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. Anomalous thermal expansion in rare-earth gallium perovskites: a comprehensive powder diffraction study

    International Nuclear Information System (INIS)

    Crystal structures of rare-earth gallium perovskites LaGaO3, PrGaO3, NdGaO3 and Pr1-xNdxGaO3 (x = 0.25, 0.50, 0.75) solid solutions were investigated in the temperature range 12-300 K by high-resolution powder diffraction using synchrotron or neutron radiation. The previously reported negative thermal expansion in the b direction of the PrGaO3 lattice has been found to be persistent in Pr1-xNdxGaO3 solid solutions and its magnitude has been revealed as proportional to the amount of praseodymium. Evaluation of the obtained temperature evolution of cell dimensions indicated a weak anomalous behaviour of the b lattice parameter in NdGaO3, and its origin is supposed to be the same as in PrGaO3, i.e. a coupling of the crystal electric field levels with phonon excitations of about 23-25 meV energy. The performed bond length analysis revealed an anomalous behaviour of both LnO12 (Ln-rare-earth) and GaO6 coordination polyhedra, which can be a structural manifestation of anomalous thermal expansion in the considered compounds.

  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. 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

  5. Thermal expansion

    International Nuclear Information System (INIS)

    Thermal expansion of fuel pellet is an important property which limits the lifetime of the fuels in reactors, because it affects both the pellet and cladding mechanical interaction and the gap conductivity. By fitting a number of available measured data, recommended equations have been presented and successfully used to estimate thermal expansion coefficient of the nuclear fuel pellet. However, due to large scatter of the measured data, non-consensus data have been omitted in formulating the equations. Also, the equation is strongly governed by the lack of appropriate experimental data. For those reasons, it is important to develop theoretical methodologies to better describe thermal expansion behaviour of nuclear fuel. In particular, first-principles and molecular dynamics simulations have been certainly contributed to predict reliable thermal expansion without fitting the measured data. Furthermore, the two theoretical techniques have improved on understanding the change of fuel dimension by describing the atomic-scale processes associated with lattice expansion in the fuels. (author)

  6. Resistance and thermal expansion anomalous change in Cr-Re and Cr-Os alloys above Neel temperature

    International Nuclear Information System (INIS)

    Temperature dependences of electric resistance and thermal expansion of alloy series Cr-Re and Cr-Os in the range of ternary points concentration on phase diagrams of magnetic transformations are studied. It is shown, that with the increase in Re and Os concentration in chromium alloys to the concentration of ternary points during their heating above Tsub(N), an anomalous nonlinear to a certain temperature Tsub(l), and above Tsub(l) - a linear change in electric resistance and thermal expansion are observed. The highest anomalies of the properties and values of Tsub(l)-Tsub(N) temperature ranges are observed at the concentration of ternary points. With further increase in Re and Os concentration in the alloys both anomalies and Tsub(l)-Tsub(N) values decrease, but remain higher than those of pure chromium. Such anomalies are explained by the change in magnetic structure and first of all the values of domains, structure of domain boundaries of phase ao.reement with different magnetic order and with the possibility of ferromagnetism microregion formation

  7. 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.

  8. Anomalous radial expansion in central heavy-ion reactions

    International Nuclear Information System (INIS)

    The expansion velocity profile in central heavy-ion reactions in the Fermi energy domain is examined. The radial expansion is non-hubblean and in the surface region it scales proportional to a higher exponent (α > 1) of the radius. The anomalous expansion velocity profile is accompanied by a power law nucleon density profile in the surface region. Both these features of central heavy-ion reactions disappear at higher energies, and the system follows a uniform Hubble expansion (α ≅ 1). (authors)

  9. Thermal Expansion of Polyurethane Foam

    Science.gov (United States)

    Lerch, Bradley A.; Sullivan, Roy M.

    2006-01-01

    Closed cell foams are often used for thermal insulation. In the case of the Space Shuttle, the External Tank uses several thermal protection systems to maintain the temperature of the cryogenic fuels. A few of these systems are polyurethane, closed cell foams. In an attempt to better understand the foam behavior on the tank, we are in the process of developing and improving thermal-mechanical models for the foams. These models will start at the microstructural level and progress to the overall structural behavior of the foams on the tank. One of the key properties for model characterization and verification is thermal expansion. Since the foam is not a material, but a structure, the modeling of the expansion is complex. It is also exacerbated by the anisoptropy of the material. During the spraying and foaming process, the cells become elongated in the rise direction and this imparts different properties in the rise direction than in the transverse directions. Our approach is to treat the foam as a two part structure consisting of the polymeric cell structure and the gas inside the cells. The polymeric skeleton has a thermal expansion of its own which is derived from the basic polymer chemistry. However, a major contributor to the thermal expansion is the volume change associated with the gas inside of the closed cells. As this gas expands it exerts pressure on the cell walls and changes the shape and size of the cells. The amount that this occurs depends on the elastic and viscoplastic properties of the polymer skeleton. The more compliant the polymeric skeleton, the more influence the gas pressure has on the expansion. An additional influence on the expansion process is that the polymeric skeleton begins to breakdown at elevated temperatures and releases additional gas species into the cell interiors, adding to the gas pressure. The fact that this is such a complex process makes thermal expansion ideal for testing the models. This report focuses on the thermal

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Ultraprecise thermal expansion measurements of seven low expansion materials

    Science.gov (United States)

    Berthold, J. W., III; Jacobs, S. F.

    1976-01-01

    We summarize a large number of ultraprecise thermal expansion measurements made on seven different low expansivity materials. Expansion coefficients in the -150-300 C temperature range are shown for Owens-Illinois Cer-Vit C-101, Corning ULE 7971 (titanium silicate) and fused silica 7940, Heraeus-Schott Zerodur low-expansion material and Homosil fused silica, Universal Cyclops Invar LR-35, and Simonds Saw and Steel Super Invar.

  17. 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.

  18. Pressurized electrolysis stack with thermal expansion capability

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, Richard Scott

    2015-07-14

    The present techniques provide systems and methods for mounting an electrolyzer stack in an outer shell so as to allow for differential thermal expansion of the electrolyzer stack and shell. Generally, an electrolyzer stack may be formed from a material with a high coefficient of thermal expansion, while the shell may be formed from a material having a lower coefficient of thermal expansion. The differences between the coefficients of thermal expansion may lead to damage to the electrolyzer stack as the shell may restrain the thermal expansion of the electrolyzer stack. To allow for the differences in thermal expansion, the electrolyzer stack may be mounted within the shell leaving a space between the electrolyzer stack and shell. The space between the electrolyzer stack and the shell may be filled with a non-conductive fluid to further equalize pressure inside and outside of the electrolyzer stack.

  19. 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.

  20. 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

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. Microinstability-based model for anomalous thermal confinement in tokamaks

    International Nuclear Information System (INIS)

    This paper deals with the formulation of microinstability-based thermal transport coefficients (chi/sub j/) for the purpose of modelling anomalous energy confinement properties in tokamak plasmas. Attention is primarily focused on ohmically heated discharges and the associated anomalous electron thermal transport. An appropriate expression for chi/sub e/ is developed which is consistent with reasonable global constraints on the current and electron temperature profiles as well as with the key properties of the kinetic instabilities most likely to be present. Comparisons of confinement scaling trends predicted by this model with the empirical ohmic data base indicate quite favorable agreement. The subject of anomalous ion thermal transport and its implications for high density ohmic discharges and for auxiliary-heated plasmas is also addressed

  6. Energy expansion planning by considering electrical and thermal expansion simultaneously

    International Nuclear Information System (INIS)

    Highlights: • This paper focused on the expansion planning optimization of energy systems. • Employing two form of energy: the expansion of electrical and thermal energies. • The main objective is to minimize the costs. • A new Modified Honey Bee Mating Optimization (MHBMO) algorithm is applied. - Abstract: This study focused on the expansion planning optimization of energy systems employing two forms of energy: the expansion of electrical and thermal energies simultaneously. The main objective of this investigation is confirming network adequacy by adding new equipment to the network, over a given planning horizon. The main objective of the energy expansion planning (EEP) is to minimize the real energy loss, voltage deviation and the total cost of installation equipments. Since the objectives are different and incommensurable, it is difficult to solve the problem by the conventional approaches that may optimize a single objective. So, the meta-heuristic algorithm is applied to this problem. Here, Honey Bee Mating Optimization algorithm (HBMO) as a new evolutionary optimization algorithm is utilized. In order to improve the total ability of HBMO for the global search and exploration, a new modification process is suggested such a way that the algorithm will search the total search space globally. Also, regarding the uncertainties of the new complicated energy systems, in this paper for the first time, the EEP problem is investigated in a stochastic environment by the use of probabilistic load flow technique based on Point Estimate Method (PEM). In order to evaluate the feasibility and effectiveness of the proposed algorithm, two modified test systems are used as case studies

  7. Thermal expansion behaviour of granites

    Czech Academy of Sciences Publication Activity Database

    Plevová, Eva; Vaculíková, Lenka; Kožušníková, Alena; Ritz, M.; Simha Martynková, G.

    2015-01-01

    Roč. 123, č. 2 (2015), s. 1555-1561. ISSN 1388-6150 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : thermomechanical analysis * differential thermal analysis * granites Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.042, year: 2014 http://link.springer.com/article/10.1007/s10973-015-4996-z

  8. Regression equation for describing gluten thermal expansion

    Directory of Open Access Journals (Sweden)

    J. Grodek

    2007-12-01

    Full Text Available Testing of gluten ability of thermal expansion consisted in heating a small sample of freshly washed out gluten at temperatures causing the boiling of water within it. Gluten membranes extend around forming bubbles of water vapour under increase of pressure and are simultaneously being modified thermally. At certain volume of the bubbles, the membranes achieve maximum extensibility and further increasing of water vapour pressure causes their perforation. The dynamics of the expansion process was recorded by use of a digital camera. The proposed regression equation describes the dependence of the volume increment of gluten on heating time and allows to split the thermal expansion process into hyperbolic and linear components. The hyperbolic one is determined by a three-parameter function of hyperbolic tangent. The parameters a, c and b characterize the half of extent and duration of the hyperbolic expansion and its rate, respectively. The linear component can be meant as viscous flow of gluten, therefore it is determined by a one-parameter linear function. The parameter d means the rate of linear expansion. The volume increase of strong gluten at lowest temperature (110°C was very slow and its character was only linear (d. Higher heating temperatures (above 140°C caused considerably larger and faster hyperbolic expansion (a and b of strong gluten than of the weak one. However, the weak gluten in whole range of used temperatures was distinguished by almost twice faster linear expansion (d. It may suggest the existence of significant differences between wheat cultivars in terms of extensibility of thermally modified gluten membranes.

  9. 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.

  10. Thermal expansion of fuel compacts for HTGR

    International Nuclear Information System (INIS)

    Coefficients of thermal expansion of graphite/carbon matrices and fuel compacts for HTGR were measured by a quartz push-rod dilatometer at a temperature range of 100 - 7000C. Graphite/carbon matrices were prepared by such method that needle coke graphite powder or natural graphite-petrolem coke graphite powder was first mixed with 10 or 20% of phenolic resin and pressed and calcined. Fuel compacts were prepared by the overcoating process, loading coated particles 30, 35 and 40% in these matrices. The coefficients of thermal expansion were measured in the direction parallel with and perpendicular to the forming pressure. The coefficients of thermal expansion of graphite/carbon matrices increase with temperature and those of parallel direction are larger than that those of perpendicular direction and needle coke graphite/carbon matrices is most isotropic. Matrices become isotropic with increasing binder contents from 10 to 20% and with coated particle loading. The coefficients of thermal expansion of fuel compacts slightly decrease with increasing coated particle loading from 30 to 40%. (author)

  11. 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...

  12. 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

  13. Preliminary thermal expansion screening data for tuffs

    International Nuclear Information System (INIS)

    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 2000C. 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

  14. 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.

  15. 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.

  16. 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.

  17. Elucidating Negative Thermal Expansion in MOF-5

    International Nuclear Information System (INIS)

    Multi-temperature X-ray diffraction studies show that twisting, rotation, and libration cause negative thermal expansion (NTE) of the nanoporous metal-organic framework MOF-5, Zn4O(1,4-benzenedicarboxylate)3. The near-linear lattice contraction is quantified in the temperature range 80-500 K using synchrotron powder X-ray diffraction. Vibrational motions causing the abnormal expansion behavior are evidenced by shortening of certain interatomic distances with increasing temperature according to single-crystal X-ray diffraction on a guest-free crystal over a broad temperature range. Detailed analysis of the atomic positional and displacement parameters suggests two contributions to cause the effect: (1) local twisting and vibrational motion of the carboxylate groups and (2) concerted transverse vibration of the linear linkers. The vibrational mechanism is confirmed by calculations of the dynamics in a molecular fragment of the framework.

  18. 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 ...

  19. 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.

  20. Thermal expansion of glasses at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, K.G.

    1979-01-01

    The linear thermal expansion coefficient (..cap alpha.. = (par. deltalnL/par. deltaT)/sub p/) was measured at temperatures to 1.2K for two amorphous solids, fused silica and PMMA (polymethylmethacrylate, plexiglas), using a parallel plate capacitor differential dilatometer. The low temperature expansion coefficients for these solids have the same temperature dependences as the specific heats, and show a contribution which is linear in the temperature and which can be associated with the postulate of a broad distribution of two level states. The Grueneisen parameters which are associated with this contribution are comparable for the two solids (Y approx. = -16), and suggest a further indication of common behavior for amorphous solids at low temperature. Large magnitudes for Grueneisen parameters (/..gamma../ > 5) generally are associated with tunneling models. A symmetric double harmonic oscillator tunneling model can be used to understand the sign and magnitude of ..gamma.. for these solids. This model is inconsistent with other thermal and thermodynamic data for fused silica. The existence of similar negative and large magnitude Grueneisen parameters for these two amorphous solids places an additional constraint on theories for the low temperature properties of glasses.

  1. 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.

  2. 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

  3. Negative thermal expansion of lithium aluminosilicate ceramics at cryogenic temperatures

    International Nuclear Information System (INIS)

    Five lithium aluminosilicate compositions of the LAS system have been synthesized and sintered. The coefficient of thermal expansion of the sintered samples has been studied down to cryogenic conditions. The data presented here under cryogenic conditions will be of value in the future design of new composite materials with very low thermal expansion values. The variation in thermal expansion properties with composition and sintering temperature was studied and is discussed in relation to composition and crystal structure.

  4. Modeling of silicon thermal expansion using strained phonon spectra

    International Nuclear Information System (INIS)

    Based on lattice dynamics theories, a model has been developed to examine the thermal expansion of crystalline silicon. The thermal expansion coefficient α of crystalline silicon has been extracted by using the strained phonon spectra. It is found to be 2.49 × 10−6 K−1 at room temperature. Based on the temperature dependence of second-order elastic constants and Raman scattering, a semiempirical model for the thermal expansion coefficient of crystalline silicon as a function of temperature has been presented. The obtained results are in good agreement with available experimental data, and the average deviation of thermal expansion coefficient from experiments is less than 2.4%. (paper)

  5. 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

  6. 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.

  7. Dolomite addition effects on the thermal expansion of ceramic tiles

    International Nuclear Information System (INIS)

    The thermal expansion of ceramic tiles is of greater importance in engineering applications because the ceramics are relatively brittle and cannot tolerate large internal strain imposed by thermal expansion. When ceramic bodies are produced for glazed ties the compatibility of this property of the components should be considered to avoid damage in the final products. Carbonates are an important constituent of ceramic wall-title bodies and its presence in formulations and the reactions that occur between them and other components modify body properties. The influence in expansivity by additions of calcium magnesium carbonate in a composition of wall tile bodies has been investigated. The relative content of mineralogical components was determined by X-ray diffraction and thermal expansion by dilatometric measurements. The results was indicated that with the effect of calcium-magnesium phases and porosity on thermal expansion of wall tile bodies. (author)

  8. 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.

  9. Thermal expansion study of simulated DUPIC fuel using neutron diffraction

    International Nuclear Information System (INIS)

    The lattice parameters of simulated DUPIC fuel and UO2 were measured from room temperature to 1273 K using neutron diffraction to investigate the thermal expansion and density variation with temperature. The lattice parameter of simulated DUPIC fuel is lower than that of UO2 and the linear thermal expansion of simulated DUPIC fuel is higher than that of UO2. For the temperature range from 298 to 1273 K, the average linear thermal expansion coefficients for UO2 and simulated DUPIC fuel are 10.471 ''10-6 and 10.751 ''10-6 K-1, respectively

  10. Tailoring thermal expansion in metal matrix composites blended by antiperovskite manganese nitrides exhibiting giant negative thermal expansion

    Science.gov (United States)

    Takenaka, K.; Hamada, T.; Kasugai, D.; Sugimoto, N.

    2012-10-01

    We controlled thermal expansion of metal matrix composites (MMCs) that had been blended using antiperovskite manganese nitrides with giant negative thermal expansion (NTE). The NTE of the manganese nitrides, which is isotopic, is greater than -30 ppm K-1 in α (coefficient of linear thermal expansion), which is several or ten times as large as that of conventional NTE materials. These advantages of nitrides are desirable for practical application as a thermal-expansion compensator, which can suppress thermal expansion of various materials including metals and even plastics. Powder metallurgy using pulsed electric current sintering enables us to reduce temperatures and times for fabrication of MMCs. Consequently, chemical reactions between matrix (Al, Ti, Cu) and filler can be controlled and even high-melting-point metals can be used as a matrix. Thermal expansion of these MMCs is tunable across widely various α values, even negative ones, with high reproducibility. These composites retain a certain amount of voids. Formation of rich and stable interfacial bonding, overcoming large mismatch in thermal expansion, remains as a problem that is expected to hinder better composite performance.

  11. 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.

  12. 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.

  13. 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.

  14. 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...

  15. Thermal expansion uniformity of materials for large telescope mirrors

    Science.gov (United States)

    Jacobs, S. F.; Shough, D.; Connors, C.

    1984-01-01

    Uniformity of thermal expansion has been measured for fused quartz and borosilicate glass. The variation of expansion coefficient for three melts of TO8E was 5 x 10 to the -9th/K over a temperature range of 300 to 100 K and was found to vary linearly with position in the melt. This spatial gradient averaged 3.5 x 10 to the -11th/K-cm. The room-temperature thermal expansivity variation of Duran (Tempax) glass was about 27 x 10 to the -9th/K, while that of E6 glass was about 52 x 10 to the -9th/K.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Nonlinear acoustics and the thermal expansivity of glass

    Science.gov (United States)

    Cantrell, John H.; Yost, William T.

