  11. Thermal expansion of the high-Tc superconductors REBa2Cu3O7 (RE = Y, Dy) revisited at low temperatures

    International Nuclear Information System (INIS)

    The linear thermal expansion coefficient α(T) of two high-Tc superconductors, YBa2Cu3O7 and DyBa2Cu3O7 has been revisited in the 4.5-80 K temperature range. The X-ray diffraction analysis and microstructural characterization using scanning electron microscopy confirm an orthorhombic single phase with an average of the grain size of about 20 μm for both polycrystalline samples. In the case of the Dy compound, a small magnetic excess superimposed to the high phonon contribution is observed in the T3 term, whereas no anomaly is detected below 40 K. The deduced magnetic contribution αm(T) which increases monotonically with rising temperature is attributed to the CF interactions induced by the 4f electric quadrupole moment of the Dy Kramers ions. A discussion and a comparison with respect to the previous experimental and theoretical works are presented.

  12. The mechanism of the area negative thermal expansion in KBe2BO3F2 family crystals: A first-principles study

    International Nuclear Information System (INIS)

    A very recent study demonstrated that the KBe2BO3F2 (KBBF) family of crystals, including KBBF, RbBe2BO3F2, and CsBe2BO3F2, are the only known borates exhibiting a rarely occurring isotropic area negative thermal expansion (NTE) behavior, over a very large temperature range. In the present work, the NTE mechanism in these crystals is comprehensively investigated using the first-principles calculations. It is revealed that the area NTE behavior mainly originates from the concerted distortion of [BeO3F] tetrahedra in the two-dimensional [Be2BO3F2]∞ framework with respect to temperature, while the [BO3] triangles remain almost rigid. Moreover, the different magnitude of NTE effect in the three crystals is attributed to the interaction difference between the alkali metal atoms (K, Rb, or Cs) and the [Be2BO3F2]∞ layer

  13. The mechanism of the area negative thermal expansion in KBe2BO3F2 family crystals: A first-principles study

    Science.gov (United States)

    Jiang, Xingxing; Molokeev, Maxim S.; Li, Wei; Wu, Shaofan; Lin, Zheshuai; Wu, Yicheng; Chen, Chuangtian

    2016-02-01

    A very recent study demonstrated that the KBe2BO3F2 (KBBF) family of crystals, including KBBF, RbBe2BO3F2, and CsBe2BO3F2, are the only known borates exhibiting a rarely occurring isotropic area negative thermal expansion (NTE) behavior, over a very large temperature range. In the present work, the NTE mechanism in these crystals is comprehensively investigated using the first-principles calculations. It is revealed that the area NTE behavior mainly originates from the concerted distortion of [BeO3F] tetrahedra in the two-dimensional [Be2BO3F2]∞ framework with respect to temperature, while the [BO3] triangles remain almost rigid. Moreover, the different magnitude of NTE effect in the three crystals is attributed to the interaction difference between the alkali metal atoms (K, Rb, or Cs) and the [Be2BO3F2]∞ layer.

  14. High-resolution thermal expansion measurements of BaCuSi4O10 and BaCuSi2O6

    Science.gov (United States)

    Masunaga, Sueli; Rebello, Alwyn; Neumeier, J. J.

    2014-03-01

    BaCuSi4O10 and BaCuSi2O6 were used in many ancient Chinese artifacts as synthetic pigments, and recently named as Han Blue and Han Purple, respectively. Besides being important synthetic pigments of ancient and modern times, these compounds have attracted scientific and technological interest due to their luminescent properties. Moreover, Han Purple is a spin-dimer compound with an interesting phase diagram and a potential solid state device for exploring quantum effects in magnetic field induced Bose-Einstein condensation. In this work, we study BaCuSi2O6 and BaCuSi4O10 single crystals grown by floating zone method and flux growth technique, respectively. The results of thermal expansion, specific heat, and magnetization measurements of these compounds will be presented in detail. This work is supported by CNPq-Brazil under Grant No 237050/2012-9 and National Science Foundation DMR-0907036.

  15. Quartz: structural and thermodynamic analyses across the α ↔ β transition with origin of negative thermal expansion (NTE) in β quartz and calcite

    Energy Technology Data Exchange (ETDEWEB)

    Antao, Sytle M.