    1992-01-01

    The paper shows the intrinsic relationship between acoustical nonlinearity and the thermal expansivity of crystalline solids (a thermal measure of anharmonicity) from consideration of the 'static' radiation field generated by the vibrating lattice (atomic) sources of the crystal. A modification of the theory to account for long-range structural disorder in glass is proposed and applied to an explanation of the zero thermal expansivity at the cross-over temperature in silicate and titanium silicate glasses. Experimental evidence which validates the essential features of the theory is presented. An application of nonlinearity measurement, based on these results, to the processing of ULE glass, where the addition of titanium in various amounts is used to establish the temperature at which the zero thermal expansivity occurs, is suggested.

  1. 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.

  2. Pressure effects on thermal conductivity and expansion of geologic materials

    International Nuclear Information System (INIS)

    Through analysis of existing data, an estimate is made of the effect of pressure or depth on the thermal conductivity and expansion of geologic materials which could be present in radioactive waste repositories. In the case of homogeneous dense materials, only small shifts are predicted to occur at depths less than or equal to 3 km, and these shifts will be insignificant as compared with those caused by temperature variations. As the porosity of the medium increases, the variation of conductivity and expansion with pressure becomes greater, with conductivity increasing and expansion decreasing as pressure increases. The pressure dependence of expansion can be found from data on the temperature variation of the isobaric compressibility. In a worst case estimate, a decrease in expansion of approx. 25% is predicted for 5% porous sandstone at a depth of 3 km. The thermal conductivity of a medium with gaseous inclusions increases as the porosity decreases, with the magnitude of the increase being dependent on the details of the porosity collapse. Based on analysis of existing data on tuff and sandstone, a weighted geometric mean formula is recommended for use in calculating the conductivity of porous rock. As a result of this study, it is recommended that measurement of rock porosity versus depth receive increased attention in exploration studies and that the effect of porosity on thermal conductivity and expansion should be examined in more detail

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Thermal expansion studies of carbon nanotube-reinforced silver nanocomposite

    International Nuclear Information System (INIS)

    In the present study, a simple and highly effective physical mixing method was used to synthesise carbon nanotube (CNT)-reinforced silver nanocomposites. Composites were prepared with different contents (vol%) of functionalised multiwall nanotubes. The microstructure of synthesised nanocomposites was analysed by X-ray diffraction, electron diffraction spectroscopy, and scanning electron microscopy. Microstructural characterisations revealed good distribution of nanotubes in the silver matrix. The thermal expansion behaviour of the composites was studied in reference to the variation in nanotube volume content in the silver matrix. It was observed that the coefficient of thermal expansion decreased with the increase in the percentage of CNT volume. The thermal expansion of the CNT-reinforced silver composites decreased to 55 % of pure silver upon the introduction of 6 vol% of nanotubes into the silver matrix. The thermal expansion behaviour of the CNT-reinforced silver composites was also analysed theoretically using the rule of mixture and Schapery's model. The CNT-reinforced silver composites may be a promising contact and thermal management material in electronic devices.

  8. Thermal expansion of epoxy-fiberglass composite specimens

    International Nuclear Information System (INIS)

    The thermal expansion behavior of three epoxy-fiberglass composite specimens was measured from 20 to 1200C (70 to 2500F) using a fused quartz push-rod dilatometer. Billets produced by vacuum impregnating layers of two types of fiberglass cloth with an epoxy resin were core-drilled to produce cylindrical specimens. These were used to study expansion perpendicular and parallel to the fiberglass layers. The dilatometer is held at a preselected temperature until steady-state is indicated by stable length and temperature data. Before testing the composite specimens, a reliability check of the dilatometer was performed using a copper secondary standard. This indicated thermal expansion coefficient (α) values within +-2% of expected values from 20 to 2000C

  9. 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.

  10. 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...

  11. The effect of leucite crystallization and thermal history on thermal expansion measurement of dental porcelains

    Science.gov (United States)

    Khajotia, Sharukh Soli

    1997-12-01

    Objectives. Measurement of thermal expansion in glassy materials is complicated by thermal history effects. The purpose of this research was to determine whether the occurrence of structural relaxation in glassy materials, such as dental porcelains, and changes in porcelain leucite content could interfere with the accurate measurement of the coefficient of thermal expansion during the thermal expansion measurement itself. Methods. In a randomized design, thermal expansion specimens were fabricated using six commercial body porcelains and the leucite-containing Component No. 1 frit (Weinstein et al. patent, 1962), and subjected to one of the following heat treatments: a single heating run at 3sp°C/min in a conventional dilatometer followed by air quenching; three successive low-rate heating and cooling thermal expansion runs at 3sp°C/min in a conventional dilatometer; or three successive high-rate heating and cooling thermal expansion runs at 600sp°C/min in a laser dilatometer. The remaining specimens were left untreated and served as controls. Potential changes in porcelain leucite content were monitored via quantitative X-ray diffraction. Thermal expansion data for each run over a temperature range of 25-500sp°C and the leucite content of all specimens were subjected to repeated measures analysis of variance. Results. The thermal expansion coefficient measured on first slow heating was significantly lower than the values for succeeding low-rate heating and cooling runs in all materials (p $ 0.05). No significant effect of dilatometer thermal treatments on leucite content (p >$ 0.05) was shown for all materials studied using both dilatometers. Significance. The crystallization of additional amounts of leucite during thermal expansion runs can be ruled out as a possible interference in the determination of the thermal expansion coefficient of dental porcelain. Conventional dilatometer measurements exhibited structural relaxation during the first heating run, as

  12. 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)

  13. On the thermal expansion of nanohole free volume in perfluoropolyethers.

    Science.gov (United States)

    Consolati, G

    2005-05-26

    To determine the free volume in polymers, positron annihilation lifetime spectroscopy data are transformed into nanohole volumes by modeling the cavities as spheres or, more generally, using geometries assuming an isotropic thermal expansion. However, this guess could be unrealistic owing to the irregular shape of nanoholes and constrained movements of the macromolecules. In this work, it is shown that a comparison of hole-lattice theory with positron and dilatometric data for a homologous series of perfluoropolyethers supplies information on the anisotropic expansion of nanoholes; the relation between volume and typical unconstrained size of the cavities can be expressed by a power law with noninteger exponents. PMID:16852223

  14. 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.

  15. Magnetic susceptibilities and thermal expansion of artificial graphites

    International Nuclear Information System (INIS)

    Starting from measurements of the magnetic susceptibility made in the two principal directions of a graphite bar, the distribution function of the normals to the carbon planes in the crystallites has been evaluated. The effect of different variation in the manufacturing process on this crystalline anisotropy has been studied. From this crystalline anisotropy we have calculated the thermal expansion coefficient possessed by a compact mass of crystallites having exactly the same orientational anisotropy as the porous body consideration. The difference between this and the observed expansion coefficient leads to the determination of the expansion of the non-graphitic part of the mass which turns out to have a negative value and is also anisotropic. We have attempted to draw some conclusions from this result. (author)

  16. 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.

  17. Low-temperature thermal expansion of URhGe

    International Nuclear Information System (INIS)

    URhGe is one of the few ferromagnetic superconductors. At ambient pressure, it exhibits superconductivity with an upper critical field of B parallelbc2∼2 T. A characteristic feature of these superconductors is their strong magnetic anisotropy. In URhGe, the magnetic field can be used to tune the system to a metamagnetic transition where the magnetic moment reveals a sudden rotation in the crystallographic bc plane and superconductivity reappears at a magnetic field of B∼12 T with B parallel b. To study the anisotropic coupling of ferromagnetism and superconductivity to the crystal lattice, we performed thermal expansion measurements of a URhGe crystal in the temperature range 30 mKC∼10 K and confirm bulk superconductivity below Tsc∼0.2 K. The field dependence of the thermal expansion and first results of the uniaxial pressure dependences of Tsc are presented and discussed in comparison with related U-based superconductors.

  18. 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...

  19. Anomalous Viscosity, Resistivity, and Thermal Diffusivity of the Solar Wind Plasma

    OpenAIRE

    Verma, Mahendra K.

    1995-01-01

    In this paper we have estimated typical anomalous viscosity, resistivity, and thermal difffusivity of the solar wind plasma. Since the solar wind is collsionless plasma, we have assumed that the dissipation in the solar wind occurs at proton gyro radius through wave-particle interactions. Using this dissipation length-scale and the dissipation rates calculated using MHD turbulence phenomenology [{\\it Verma et al.}, 1995a], we estimate the viscosity and proton thermal diffusivity. The resistiv...

  20. 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.

  1. Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles

    International Nuclear Information System (INIS)

    It is shown that a ''nanofluid'' consisting of copper nanometer-sized particles dispersed in ethylene glycol has a much higher effective thermal conductivity than either pure ethylene glycol or ethylene glycol containing the same volume fraction of dispersed oxide nanoparticles. The effective thermal conductivity of ethylene glycol is shown to be increased by up to 40% for a nanofluid consisting of ethylene glycol containing approximately 0.3 vol% Cu nanoparticles of mean diameter <10 nm. The results are anomalous based on previous theoretical calculations that had predicted a strong effect of particle shape on effective nanofluid thermal conductivity, but no effect of either particle size or particle thermal conductivity

  2. Thermal expansion of neptunium-plutonium mixed oxides

    International Nuclear Information System (INIS)

    Thermal expansion of NpyPu1-yO2-x (y=0, 0.05, 0.1, 0.2 and 0.5) solid solutions was studied by high-temperature powder X-ray diffraction method at temperatures between room temperature and 1273 K in air and in He-8%H2 atmospheres. From the comparison of lattice parameters measured in air and in He-8%H2, all of these solid solutions appeared to be the stoichiometric composition when heated in air. The specimens heated in He-8%H2 became slightly hypo-stoichiometric above 1100 K, and the oxygen deficiency was estimated to be about 0.003 at 1273 K. The linear thermal expansion (LTE) of NpyPu1-yO2 decreased with increasing Np content at high temperatures, which was consistent with the fact that the LTE value of NpO2 was smaller than that of PuO2. The specific heat capacities at constant pressure Cp of these solid solutions were calculated from the thermodynamic relation Cp (J K-1 mol-1)=βV/κaγ using the measured thermal expansion data and estimated mechanical properties. Although the calculated Cp yielded about 20% larger values than those of the literature at high temperatures, the calculated Cp curves showed a similar temperature dependence to the literature one as well as a reasonable composition (Np content) dependence. (orig.)

  3. 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.

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. HAZARDS OF THERMAL EXPANSION FOR RADIOLOGICAL CONTAINER ENGULFED IN FIRE

    Energy Technology Data Exchange (ETDEWEB)

    Donna Post Guillen

    2013-05-01

    Fire accidents pose a serious threat to nuclear facilities. It is imperative that transport casks or shielded containers designed to transport/contain radiological materials have the ability to withstand a hypothetical fire. A numerical simulation was performed for a shielded container constructed of stainless steel and lead engulfed in a hypothetical fire as outlined by 10 CFR §71.73. The purpose of this analysis was to determine the thermal response of the container during and after the fire. The thermal model shows that after 30 minutes of fire, the stainless steel will maintain its integrity and not melt. However, the lead shielding will melt since its temperature exceeds the melting point. Due to the method of construction of the container under consideration, ample void space must be provided to allow for thermal expansion of the lead upon heating and melting, so as to not overstress the weldment.

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

    International Nuclear Information System (INIS)

    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

  10. 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.

  11. Thermal expansion and Grueneisen parameters of high Tc superconductors

    International Nuclear Information System (INIS)

    This paper reports that the thermal expansion of a material is of basic interest because it is part of the equation-of-state, that is the relation between pressure P, volume V and temperature T. It is of technical interest because of engineering requirements for compatibility of materials and associated estimates of stress and strain in structures where temperatures change. In the case of high-Tc superconductors, knowledge of their expansion behavior is complementary to knowledge of heat capacity at constant pressure Cp (or constant volume Cv) and the elastic stiffnesses cij in understanding the interaction energy and its volume dependence. Technically, it is also necessary for successful design of thin-film devices, cables, etc. Our state of knowledge of thermal expansion and elastic moduli, particularly of well-characterized low-porosity specimens and single crystals is still very inadequate but the present survey may help to pin-point the areas of agreement and some of the deficiencies in data

  12. 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.

  13. 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.

  14. Copper-based conductive composites with tailored thermal expansion.

    Science.gov (United States)

    Della Gaspera, Enrico; Tucker, Ryan; Star, Kurt; Lan, Esther H; Ju, Yongho Sungtaek; Dunn, Bruce

    2013-11-13

    We have devised a moderate temperature hot-pressing route for preparing metal-matrix composites which possess tunable thermal expansion coefficients in combination with high electrical and thermal conductivities. The composites are based on incorporating ZrW2O8, a material with a negative coefficient of thermal expansion (CTE), within a continuous copper matrix. The ZrW2O8 enables us to tune the CTE in a predictable manner, while the copper phase is responsible for the electrical and thermal conductivity properties. An important consideration in the processing of these materials is to avoid the decomposition of the ZrW2O8 phase. This is accomplished by using relatively mild hot-pressing conditions of 500 °C for 1 h at 40 MPa. To ensure that these conditions enable sintering of the copper, we developed a synthesis route for the preparation of Cu nanoparticles (NPs) based on the reduction of a common copper salt in aqueous solution in the presence of a size control agent. Upon hot pressing these nanoparticles at 500 °C, we are able to achieve 92-93% of the theoretical density of copper. The resulting materials exhibit a CTE which can be tuned between the value of pure copper (16.5 ppm/°C) and less than 1 ppm/°C. Thus, by adjusting the relative amount of the two components, the properties of the composite can be designed so that a material with high electrical conductivity and a CTE that matches the relatively low CTE values of semiconductor or thermoelectric materials can be achieved. This unique combination of electrical and thermal properties enables these Cu-based metal-matrix composites to be used as electrical contacts to a variety of semiconductor and thermoelectric devices which offer stable operation under thermal cycling conditions. PMID:24175870

  15. Nickel silicides and germanides: Phases formation, kinetics and thermal expansion

    International Nuclear Information System (INIS)

    Thin film germanide reactions are often declared to be the same as silicides reactions which were far more studied. In this paper, we present a comparative study of the phase formation and kinetics of nickel silicides and nickel germanides by several experimental techniques. The samples, composed of a nanometric nickel film (50 nm) deposited on silicon or germanium substrates, have been examined by several 'in situ' real time measurements: X-ray diffraction (XRD), and differential scanning calorimetry (DSC). These original DSC and 'in situ' XRD measurements have allowed us to determine the interfacial reaction rate for Ni2Si using a linear-parabolic law. During the relatively fast DSC ramp, the growth is mainly controlled by the interface while isothermal heat treatments lead to a mainly diffusion control. In contrary to what is usually found for nickel silicide and germanides, a simultaneous growth of Ni5Ge3 and NiGe has been found during 'in situ' XRD measurements. The different behavior between the Ni-Si system (sequential formation) and the Ni-Ge system (simultaneous formation) is interpreted in term of diffusion and interface controlled growth. In addition, in devices, the film stability and the stress of the silicides or the germanides can be affected by an important physical characteristic that is the anisotropy of dilatation coefficient. In this work, the lattice parameters and linear thermal expansion coefficients (γa, γb and γc) of the orthorhombic Ni(Si1-XGeX) compounds with 0 ≤ X ≤ 1 were determined from high temperature X-ray diffraction data (298-1073 K). A negative thermal expansion coefficient of the b lattice parameter of Ni(Si1-XGeX) for all the studied Ge concentration was observed: the magnitude of this negative thermal expansion coefficient is decreasing with increasing Ge concentration

  16. Thermal expansion of Al3Ce at very low temperatures

    International Nuclear Information System (INIS)

    Below 1 K the thermal expansion coefficient α of Al3Ce is negative and linearly approaches zero at 0 K. The pressure variation of the specific heat γT deduced from the initial variation of α is very strong: 0.62 J/K2 mole kbar. These properties cannot be interpreted with a single ion Kondo effect model but can be interpreted in terms of Fermi liquid (F.L.) behavior. The magnetostriction experiments clearly show the differences between an ordinary F.L. such as 3He and the F.L. built with a lattice of magnetic ions coupled with and by itinerant electrons

  17. 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.

  18. 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.

  19. Anomalous Thermal Behavior in Microcalorimeter Gamma-Ray Detectors

    International Nuclear Information System (INIS)

    Improving the resolution of gamma-ray detectors is important for many fields, including determinations of the Lamb shift in atoms with high atomic numbers, nuclear treaty verification, and environmental monitoring. High-purity germanium detectors are currently the tool of choice for precision gamma-ray spectroscopy. The resolution of these detectors is limited to about 500 eV full-width-at-half-maximum at 100 keV by Fano statistics. In comparison, low-temperature microcalorimeters can provide over an order of magnitude improvement in photon resolution. For instance, a gamma-ray microcalorimeter has achieved 25 eV FWHM resolution at 103 keV. These calorimeters consist of two components, a bulk absorber to stop incident gamma rays and a thermometer made from a thin film electrically biased in the superconducting-to-normal phase transition, called a Transition Edge Sensor, or TES. The standard absorber is bulk, superconducting tin. While tin has historically been the best performing absorber, pulse decays in Sn devices are much slower than predicted. We have begun a systematic study of absorber behavior in order to assess and improve response times. This study leverages two capabilities: the ability to microfabricate highly uniform arrays of gamma-ray detectors and the ability to read out many detectors in a single cool-down using SQUID multiplexer circuits. Here, we present two experiments to identify the source of thermal time constants. The first involves varying properties of the Sn absorber including purity, vendor, and crystal grain size. The second examines the role of the other elements in the microcalorimeter assembly.

  20. 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

  1. Thermal expansion behaviour of high performance PEEK matrix composites

    International Nuclear Information System (INIS)

    The thermal expansion behaviour of high performance poly(ether-ether-ketone) (PEEK) composites reinforced with micro- (8 μm) and nano- (39 nm) sized Al2O3 particles was studied. The distribution of Al2O3 in the PEEK matrix was studied by scanning electron microscopy and transmission electron microscopy. The coefficient of thermal expansion (CTE) was reduced from 58 x 10-6 deg. C-1 for pure PEEK to 22 x 10-6 deg. C-1 at 43 vol% micro-Al2O3 and to 23 x 10-6 deg. C-1 at 12 vol% nano-Al2O3 composites. For a given volume fraction, nano-Al2O3 particles are more effective in reducing the CTE of composites than that of micro-Al2O3 particles. This may be attributed to the much higher interfacial area or volume of nanocomposites than that of microcomposites. The upper limit and lower limit of the Schapery model separately fit closely the CTE of the micro- and nano-composites, respectively. Other models such as the rule of mixture and Kerner and Turner models were also correlated with the data

  2. 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.

  3. 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.

  4. 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...

  5. 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...

  6. Lattice dynamics and thermal expansion behavior in the metal cyanides M CN (M =Cu , Ag, Au): Neutron inelastic scattering and first-principles calculations

    Science.gov (United States)

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

    2016-04-01

    We report measurement of temperature dependence of phonon spectra in quasi-one-dimensional metal cyanides M CN (M =Cu , Ag, Au). Ab initio lattice dynamics calculations have been performed to interpret the phonon spectra as well as to understand the anomalous anisotropic thermal expansion behavior in these compounds. We bring out the differences in the phonon mode behavior to explain the differences in the thermal expansion behavior among the three compounds. The chain-sliding modes are found to contribute maximum to the negative thermal expansion along the "c " axis in the Cu and Ag compounds, while the same modes contribute to positive thermal expansion in the Au compound. Several low-energy transverse modes lead to positive thermal expansion in the a -b plane in all the compounds. The calculated Born-effective charges show that AuCN has a covalent nature of bonding, which results in least distortion as well as the least number of unstable modes among the three cyanides. This result is well correlated with the fact that the coefficient of negative thermal expansion along the c axis in AuCN is the smallest.

  7. 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.

  8. Radial thermal expansion of simulated binary alloy metallic fuel pin

    International Nuclear Information System (INIS)

    Metallic alloys based fuels are preferred fuels for future fast breeder reactors in India due to their high breeding ratio, short doubling time, higher fissile atom density, higher thermal conductivity, better neutronic properties as compared to the ceramic fuels like oxide, carbide or nitrides. Sodium bonded U- Pu- Zr ternary fuel with T91 cladding and metallic bonded U-15%Pu binary fuel with T91 cladding having a thin 'Zr' liner inside are the two proposed designs in this regard. In the latter case, 'Zr' layer acts as a barrier layer to prevent fuel clad chemical interaction. Since this fuel composition and the design of the fuel pin differ from the conventional ones, in depth studies are needed both from the reactor engineering and performance point of view. Thermal properties of fuels and cladding material and their mutual interaction (both chemical and mechanical) play a very important role in optimizing many design criteria. The present paper summarizes some of the data generated for thermal expansion of mechanical bonded fuel pin design in the radial direction with 'U' metal having two symmetrical cut design loaded inside the T91 cladding tube with the 'Zr' liner material in-between the fuel and the cladding. The mechanical bonding was carried out by swaging to ensure no gap between the fuel and clad on as fabricated fuel pin

  9. Harmonic and Anharmonic Properties of Diamond Structure Crystals with Application to the Calculation of the Thermal Expansion of Silicon. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Wanser, K. H.

    1981-01-01

    Silicon has interesting harmonic and anharmonic properties such as the low lying transverse acoustic modes at the X and L points of the Brillouin zone, negative Gruneisen parameters, negative thermal expansion and anomalous acoustic attenuation. In an attempt to understand these properties, a lattice dynamical model employing long range, nonlocal, dipole-dipole interactions was developed. Analytic expression for the Gruneisen parameters of several modes are presented. These expressions explain how the negative Gruneisen parameters arise. This model is applied to the calculation of the thermal expansion of silicon from 5K to 1700K. The thermoelastic contribution to the acoustic attenuation of silicon is computed from 1 to 300 K. Strong attenuation anomalies associated with negative thermal expansion are found in the vicinity of 17K and 125K.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate.

    Science.gov (United States)

    Fortes, A Dominic; Wood, Ian G; Alfè, Dario; Hernández, Eduardo R; Gutmann, Matthias J; Sparkes, Hazel A

    2014-12-01

    We have determined the crystal structure of ammonium carbonate monohydrate, (NH4)2CO3·H2O, using Laue single-crystal diffraction methods with pulsed neutron radiation. The crystal is orthorhombic, space group Pnma (Z = 4), with unit-cell dimensions a = 12.047 (3), b = 4.453 (1), c = 11.023 (3) Å and V = 591.3 (3) Å(3) [ρcalc = 1281.8 (7) kg m(-3)] at 10 K. The single-crystal data collected at 10 and 100 K are complemented by X-ray powder diffraction data measured from 245 to 273 K, Raman spectra measured from 80 to 263 K and an athermal zero-pressure calculation of the electronic structure and phonon spectrum carried out using density functional theory (DFT). We find no evidence of a phase transition between 10 and 273 K; above 273 K, however, the title compound transforms first to ammonium sesquicarbonate monohydrate and subsequently to ammonium bicarbonate. The crystallographic and spectroscopic data and the calculations reveal a quite strongly hydrogen-bonded structure (EHB ≃ 30-40 kJ mol(-1)), on the basis of H...O bond lengths and the topology of the electron density at the bond critical points, in which there is no free rotation of the ammonium cation at any temperature. The barrier to free rotation of the ammonium ions is estimated from the observed librational frequency to be ∼ 36 kJ mol(-1). The c-axis exhibits negative thermal expansion, but the thermal expansion behaviour of the a and b axes is ormal. PMID:25449618

  15. 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

  16. 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.

  17. 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.

  18. Thermal expansion and phase transitions of α-AlF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Morelock, Cody R.; Hancock, Justin C. [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2014-11-15

    ReO{sub 3}-type materials are of interest for their potential low or negative thermal expansion. Many metal trifluorides MF{sub 3} adopt the cubic form of this structure at elevated temperatures, which rhombohedrally distorts upon cooling. The rhombohedral form displays strong positive volume thermal expansion, but cubic MF{sub 3} display much lower and sometimes negative thermal expansion. The expansion behavior of α-AlF{sub 3} was characterized via synchrotron powder diffraction between 323 and 1177 K. α-AlF{sub 3} is rhombohedral at ambient conditions and displays strongly anisotropic thermal expansion. The volume coefficient of thermal expansion (CTE), α{sub V}, at 500 K is ∼86 ppm K{sup −1}, but the linear CTE along the c-axis, α{sub c}, is close to zero. α-AlF{sub 3} becomes cubic on heating to ∼713 K and continues to show positive thermal expansion above the phase transition (α{sub V}(900 K) ∼25 ppm K{sup −1}). - Graphical abstract: α-AlF{sub 3} has a rhombohedrally distorted ReO{sub 3}-type structure at ambient conditions and displays strongly positive volume thermal expansion that is highly anisotropic; the material becomes cubic on heating above ∼713 K and continues to show positive thermal expansion. - Highlights: • ReO{sub 3}-type α-AlF{sub 3} displays strongly anisotropic thermal expansion below 713 K. • α-AlF{sub 3} is cubic above 713 K and maintains positive (isotropic) thermal expansion. • The volume CTE changes from ∼86 to ∼25 ppm K{sup −1} on heating from 500 to 900 K. • The PTE of cubic α-AlF{sub 3} may be due to the presence of local octahedral tilts.

  19. 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.

  20. Thermal expansion measurements on Fe substituted URu2Si2

    Science.gov (United States)

    Ran, Sheng; Wolowiec, Christian; Jeon, Inho; Pouse, Naveen; Kanchanavatee, Noravee; Huang, Kevin; Maple, M. Brian; Dapron, Tyler; Williamsen, Mark; Snow, David; Martien, Dinesh; Spagna, Stefano

    The search for the order parameter of the hidden order (HO) phase in URu2Si2 has attracted an enormous amount of attention for the past three decades. The small antiferromagnetic moment of only ~0.03 μB/U found in the HO phase is too small to account for the entropy of ~0.2Rln(2) derived from the second order mean field BCS-like specific heat anomaly associated with the HO transition that occurs below To = 17.5 K. A first order transition from the HO phase to a large moment antiferromagnetic (LMAFM) phase occurs under pressure. We have recently demonstrated that tuning URu2Si2B>by substitution of Fe for Ru reproduces the temperature vs applied pressure phase diagram.and offers an opportunity to study the HO and LMAFM phases at atmospheric pressure. Motivated by this observation, we performed thermal expansion measurements on URu2-xFexSi2 single crystals for various values of x in both the HO and LMAFM regions of the phase diagram. Interesting preliminary results have emerged from these studies that shed light on the LMAFM phase and its relationship with the elusive HO phase. Research in UCSD is supported by US DOE BES under Grant No. DE-FG02-04-ER46105 (materials synthesis and characterization) and US NSF under Grant No. DMR-1206553 (low temperature measurements).

  1. Thermal expansion of C60 single crystals under pressure

    International Nuclear Information System (INIS)

    The thermal expansion and compressibility of C60 single crystals have been investigated by a newly developed capacitive dilatometer. The dilatometer was integrated in a high pressure cell and exposed to a hydrostatic pressure of maximal 0.85 GPa with He or Ar as pressure transmitting medium. The relative length change of the C60-samples was measured with a resolution of ΔL/L∼10-9. The crystals consist of weakly bonded C60-molecules which can rotate nearly free at room temperature. The gradual freezing-in of the rotational motions leads to a first order phase transition at 260 K and a glass transition at 90 K. The pressure dependence of these transitions was determined in a temperature range from 50 K to 325 K up to a pressure of 0.85 GPa. The phase transition at 260 K shows a positive pressure dependence of 174 K/GPa. The glass transition temperature first increases with 75 K/GPa under pressure, then it jumps discontinuously by 10 K at 0.15 GPa followed by a further increase with a slope of 54 K/GPa. The jump in the glass transition temperature at 0.15 GPa can be explained with an orientation-dependent interaction between the C60-molecules. (orig.)

  2. 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.

  3. 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.

  4. 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}.

  5. Laboratory measurements of the coefficient of thermal expansion of Olkiluoto drill core samples

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, U. [Swedish Cement and Concrete Research Inst., Boras (Sweden)

    2012-04-15

    The coefficient of thermal expansion and the wet density has been determined on 22 specimens from the ONKALO drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226, Olkiluoto, Finland. The coefficient of thermal expansion has been determined in the temperature interval 20-60 deg C. The results indicated that the thermal expansion was almost linear, and the coefficient of thermal expansion for the investigated specimens range between 3.2 and 14.4 x 10{sup -6} mm/mm deg C, and the wet density between 2,610 and 2,820 kg/m{sup 3}. The granite pegmatite has slightly lower coefficient of thermal expansion and wet density than gneissic rocks. (orig.)

  6. Laboratory measurements of the coefficient of thermal expansion of Olkiluoto drill core samples

    International Nuclear Information System (INIS)

    The coefficient of thermal expansion and the wet density has been determined on 22 specimens from the ONKALO drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226, Olkiluoto, Finland. The coefficient of thermal expansion has been determined in the temperature interval 20-60 deg C. The results indicated that the thermal expansion was almost linear, and the coefficient of thermal expansion for the investigated specimens range between 3.2 and 14.4 x 10-6 mm/mm deg C, and the wet density between 2,610 and 2,820 kg/m3. The granite pegmatite has slightly lower coefficient of thermal expansion and wet density than gneissic rocks. (orig.)

  7. Anomalously low thermal conductivity and thermoelectric properties of new cationic clathrates in the Sn-In-As-I system

    International Nuclear Information System (INIS)

    Single-crystal samples of cationic clathrates in the Sn-In-As-I system with different indium contents have been synthesized. Their crystal structure has been analyzed and their thermoelectric properties have been measured. These compounds are found to be n-type semiconductors with high absolute values of the Seebeck coefficient (S = 400–600 μV/K) and anomalously low thermal conductivity (κ ≤ 0.4 W/(m/K) at 300 K, which is characteristic of amorphous materials. The reasons for the anomalously low thermal conductivity of these semiconductors are discussed and ways for optimizing their thermoelectric properties are shown.

  8. Role of multiple helicity nonlinear interaction of tearing modes in dynamo and anomalous thermal transport in the Reversed Field Pinch

    International Nuclear Information System (INIS)

    A theory of magnetic fluctuation dynamics, the dynamo mechanism, and anomalous thermal transport in the Reversed Field Pinch is presented. Nonlinear generation of and coupling to m greater than or equal to 2 modes is advanced as an m=1 tearing modes sustain the magnetic configuration and stabilize themselves by lowering the safety factor on axis (q(0)) are elucidated. The nonlinear dynamics of resistive interchange modes is discussed. Stochastic magnetic field transport arguments are used to estimate anomalous thermal conductivity and confinement scalings

  9. Thermal expansion of CaFe2As2: Effect of cobalt doping and postgrowth thermal treatment

    Science.gov (United States)

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

    2013-08-01

    We report thermal expansion measurements on Ca(Fe1-xCox)2As2 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 different response of transition temperatures to the in-plane and the c-axis stress. These features, and consequently the inferred pressure derivatives, are very large, clearly and substantially exceeding those in the Ba(Fe1-xCox)2As2 family. For all transitions the c-axis response is dominant.

  10. Electrical properties and thermal expansion of strontium aluminates

    International Nuclear Information System (INIS)

    Highlights: • Sr3Al2O6, SrAl2O4 and Sr4Al14O25 ceramics are semiconductors. • Electrical conductivity is as low as 10−6−4×10−5 S/cm at 1273 K in dry air. • SrAl2O4 is a mixed conductor with predominant ionic conductivity. • Sr3Al2O6 shows significant contribution of protonic transport in wet atmospheres. • Average TECs vary in the range (8.5–11.1)×10−6 K−1 and are p(O2)-independent. - Abstract: Strontium aluminate ceramics, including Sr3Al2O6, SrAl2O4 and Sr4Al14O25, synthesized by glycine–nitrate combustion and sintered at 1773 K in air, were characterized by thermal analysis, dilatometry and electrical measurements in controlled atmospheres. All studied strontium aluminates are semiconductors with electrical conductivities as low as 10−6−4×10−5 S/cm at 1273 K in dry air. Electrical measurements in controlled atmospheres in combination with ion transference number determination demonstrated that SrAl2O4 is a mixed conductor with predominant ionic conductivity and increasing n-type and p-type electronic contributions under highly reducing and oxidizing conditions, respectively. While the behavior of electrical conductivity of Sr3Al2O6 in dry atmospheres was qualitatively similar to that of SrAl2O4, a significant increase of conductivity in wet atmospheres was attributed to a protonic contribution to electrical conduction, in correlation with thermogravimetric data and the tendency of this material to form a hydrogarnet at low temperatures. The average thermal expansion coefficients of strontium aluminates, (8.5–11.1)×10−6 K−1 at 333–1373 K, increase with increasing strontium content in the sequence Sr4Al14O25 < SrAl2O4 < Sr3Al2O6 and are essentially independent of oxygen partial pressure

  11. 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

  12. 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)

  13. Thermal expansion of PBX 9501 and PBX 9502 plastic-bonded explosives

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Darla Graff [Los Alamos National Laboratory; Brown, Geoff W [Los Alamos National Laboratory; Deluca, Racci [Los Alamos National Laboratory; Giambra, Anna [Los Alamos National Laboratory; Sandstrom, Mary [Los Alamos National Laboratory

    2009-01-01

    Two applications of thermal expansion measurements on plastic-bonded explosive (PBX) composites are described. In the first dilatometer application, thermal expansion properties of HMX-based PBX 9501 are measured over a broad thermal range that includes glass and domain-restructuring transitions in the polymeric binder. Results are consistent with other thermal measurements and analyses performed on the composite, as well as on the binder itself. The second application used the dilatometer to distinguish the reversible and irreversible components of thermal expansion in PBX 9502, a TATB-based explosive. Irreversible expansion of the composite is believed to derive from the highly-anisotropic coefficient of thermal expansion (CTE) values measured on single T A TB crystals, although the mechanism is not well understood. Effects of specimen density, thermal ramp rate, and thermal range variation (warm first or cold first) were explored, and the results are presented and discussed. Dilatometer measurements are ongoing towards gaining insight into the mechanism(s) responsible for PBX 9502 irreversible thermal expansion.

  14. Thermally-induced expansion in the 8 GeV/c $\\pi^{-} + ^{197}Au$ reaction

    CERN Document Server

    Lefort, T; Botvina, A S; Durand, D; Kwiatkowski, K K; Hsi, W C; Pienkowski, L; Back, B B; Breuer, H; Gushue, S; Korteling, R G; Martin, R L E; Ramakrishnan, E; Remsberg, L P; Rowland, D; Ruangma, A; Viola, V E; Winchester, E M; Yennello, S J

    2000-01-01

    Fragment kinetic energy spectra for reactions induced by 8.0 GeV/c order to deduce the possible existence and influence of thermal expansion. The average fragment kinetic energies are observed to increase systematically with fragment charge and to be nearly independent of excitation energy. Comparison of the data with statistical multifragmentation models indicates the onset of extra collective thermal expansion near an excitation energy of E*/A expansion observed in heavy-ion-induced reactions, consistent with the interpretation that the latter expansion may be driven primarily by dynamical effects such as compression/decompression.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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)

  4. 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.

  5. 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.

  6. Thermal expansion of Ti5Si3 with Ge, B, C, N, or O additions

    International Nuclear Information System (INIS)

    The crystallographic thermal expansion coefficients of Ti5Si3 from 20 to 1000 degree sign C as a function of B, C, N, O, or Ge content were measured by high-temperature x-ray diffraction using synchrotron sources at Cornell University (Cornell High Energy Synchrotron Source; CHESS) and Argonne National Laboratory (Advanced Photon Source; APS). Whereas the ratio of the thermal expansion coefficients along the c and a axes was approximately 3 for pure Ti5Si3, this ratio decreased to about 2 when B, C, or N atoms were added. Additions of O and Ge were less efficient at reducing this thermal expansion anisotropy. The extent by which the thermal expansion was changed when B, C, N, or O atoms were added to Ti5Si3 correlated with their expected effect on bonding in Ti5Si3. (c) 2000 Materials Research Society

  7. 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…

  8. 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.

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

    International Nuclear Information System (INIS)

    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

  10. 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...

  11. Impact on Nonlinear Vertical Variation of GNSS Reference Stations Caused by Thermal Expansion

    Directory of Open Access Journals (Sweden)

    JIANG Weiping

    2015-05-01

    Full Text Available Thermal expansion of GPS monuments and nearby bedrock could result in vertical changes in the coordinate time series of GNSS reference stations. In this paper, an improved method was developed to compute the magnitude of vertical variations caused by thermal expansion. Firstly, we calculated the effect on GPS monument and bedrock caused by thermal expansion based on land surface temperature data of GNSS reference stations and thermal expansion model. Secondly, we estimated the circular frequencies, amplitudes and phases using the method of least squares fitting instead of the current method which estimated only the amplitudes and phases information. Finally, we studied the periodic characteristics of the vertical variations caused by our modified thermal expansion model. Through analyzing the results of 9 representative IGS stations, we concluded that thermal expansion of GPS monuments and nearby bedrock could result in vertical variations of GNSS stations. The maximum variations could reach up to 0.57 mm and 1.85 mm at these stations respectively. The vertical variation caused by thermal expansion exhibited both annual and semiannual characteristics, which could explain 11.2% and 3.3% of the total annual and semi-annual variations in the up component of the coordinate time series respectively, and the magnitudes became larger with the increasing of their latitudes. Meanwhile, the amplitudes of the annual variations were much larger than that of the semi-annual variations. Meanwhile, some other small period (about 51 days was also detected at some of these stations. In addition, we chose 107 IGS reference stations and computed the annual amplitudes and phases caused by thermal expansion of all these stations based on the method aforesaid. The results show that the maximum annual amplitude can reach to 3.3 mm, and their magnitudes show positive correlation with their latitudes prominently.