    2016-04-01

    The temperature variation,T, of the crystal structure of quartz, SiO2, from 298 to 1235 K was obtained with synchrotron powder X-ray diffraction data and Rietveld structure refinements. The polymorphic transformation fromP3221 (low-T, α quartz) toP6222 (high-T, β quartz) occurs at a transition temperature,Ttr= 847 K. TheTvariations of spontaneous strains and several structural parameters are fitted to an order parameter,Q, using Landau theory. The change in Si atom coordinate, Six, givesTtr-Tc= 0.49 K, which indicates an α ↔ β transition that is weakly first order and nearly tricritical in character (Q4T). Strains give higherTtr-Tcvalues (≃ 7 K). Other fitted parameters are the oxygen Ozcoordinate, Si—Si distance, Si—O—Si and φ angles, and intensity of the (111) reflection,I111. In α quartz, the Si—Si distance increases withTbecause of cation repulsion, so the Si—O—Si angle increases (and φ decreases) and causes the thermal expansion of the framework structure that consists of corner-sharing distorted rigid SiO4tetrahedra. The Si—Si distances contract withTand cause negative thermal expansion (NTE) in β quartz because of increasing thermal librations of the O atom in the Si—O—Si linkage that occur nearly perpendicular to the Si—Si contraction. In calcite, CaCO3, the short Ca—Ca distance expands withT, but the next-nearest Ca—Ca distance, which is of equal length to theaaxis, contracts withTand causes NTE along

  16. 高导热率低膨胀复合型硅橡胶及导热填料研究进展%Progress of high thermal conductivity and low expansion composite silicone rubber and thermally conductive filler

    Institute of Scientific and Technical Information of China (English)

    袁腾; 周显宏; 王锋; 涂伟萍; 柯文皓

    2014-01-01

    Advances in the high thermal conductivity and low expansion rate silicone rubber and thermally con-ductive filler were summarized.First,the common thermally conductive filler and basic properties of thermally conductive filler were introduced,including metals,oxides,nitrides,carbides,etc..And the performance characteristics of various types of thermally conductive filler was described in detail and pointed out the influ-ence of the basic performance of the thermal conductivity on thermal conductivity,including filler ratio,size, size distribution,shape and surface properties of the filler and so on.Followed by a detailed description of the basic ways to improve thermal conductivity were given,including introduction of thermal conductivity mecha-nism;matrix materials research;development of new high-performance thermally conductive filler;conduct thermally conductive filler surface modification;silicone rubber molding process optimization,etc..Then some basic ways to reduce the coefficient of thermal expansion were introduced,including modification of inorganic nanoparticles and so on.Finally,some of the basic problems acurrently existing in the field and some ideas of solutions were advanced and the development trends were prospected.%主要综述了高导热率低膨胀加成型硅橡胶及导热填料的研究进展。首先介绍了常见的导热填料及其基本性能,主要包括金属类、氧化物类、氮化物类、碳化物类等;详细描述了各类填料的性能特点,并指出了填料基本性能对导热系数的影响,主要包括填料的比例、尺寸、尺寸分布、形状及填料的表面性质等。其次详细介绍了提高导热系数的基本途径,主要包括导热机理介绍;基体材料研究;研发新型高性能导热填料;进行导热填料表面改性;对硅橡胶成型工艺进行优化等;然后介绍了降低热膨胀系数的一些基本途径,主要包括无机纳米粒子改

  17. Thermal Expansion and Compressibility in Superconducting NaxCoO2o4xD2O (x?1/3): Evidence for Pressure-Induced Charge Redistribution

    OpenAIRE

    Jorgensen, J. D.; Avdeev, M.; Hinks, D. G.; Barnes, P. W.; Short, S.(Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom)

    2005-01-01

    We have performed thermal expansion and compressibility measurements on the recently discovered superconducting material NaxCoO2*4xD2O (x=1/3) using neutron powder diffraction over the temperature range 10-295 K and the pressure range 0-0.6 GPa. Pressure measurements were done in a helium-gas pressure cell. Both the thermal expansion and compressibility are very anisotropic, with the largest effects along the c axis, as would be expected for a layered material with weak hydrogen bonding nomin...

  18. Molecular Dynamics Simulation of Thermal Sensitivity,Thermal Expansion and Mechanical Properties of PBX9501%PBX9501热感度、热膨胀及力学性能的分子动力学模拟

    Institute of Scientific and Technical Information of China (English)