  12. 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.

  13. Anisotropy of thermal expansion and electric resistance of cermet germanium telluride

    International Nuclear Information System (INIS)

    Anisotropies of thermal expansion α and electric resistance ρ of cermet germanium telluride were investigated depending on pressing conditions. It is shown that anisotropy of cermet germanium telluride depends sufficiently on pressing conditions with respect to thermal expansion and electric resistance. It was established that anisotropy of the cermet germanium telluride was strongly affected by pressing force and temperature. Anisotropy of the cermet germanium telluride also depends with respect to α and ρ on the material and size of the mould

  14. 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

  15. 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.

  16. 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

  17. Development of brazed connections stable in thermal cycling for materials with different coefficients of thermal expansion

    International Nuclear Information System (INIS)

    The need for temperature change resestance (in the region of 50 to 10000C) of joints between different materials, especially soldered joints between pipes consisting of materials having very different thermal expansion coefficients, gives rise to great engineering problems. If these joints are stressed by temperature changing processes, such high tensions can occur in the joint zone, mainly tensile stress, that the joint may be destroyed and thus of no use. A new construction was developed as auxiliary measure in which the tensile stress in reduced to a great extent. In this construction, both pipe ends which are inserted into are another to be joined, have several axial slits in the region of the depth of insertion. The assembly of this construction and its testing are described. Application tips to create this kind of joints between non-metallic materials are given. (orig.)

  18. 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.

  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. Measurement of thermal expansion by double extensometers between 290 K and 5 K

    International Nuclear Information System (INIS)

    We developed an apparatus for the measurement of thermal expansion using double extensometers between 290 K and 5 K. The sample was set vertically in a variable temperature cryostat and its expansion or contraction was measured using the extensometers directly attached to the sample. The temperatures of the samples were controlled with He gas from the cryostat and a heater wounded around the sample chamber. In order to ensure the validity of this system, we measured the thermal expansion of Ag plates with different thicknesses. As a result, the measured thermal expansion curves were confirmed to show good agreement with each other for Ag plates with thickness of 3 mm, 1 mm and 0.2 mm. Good agreement was also ensured for the curves measured during both the cooling and warming processes. These results suggest that our system will be applicable for superconducting composites with a cross-section as small as 1 mm2

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

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

    Science.gov (United States)

    Takezawa, Akihiro; Kobashi, Makoto; Kitamura, Mitsuru

    2015-07-01

    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.

  9. Effect of gamma irradiation on density and thermal expansion changes of uniaxial oriented LLDPE

    International Nuclear Information System (INIS)

    Complete text of publication follows. It is well known that gamma irradiation induces cross-linking in the amorphous phase of isotropic polyethylene, or chain scission in highly oriented fibers and films. Thermomechanical behavior and values of density are the reflection of the changes induced by gamma irradiation. Namely, scission of macromolecules, in general, increases thermal expansion coefficient and decreases density and vice versa. On the other hand, as it is well known, the thermal expansion behavior of oriented polymers shows marked anisotropy. It was found that many highly oriented polymers show a negative coefficient of thermal expansion in the draw direction and a positive coefficient in the transverse direction. It has been suggested that, apart from any intrinsic crystalline contribution, a significant part of the negative thermal expansion coefficients obtained for highly oriented polymers arises from the effect of entropy internal stresses in the amorphous regions. From our previous work, the thermal coefficients in draw direction of irradiated samples rise in the glass transition temperature range and it was related to the effects of cross-linking in the amorphous phase of LDPE. In our present work we observed initial decrease in density with absorbed dose, up to 35 kGy, and subsequent increase up to a dose of 500 kGy. The observed increase in thermal expansion coefficient followed the changes in density and is related to the parallel processes of chain scission and net cross-linking in the amorphous phase of LLDPE, induced by gamma irradiation

  10. 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

  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. 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

  13. 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.

  14. 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.

  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. 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.

  17. 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

  18. The Penn State Nodal Expansion Transient Analysis Technique with thermal-hydraulic feedback

    International Nuclear Information System (INIS)

    The nuclear engineering department of the Pennsylvania State University has under development a nodal neutron kinetics code. The PEnn State Nodal Expansion TRansient Analysis TEchnique (PENETRATE) performs two-group, three-dimensional nodal kinetics calculations using the nodal expansion method (NEM). The focus of this discussion is its performance in the solution of the Langenbuch-Maurer-Werner light water rector (LMW LWR) problem. This transient requires an accurate model of both control rod motion and coupled thermal-hydraulic feedback

  19. Non-contact measurement of linear thermal expansion coefficients of solid materials by infrared image correlation

    International Nuclear Information System (INIS)

    A new non-contact optical method (IIC, infrared image correlation) for the determination of the coefficients of thermal expansion of solid materials is presented. The proposed method is based on performing a digital image correlation between thermal images recorded at different temperatures by means of an infrared camera. It allows the coefficient of thermal expansion of both isotropic and anisotropic solid materials to be determined by measuring simultaneously the fractional increase in length and the actual thermal field over a small region of interest in which a dual-emissivity stochastic speckle pattern has been created. The results reported in this paper prove the effectiveness of the proposed method that can be applied either to carry out reference measurements in laboratory or to evaluate thermal stresses and strains on structural components in-field. (paper)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

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

    Science.gov (United States)

    Inoue, Daiki; Kaido, Daisuke; Yoshikawa, Yuta; Minegishi, Mitsuyuki; Matsumoto, Koichi; Abe, Satoshi

    2014-12-01

    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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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).

  13. 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.

  14. Tunable blue laser compensates for thermal expansion of the medium in holographic data storage.

    Science.gov (United States)

    Tanaka, Tomiji; Sako, Kageyasu; Kasegawa, Ryo; Toishi, Mitsuru; Watanabe, Kenjiro

    2007-09-01

    A tunable laser optical source equipped with wavelength and mode-hop monitors was developed to compensate for thermal expansion of the medium in holographic data storage. The laser's tunable range is 402-409 nm, and supplying 90 mA of laser diode current provides an output power greater than 40 mW. The aberration of output light is less than 0.05 lambdarms. The temperature range within which the laser can compensate for thermal expansion of the medium is estimated based on the tunable range, which is +/-13.5 degrees C for glass substrates and +/-17.5 degrees C for amorphous polyolefin substrates. PMID:17805360

  15. 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 ℃.

  16. Identity period and thermal expansion coefficient of rare earth hexaborides at temperatures of 5-320 K

    International Nuclear Information System (INIS)

    For five compounds of MB6 (M = Ce, Pr, Nd, Gd, Tb) hexaborides one studied experimentally temperature dependences of crystalline lattice period and linear thermal expansion coefficient. One determined lattice constituents of thermal expansion coefficient of hexaborides. On the basis of analysis of temperature curves one made conclusion that processes of splitting of energy levels governing the Schottky contribution into thermal capacity did not practically affect expansion of hexaborides

  17. Computational investigation on thermal expansivity behavior of Al 6061-SiC-Gr hybrid metal matrix composites

    Science.gov (United States)

    Mohan Krishna, S. A.; Shridhar, T. N.; Krishnamurthy, L.

    2015-08-01

    Metal matrix composites (MMCs) have been regarded as one of the most principal classifications in composite materials. The thermal characterization of hybrid MMCs has been increasingly important in a wide range of applications. The coefficient of thermal expansion is one of the most important properties of MMCs. Since nearly all MMCs are used in various temperature ranges, measurement of coefficient of thermal expansion (CTE) as a function of temperature is necessary in order to know the behavior of the material. In this research paper, the evaluation of thermal expansivity has been accomplished for Al 6061, silicon carbide (SiC) and Graphite (Gr) hybrid MMCs from room temperature to 300°C. Aluminum (Al)-based composites reinforced with SiC and Gr particles have been prepared by stir casting technique. The thermal expansivity behavior of hybrid composites with different percentage compositions of reinforcements has been investigated. The results have indicated that the thermal expansivity of the different compositions of hybrid MMCs decreases by the addition of Gr with SiC and Al 6061. Few empirical models have been validated for the evaluation of thermal expansivity of composites. Using the experimental values namely modulus of elasticity, Poisson's ratio and thermal expansivity, computational investigation has been carried out to evaluate the thermal parameters namely thermal displacement, thermal strain and thermal stress.

  18. Effect of microstructural banding in hot-work tool steel on thermal expansion anisotropy

    OpenAIRE

    B. Pawłowski; P. Bała; R. Dziurka; J. Krawczyk

    2013-01-01

    Purpose: The objective of the present work was to study the effect of the microstructural banding on the thermal anisotropy of hot-work tool steel used for die for aluminium alloy die-casting. In particular, the major purpose of this research was to find possible correlation between geometrically oriented thermal expansion coefficient values and the presence of number of parallel cracks on the working surface of die.Design/methodology/approach: The studies were performed on the specimens whic...

  19. 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.

  20. Tailored functional materials with controlled thermal expansion and excellent thermal conductivity

    International Nuclear Information System (INIS)

    Engineering materials are mainly used for structures. Therefore high-strength, stiffness and sufficient toughness are of prime importance. For a long time engineers thought first in terms of metals. Material scientists developed alloys tailored to the needs of industry. Ceramics are known to be brittle and therefore not suitable in the first place for structural application under stress. Polymers with their low modulus became attractive when reinforced with high-strength fibres. Composites processed by polymer, metal or ceramic matrices and high-strength reinforcements have been introduced into many sectors of industry. Engineering materials for structural applications fulfil a function: they withstand high stresses, temperatures, fatigue, creep etc. But usually we do not call them functional materials. Functional materials serve applications apart from classical engineering fields. Electricity conducting materials, semi conductors, memory alloys and many others are called functional materials. Because of the fact that the basic physical properties cannot be changed in single-phase materials, the combination of two and more materials with different properties lead to components with new and tailored properties. A few techniques for preparation are described as powder metallurgy, infiltration of prepegs and compaction of precoated fibres/particles. The lecture is focusing on carbon fibre/particle reinforced Metal Matrix Materials. The achievable properties, in particular the thermal conductivity originating from the base materials is depending on the orientation of the fibres and interfacial contacts in the composite. The carefully controlled expansion behaviour is the most important property to use the material as a heat sink in electronic assemblies. (author)

  1. Zero Thermal Expansion in a Nanostructured Inorganic-Organic Hybrid Crystal

    International Nuclear Information System (INIS)

    There are very few materials that exhibit zero thermal expansion (ZTE), and of these even fewer are appropriate for electronic and optoelectronic applications. We find that a multifunctional crystalline hybrid inorganic-organic semiconductor, β-ZnTe(en)0.5 (en denotes ethylenediamine), shows uniaxial ZTE in a very broad temperature range of 4-400 K, and concurrently possesses superior electronic and optical properties. The ZTE behavior is a result of compensation of contraction and expansion of different segments along the inorganic-organic stacking axis. This work suggests an alternative route to designing materials in a nanoscopic scale with ZTE or any desired positive or negative thermal expansion (PTE or NTE), which is supported by preliminary data for ZnTe(pda)0.5 (pda denotes 1,3-propanediamine) with a larger molecule

  2. 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

  3. 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.

  4. 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.

  5. 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.

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

    DEFF Research Database (Denmark)

    Sigmund, Ole; Torquato, S.

    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 therma...

  7. Thermal Expansion and Electrical Resistivity Studies of Nickel and ARMCO Iron at High Temperatures

    Science.gov (United States)

    Palchaev, D. K.; Murlieva, Zh. Kh.; Gadzhimagomedov, S. H.; Iskhakov, M. E.; Rabadanov, M. Kh.; Abdulagatov, I. M.

    2015-11-01

    The electrical resistance, ρ (T), and thermal expansion coefficient, β (T), of nickel and ARMCO iron have been simultaneously measured over a wide temperature range from (300 to 1100) K. The well-known standard four-probe potentiometric method was used for measurements of the electrical resistance. The thermal expansion coefficient was measured using the quartz dilatometer technique. Both techniques were combined in the same apparatus for simultaneous measurements of the electrical resistance and TEC for the same specimen. The combined expanded uncertainty of the electrical resistance and thermal expansion coefficient measurements at the 95 % confidence level with a coverage factor of k = 2 is estimated to be 0.5 % and (1.5 to 4.0) %, respectively. The distinct ρ (T) scattering contribution (phonon ρ _{ph}, magnetic ρ m, and residual ρ S) terms were separated and extracted from the measured total resistivity. The physical nature and details of the temperature dependence of the electrical resistance of solid materials and correct estimations of the contributions of various scattering mechanisms to the measured total resistivity were discussed in terms of the anharmonic effect. We experimentally found simple, universal, physically based, semiempirical linear correlations between the kinetic coefficient (electrical resistance) and a thermodynamic (equilibrium) property, the thermal expansion coefficient, of solid materials. The developed, physically based, correlation model has been successfully applied for nanoscale materials (ferromagnetic nickel nanowire). A new s-d-exchange interaction energy determination technique has been proposed.

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

    International Nuclear Information System (INIS)

    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.

  9. Investigation of Thermal Expansion and Physical Properties of Carbon Nanotube Reinforced Nanocrystalline Aluminum Nanocomposite

    Science.gov (United States)

    Sharma, Manjula; Sharma, Vimal

    2016-02-01

    Carbon nanotube (CNT) reinforced nanocrystalline aluminum matrix composites are fabricated by a simple and effective physical mixing method with sonication. In this study, the microstructural characterisations and property evaluations of the nanocomposites were performed. The structural characterisations revealed that CNTs were dispersed, embedded, and anchored within the metal matrix. A strong interfacial adhesion appeared between CNTs and nanocrystalline aluminum as a result of the fabrication process. Raman and Fourier transform infrared spectroscopic studies also confirmed the surface adherence of CNTs with nanocrystalline aluminum matrix during the fabrication process. Thermal expansion behaviour of CNT-reinforced aluminum matrix composites was investigated up to 240°C using a dilatometer. The coefficient of thermal expansion of the nanocomposites decreased continuously with the increasing content of CNTs. The maximum reduction of 82% was found for 4 wt% CNTs in the nanocomposite. The coefficient of thermal expansion variation with CNTs was also compared with the predictions from the thermoelastic models. The expansion behaviour of the nanocomposites was correlated to the microstructure, internal stresses, and phase segregations. The electrical and thermal conductivity was also studied and was observed to decrease for all reinforced CNT weight fractions.

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

    Science.gov (United States)

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

    2012-02-01

    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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Waste Package Outer Barrier Stress Due to Thermal Expansion with Various Barrier Gap Sizes

    International Nuclear Information System (INIS)

    The objective of this activity is to determine the tangential stresses of the outer shell, due to uneven thermal expansion of the inner and outer shells of the current waste package (WP) designs. Based on the results of the calculation ''Waste Package Barrier Stresses Due to Thermal Expansion'', CAL-EBS-ME-000008 (ref. 10), only tangential stresses are considered for this calculation. The tangential stresses are significantly larger than the radial stresses associated with thermal expansion, and at the WP outer surface the radial stresses are equal to zero. The scope of this activity is limited to determining the tangential stresses the waste package outer shell is subject to due to the interference fit, produced by having two different shell coefficients of thermal expansions. The inner shell has a greater coefficient of thermal expansion than the outer shell, producing a pressure between the two shells. This calculation is associated with Waste Package Project. The calculations are performed for the 21-PWR (pressurized water reactor), 44-BWR (boiling water reactor), 24-BWR, 12-PWR Long, 5 DHLW/DOE SNF - Short (defense high-level waste/Department of Energy spent nuclear fuel), 2-MCO/2-DHLW (multi-canister overpack), and Naval SNF Long WP designs. The information provided by the sketches attached to this calculation is that of the potential design for the types of WPs considered in this calculation. This calculation is performed in accordance with the ''Technical Work Plan for: Waste Package Design Description for SR (Ref.7). The calculation is documented, reviewed, and approved in accordance with AP-3.12Q, Calculations (Ref.1)

  16. 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.

  17. 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.

  18. 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.

  19. Effect of microstructural banding in hot-work tool steel on thermal expansion anisotropy

    Directory of Open Access Journals (Sweden)

    B. Pawłowski

    2013-01-01

    Full Text Available Purpose: The objective of the present work was to study the effect of the microstructural banding on the thermal anisotropy of hot-work tool steel used for die for aluminium alloy die-casting. In particular, the major purpose of this research was to find possible correlation between geometrically oriented thermal expansion coefficient values and the presence of number of parallel cracks on the working surface of die.Design/methodology/approach: The studies were performed on the specimens which were cut from the failed prematurely die along the three axes of the coordinate system (X-axe was parallel to the cracks direction. Macroscopic, metallographic, SEM and dilatometric examination were made.Findings: Surface cracks of die are parallel to the microstructural banding orientation. Differences in the values of thermal expansion coefficient determined along the three axes of the coordinate system probably promote cracks propagation direction.Research limitations/implications: Studies were performed on the single prematurely failed die for economic reason. This work findings should be compared to the similar examinations results obtained for the another failed dies.Practical implications: The incorrect microstructural banding orientation of the die core and related differences in the values of thermal expansion coefficient promote crack propagation.Originality/value: This show the relationship between microstructural banding and the thermal anisotropy of hot-work tool steel used for die for aluminium alloy die-casting.

  20. 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.

  1. 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.

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

    International Nuclear Information System (INIS)

    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

  3. 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.

  4. 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.

  5. Low-temperature X-ray diffraction studies of thermal expansion in LiB3O5 single crystals

    International Nuclear Information System (INIS)

    Lattice parameters of a nonlinear optical LiB3O5 crystal were measured by X-ray diffraction method in the temperature range 80-300 K. The values of thermal expansion coefficients along the main crystallographic axes were determined from the temperature dependence of the crystallographic parameters. A pronounced anisotropy in thermal expansion was established in the temperature range studied

  6. 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.

  7. 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)

  8. 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.

  9. 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.

  10. 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.

  11. The influence of thermal expansion of a composite material on embedded polarimetric sensors

    International Nuclear Information System (INIS)

    Some of the most critical issues of the influence of the thermal expansion of composite materials on embedded polarimetric sensors for measurements of strain and temperature are studied in this paper. A composite material sample with polarimetric fiber sensors embedded in two distinct layers of a multi-layer composite structure is fabricated and characterized. The polarimetric fiber sensors used in this study are based on Panda type fiber and polarization maintaining photonic crystal fiber (PM-PCF). The temperature sensitivities of polarimetric fiber sensors with acrylate buffer coated and buffer stripped polarization maintaining optical fibers are measured in free space and compared with those for sensors embedded in the composite material. It is found that a polarimetric fiber sensor with an acrylate coating embedded in the composite material shows the same response as the one in free space while the coating stripped fiber polarimetric sensor shows significant temperature sensitivity when embedded in the composite material. This is due to the stress induced change in birefringence created by the thermal expansion of the composite material, while in the case of a buffer coated fiber, the effect is considerably reduced as the thermal stress is largely eliminated by the buffer coating. The results obtained in this study demonstrated that thermal expansion of the composite material is the main source of error in strain and temperature measurement using embedded polarimetric fiber sensors and that more accurate strain and temperature measurements can be obtained with buffer coated polarimetric fiber sensors

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. Volume thermal expansivity for lower mantle region of earth under adiabatic condition

    International Nuclear Information System (INIS)

    A reciprocal equation for the volume dependence of Anderson–Grüneisen parameter has been proposed. This equation has been found to fit the seismic data for the lower mantle region of the Earth. We have developed a new expression for predicting the values of density (volume) dependence of volume thermal expansivity under adiabatic conditions based on the reciprocal equation for the volume dependence of Anderson–Grüneisen parameter. It is found that our relationship fits well the seismic data on volume thermal expansivity for lower mantle corresponding to a wide range of pressures (0–135.75 GPa). These equations thus proposed are found to be consistent with the thermodynamic constraints

  17. 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

  18. 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.

  19. 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

  20. Thermal expansion of CaFe2As2: effect of annealing and cobalt doping

    Science.gov (United States)

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

    2013-03-01

    Careful choice of Co concentration and annealing/quenching temperature in the Ca(Fe1-xCox)2As2 series allows for tuning the ground state of the from orthorhombic-antiferromagnetic to superconducting to collapsed tetragonal.In this talk temperature-dependent, c-axis, thermal expansion measurements on several sets of Co-doped CaFe2As2 single crystals that were subjected to a variety of annealing conditions will be presented. These samples were chosen to cover all salient regions of the 3D x -Tanneal - T phase diagram. The thermal expansion signatures of different types of phase transitions observed in these series will be discussed and comparison with the other measurements will be made. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under contract No. DE-AC02-07CH11358.

  1. 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.

  2. 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.

  3. 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.

  4. Thermal expansion and solubility limits of cerium-doped lanthanum zirconates

    International Nuclear Information System (INIS)

    Highlights: ► Ce-doped La2Zr2O7 was prepared by the coprecipitation–calcination method. ► In situ HT-XRD measurements revealed that is much stable than 8YSZ at high temperature. ► Its thermal expansion is better than 8YSZ. - Abstract: A series of compositions with the general formula La2(Zr2−2xCe2x)O7 (0 ≤ x ≤ 0.75) were prepared by the coprecipitation–calcination method and characterized by powder XRD. The composition of prepared ceramic materials changed from single pyrochlore structure to the mixture with pyrochlore structure and fluorite structure as x increased. The lattice parameters decreased firstly and then increased while the amount of Ce4+ at 298 K was increased. The thermal expansion coefficient of La2Zr2O7 was improved by a number of Ce4+ adoptions at high temperature.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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

  11. History-dependent thermal expansion in NbO{sub 2}F

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Josefsberg, Ryan E.; Gallington, Leighanne C.; Morelock, Cody R.; Monaco, Christopher M. [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States)

    2014-05-01

    Materials with cubic ReO{sub 3}-type structures are of interest for their low or negative thermal expansion characteristics. TaO{sub 2}F is known to display almost zero thermal expansion over a wide temperature range. On heating NbO{sub 2}F, its volume coefficient of thermal expansion decreases from ∼+45 ppm K{sup −1} at 100 K to almost zero at 400 K. NbO{sub 2}F is cubic between 100 and 500 K. Samples of “NbO{sub 2}F” prepared by the digestion of Nb{sub 2}O{sub 5} in aqueous HF followed by mild drying contain hydroxyl defects and metal vacancies. On heating, they can undergo irreversible chemical changes while maintaining a cubic ReO{sub 3}-type structure. The possibility of hydroxyl defect incorporation should be considered when preparing oxyfluorides for evaluation as battery materials. - Graphical abstract: “NbO{sub 2}F” prepared by the digestion of Nb{sub 2}O{sub 5} in HF contains cation vacancies and hydroxyl groups. It undergoes irreversible changes on heating to low temperatures, unlike NbO{sub 2}F prepared by the solid state reaction of Nb{sub 2}O{sub 5} and NbF{sub 5}. - Highlights: • The digestion of Nb{sub 2}O{sub 5} in aqueous HF followed by mild drying does not produce NbO{sub 2}F. • The ReO{sub 3}-type product from the HF digestion of Nb{sub 2}O{sub 5} contains metal vacancies and hydroxyl. • The thermal expansion coefficient of NbO{sub 2}F decreases on heating and approaches zero at ∼400 K.

  12. 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)

  13. 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 ...

  14. History-dependent thermal expansion in NbO2F

    International Nuclear Information System (INIS)

    Materials with cubic ReO3-type structures are of interest for their low or negative thermal expansion characteristics. TaO2F is known to display almost zero thermal expansion over a wide temperature range. On heating NbO2F, its volume coefficient of thermal expansion decreases from ∼+45 ppm K−1 at 100 K to almost zero at 400 K. NbO2F is cubic between 100 and 500 K. Samples of “NbO2F” prepared by the digestion of Nb2O5 in aqueous HF followed by mild drying contain hydroxyl defects and metal vacancies. On heating, they can undergo irreversible chemical changes while maintaining a cubic ReO3-type structure. The possibility of hydroxyl defect incorporation should be considered when preparing oxyfluorides for evaluation as battery materials. - Graphical abstract: “NbO2F” prepared by the digestion of Nb2O5 in HF contains cation vacancies and hydroxyl groups. It undergoes irreversible changes on heating to low temperatures, unlike NbO2F prepared by the solid state reaction of Nb2O5 and NbF5. - Highlights: • The digestion of Nb2O5 in aqueous HF followed by mild drying does not produce NbO2F. • The ReO3-type product from the HF digestion of Nb2O5 contains metal vacancies and hydroxyl. • The thermal expansion coefficient of NbO2F decreases on heating and approaches zero at ∼400 K

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

    OpenAIRE

    Fahrmann Michael G.; Srivastava S. Krishna; Pike Lee M.

    2014-01-01

    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 t...

  17. 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.

  18. 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

  19. 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.

  20. A study on the thermal expansion characteristics of simulated spent fuel and simulated DUPIC fuel

    International Nuclear Information System (INIS)

    Thermal expansions of simulated spent PWR fuel and simulated DUPIC fuel were studied using a dilatometer in the temperature range from 298 to 1900 K. The densities of simulated spent PWR fuel and simulated DUPIC fuel used in the measurement were 10.28 g/cm3 (95.35 % of TD) and 10.26 g/cm3 (95.14 % of TD), respectively. Their linear thermal expansions of simulated fuels are higher than that of UO2, and the difference between these fuels and UO2 increases progressively as temperature increases. However, the difference between simulated spent PWR fuel and simulated DUPIC fuel can hardly be observed. For the temperature range from 298 to 1900 K, the values of the average linear thermal expansion coefficients for simulated spent PWR fuel and simulated DUPIC fuel are 1.391 10-5 and 1.393 10-5 K-1, respectively. As temperature increases to 1900 K, the relative densities of simulated spent PWR fuel and simulated DUPIC fuel decrease to 93.81 and 93.76 % of initial densities at 298 K, respectively

  1. 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

  2. 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.

  3. Thermal Effects in Jaynes-Cummings Model Derived with Low-Temperature Expansion

    Science.gov (United States)

    Azuma, Hiroo; Ban, Masashi

    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 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 dependence of the period.

  4. 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...

  5. 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.

  6. 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.

  7. Experimental determinations of the pre- and postirradiation thermal transport and thermal expansion properties of simulated fuel rods for an HTGR

    International Nuclear Information System (INIS)

    The thermal conductivity, electrical resistivity, coefficient of thermal expansion, volume, and Seebeck coefficient of simulated fuel rods for a high-temperature gas-cooled reactor (HTGR) were measured before and after neutron irradiations to 13.5 x 1025 neutrons/m2 at nominal irradiation temperatures of 1220 K. These measurements were made as functions of volume percent particle loading, temperature, and neutron fluence. The thermal conductivities decrease with increasing particle loading at all measurement temperatures. The large difference between the properties of specimens from two fabrication processes (extrusion and slug injection) is attributed to the fact that the densities of the continuous phases within the elements differ by a factor of 2.6. Increases in the thermal conductivity with initial neutron fluence of some of the extruded specimens are attributed to partial ordering of carbonaceous material within the composites, but an unambiguous quantitative analysis is difficult. Some electrical resistivity results obtained on slug-injected unirradiated fuel rods show that the thermal conductivity would probably be affected by graphite shim content

  8. A phenomenological expression to describe the temperature dependence of pressure-induced softening in negative thermal expansion materials

    International Nuclear Information System (INIS)

    By exploring a simple model of a negative thermal expansion (NTE) system, we introduce a phenomenological expression to describe the temperature dependence of the pressure-induced softening in NTE structures. (paper)

  9. 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.

  10. 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.

  11. 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

  12. In situ test structures for the thermal expansion coefficient and residual stress of polysilicon thin films

    International Nuclear Information System (INIS)

    In this research, micromachined devices consisting of four micro-rotating structures for the in situ determination of the thermal expansion coefficient (TEC), tensile and compressive residual stress of polysilicon thin films are studied. The structures are heated electrically and deflect due to the thermal expansion. The lateral displacements of the devices are related to the thermal stress and residual stress of the test beams. The micro-rotating structures are arranged, so that the lateral displacements are designed to be either a constant value which is used to determine the TEC of the thin film or a variable value that changes with the residual stress of the thin film. An analytical model of the test structure is presented. The finite element software ANSYS is used to verify the analytical model and provide guidelines for the structure design. Experimental results with a surface micromachined polysilicon thin film are used to demonstrate the proposed method. In the experiments, a current–voltage measurement system only is required. The TEC for the polysilicon thin film is obtained to be (2.61 ± 0.04) × 10−6 K−1 from 400 to 420 K and the residual stress is measured as −(10.15 ± 0.70) MPa. (paper)

  13. In search of zero thermal expansion anisotropy in Mo5Si3 by strategic alloying

    International Nuclear Information System (INIS)

    Highlights: • For the first time, theoretical prediction of achieving isotropic thermal expansion anisotropy (TEA) for T1 phase Mo5Si3 by alloying with a mere 17.5% Al substitution on the Si sites. Most effective alloying proposed for the said system up to date. • The theoretical approach is verified by simulating the experimentally observed unusual TEA behaviour for (Mo,V)5Si3 alloys as a function of percent alloying. • The 2nd order and 3rd order elastic constants we explain the origin of the TEA in T1 phase for Mo5Si3 system and how Al effect in reducing the TEA. • We use directional dependent phonon density of state, a novel approach, to identify the origin of the anisotropy and show this method of analysis could be used for other intermetallic alloys as well. - Abstract: Reducing the thermal expansion anisotropy (TEA) of alloy compounds is one of the most important issues for their potential applications in high temperature environment. The Mo5Si3 (T1 phase) is known to be an important intermetallic compound with high melting temperature. Unfortunately, its large TEA renders it unsuitable for high temperature structural/coating applications. Many attempts have been made in the past to reduce TEA by substituting Mo by other transition metal ions such as V with little success and some unexpected observations. Here we use accurate ab initio molecular dynamics (AIMD) simulations to obtain the TEA from thermal expansion coefficients for two T1 phase alloy systems (Mo,V)5Si3 and Mo5(Si,Al)3. We demonstrate that strategic alloying with Al substituting Si can achieve zero TEA for T1 phase. The microscopic origin of this outstanding thermomechanical properties in this alloy is explained by the calculation of higher order elastic constants in conjunction with atom and direction-resolved phonon density of states

  14. 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.

  15. 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.

  16. Anharmonic phonon quasiparticle theory of zero-point and thermal shifts in insulators: Heat capacity, bulk modulus, and thermal expansion

    Science.gov (United States)

    Allen, Philip B.

    2015-08-01

    The quasiharmonic (QH) approximation uses harmonic vibrational frequencies ωQ ,H(V ) computed at volumes V near V0 where the Born-Oppenheimer (BO) energy Eel(V ) is minimum. When this is used in the harmonic free energy, QH approximation gives a good zeroth order theory of thermal expansion and first-order theory of bulk modulus, where nth-order means smaller than the leading term by ɛn, where ɛ =ℏ ωvib/Eel or kBT /Eel , and Eel is an electronic energy scale, typically 2 to 10 eV. Experiment often shows evidence for next-order corrections. When such corrections are needed, anharmonic interactions must be included. The most accessible measure of anharmonicity is the quasiparticle (QP) energy ωQ(V ,T ) seen experimentally by vibrational spectroscopy. However, this cannot just be inserted into the harmonic free energy FH. In this paper, a free energy is found that corrects the double-counting of anharmonic interactions that is made when F is approximated by FH( ωQ(V ,T ) ) . The term "QP thermodynamics" is used for this way of treating anharmonicity. It enables (n +1 ) -order corrections if QH theory is accurate to order n . This procedure is used to give corrections to the specific heat and volume thermal expansion. The QH formulas for isothermal (BT) and adiabatic (BS) bulk moduli are clarified, and the route to higher-order corrections is indicated.

  17. 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.

  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. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. 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 that......-called Vigdergauz microstructures that realize the bounds. For three phases, the optimal microstructures are also compared with new rigorous bounds and again it is shown that the method yields designed materials with thermoelastic properties that are close to the bounds. The three-phase design method is illustrated...

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

    OpenAIRE

    Stella Crosara Lopes; Valéria Oliveira Pagnano; João Manuel Domingos de Almeida Rollo; Mônica Barbosa Leal; Osvaldo Luiz Bezzon

    2009-01-01

    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 cera...

  7. Mechanical properties and negative thermal expansion of a dense rare earth formate framework

    Science.gov (United States)

    Zhang, Zhanrui; Jiang, Xingxing; Feng, Guoqiang; Lin, Zheshuai; Hu, Bing; Li, Wei

    2016-01-01

    The fundamental mechanical properties of a dense metal-organic framework material, [NH2CHNH2][Er(HCOO)4] (1), have been studied using nanoindentation technique. The results demonstrate that the elastic moduli, hardnesses, and yield stresses on the (021)/(02-1) facets are 29.8/30.2, 1.80/1.83 and 0.93/1.01 GPa, respectively. Moreover, variable-temperature powder and single-crystal X-ray diffraction experiments reveal that framework 1 shows significant negative thermal expansion along its b axis, which can be explained by using a hinge-strut structural motif.

  8. 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.

  9. 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

  10. 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...

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Degradation of rocks, through cracking caused by differential thermal expansion, in relation to nuclear waste repositories

    International Nuclear Information System (INIS)

    Heating to temperatures up to 5000C gives a reduction in Young's modulus and increases in permeability of granitic rocks and it is likely that a major reason is grain boundary cracking. The cracking of grain boundary facets in polycrystalline multiphase materials showing anistropic thermal expansion behaviour is controlled by several microstructural factors in addition to the intrinsic thermal and elastic properties. Of specific interest are the relative orientations of the two grains meeting at the facet, and the size of the facet; these factors thus introduce two statistical aspects to the problem and these are introduced to give quantitative data on crack density versus temperature. The theory is compared with experimental measurements of Young's modulus and permeability for various rocks as a function of temperature. There is good qualitative agreement, and the additional (mainly microstructural) data required for a quantitative comparison are defined. 6 figures, 2 tables

  17. 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.

  18. 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; Somers, Marcel A. J.

    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...

  19. 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.

  20. 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.

  1. 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.

  2. 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.))

  3. Thermal expansion-crystallite size-strain relations in fast neutron irradiated lithia porcelain

    International Nuclear Information System (INIS)

    Factors affecting radiation induced defects in lithia aluminosilicate porcelain were investigated. Porcelains with β-eucryptite (Li2O.Al2O3.2SiO2), its solid solution (SS) (Li2O.Al2O3.3SiO2) and β-spodumen (Li2O.Al2O3.4SiO2) were prepared and vitrified. Irradiation was performed at room temperature with three fluences from 252Cf. X-ray line profile analysis, thermal expansion and scanning electron microscopy were carried out pre- and post-irradiation. Results showed that when large crystallites were present in strain free body such as β-spodumen (tetragonal) their sizes were greatly influenced. Both high strain and large crystallite size in hexagonal β-eucryptite were severely reduced. In the solid solution (SS) β-eucryptite having minimum crystallite size and strain free level, defects appeared as swelling of the crystallites. Accompanying morphological changes conformed with the above findings. The negativity of thermal expansion increased with low fluences rather than higher ones leading to recovery of induced defects. The optimum neutron fluence, inducing maximum change, proved to be composition dependent. A wave behaviour of the induced change was interpreted in terms of radiation damage followed by saturation and further annihilation. (author)

  4. Effect of x-ray irradiation on thermal expansion of KCl single crystals

    International Nuclear Information System (INIS)

    The apparatus designed and fabricated earlier for accurate measurement of changes in length of solids through changes in capacitance of a condenser has been improved considerably to step up the accuracy of measurement to 10sup(-6) cm. Using this set-up, the thermal expansion of KCl single crystals before and after X-ray irradiation has been studied. It is found that the linear thermal expansion co-efficient (α) of X-ray irradiated KCl crystal increases to 47 x 10sup(-6)/deg C around room temperature, but attains the α value of unirradiated sample (39.8 x 10sup(-6)/deg C) in the temperature range 125deg C to 200deg C. From these data the number of vacancies created in KCl at room temperature by X-ray irradiation is calculated to be 9 x 10sup(17)/c.c. which is in fairly good agreement with the value 6 x 10sup(17)/c.c. calculated from optical absorption measurements taken on the same sample in the laboratory. (auth.)

  5. 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.

  6. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

    Directory of Open Access Journals (Sweden)

    Birm-June Kim

    2013-09-01

    Full Text Available The effect of individual and combined talc and glass fibers (GFs on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

  7. 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

  8. 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.

  9. Thermodynamic Predictions of Thermal Expansivity and Elastic Compliances at High Temperatures and Pressures Applied to Perovskite Crystals

    Science.gov (United States)

    Burns, S. J.

    2016-01-01

    The possibility of near zero thermal expansion coefficients at very high pressures is explored for application to the Earth's core materials and mantle dynamics. The pressures in the Earth are large enough to effectively reduce thermal expansion coefficients to values which will decouple heat from mechanical work. It is shown that at pressures below the bulk modulus the thermal expansion coefficient will approach zero in all simple linear-elastic crystalline models. Advanced models of crystalline elastic solids based on interatomic potentials and density functional theory are shown to violate Gibb's potential for a solid, crystalline material described by three elastic matrix compliance entries; it is established that the temperature dependence of S 11 and S 12 are thermodynamically identical; it is also established that the pressure dependence of S 11 and S 12 are thermodynamically identical. The basis for thermal energy in materials is the phonon energy in solids. However, it is noted that heat capacity measurements which are obtained from constant pressure heat capacity conditions converted to constant volume values on isobars are not in the correct state when compared to theoretical models; at atmospheric pressure there may be very little difference between these states but at very high pressures the effect may be major. Very large pressures always reduce thermal expansion coefficients; the importance of very small thermal expansion coefficients is discussed in relation to physical processes deep in the core and mantle of the Earth.