    张文英; 邓晓雅; 陈思瑾; 吕臻珂; 洪慧玲; 袁帅; 唐红; 豆育升

    2016-01-01

    Molecular dynamics simulation was used to explore the thermal sensitivity ,thermal expansion and mechanical properties of PBX9501 explosive at different temperatures and pressures .The change in maximum trigger bond lengths of components in the sysem was used to judge the influence of temperature on the thermal sensitivity of the system .The ther‐mal expansion coefficients at different temperatures were predicted .The variations of mechanical properties with tempera‐tures and pressures were analyzed by static mechanics theory .The results show that the sensitivity of PBX9501 increases with increasing temperature in the range of 295-450 K and the maximum trigger bond length increases significantly at 375 K .The thermal expansion coefficient decreases with the increase of temperature .The brittleness is more remarkable with increasing temperature ,and the toughness is better with increasing pressure .%采用分子动力学模拟研究了不同温度和压强条件下PBX9501炸药的热感度、热膨胀和力学性能。通过体系中各组分最大引发键键长的变化判断温度对其热感度的影响;预测了 PBX9501体系在不同温度下的热膨胀系数;采用静态力学理论分析其力学性能随温度和压强的变化。结果表明,在295~450 K ,随温度的升高,PBX9501炸药的敏感性增大,且在375K时其引发键的最大键长显著增大;热膨胀系数随温度升高而减小;随温度升高其脆性越明显,随压强的增加其韧性越好。

  19. Anomalous Chiral Superfluidity

    OpenAIRE

    Lublinsky, Michael(Physics Department, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel); Zahed, Ismail

    2009-01-01

    We discuss both the anomalous Cartan currents and the energy-momentum tensor in a left chiral theory with flavour anomalies as an effective theory for flavored chiral phonons in a chiral superfluid with the gauged Wess-Zumino-Witten term. In the mean-field (leading tadpole) approximation the anomalous Cartan currents and the energy momentum tensor take the form of constitutive currents in the chiral superfluid state. The pertinence of higher order corrections and the Adler-Bardeen theorem is ...

  20. Effects of heat treatment temperature on crystallization and thermal expansion coefficient of Li2 O-Al2 O3-SiO2

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 贾明; 刘树江

    2004-01-01

    The basic glass of Li2 O-Al2 O3-SiO2 system using P2O5 as nucleator was prepared by means of conventional melt quenching technology, and the heat-treatment process was determined by using differential thermal analysis. The crystalline phases and the microstructure of the glass-ceramics were investigated by using X-ray diffraction and scanning electron microscopy. The results show that the glass based on Li2 O-Al2 O3-SiO2 oxides using P2 O5 as nucleator can be prepared at lower melt temperature of 1 450 ℃ and the glass-ceramics with lower thermal expansion coefficient of 21.6 × 10-7 ℃ 1 can also be obtained at 750 ℃. The glass-ceramics contain a few crystal phases in which the main crystal phase is β-quartz solid solution and the second crystal phase is β-spodumene solid solution. When the heat treatment temperature is not higher than 650 ℃, the transparent glass-ceramics containing β-quartzsolid solution can be prepared. β-quartz solid solution changes into β-spodumene solid solution at about 750 ℃. And the appearance of the glass-ceramics changes from translucent, part opaque to complete opaque with increasing temperature.

  1. Study of ytterbium doping effects on structural, mechanical and opto-thermal properties of sprayed ZnO thin films using the Boubaker Polynomials Expansion Scheme (BPES)

    Energy Technology Data Exchange (ETDEWEB)

    Amlouk, A. [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Boubaker, K., E-mail: mmbb11112000@yahoo.f [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Amlouk, M. [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Bouhafs, M. [Unite de Recherche MA2I, Ecole Nationale d' Ingenieurs de Tunis, B.P. 37 Le Belvedere, 1002 Tunis (Tunisia)

    2009-10-19

    In this work, ZnO thin films have been grown on glass substrates by using a solution of propanol (C{sub 3}H{sub 8}O), water (H{sub 2}O) and zinc acetate (Z{sub n}(CH{sub 3}CO{sub 2}){sub 2}) in acidified medium (pH 5). The obtained films were n doped with ytterbium (Yb) at the rates of 100, 200 and 300 ppm. The structural features of the doped films were investigated using XRD, atomic force microscopy and scanning electronic microscopy techniques. XRD analysis shows a strong (0 0 2) X-ray diffraction line for increasing Yb-doping amounts. This c-axis preferential orientation of ZnO crystallites is naturally required to use this oxide as transparent conductor in optoelectronic applications. Atomic force microscopy (AFM) analysis shows an enhancement in the surface roughness of the doped ZnO:Yb thin films. Optical measurements were performed in 300-1800 nm domain via transmittance T(lambda) and reflectance R(lambda) spectra. Conjoint optical and thermal properties were deduced from the optical measurements in reference to the Amlouk-Boubaker opto-thermal expansivity psi{sub AB}. Optically relevant ytterbium doping effects have been discussed. Finally, mechanical measurements have been carried out using Vickers standard disposal. The results confirmed the structural and functional changes that several recent studies attributed to ytterbium doping.