  10. Determining the thermal expansion coefficient of thin films for a CMOS MEMS process using test cantilevers

    International Nuclear Information System (INIS)

    Many standard CMOS processes, provided by existing foundries, are available. These standard CMOS processes, with stacking of various metal and dielectric layers, have been extensively applied in integrated circuits as well as micro-electromechanical systems (MEMS). It is of importance to determine the material properties of the metal and dielectric films to predict the performance and reliability of micro devices. This study employs an existing approach to determine the coefficients of thermal expansion (CTEs) of metal and dielectric films for standard CMOS processes. Test cantilevers with different stacking of metal and dielectric layers for standard CMOS processes have been designed and implemented. The CTEs of standard CMOS films can be determined from measurements of the out-of-plane thermal deformations of the test cantilevers. To demonstrate the feasibility of the present approach, thin films prepared by the Taiwan Semiconductor Manufacture Company 0.35 μm 2P4M CMOS process are characterized. Eight test cantilevers with different stacking of CMOS layers and an auxiliary Si cantilever on a SOI wafer are fabricated. The equivalent elastic moduli and CTEs of the CMOS thin films including the metal and dielectric layers are determined, respectively, from the resonant frequency and static thermal deformation of the test cantilevers. Moreover, thermal deformations of cantilevers with stacked layers different to those of the test beams have been employed to verify the measured CTEs and elastic moduli. (paper)

  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

    International Nuclear Information System (INIS)

    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. 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.

  15. The origin of the anomalous thermal dependence of the band-gap in Black Phosphorus

    OpenAIRE

    Villegas, Cesar E. P.; Rocha, A. R.; Marini, Andrea

    2016-01-01

    Black Phosphorus (BP) has gained renewed attention due to its singular anisotropic electronic and optical properties that might be exploited for a wide range of technological applications. In this respect, the thermal properties are particularly important both to predict its room temperature operation and to determine its thermoelectric potential. From this point of view, one of the most spectacular and poorly understood phenomena is, indeed, the BP temperature-induced band-gap opening: when ...

  16. 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...

  17. Thermal Expansion of Iron-Rich Alloys and Implications for the Earth's Core

    International Nuclear Information System (INIS)

    Understanding the thermal-chemical state of the Earth's core requires knowledge of the thermal expansion of iron-rich alloys at megabar pressures and high temperatures. Our survey of literature revealed a significant lack of such data. We have determined the unit-cell parameters of the iron-sulfur compound Fe3S by using synchrotron x-ray diffraction techniques and externally heated diamond-anvil cells at pressures up to 42.5 GPa and temperatures up to 900 K. The zero-pressure thermal expansivity of Fe3S is determined in the form α = a1 + a2 T, where a1 = 3.0 ± 1.3 x 10-5 K-1 and α2 = 2.8 ± 1.5 x 10-8 K-2. The temperature dependence of isothermal bulk modulus (∂KT,0/∂T)P is estimated at -3.75 ± 1.80 x 10-2 GPa K-1. Our data at 42.5 GPa and 900 K suggest that ∼2.1 at. % (1.2 wt. %) sulfur produces 1% density deficit in iron. We have also carried out energy-dispersive x-ray diffraction measurements on pure iron and Fe0.864Si0.136 alloy samples that were placed symmetrically in the same multianvil cell assemblies, using the SPring-8 synchrotron facility in Japan. Based on direct comparison of unit cell volumes under presumably identical pressures and temperatures, our data suggest that at most 3.2 at. % (1.6 wt. %) silicon is needed to produce 1% density deficit with respect to pure iron

  18. 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

  19. 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.

  20. 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.

  1. 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. PMID:24880401

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

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, P. K., E-mail: premkdubey@gmail.com; Kumar, Yudhisther; Gupta, Reeta; Jain, Anshul; Gohiya, Chandrashekhar [Acoustics, Ultrasonics, Vibration Standards and Electronics Instrumentation Cell, CSIR–National Physical Laboratory, New Delhi 110012 (India)

    2014-05-15

    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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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).

  11. Vendor Capability for Low Thermal Expansion Mask Substrates for EUV Lithography

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K L; Taylor, J S; Hector, S D; Yan, P Y; Ramamoorthy, A; Brooker, P D

    2002-04-12

    Development of manufacturing infrastructure is required to ensure a commercial source of mask substrates for the timely introduction of EUVL. Improvements to the low thermal expansion materials that compose the substrate have been made, but need to be scaled to production quantities. We have been evaluating three challenging substrate characteristics to determine the state of the infrastructure for the finishing of substrates. First, surface roughness is on track and little risk is associated with achieving the roughness requirement as an independent specification. Second, with new flatness-measuring equipment just coming on line, the vendors are poised for improvement toward the SEMI P37 flatness specification. Third, significant acceleration is needed in the reduction of defect levels on substrates. The lack of high-sensitivity defect metrology at the vendors' sites is limiting progress in developing substrates for EWL.

  12. Large isotropic negative thermal expansion above a structural quantum phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Handunkanda, Sahan Uddika; Curry, Erin B.; Voronov, Vladimir; Said, Ayman H.; Guzman-Verri, Gian G.; Brierley, Richard; Littlewood, Peter B.; Hancock, Jason N.

    2015-10-01

    Perovskite structured materials contain myriad tunable ordered phases of electronic and magnetic origin with proven technological importance and strong promise for a variety of energy solutions. An always-contributing influence beneath these cooperative and competing interactions is the lattice, whose physics may be obscured in complex perovskites by the many coupled degrees of freedom which makes these systems interesting. Here we report signatures of an approach to a quantum phase transition very near the ground state of the nonmagnetic, ionic insulating, simple cubic perovskite material ScF3 and show that its physical properties are strongly effected as much as 100 K above the putative transition. Spatial and temporal correlations in the high-symmetry cubic phase determined using energy- and momentum-resolved inelastic X-ray scattering as well as X-ray diffraction reveal that soft mode, central peak and thermal expansion phenomena are all strongly influenced by the transition.

  13. 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...

  14. 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.

  15. 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

  16. 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

    optimizes an objective function (e.g. thermoelastic properties) subject to certain constraints, such as elastic symmetry or volume fractions of the constituent phases, within a periodic base cell. The effective properties of the material structures are found using the numerical homogenization method based...... 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......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 that...

  17. 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

  18. Thermal Expansion Behavior of Hexagonal ZnS Single-Crystal Nanowires Embedded in Anodized Aluminum Oxide Template

    International Nuclear Information System (INIS)

    The thermal expansion behavior of semiconductor single-crystal nanowire arrays is of importance for their applications in electronic and optoelectronic nanodevices. We prepare hexagonal ZnS single-crystal nanowire arrays growing along the [110] direction via electrodeposition. The thermal expansion properties of the as-prepared ZnS nanowires have been studied by in situ x-ray diffraction method. The thermal expansion coefficient (TEC) of the ZnS nanowires decreases consistently from room temperature to 225° C where it reaches a minimum value, and then increases rapidly. The average TEC in the studied temperature range is 4.74 × 10−6/°C, which is smaller than that of the conventional bulk counterpart

  19. 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.

  20. Best estimate analysis of the thermal expansion scenario during shutdown in a PWR

    International Nuclear Information System (INIS)

    In this paper we examine the consequences following the hypothetical failure of the Residual Heat Removal (RHR) system during the shutdown operating mode in a Pressurized Water Reactor (PWR). If the RHR system decay heat removal capability cannot be ensured, then the decay heat released in the core will heat up the Reactor Coolant System (RCS) inventory and will cause it to expand. If the thermal expansion is such that the entire RCS becomes ''water-solid'', that is, completely filled with water, then further expansion will result in a rapid increase of the RCS pressure. Such a situation could threaten the integrity of the RCS pressure boundary and lead to a dangerous break in the primary system or in the lines of the systems connected to it, e.g. RHR system. The pressure increase can be arrested by the opening of the pressurizer relief valves (PORVs) or, in those PWRs in which the RHR system is not isolated after it fails, by the opening of the pressure relief valve in the RHR system line. The purpose of the analyses presented in this paper is to determine whether mitigating measures, such as the opening of only one of the PORV and the RHR relief valve, are capable of preventing a fast pressure increase. (author)

  1. 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.

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

    International Nuclear Information System (INIS)

    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

  3. 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

  4. 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.

  5. 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.

  6. Magnetization, crystal structure and anisotropic thermal expansion of single-crystal SrEr2O4

    OpenAIRE

    Li, Hai-Feng; Wildes, Andrew; Hou, Binyang; Zhang, Cong; Schmitz, Berthold; Meuffels, Paul; Roth, Georg; Brückel, Thomas

    2014-01-01

    The magnetization, crystal structure, and thermal expansion of a nearly stoichiometric Sr$_{1.04(3)}$Er$_{2.09(6)}$O$_{4.00(1)}$ single crystal have been studied by PPMS measurements and in-house and high-resolution synchrotron X-ray powder diffraction. No evidence was detected for any structural phase transitions even up to 500 K. The average thermal expansions of lattice constants and unit-cell volume are consistent with the first-order Gr\\"uneisen approximations taking into account only th...

  7. 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.

  8. 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.

  9. Anomalous Thermal Relaxation Induced by the Granular Composition of Berea Sandstone

    Science.gov (United States)

    Ulrich, T.; McCall, K. R.; Guyer, R.

    2003-12-01

    Berea sandstone is a well-studied material known to be nonlinearly elastic. For example, stress-strain measurements for stresses less than 30 MPa are repeatably hysteretic and display end-point memory. In an effort to understand the energy scales of the mechanisms causing nonlinear elasticity in Berea sandstone, we have studied the temperature dependence of sample resonances. Resonances are related to the elastic moduli of a sample, and thus indicate whether or not a sample is hardening or softening as a function of temperature. We find that for temperatures in the range 100 K -- 330 K, sample resonance frequencies display significant hysteresis, and several unusual behaviors. Elastic softening is observed as temperature decreases, rather than the expected monotonic increase. In addition, while measurements are repeatable, they are rate dependent on a timescale much longer than the calculated timescale for temperature equilibrium across the sample. It is our hypothesis that this unusual elastic behavior and the slow onset of thermal equilibrium arises from the granular nature of the material. A series of time and temperature dependent experiments was designed and executed to investigate this hypothesis. We will discuss the results of these measurements and their implications for future research.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. An anomalous thermal water from Hofsstadir western Iceland: Evidence for past CO2 flushing

    International Nuclear Information System (INIS)

    The geothermal field at Hofsstadir northern Snæfellsnes peninsula, Iceland produces low-temperature geothermal water with about 5.4‰ salinity. The fluid temperature is 87 °C, near the reservoir temperature of 90 °C as assessed from mineral solution/equilibrium conditions. The stable isotopic ratios δ2H and δ18O show that the water is significantly lighter than present day precipitation anywhere on the Snæfellsnes peninsula. It is offset from the meteoric water line towards isotopically depleted 18O values, most likely due to CO2(g) – H2O exchange at earlier times during evolution of the system. Such a concentration of stable isotopes is unique for Icelandic groundwaters and has not been encountered anywhere else in Iceland. The water may either have its origin far north of the Bay of Breidafjörður in the highland of the western fjordlands or dating back to a Pre-Holocene age when local precipitation was considerably lighter due to the cold climate at that time. The water is highly concentrated in Ca in comparison with seawater and also compared to that of geothermal saline water elsewhere, which indicates intensive and prolonged water–rock interaction. The 14C concentration is low, about 7.4 pMC (percent modern C), compared to the cold local groundwater of about 74.6 pMC. δ13C for the thermal and cold waters is −4.9‰ and −2.3‰, respectively. The geothermal water is used for heating the small town of Stykkishólmur through a central heat exchanger plant due to the high salinity of the water. The outbuilding of a health resort has been planned and the water has been used successfully for the treatment of psoriasis and is claimed to have beneficial effects in bathing therapy for rheumatism as well as for drinking cures.

  16. Thermal expansion of free-standing graphene: benchmarking semi-empirical potentials

    International Nuclear Information System (INIS)

    The thermodynamical properties of free-standing graphene have been investigated under constant zero pressure as a function of temperature using Monte Carlo simulations. A variety of atomistic models have been used, including the simple three-body Stillinger potential and a series of bond-order many-body potentials based on the Tersoff–Brenner seminal models, with recent reparametrizations dedicated to graphene, extensions to medium-range or long-range dispersion corrections. In addition, we have also tested a tight-binding potential in the fourth-moment approximation. The simulations reveal significant discrepancies in the in-plane lattice parameter and the thermal expansion coefficient, which despite showing monotonically increasing variations with temperature, can be positive, negative or change sign at moderate temperature depending on the potential. Comparison with existing experimental and theoretical data obtained from complementary approaches indicates that empirical potentials limited to nearest-neighbour interactions give rather dispersed results, and that van der Waals corrections generally tend to flatten the variations of the in-plane lattice constant, in contradiction with experiment. Only the medium-range corrected potentials of Los and Fasolino, as well as the tight-binding model in the fourth-moment approximation, are reasonably close to the reference results near room temperature. Our results suggest that classical potentials should be used with caution for thermal properties. (paper)

  17. 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.

  18. 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.

  19. Temperature Dependence of Density and Thermal Expansion of Wrought Aluminum Alloys 7041, 7075 and 7095 by Gamma Ray Attenuation Method

    OpenAIRE

    Nallacheruvu Gopi Krishna; Ammiraju Sowbhagya Madhusudhan Rao; Kalvala Gopal Kishan Rao; Kethireddy Narender

    2013-01-01

      The gamma quanta attenuation studies have been carried out to determine mass attenuation coefficients of 7041, 7075 and 7095 wrought aluminum alloys. The temperature dependence of linear attenuation coefficient, density and thermal expansion of these wrought aluminum alloys in the temperature range 300 K - 850 K have been reported. The measurements were done by using a gamma ray densitometer designed and fabricated in our laboratory. The data on variation of density and linear thermal expa...

  20. 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...

  1. Application of laser Raman spectroscopy to the study of actinides, anomalous thermal expansion materials and ancient paintings. Chapter IT-22

    International Nuclear Information System (INIS)

    After a brief introduction to Raman spectroscopy this talk will highlight some of our work such as (i) uranium metal, (ii) (U1-yCey)O2, (iii) structure of Zn(CN)2, (iv) NaZr2(PO4)3 and (v) ancient paintings

  2. 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

  3. 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

  4. 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.

  5. Thickness dependent stresses and thermal expansion of epitaxial LiNbO{sub 3} thin films on C-sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Bartasyte, A., E-mail: ausrine.bartasyte@femto-st.fr [Institute FEMTO-ST, CNRS (UMR 6174), University of Franche-Comté, 15B avenue des Montboucons, 25030 Besançon (France); Institute Jean Lamour, (UMR 7198) CNRS – Lorraine University, Parc de Saurupt, 54042 Nancy (France); Plausinaitiene, V.; Abrutis, A.; Stanionyte, S. [University of Vilnius, Dept. of General and Inorganic Chemistry, Naugarduko 24, Vilnius (Lithuania); Margueron, S. [Laboratoire Matériaux Optiques, Photonique et Systèmes, EA 4423, Lorraine University and Supelec, 2 rue Eduard Belin, Metz (France); Kubilius, V. [University of Vilnius, Dept. of General and Inorganic Chemistry, Naugarduko 24, Vilnius (Lithuania); Boulet, P. [Institute Jean Lamour, (UMR 7198) CNRS – Lorraine University, Parc de Saurupt, 54042 Nancy (France); Huband, S.; Thomas, P.A. [Department of Physics, University of Warwick, Coventry (United Kingdom)

    2015-01-15

    LiNbO{sub 3} films of high epitaxial quality and with thicknesses of 120–500 nm were deposited at 650 °C on C-sapphire by atmospheric pressure metal-organic chemical vapour deposition. Li nonstoichiometry, residual stresses, twinning, and thermal expansion of the films as a function of the film thickness were investigated by means of Raman spectroscopy and X-ray diffraction. The relaxation of residual stresses, Li{sub 2}O loss, inelastic deformation and elastic hysteresis during cycles of heating up to 860 °C and cooling down to room temperature were studied, as well. The residual stresses and thermal expansion of films were highly thickness dependent. It was shown that the {011"¯2} twinning contributed to the stress relaxation in the thick LiNbO{sub 3} films. - Highlights: • Identification of ((011{sup ¯}2)) system twins in LiNbO{sub 3} films by means of XRD. • Stress relaxation by mechanical twinning in LiNbO{sub 3} thin films. • Tunning of in-plane and out-of-plane thermal expansion of thin films. • Better understanding of the relaxation mechanisms and residual stresses. • Relationship between clamped thermal expansion and film thickness.

  6. 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.

  7. 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.

  8. 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.