  2. High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application

    Science.gov (United States)

    2003-01-01

    Many critical gas turbine engine components are currently made from Ni-base superalloys that are coated with a thermal barrier coating (TBC). The TBC consists of a ZrO2-based top coat and a bond coat that is used to enhance the bonding between the superalloy substrate and the top coat. MCrAlY alloys (CoCrAlY and NiCrAlY) are currently used as bond coats and are chosen for their very good oxidation resistance. TBC life is frequently limited by the oxidation resistance of the bond coat, along with a thermal expansion mismatch between the metallic bond coat and the ceramic top coat. The aim of this investigation at the NASA Glenn Research Center was to develop a new longer life, higher temperature bond coat by improving both the oxidation resistance and the thermal expansion characteristics of the bond coat. Nickel aluminide (NiAl) has excellent high-temperature oxidation resistance and can sustain a protective Al2O3 scale to longer times and higher temperatures in comparison to MCrAlY alloys. Cryomilling of NiAl results in aluminum nitride (AlN) formation that reduces the coefficient of thermal expansion (CTE) of the alloy and enhances creep strength. Thus, additions of cryomilled NiAl-AlN to CoCrAlY were examined as a potential bond coat. In this work, the composite alloy was investigated as a stand-alone substrate to demonstrate its feasibility prior to actual use as a coating. About 85 percent of prealloyed NiAl and 15 percent of standard commercial CoCrAlY alloys were mixed and cryomilled in an attritor with stainless steel balls used as grinding media. The milling was carried out in the presence of liquid nitrogen. The milled powder was consolidated by hot extrusion or by hot isostatic pressing. From the consolidated material, oxidation coupons, four-point bend, CTE, and tensile specimens were machined. The CTE measurements were made between room temperature and 1000 C in an argon atmosphere. It is shown that the CTE of the NiAl-AlN-CoCrAlY composite bond coat

  3. X-ray study of the thermal expansion anisotropy in AgGaS2 and AgInS2 compounds over the temperature range from 80 to 650 K

    International Nuclear Information System (INIS)

    The lattice parameters α and c of the AgGaS2 and AgInS2 compounds are determined as a function of temperature by X-ray diffraction method in the temperature range from 80 to 650 K. The data are used to evaluate the coefficients of thermal expansion, perpendicular (α/sub perpendicular/) and parallel (α/sub parallel/) to the principal axis, and the thermal expansion of the A-C (α/sub AC/) and B-C (α/sub BC/) bonds. It is found that for the two compounds almost over the whole investigated temperature range the coefficients of expansion α/sub parallel/ and α/sub BC/ are negative while the coefficients α/sub perpendicular/ and α/sub AC/ are positive. (auhtor)

  4. Teaching Activities for the Construction of a Precursor Model in 5- to 6-Year-Old Children's Thinking: The Case of Thermal Expansion and Contraction of Metals

    Science.gov (United States)

    Ravanis, Konstantinos; Papandreou, Maria; Kampeza, Maria; Vellopoulou, Angeliki

    2013-01-01

    This article presents the results of empirical research on the construction of a precursor model of the phenomenon of thermal expansion and contraction of metals in preschool children's thinking, which is compatible with the model used in science education. The research included 87 children aged 5-6. It was conducted at four stages, during…

  5. Thermal Expansion Characteristics and Thermal Conductivity of FeCo-based Bulk Amorphous Alloys%铁钴基块体非晶合金的热膨胀特性和热导率

    Institute of Scientific and Technical Information of China (English)

    陈庆军; 王健; 沈军; 周贤良; 华小珍; 董应虎

    2016-01-01

    采用真空非自耗电弧炉制备出Fe24+xCo24-xCr15Mo14C15B6Y2(x=0,2,4,6,8,at%)块体非晶合金,利用热膨胀测试仪和激光闪射热导率测试仪测量合金的热膨胀系数和热导率并与差示扫描量热曲线和高温XRD图谱进行对比,研究不同Co含量块体非晶合金的线性热膨胀行为随温度的变化规律和Co元素含量、不同组织对铁钻基块体合金热导率的影响.结果表明,随着Co含量减小,不同Co含量铁钴基非晶合金均出现规律相似的两次晶化过程,并且二次晶化起始温度依次提高.当x=0时,在875℃附近热膨胀系数出现第3个极大值点;25℃时Fe24+xCo24-xCr15Mo14C15B6Y2 (x=0,2,4,6,8)铁钴基非晶合金热导率在7.12~7.35 W/(m·K)范围内,在700℃温度退火处理的Fe24+xCo24-xCr15Mo14C15B6Y2 (x=0,2,4,6,8)铁钴基非晶合金的热导率值为7.5~9.46 W/(m·K),然而920℃退火处理后,热导率变化比较显著并出现先升高后下降的趋势.%Fe24+xCo24-xCr15Mo14C15B6Y2(x=0,2,4,6,8,at%) bulk amorphous alloys were prepared by a non-consumable arc-melting furnace.The thermal expansion coefficient and thermal conductivity of the amorphous alloy were tested by thermal expansion test instrument and laser indeed thermal conductivity tester,respectively,and the results were compared with the differential scanning calorimetry (DSC) curves and XRD patterns.Linear thermal expansion behavior with the temperature change of FeCo-based amorphous alloys with different Co contents and the effect of different Co element contents and different organizations on thermal conductivity of FeCo-base amorphous alloy were investigated.The results show that with the decrease of Co content,FeCo-base amorphous alloys have two crystallization processes,and the initial and the secondary crystallization temperature increase in turn.Thermal expansion coefficient of Fe24Co24Cr15Mo14C15B6Y2 has the third maximum point around 875 ℃.At 25 ℃,thermal conductivity of the Fe

  6. Anomalous Higgs couplings

    CERN Document Server

    González-Garciá, M Concepción

    1999-01-01

    We review the effects of new effective interactions on Higgs-boson phenomenology. New physics in the electroweak bosonic sector is expected to induce additional interactions between the Higgs doublet field and the electroweak gauge bosons, leading to anomalous Higgs couplings as well as anomalous gauge-boson self-interactions. Using a linearly realized SU(2)/sub L/*U(1)/sub Y/ invariant effective Lagrangian to describe the bosonic sector of the Standard Model, we review the effects of the new effective interactions on the Higgs- boson production rates and decay modes. We summarize the results from searches for the new Higgs signatures induced by the anomalous interactions in order to constrain the scale of new physics, in particular at CERN LEP and Fermilab Tevatron colliders. (43 refs).

  7. Anomalous Coronary Artery: Run of a Lifetime.

    Science.gov (United States)

    Green, Michael Stuart; Sehgal, Sankalp; Smukler, Naomi; Suber, LaDouglas Jarod; Saththasivam, Pooven

    2016-09-01

    The anatomy of the coronary circulation is well described with incidence of congenital anomalies of approximately 0.3% to 1.0%. Although often incidental, 20% are life-threatening. A 25-year-old woman with syncopal episodes collapsed following a 10-km run. Coronary anatomy evaluation showed an anomalous left main coronary artery originating from the right sinus of valsalva and following a course between the aorta and the pulmonary outflow tract. Percutaneous coronary intervention was followed by eventual surgical revascularization. Abnormal course of coronary arteries plays a role in the pathogenesis of sudden death on exertion. Origin of the left main coronary from the right sinus of valsalva is a rare congenital anomaly. The expansion of the roots of the aorta and pulmonary trunk with exertion lead to compression of the coronary artery and syncope. Our patient raises awareness of a potentially fatal coronary artery path. Intraoperative identification of anomalous coronaries by utilizing intraoperative transesophageal echocardiography was critical.

  8. Anomalous chiral superfluidity

    Energy Technology Data Exchange (ETDEWEB)

    Lublinsky, Michael, E-mail: lublinsky@phys.uconn.ed [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States); Physics Department, Ben-Gurion University, Beer Sheva 84105 (Israel); Zahed, Ismail [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2010-02-08

    We discuss both the anomalous Cartan currents and the energy-momentum tensor in a left chiral theory with flavor anomalies as an effective theory for flavored chiral phonons in a chiral superfluid with the gauged Wess-Zumino-Witten term. In the mean-field (leading tadpole) approximation the anomalous Cartan currents and the energy-momentum tensor take the form of constitutive currents in the chiral superfluid state. The pertinence of higher order corrections and the Adler-Bardeen theorem is briefly noted.