  9. Development of fabrication method for thermal expansion difference irradiation temperature monitor

    International Nuclear Information System (INIS)

    This report describes the development activities for the fabrication of the Thermal Expansion Difference irradiation temperature monitor (TED) at the Oarai Engineering Center (OEC)/PNC. TED is used for various irradiation tests in the experimental fast reactor JOYO. TED is the most accurate off-line temperature monitor used for irradiation examination. The TED is composed of a metallic sphere lid and either a stainless steel or nickel alloy container. Once the container is filled with sodium, the metallic sphere lid is sealed by using a resistance weld. This capsule is then loaded into a reactor. Once a TED is loaded into the JOYO reactor, the sodium inside the metallic container increases as a result of thermal expansion. The TED identifies the peak irradiation temperature of the reactor based on a formula correlating temperature to increment values. This formula is established specifically for the particular TED being used during a calibration process performed when the TED is fabricated. Initially the TED was developed by Argonne National Laboratory (ANL) in the United States, and was imported by PNC for use in the JOYO reactor. In 1992 PNC decided to fabricate TED domestically in order to ensure the stability of future supplies. Based on technical information provided by ANL, PNC began fabrication of a TED on an experimental basis. In addition, PNC endeavored to make the domestically produced TED more efficient. This involved improving the techniques used in the sodium filling and the metallic sphere welding processes. These quality control efforts led to PNC's development of processes enabling the capsules to be filled with sodium to nearly 100%. As a result, the accuracy of the temperature dispersion in the out-pile calibration test was improved from +/-10degC to +/-5degC. In 1996 the new domestically fabricated TED was attached to a JOYO irradiation rig. In March of 1997, irradiation of the rig was started on the 30th duty cycle operation, and should be

  10. High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS

    International Nuclear Information System (INIS)

    Results of simultaneous thermal analysis, synchrotron and neutron powder diffraction in the range from room temperature up to the melting point at 936 K on non-superionic orthorhombic β-AgCuS as well as on superionic hexagonal α- and cubic δ-AgCuS are reported. On heating the sample is only stable in argon. The following phase transitions occur in AgCuS at elevated temperatures: β361K → α399K →α+δ 439K→δ. The volume changes at the superionic β→α and α→δ phase transitions are about 2.3 and 0.6%. The volume thermal expansion coefficients are 26 x 10-6, 130 x 10-6 and 85 x 10-6 K-1 for the pure β-, α- and δ-phases, respectively. Models for the average structures of α- and δ-AgCuS are proposed and discussed. Ionic conductivity in δ-AgCuS may originate from cation jumps in 'skewed' directions between nearest-neighbour tetrahedral sites via the peripheries of the octahedral cavities. A correlation between the temperature dependence of the cation redistribution in δ-AgCuS and the temperature dependence of the ionic conductivity is assumed. A two-dimensional nature of the ionic conductivity due to cation jumps in slabs perpendicular to the c-direction is supposed for α-AgCuS. There is no evidence for ionic diffusion through the (1/2, 1/2, 1/2) site in directions in either superionic α- or δ-phases

  11. Analytical method for estimating the thermal expansion coefficient of metals at high temperature

    International Nuclear Information System (INIS)

    In this paper, we propose an analytical method for estimating the thermal expansion coefficient (TEC) of metals at high-temperature ranges. Although the conventional method based on quasiharmonic approximation (QHA) shows good results at low temperatures, anharmonic effects caused by large-amplitude thermal vibrations reduces its accuracy at high temperatures. Molecular dynamics (MD) naturally includes the anharmonic effect. However, since the computational cost of MD is relatively high, in order to make an interatomic potential capable of reproducing TEC, an analytical method is essential. In our method, analytical formulation of the radial distribution function (RDF) at finite temperature realizes the estimation of the TEC. Each peak of the RDF is approximated by the Gaussian distribution. The average and variance of the Gaussian distribution are formulated by decomposing the fluctuation of interatomic distance into independent elastic waves. We incorporated two significant anharmonic effects into the method. One is the increase in the averaged interatomic distance caused by large amplitude vibration. The second is the variation in the frequency of elastic waves. As a result, the TECs of fcc and bcc crystals estimated by our method show good agreement with those of MD. Our method enables us to make an interatomic potential that reproduces the TEC at high temperature. We developed the GEAM potential for nickel. The TEC of the fitted potential showed good agreement with experimental data from room temperature to 1000 K. As compared with the original potential, it was found that the third derivative of the wide-range curve was modified, while the zeroth, first and second derivatives were unchanged. This result supports the conventional theory of solid state physics. We believe our analytical method and developed interatomic potential will contribute to future high-temperature material development. (paper)

  12. 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

  13. 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.

  14. 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.)

  15. 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.

  16. 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.

  17. 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.

  18. 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.)

  19. 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.

  20. Frequency-Based Investigation of Charge Neutralization Processes and Thermal Cavity Expansion in Gyrotrons

    Science.gov (United States)

    Schlaich, Andreas; Wu, Chuanren; Pagonakis, Ioannis; Avramidis, Konstantinos; Illy, Stefan; Gantenbein, Gerd; Jelonnek, John; Thumm, Manfred

    2015-09-01

    During the first hundred milliseconds, the frequency and RF output power of long pulse operating gyrotrons undergo deterministic variation. This well-known behavior is caused by the thermal expansion of the cavity and internal electrostatic processes related to the ionization of residual gas. A macroscopic analytical investigation of the gas conditions in modern gyrotrons indicates that ionization processes are unlikely to influence the overall internal gas pressure. In combination with electrostatic potential considerations, it was found that the beam depression voltage is not fully neutralized; in the case of W7-X gyrotrons, a maximum value of about 60 % neutralization is expected, in conflict with the common assumption of full neutralization in steady state. Using experimentally measured frequency shifts and the Evridiki gyrotron interaction simulation code, a fitting process was employed to further investigate these effects. The results are in very good agreement with the theoretical predictions and allow a separation of the time constants of the two processes causing the frequency tuning.

  1. Giant negative thermal expansion covering room temperature in nanocrystalline GaNxMn3

    International Nuclear Information System (INIS)

    Nanocrystalline antiperovskite GaNxMn3 powders were prepared by mechanically milling. The micrograin GaNxMn3 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

  2. 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)

  3. Theoretical Studies of Interactions Between TATB Molecules and the Origins of Anisotropic Thermal Expansion and Growth

    Energy Technology Data Exchange (ETDEWEB)

    Gee, R H; Roszak, S M; Fried, L E

    2002-03-28

    TATB containing explosives tend to permanently expand as their temperatures are increased or thermally cycled, a phenomenon known as ''ratchet-growth.'' Several mechanisms as to the cause of the non-reversible growth have been proposed, and are taken up here using various different modeling techniques. High-level quantum chemistry calculations have been used in parameterization of a classical potential function suitable for atomistic simulations of TATB. The quantum-chemistry-based force field for TATB was validated by comparing condensed phase properties obtained from molecular dynamics simulations with available experimental data. No permanent growth was manifest at the molecular level. Dissipative particle dynamics simulations were carried out in order to study the geometric packing effects on the mesoscopic scale, similar to the scales representative of Ultrafine. No permanent growth was identified when only simple packing effects were considered in the TATB model. However, non-reversible growth was displayed when crystal fracture capabilities were incorporated in the model, suggesting that crystal fracture induced by the anisotropic volume expansion of TATB is the root cause for the permanent growth seen in TATB containing explosives.

  4. The relationship between irradiation induced dimensional change and the coefficient of thermal expansion: A new look

    International Nuclear Information System (INIS)

    In the 1960s, J.H.W. Simmons derived a theoretical relationship between the coefficient of thermal expansion (CTE) and dimensional changes in irradiated graphite. At low irradiation dose, the theory was shown to be consistent with experimental observations. However, at higher doses the results diverge. Despite this, modified versions of this theory have been used as the basis of the design and life prediction calculations for graphite-moderated reactors. This paper revisits Simmons's theory, summarising the assumptions made in its derivation. The paper then modifies and applies the theory to the dimensional change and CTE change behaviour in isotropic nuclear graphite, making use of trends in irradiated behaviour recently derived using finite element analyses. The importance of these issues to present HTR technology is that the life of HTR graphite components is related to their irradiated dimensional change behaviour. A more in depth understanding of this behaviour will allow suitable graphite material to be selected or new graphite types to be developed. (author)

  5. The relative variational model: A topological view of matter and its properties: Thermal expansion

    International Nuclear Information System (INIS)

    Formal definitions of convergence, connected-ness and continuity were established to characterize and describe the crystalline solid and its properties as a unified notion in the topological space. The crystalline solid is a previously empty space that has been filled with atoms and phonons, i.e., the crystal is built with packages of matter and energy in a regular and orderly repetitive pattern along three orthogonal dimensions of the space. The spatial occupation of the atom in the crystal structure is determined by its mean vibrational volume. Thus, the changes of volume and the changes of internal energy are intrinsically linked. In fact, physical and material properties are the interdependent and bijective quantifications associated with variations of the internal energy. These properties are modeled by means of an intrinsic and invariable form function: the Relative Variational Model. In this paper, the experimental data of the thermal expansion for the oxides Al2O3 and UO2 were analytically depicted by means of this model in the temperature range of 0 K up to the melting point. (authors)

  6. 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%.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Crystal structure, thermal expansivity, and elasticity of OH-chondrodite: trends among dense hydrous magnesium silicates

    Science.gov (United States)

    Ye, Yu; Jacobsen, Steven D.; Mao, Zhu; Duffy, Thomas S.; Hirner, Sarah M.; Smyth, Joseph R.

    2015-04-01

    We report the structure and thermoelastic properties of OH-chondrodite. The sample was synthesized at 12 GPa and 1523 K, coexisting with hydroxyl-clinohumite and hydrous olivine. The Fe content Fe/(Fe + Mg) is 1.1 mol%, and the monoclinic unit-cell parameters are as follows: a = 4.7459(2) Å, b = 10.3480(7) Å, c = 7.9002(6) Å, α = 108.702(7)°, and V = 367.50(4) Å3. At ambient conditions, the crystal structure was refined in space group P21/ b from 1915 unique reflection intensities measured by single-crystal X-ray diffraction. The volume thermal expansion coefficient was measured between 150 and 800 K, resulting in α V = 2.8(5) × 10-9 (K-2) × T + 40.9(7) × 10-6 (K-1) - 0.81(3) (K)/ T 2, with an average value of 38.0(9) × 10-6 (K-1). Brillouin spectroscopy was used to measure a set of acoustic velocities from which all 13 components ( C ij ) of the elastic tensor were determined. The Voigt-Reuss-Hill average of the moduli yields for the adiabatic bulk modulus, K S0 = 117.9(12) GPa, and for shear modulus, G 0 = 70.1(5) GPa. The Reuss bound on the isothermal bulk modulus ( K T0) is 114.2(14) GPa. From the measured thermodynamic properties, the Grüneisen parameter ( γ) is calculated to be 1.66(4). Fitting previous static compression data using our independently measured bulk modulus (isothermal Reuss bound) as a fixed parameter, we refined the first pressure derivative of the bulk modulus, K T' = 5.5(1). Systematic trends between H2O content and physical properties are evaluated among dense hydrous magnesium silicate phases along the forsterite-brucite join.

  15. 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

  16. Systematic and controllable negative, zero, and positive thermal expansion in cubic Zr(1-x)Sn(x)Mo2O8.

    Science.gov (United States)

    Tallentire, Sarah E; Child, Felicity; Fall, Ian; Vella-Zarb, Liana; Evans, Ivana Radosavljević; Tucker, Matthew G; Keen, David A; Wilson, Claire; Evans, John S O

    2013-08-28

    We describe the synthesis and characterization of a family of materials, Zr1-xSnxMo2O8 (0 < x < 1), whose isotropic thermal expansion coefficient can be systematically varied from negative to zero to positive values. These materials allow tunable expansion in a single phase as opposed to using a composite system. Linear thermal expansion coefficients, αl, ranging from -7.9(2) × 10(-6) to +5.9(2) × 10(-6) K(-1) (12-500 K) can be achieved across the series; contraction and expansion limits are of the same order of magnitude as the expansion of typical ceramics. We also report the various structures and thermal expansion of "cubic" SnMo2O8, and we use time- and temperature-dependent diffraction studies to describe a series of phase transitions between different ordered and disordered states of this material. PMID:23895493

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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...

  2. 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

  3. Anomalous heat conduction and anomalous diffusion in nonlinear lattices, single walled nanotubes, and billiard gas channels

    OpenAIRE

    Li, Baowen; Wang, Jiao; Wang, Lei; Zhang, Gang

    2004-01-01

    We study anomalous heat conduction and anomalous diffusion in low dimensional systems ranging from nonlinear lattices, single walled carbon nanotubes, to billiard gas channels. We find that in all discussed systems, the anomalous heat conductivity can be connected with the anomalous diffusion, namely, if energy diffusion is $\\sigma^2(t)\\equiv =2Dt^{\\alpha} (01$) implies an anomalous heat conduction with a divergent thermal conductivity ($\\beta>0$), and more interestingly, a subdiffusion ($\\a...

  4. 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.

  5. 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.

  6. Effect of early age thermal history on the expansion due to delayed ettringite formation : Experimental study and model calibration

    OpenAIRE

    Baghdadi, N.; SEIGNOL, JF; MARTIN, RP; RENAUD, JC; Toutlemonde, F.

    2008-01-01

    In this paper, we present an experimental study carried out at LCPC to quantify the influence of major parameters on Delayed Ettringite Formation. The main interaction concerns three factors : temperature reached, duration of heat treatment at early age and storage conditions. We used the results of the experimental study to calibrate a coupling law which predicts the potential of concrete expansion affected by DEF as a function of the thermal history at early age. This coupling law is part o...

  7. 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...

  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. 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.)

  10. Thermal expansion and magnetostriction measurements on a CeCu5.85Au0.15 single crystal

    International Nuclear Information System (INIS)

    A well-studied magnetic quantum critical point (QCP) exists at the onset of antiferromagnetic order in the heavy-fermion system CeCu6-xAux with a critical gold concentration of xc∼0.1. Due to the instability at the QCP the entropy S shows at finite temperatures a maximum as a function of x, volume, or pressure p. The maximum leads to a sign change of the thermal expansion coefficient, α=-(1/V)(∂S/∂p), and of the Grueneisen parameter Γ, the ratio of α and specific heat. This feature and the divergence of Γ at T→0 are important thermodynamic probes to detect and classify QCPs. We report low-temperature thermal expansion and magnetostriction measurements on a CeCu5.85Au0.15 single crystal with a Neel temperature of TN∼90 mK. The thermal expansion was measured along all orthorhombic axes in a temperature range of 30 mK< T<10 K in magnetic fields parallel to the c axis of up to 3T. The results are compared with theoretical predictions and measurements on other heavy-fermion compounds close to a QCP

  11. 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

  12. 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 %.

  13. A study on density, melting point, thermal expansion, creep, thermal diffusivity and thermal conductivity of the simulated rock-like oxide (ROX) fuels

    Energy Technology Data Exchange (ETDEWEB)

    Yanagisawa, Kazuaki; Shirasu, Noriko; Muromura, Tadasumi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ohmichi, Toshihiko; Matsuda, Tetsushi

    1999-03-01

    A new type of fuel, that is, rock-like oxide (ROX) fuel composed of PuO{sub 2}-SZR (stabilized zirconia)-MgAl{sub 2}O{sub 4} is under development at JAERI. To prepare the data base, the simulated ROX fuel in which original PuO{sub 2} was replaced by UO{sub 2} was fabricated and brought to out-of-pile tests. Main remarks obtained within this experimental scope are: (1) It was found from the present study that the simulated ROX fuel was successfully fabricated. (2) The gas immersion density of the simulated ROX fuels had values ranging from 4.9 to 5.4 g/cc, which were of order of about 47-52% of that of UO{sub 2}. SZR increased the density of while MgAl{sub 2}O{sub 4}. (3) Melting point of the simulated ROX fuel was revealed to be 1,911 {+-} 39degC, about 30% lower than that of UO{sub 2} fuel. (4) The difference in linear thermal expansion (LTE) between the simulated ROX fuel and the UO{sub 2} fuel was little up to temperatures of 1,500degC. The LTE was increased with the increase of SZR. (5) The creep rate of simulated ROX fuel was strongly dependent on the amount of MgAl{sub 2}O{sub 4}, where the role of Al{sub 2}O{sub 3} dissolved in MgAl{sub 2}O{sub 4} is important. The creep propensity was similar between the simulated ROX fuel and UO{sub 2} fuel. (6) The magnitude of hardness (Hv) was sensitive to the Al{sub 2}O{sub 3} contained in MgAl{sub 2}O{sub 4}, hence the increase of Al{sub 2}O{sub 3} made the simulated ROX fuel more hard. (7) The difference in thermal diffusivity between the simulated ROX fuel and the UO{sub 2} was not so significant. (8) The difference in thermal conductivity between the simulated ROX and UO{sub 2} fuel is little. Degradation of the thermal conductivity occurred by the increase of SZR. (9) Among three candidates of the simulated ROX fuels studied in the present paper, the sample consisted of 26wt%UO{sub 2}-24wt%SZR-50wt%MgAl{sub 2}O{sub 4} seems to have the most feasible performance for future studies. (J.P.N.)

  14. The Holocene Thermal Maximum as a Time of Rapid Peat Accumulation and Peatland Expansion in Alaska

    Science.gov (United States)

    Jones, M. C.; Yu, Z.; Peteet, D. M.

    2009-05-01

    High latitudes are particularly sensitive to climate warming resulting from a number of important positive feedbacks, including increasing albedo from changing sea ice extent, snow and vegetation cover, and feedbacks to the carbon cycle. The fate of high latitude ecosystems and associated climate feedbacks in response to warming remains uncertain, particularly in boreal peatlands, which store roughly one-third of the global carbon pool. In order to understand how peatlands respond to climate warming, we examined Holocene carbon accumulation rates from four peatlands on the Kenai Peninsula, Alaska, focusing on the early Holocene (~11,000-9000 cal yr BP), a time when the climate was warmer than today. Basal dates from over 200 peat cores across Alaska were compiled to examine the timing and spatial distribution of peatland initiation across Alaska, and available pollen data from the North American Pollen Database (NAPD) and the Paleoenvironmental Arctic Sciences (PARCS) databases were used to examine associated vegetation distribution patterns. Our study reveals that the highest rates of carbon accumulation on the Kenai Peninsula occurred during the early Holocene Thermal Maximum (HTM), which also corresponds to the highest number of peat basal dates both on the Kenai and across Alaska, indicating that not only vertical peat growth but also lateral peatland expansion was high. We suggest that the warm summers and longer growing season during the early Holocene in Alaska resulted in high net primary productivity (NPP), rapid peat burial, and the greatest carbon accumulation rates. Rapid rates of accumulation and burial may have minimized the effects of aerobic decomposition. In addition, a change in the seasonal timing of precipitation and moisture availability and an increase in summer precipitation may have decreased drought stress, promoting peatland initiation and peat growth. We also speculate that the dominance of broad-leafed deciduous forests and abundant

  15. 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.

  16. 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

  17. 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.

  18. 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...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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...

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. Thermal expansion of CaIrO3 post-perovskite determined by time-of-flight measurements

    International Nuclear Information System (INIS)

    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

  12. Phase constitution and thermal expansion of YBa2Cu3O/sub 7-//sub δ/ single crystals

    International Nuclear Information System (INIS)

    We present an x-ray diffraction study of YBa2Cu3O/sub 7-//sub δ/ single crystals. High-resolution scans reveal two orthorhombic phases with different lattice constants but a common orientation indicating a phase separation into phases with δ≅0.0 and 0.3. Thermal expansions of the unit cell parameters of both phases measured between 10 and 300 K were fit using a quasi-harmonic approximation giving a best-fit Debye temperature of 370 +- 5 K. The measured orthorhombicities were found to change smoothly through the superconducting transition temperature without any anomaly

  13. 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...

  14. Laser ablation in CdZnTe crystal due to thermal self-focusing: Secondary phase hydrodynamic expansion

    Science.gov (United States)

    Medvid', A.; Mychko, A.; Dauksta, E.; Kosyak, V.; Grase, L.

    2016-06-01

    The present paper deals with the laser ablation in CdZnTe crystal irradiated by pulsed infrared laser. Two values of threshold intensities of the laser ablation were determined, namely of about 8.5 and 6.2 MW/cm2 for the incident and the rear surfaces, correspondingly. Lower intensity of the laser ablation for the rear surface is explained by thermal self-focusing of the laser beam in the CdZnTe crystal due to heating of Te inclusions with a following hydrodynamic expansion.

  15. 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.

  16. 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...