  9. Spin-phonon coupling, high-pressure phase transitions, and thermal expansion of multiferroic GaFeO3: A combined first principles and inelastic neutron scattering study

    Science.gov (United States)

    Gupta, Mayanak Kumar; Mittal, Ranjan; Zbiri, Mohamed; Singh, Ripandeep; Rols, Stephane; Schober, Helmut; Chaplot, Samrath Lal

    2014-10-01

    We have carried out an extensive phonon study on multiferroic GaFeO3 to elucidate its dynamical behavior. Inelastic neutron scattering measurements are performed over a wide temperature range, 150 to 1198 K. First principles lattice dynamical calculations are done for the sake of the analysis and interpretation of the observations. The comparison of the phonon spectra from magnetic and nonmagnetic calculations highlights pronounced differences. The energy range of the vibrational atomistic contributions of the Fe and O ions are found to differ significantly in the two calculation types. Therefore, magnetism induced by the active spin degrees of freedom of Fe cations plays a key role in stabilizing the structure and dynamics of GaFeO3. Moreover, the computed enthalpy in various phases of GaFeO3 is used to gain deeper insights into the high-pressure phase stability of this material. Further, the volume dependence of the phonon spectra is used to determine its thermal expansion behavior.

  10. Superplastic forming of Ti6Al4V alloy using ZrO_2-TiO_2 ceramic die with adjustable linear thermal expansion coefficient

    Institute of Scientific and Technical Information of China (English)

    JIANG Shao-song; ZHANG Kai-feng

    2009-01-01

    Firstly, the relation between the coefficient of thermal expansion(CTE) and the volume fraction of TiO_2 was investigated, and also the influence of relative density of ceramic on the CTE was studied. The results show that the volume fraction, of TiO_2 and the relative density both make influence on the CTE of ZrO_2-TiO_2 ceramic. According to the results, the ZrO_2-TiO_2(volume fraction of TiO_2 is 27%) ceramic die with the similar CTE (8.92×10~(-6)℃~(-1)) to Ti6Al4V was fabricated. Secondly, to evaluate the dimensional accuracy of the workpiece superplastically formed, the Ti6Al4V impression experiment was performed. The result shows that the dimensional inaccuracy of workpieee is 0.003. Thirdly, in order to evaluate the practicability, the experiment of superplastic forming Ti6Al4V using ZrO_2-TiO_2 cylinder ceramic die was carried out. The Ti6Al4V cylinder shows good shape retention and surface quality, and high dimensional accuracy. The ceramic dies seem to be adequate for superplastic forming the high accuracy Ti6Al4V,and the trials have confirmed the potential of the ZrO2-TiO2 ceramic die.

  11. Crystal structures, thermal expansion and phase transitions of mixed Pr{sub 1-x}La{sub x}AlO{sub 3} perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Basyuk, Tetyana; Vasylechko, Leonid [Lviv Polytechnic National University (Ukraine); Syvorotka, Igor [SRC, Carat, Lviv (Ukraine); Schmidt, Ulrike [Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany); Trots, Dmytro [HASYLAB, DESY, Hamburg (Germany); Niewa, Rainer [Technische Universitaet Muenchen, Garching (Germany)

    2009-05-15

    The crystal structures, thermal expansion and phase transitions of mixed Pr{sub 1-x}La{sub x}AlO{sub 3} perovskites have been examined by using an in situ high resolution X-ray powder diffraction technique applying synchrotron radiation in a wide temperature range of 12-1173 K. At room temperature all samples in the PrAlO{sub 3}-LaAlO{sub 3} pseudo-binary system adopt the rhombohedral perovskite-like structure. At elevated temperatures, all Pr{sub 1-x}La{sub x}AlO{sub 3}compositions undergo continuous phase transitions from rhombohedral to cubic structures. The sequence of the low-temperature (LT) phase transformations R anti 3 c<->Imma<->C2/m has been observed in Pr{sub 1-x}La{sub x}AlO{sub 3} samples. Temperatures of HT and LT phase transitions in Pr{sub 1-x}La{sub x}AlO{sub 3}decrease with decreasing Pr content. Crystal structure parameters for all compositions Pr{sub 1-x}La{sub x}AlO{sub 3} have been determined. Based on in situ powder diffraction and DTA/DSC data, the phase diagram of the PrAlO{sub 3}-LaAlO{sub 3}pseudo-binary system has been constructed. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The mechanism of the area negative thermal expansion in KBe{sub 2}BO{sub 3}F{sub 2} family crystals: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xingxing [Center for Crystal Research and Development, Key Lab of Functional Crystals and Laser Technology of Chinese Academy of Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Molokeev, Maxim S. [Laboratory of Crystal Physics, Kirensky Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Department of Physics, Far Eastern State Transport University, Khabarovsk 680021 (Russian Federation); Li, Wei [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Shaofan [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Lin, Zheshuai, E-mail: zslin@mail.ipc.ac.cn; Wu, Yicheng; Chen, Chuangtian [Center for Crystal Research and Development, Key Lab of Functional Crystals and Laser Technology of Chinese Academy of Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-02-07

    A very recent study demonstrated that the KBe{sub 2}BO{sub 3}F{sub 2} (KBBF) family of crystals, including KBBF, RbBe{sub 2}BO{sub 3}F{sub 2}, and CsBe{sub 2}BO{sub 3}F{sub 2}, are the only known borates exhibiting a rarely occurring isotropic area negative thermal expansion (NTE) behavior, over a very large temperature range. In the present work, the NTE mechanism in these crystals is comprehensively investigated using the first-principles calculations. It is revealed that the area NTE behavior mainly originates from the concerted distortion of [BeO{sub 3}F] tetrahedra in the two-dimensional [Be{sub 2}BO{sub 3}F{sub 2}]{sub ∞} framework with respect to temperature, while the [BO{sub 3}] triangles remain almost rigid. Moreover, the different magnitude of NTE effect in the three crystals is attributed to the interaction difference between the alkali metal atoms (K, Rb, or Cs) and the [Be{sub 2}BO{sub 3}F{sub 2}]{sub ∞} layer.

  13. Structure and Thermal Expansion of Calcium-Thorium Apatite, [Ca4]F[Ca2Th4]T[(SiO4)6]O2.

    Science.gov (United States)

    Bulanov, Evgeny N; Wang, Jingxian; Knyazev, Alexander V; White, Tim; Manyakina, Marina E; Baikie, Tom; Lapshin, Alexander N; Dong, ZhiLi

    2015-12-01

    Thorium silicate apatite with the formula [Ca3.84Th0.16]F[Ca2.79Th3.21]T(SiO4)6O2 · x(H) was synthesized by solid-state reaction, and its structure refined in P63/m from powder X-ray diffraction (XRD) data using the Rietveld method (a = 9.50172(9) Å, c = 6.98302(8) Å, V = 545.98(1) Å(3); R-Bragg = 2.102%). It was found that thorium partitions strongly to the tunnel (T) 6h position rather than the framework (F) 4f site. Fourier transform infrared spectroscopy revealed only SiO4 tetrahedron, with SiO5 and SiO6 groups, sometimes observed in siliceous apatites absent, at least to the limit of detection of this technique. Thermal expansion of the thorium apatite determined by high-temperature XRD from 298-1173 K found Δa (0.87%) dilation to exceed Δc (0.73%) with increasing temperature consistent with other silicate apatites. PMID:26562353

  14. Paramagnetic limiting of the upper critical field of KFe{sub 2}As{sub 2} studied by low temperature thermal expansion and magnetostriction

    Energy Technology Data Exchange (ETDEWEB)

    Zocco, Diego A.; Grube, Kai; Zaum, Sebastian; Eilers, Felix; Schaefer, Roland; Wolf, Thomas; Burger, Philipp; Hardy, Frederic; Boehmer, Anna; Meingast, Christoph [Institut fuer Festkoerperphysik, Karlsruhe Institute of Technology, Karlsruhe (Germany); Loehneysen, Hilbert von [Institut fuer Festkoerperphysik, Karlsruhe Institute of Technology, Karlsruhe (Germany); Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2013-07-01

    We present low-temperature thermal expansion and magnetostriction measurements of single crystals of KFe{sub 2}As{sub 2} (T{sub c} ∝ 3.4 K) in magnetic fields up to 14 T applied parallel and perpendicular to the c-axis of the samples (B{sub c2}{sup c} ∝ 1.5 T and B{sub c2}{sup ab} ∝ 4.8 T). In the normal state, quantum oscillations of the sample length were observed for B parallel c and B perpendicular to c, giving estimated mean-free-path values of 177 and 52 nm, respectively, indicating that the superconducting state can be described as being in the clean limit (ξ{sub 0}{sup ab} ∝ 10 nm). While the superconducting state is limited by orbital pair-breaking effects when magnetic fields are applied parallel to the c-axis, our measurements confirm strong paramagnetic effects on B{sub c2}(T) along the ab direction, as it was similarly found in other Fe-based materials such as LiFeAs and FeSe{sub 1-x}Te{sub x}.

  15. Anomalous pion decay revisited

    CERN Document Server

    Battistel, O A; Nemes, M C; Hiller, B

    1999-01-01

    An implicit four dimensional regularization is applied to calculate the axial-vector-vector anomalous amplitude. The present technique always complies with results of Dimensional Regularization and can be easily applied to processes involving odd numbers of $\\gamma_5$ matrices. This is illustrated explicitely in the example of this letter.