  17. 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.

  18. Negative thermal expansion and broad band photoluminescence in a novel material of ZrScMo2VO12

    OpenAIRE

    Xianghong Ge; Yanchao Mao; Xiansheng Liu; Yongguang Cheng; Baohe Yuan; Mingju Chao; Erjun Liang

    2016-01-01

    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 monoc...

  19. Application of Mythen Detector In-situ XRD Study on The Thermal Expansion Behavior of Metal Indium

    OpenAIRE

    DU, RONG; Chen, Zhongjun; Cai, Quan; Fu, Jianlong; Gong, Yu; Wu, Zhonghua

    2015-01-01

    A Mythen detector has been equipped at the beamline 4B9A of Beijing Synchrotron Radiation Facility, which can be used for in-situ real-time 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 film was heated from 30 to 160 {\\deg}C with a heating rate of 2 {\\deg}C/min. The in-situ XRD full-profiles were collected with a rate of one profile per...

  20. 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.

  1. 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.

  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. 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.

  4. An explanation for anomalous thermal conductivity behaviour in nanofluids as measured using the hot-wire technique

    International Nuclear Information System (INIS)

    Several efforts have been made to explain thermal conductivity enhancements in fluids due to the addition of nanoparticles. However, until now, there has been no general consensus on this issue. In this work a simple experiment is described that demonstrates a possible cause of misinterpretation of the experimental data of thermal conductivity obtained when using the hot-wire technique (HWT) in these systems. It has been demonstrated that the thermal conductivity of a two-layer sample of two non-miscible phase systems determined by means of the HWT must be modelled using a series thermal resistance model with consideration of the interfacial layers between different phases. This result sheds light on the thermal conductivity enhancement in nanofluids with respect to the values corresponding to the base fluid, suggesting that this increase can be explained using the above-mentioned model and not by application of empirical formulae for effective media, as done before. (paper)

  5. An Investigation of the Thermal Expansion Coefficient for Resin Concrete with ZrW2O8

    Directory of Open Access Journals (Sweden)

    Kuangzhe Lin

    2015-08-01

    Full Text Available This paper presents a novel resin concrete obtained by adding cubic zirconium tungstate (ZrW2O8 as filler. A prediction algorithm on the thermal expansion coefficient (CTE of resin concrete (including filler was established on the basis of the meso-mechanics method and a three-phase model for concrete. The concept of twice mixing was also proposed for prediction accuracy. Then, a 2D and 3D irregular polygon aggregate particles packing model was set up by Matlab and the properties of the packing model were simulated by finite element analysis. Finally, resin concrete samples were made and their CTE were measured. Mix proportion and addition of ZrW2O8 as influencing factors were considered in this experiment. The CTE of resin concrete was verified by comparing results of the prediction model, simulation model and experiment. The optimum CTE obtained from the experiment was 1.504 × 10−6/K. Compared with 6.817 × 10−6/K without ZrW2O8, it was found that the addition of ZrW2O8 to resin concrete can make it perform significantly better in thermal expansion.

  6. 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.

  7. 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.

  8. Crystal structure, thermal expansion and electrical properties of GdCo0.67Ga1.33 compound

    International Nuclear Information System (INIS)

    A new ternary compound GdCo0.67Ga1.33 was synthesized and its crystal structure was determined by the Rietveld refinement of X-ray powder diffraction data. This compound crystallizes in the orthorhombic, space group Imma (No. 74) with the CeCu2 structure type, and a=0.43625(2) nm, b=0.70935(3) nm, c=0.75705(4) nm, Z=4 and Dcalc=8.207 g/cm3. The thermal expansion of GdCo0.67Ga1.33 was studied by high temperature powder X-ray diffraction technique in the temperature range of 301–598 K. The volumetric coefficient of thermal expansion, αV, can be represented by αV(T)=4.73×10−6+8.45×10−8T. The Debye temperature of GdCo0.67Ga1.33 is calculated to be ΘD=261.6 K. The electrical properties of this compound were measured between 5 and 300 K. Temperature variations of electrical resistivity suggest that magnetic ordering occurs at low temperature. The residual resistivity ratio RRR of the compound is about 1.2

  9. Acoustical Studies of L-leucine and L-asparagine in aqueous electrolyte through thermal expansion coefficient

    Science.gov (United States)

    Jajodia, S.; Chimankar, O. P.; Kalambe, A.; Goswami, S. G.

    2012-12-01

    Amino acids are the building blocks of the proteins; their study provides important information, about the behaviour of larger biomolecules such as proteins. The properties of proteins such as their structure, solubility, denaturation, etc. are greatly influenced by electrolytes. Ultrasonic velocity and density values have been used for evaluation of thermal expansion coefficient and adiabatic compressibility for ternary systems (amino acid/salt + water) namely L-leucine / L-asparagine each in 1.5 M aqueous solution of NaCl used as solvent for various concentrations and at different temperatures (298.15K - 323.15K). Present paper reports the variation of various thermoacoustical parameters such as Moelwyn-Hughes parameter (C1), Beyer's non-linearity parameter (B/A), internal pressure (Pi), fractional free volume (f), available volume (Va), repulsive exponent (n), molecular constant (r), van der Waals' constant (b), Debye temperatue (θD), etc. have been computed from the thermal expansion coefficient with the change of concentration and temperature. The variations of all these parameters have been interpreted in terms of various intermolecular interactions such as strong, weak, charge transfer, complex formation, hydrogen bonding interaction. The structure making and breaking properties of the interacting components existing in proposed ternary systems. It shows the associating and dissociating tendency of the molecules of solute in solvent.The hetromolecular interactions are present in both the ternary systems.

  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 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.

  12. 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

  13. 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)

  14. 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...

  15. 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)

  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. Survival and expansion of Pistia stratiotes L. in a thermal stream in Slovenia

    OpenAIRE

    Šajna, Nina; Haler, Maja; Škornik, Sonja; Kaligarič, Mitja

    2012-01-01

    We report about successful winter survival of a tropical plant Pistia stratiotes in a natural thermal stream Topla in Slovenia in temperate climate zone in central Europe. Only 2 years after its first occurrence in 2001 P. stratiotes managed to cover most of the water body where the thermal springs cause an elevated temperature (>17 °C year round). Enhanced biomass production of this invasive species took place in spring and summer and new stolons were formed at the end of the vegetation seas...

  18. 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

  19. 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.

  20. Thermal Fronts in Solar Flares

    Science.gov (United States)

    Karlický, Marian

    2015-12-01

    We studied the formation of a thermal front during the expansion of hot plasma into colder plasma. We used a three-dimensional electromagnetic particle-in-cell model that includes inductive effects. In early phases, in the area of the expanding hot plasma, we found several thermal fronts, which are defined as a sudden decrease of the local electron kinetic energy. The fronts formed a cascade. Thermal fronts with higher temperature contrast were located near plasma density depressions, generated during the hot plasma expansion. The formation of the main thermal front was associated with the return-current process induced by hot electron expansion and electrons backscattered at the front. A part of the hot plasma was trapped by the thermal front while another part, mainly with the most energetic electrons, escaped and generated Langmuir and electromagnetic waves in front of the thermal front, as shown by the dispersion diagrams. Considering all of these processes and those described in the literature, we show that anomalous electric resistivity is produced at the location of the thermal front. Thus, the thermal front can contribute to energy dissipation in the current-carrying loops of solar flares. We estimated the values of such anomalous resistivity in the solar atmosphere together with collisional resistivity and electric fields. We propose that the slowly drifting reverse drift bursts, observed at the beginning of some solar flares, could be signatures of the thermal front.

  1. 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.

  2. Spatial variability in the coefficient of thermal expansion induces pre-service stresses in computer models of virgin Gilsocarbon bricks

    Science.gov (United States)

    Arregui-Mena, José David; Margetts, Lee; Griffiths, D. V.; Lever, Louise; Hall, Graham; Mummery, Paul M.

    2015-10-01

    In this paper, the authors test the hypothesis that tiny spatial variations in material properties may lead to significant pre-service stresses in virgin graphite bricks. To do this, they have customised ParaFEM, an open source parallel finite element package, adding support for stochastic thermo-mechanical analysis using the Monte Carlo Simulation method. For an Advanced Gas-cooled Reactor brick, three heating cases have been examined: a uniform temperature change; a uniform temperature gradient applied through the thickness of the brick and a simulated temperature profile from an operating reactor. Results are compared for mean and stochastic properties. These show that, for the proof-of-concept analyses carried out, the pre-service von Mises stress is around twenty times higher when spatial variability of material properties is introduced. The paper demonstrates that thermal gradients coupled with material incompatibilities may be important in the generation of stress in nuclear graphite reactor bricks. Tiny spatial variations in coefficient of thermal expansion (CTE) and Young's modulus can lead to the presence of thermal stresses in bricks that are free to expand.

  3. Relation Between Thermal Expansion Coeficient and Porosity in Thick Zircon and Alumina Coatings

    Czech Academy of Sciences Publication Activity Database

    Rohan, Pavel; Chráska, Pavel; Ctibor, Pavel; Neufuss, Karel

    Ohio : Materials Park, ASM International, 2000 - (Berndt, C.), s. 1067-1070 ISBN 0-87170-680-6. [International Thermal Spray Conference/1st./. Montreal (CA), 08.05.2000-11.05.2000] R&D Projects: GA ČR GA106/97/S008 Institutional research plan: CEZ:AV0Z2043910 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  4. 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.

  5. 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.

  6. 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).

  7. 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......, 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...

  8. Recording and reading temperature tolerance in holographic data storage, in relation to the anisotropic thermal expansion of a photopolymer medium.

    Science.gov (United States)

    Tanaka, Tomiji

    2009-08-01

    In holographic data storage, it is difficult to retrieve data if the temperature difference between recording and reading exceeds 2 K. To widen this tolerance, a compensation method--adjusting the wavelengths and incident directions of the recording and reading beams--has been proposed. In this paper, for the first time, a method for calculating the recording and reading temperature tolerance using this compensation is introduced. To widen the narrow tolerance, typically +/- 10 K, it is effective to increase the coefficient of thermal expansion (CTE) of the substrate or decrease the CTE of the photopolymer. Although reducing the Numerical aperture of the objective lens is also effective, it degrades the recording density. PMID:19654823

  9. Thermal expansion studies on low-dimensional frustrated quantum magnets. The case of κ-(BEDT-TTF)2Cu2(CN)3 and azurite

    International Nuclear Information System (INIS)

    Thermal expansion measurements provide a sensitive tool for exploring a material's thermodynamic properties in condensed matter physics as they provide useful information on the electronic, magnetic and lattice properties of a material. In this thesis, thermal expansion measurements have been carried out both at ambient-pressure and under hydrostatic pressure conditions. From the materials point of view, the spin-liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 has been studied extensively as a function of temperature and magnetic field. Azurite, Cu3(CO3)2(OH)2 - a realization of a one-dimensional distorted Heisenberg chain is also studied both at ambient and hydrostatic pressure to demonstrate the proper functioning of the newly built setup ''thermal expansion under pressure''.

  10. 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

  11. 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.

  12. 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

  13. Mechanism of the low thermal expansion in α-Hf2O(PO4)2 and its zirconium analog

    International Nuclear Information System (INIS)

    The thermal expansion of recently characterized α-Zr2O(PO4)2 and α-Hf2O(PO4)2 is found to be very low (respectively 2.6 and 2.9x10-6 K-1, 20-900 deg. C). High-temperature X-ray diffraction and Rietveld analysis allowed to identify a dual contraction mechanism, involving a classical ring deformation and the rocking of bridging oxygens. - Graphical abstract: Compared to other zirconium phosphates, α-Zr2O(PO4)2 shows a remarkable low thermal expansion of 2.6x10-6 K-1

  14. 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)

  15. 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

  16. Thermal expansion, thermal conductivity, and heat capacity measurements for boreholes UE25 NRG-4, UE25 NRG-5, USW NRG-6, and USW NRG-7/7A

    International Nuclear Information System (INIS)

    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)-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 x 10-6 to 49 x 10-6 C-1 for TCw, from the negative range to 16 x 10-6 · degree C-1 for PTn, from 6.3 x 10-6 to 44 x 10-6 C-1 for TSw1, and from 6.7 x 10-6 to 37 x 10-6 · degree C-1 for TSw2. Mean values of thermal capacitance in J/cm3K (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

  17. 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.

  18. 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)

  19. Non-adiabatic effects within a single thermally-averaged potential energy surface: Thermal expansion and reaction rates of small molecules

    CERN Document Server

    Alonso, J L; Clemente-Gallardo, J; Echenique, P; Mazo, J J; Polo, V; Rubio, A; Zueco, D

    2012-01-01

    At non-zero temperature and when a system has low-lying excited electronic states, the ground-state Born--Oppenheimer approximation breaks down and the low-lying electronic states are involved in any chemical process. In this work, we use a temperature-dependent effective potential for the nuclei which can accomodate the influence of an arbitrary number of electronic states in a simple way, while at the same time producing the correct Boltzmann equibrium distribution for the electronic part. With the help of this effective potential, we show that thermally-activated low-lying electronic states can have a significant effect in molecular properties for which electronic excitations are oftentimes ignored. We study the thermal expansion of the Manganese dimer, Mn$_2$, where we find that the average bond length experiences a change larger than the present experimental accuracy upon the inclusion of the excited states into the picture. We also show that, when these states are taken into account, reaction rate const...

  20. The thermal expansion of 3C–SiC in TRISO particles by high temperature X-ray diffraction

    International Nuclear Information System (INIS)

    The lattice parameter change of SiC in TRISO particles prepared by chemical vapour deposition (CVD) was measured using high temperature X-ray diffraction, across a temperature range of 25–1400 °C. Al2O3 was used as the internal standard and the SiC temperature corrections were calibrated using its two independent lattice parameter values along the a- and c-axes. Experimental unit cell values of SiC at low temperatures corresponded well with those published in previous literature, but deviated systematically at higher temperatures. Thermal expansion coefficients of the CVD prepared SiC shell material are considered the most accurate and follow a linear trend with increasing temperature (α11 = 2.7706 × 10−9 T + 3.3048 × 10−6 K−1). The TRISO particles are described best using non-linear expansion coefficients. Apparent is the deviation in the SiC lattice constants of the shell material and the TRISO particles from which it originated. This could indicate a residual strain in the TRISO particles or a difference in sample displacement between the TRISO particles and the surrounding alumina standard. The room temperature lattice constant for the shell material is 4.36030 Å (SD 0.00006 Å) as compared with that of the TRISO sample of 4.35835 Å (SD 0.00006 Å) after adjusting the sample displacement to get alumina lattice constants as close to the accepted values. Residual stress of ∼300 MPa is calculated from the lattice constant differences

  1. Effect of composition on the degree of anisotropy of thermal expansion and electric resistance of cermet specimens of GeTe

    International Nuclear Information System (INIS)

    A study was made on α temperature coefficient of thermal expansion and ρ specific electric resistance of cermet germanium telluride for alloys close to stoichiometric composition. It is shown that anisotropy of thermal expansion of cermet germanium telluride depends sufficiently on its composition. This dependence is clearly pronounced if tellurium content in alloys equals 50.4-51.2 at.%. The maximal anisotropy is observed in the alloy containing 50.8 at.% of tellurium. The temperature of extreme value of temperature coefficient of linear expansion decreases from 440 down to 373 deg.C for alloys with 49-50.8 at.% of tellurium, and grows from 373 up to 405 deg.C if tellurium content equals 50.8-52 at.%

  2. 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

  3. 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).

  4. 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.

  5. 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.

  6. 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 method...

  7. 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.

  8. 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.

  9. Anisotropic lattice thermal expansion of PbFeBO4: A study by X-ray and neutron diffraction, Raman spectroscopy and DFT calculations

    International Nuclear Information System (INIS)

    Highlights: • Mullite-type PbFeBO4 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 PbFeBO4 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 PbO4, FeO6 and BO3 polyhedra as a function of temperature

  10. Thermal expansion and negative linear compressibility in ZnAu2(CN)4: An inelastic neutron scattering measurements and lattice dynamical studies

    International Nuclear Information System (INIS)

    ZnAu2(CN)4 shows negative thermal expansion behavior as well as negative linear compressibility. The linear thermal expansion behavior is highly anisotropic (αa~ 36.9×10-6 K-1, αc~ -57.6×10-6 K-1). On application of hydrostatic pressure the c-axis expands along which the NTE behavior has also been reported. We have performed the inelastic neutron scattering measurment using IN4C spectrometer at ILL, Grenoble France. The measurments are performed at various temperatures ranging from 150 K to 400 K as shown in Fig 1(a). From the temperature dependence measurements we observed that modes below 20 meV show significant change in energy with temperature indicating the anharmonic nature of these modes. To understand the anamolus properties from microscpic view we have been calculated in the phonon in entire Brillouin zone using DFT. Our calculation suggest that these modes mostly involve motion of Zn(CN)4 tetrahedral units connected via Au atoms. The calculated pressure dependence of the phonon energies have been used for thermal expansion calculation (Fig. 1(b)) of the compound. We observe that low energy modes below 5 meV contribute negative to the total thermal expansion (αV) behavior. However modes around 10 meV have large positive contribution to αV and results in positive volume thermal expansion behavior. The eigen vector of a zone centre phonon mode of energy around 4 meV energy with largest negative Grüneisen parameter of -9.2 suggest the twisting motion of the -Zn-NC-Au-CN-Zn- chain along with rotational motion of ZnN4 tetrahedra. Such motion would lead to contraction along c direction.

  11. 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.

  12. 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.)

  13. Anomalous transport phenomena in px+i py superconductors

    Science.gov (United States)

    Li, Songci; Andreev, A. V.; Spivak, B. Z.

    2015-09-01

    Spontaneous breaking of time-reversal symmetry in superconductors with the px+i py symmetry of the order parameter allows for a class of effects which are analogous to the anomalous Hall effect in ferromagnets. These effects exist below the critical temperature, T anomalous Hall thermal conductivity, the polar Kerr effect, the anomalous Hall effect, and the anomalous photo- and acousto-galvanic effects.

  14. 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

  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

    2016-06-01

    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.

  16. 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.

  17. 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.

  18. 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.

  19. A novel interferometric dilatometer in the 4–300 K temperature range: thermal expansion coefficient of SRM-731 borosilicate glass and stainless steel-304

    International Nuclear Information System (INIS)

    We present a newly designed heterodyne interferometric dilatometer for the measurement of the coefficient of thermal expansion of solids in the 4–300 K temperature range. The instrument can measure non-monotonic thermal expansion curves and has an accuracy better than 200 nm across the whole 4–300 K measurement range. The compensation for the misalignment of the interferometer design and the configuration of the sample holder make the instrument suitable to carry out measurements on any kind of sample that can be produced in a bar or rod shape. The measurement of a standard SRM-731 borosilicate glass and an SS-304 sample are presented and compared with literature data. (paper)

  20. 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