  16. Beta Function and Anomalous Dimensions

    DEFF Research Database (Denmark)

    Pica, Claudio; Sannino, Francesco

    2011-01-01

    We demonstrate that it is possible to determine the coefficients of an all-order beta function linear in the anomalous dimensions using as data the two-loop coefficients together with the first one of the anomalous dimensions which are universal. The beta function allows to determine the anomalous...

  17. High-temperature X-ray diffraction and thermal expansion of nanocrystalline and coarse-crystalline acanthite α-Ag2S and argentite β-Ag2S.

    Science.gov (United States)

    Sadovnikov, S I; Gusev, A I; Chukin, A V; Rempel, A A

    2016-02-14

    An in situ study of thermal expansion of polymorphic phases of coarse-crystalline and nanocrystalline silver sulfide - monoclinic acanthite α-Ag2S and cubic argentite β-Ag2S - has been carried out for the first time using the high-temperature X-ray diffraction method. The temperature dependencies of the unit cell parameters of acanthite and argentite in the interval of 300-623 K have been determined, and the thermal expansion coefficients of acanthite and argentite have been found. It is shown that the observed difference in the thermal expansion coefficients for nano- and coarse-crystalline acanthite is due to the small particle size of nanocrystalline silver sulfide leading to the growth of anharmonicity of atomic vibrations. It is established by differential thermal analysis that a reversible polymorphic acanthite-argentite phase transformation takes place at ∼449-450 K and the phase transformation enthalpy is equal to ∼3.7-3.9 kJ mol(-1). PMID:26796061

  18. Anomalous ionic conductivity of Sc sub 2 (WO sub 4) sub 3 mediated by structural changes at high pressures and temperatures

    CERN Document Server

    Secco, R A; Imanaka, N; Adachi, G

    2002-01-01

    The ionic conductivity of Sc sub 2 (WO sub 4) sub 3 at 400 deg. C shows a normal decrease with increase in pressure up to 2.9 GPa but then increases anomalously at pressures up to 4.3 GPa. Synchrotron in situ x-ray diffraction results show that Sc sub 2 (WO sub 4) sub 3 undergoes pressure-induced amorphization at pressures coincident with the reversal in conductivity behaviour. The loss of crystal structure at high pressure may be associated with the property of negative thermal expansion in Sc sub 2 (WO sub 4) sub 3.

  19. XUV-exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets. Part I: atmospheric expansion and thermal escape.

    Science.gov (United States)

    Erkaev, Nikolai V; Lammer, Helmut; Odert, Petra; Kulikov, Yuri N; Kislyakova, Kristina G; Khodachenko, Maxim L; Güdel, Manuel; Hanslmeier, Arnold; Biernat, Helfried

    2013-11-01

    The recently discovered low-density "super-Earths" Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent the most likely known planets that are surrounded by dense H/He envelopes or contain deep H₂O oceans also surrounded by dense hydrogen envelopes. Although these super-Earths are orbiting relatively close to their host stars, they have not lost their captured nebula-based hydrogen-rich or degassed volatile-rich steam protoatmospheres. Thus, it is interesting to estimate the maximum possible amount of atmospheric hydrogen loss from a terrestrial planet orbiting within the habitable zone of late main sequence host stars. For studying the thermosphere structure and escape, we apply a 1-D hydrodynamic upper atmosphere model that solves the equations of mass, momentum, and energy conservation for a planet with the mass and size of Earth and for a super-Earth with a size of 2 R(Earth) and a mass of 10 M(Earth). We calculate volume heating rates by the stellar soft X-ray and extreme ultraviolet radiation (XUV) and expansion of the upper atmosphere, its temperature, density, and velocity structure and related thermal escape rates during the planet's lifetime. Moreover, we investigate under which conditions both planets enter the blow-off escape regime and may therefore experience loss rates that are close to the energy-limited escape. Finally, we discuss the results in the context of atmospheric evolution and implications for habitability of terrestrial planets in general. PMID:24251443

  20. Anomalous diffusion of epicentres

    CERN Document Server

    Sotolongo-Costa, Oscar; Posadas, A; Luzon, F

    2007-01-01

    The classification of earthquakes in main shocks and aftershocks by a method recently proposed by M. Baiesi and M. Paczuski allows to the generation of a complex network composed of clusters that group the most correlated events. The spatial distribution of epicentres inside these structures corresponding to the catalogue of earthquakes in the eastern region of Cuba shows anomalous anti-diffusive behaviour evidencing the attractive nature of the main shock and the possible description in terms of fractional kinetics.