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Pressure formulas for liquid metals and plasmas based on the density-functional theory  [PDF]
Junzo Chihara,Ichirou Fukumoto,Mitsuru Yamagiwa,Hiroo Totsuji
Physics , 2001, DOI: 10.1088/0953-8984/13/33/301
Abstract: At first, pressure formulas for the electrons under the external potential produced by fixed nuclei are derived both in the surface integral and volume integral forms concerning an arbitrary volume chosen in the system; the surface integral form is described by a pressure tensor consisting of a sum of the kinetic and exchange-correlation parts in the density-functional theory, and the volume integral form represents the virial theorem with subtraction of the nuclear virial. Secondly on the basis of these formulas, the thermodynamical pressure of liquid metals and plasmas is represented in the forms of the surface integral and the volume integral including the nuclear contribution. From these results, we obtain a virial pressure formula for liquid metals, which is more accurate and simpler than the standard representation. From the view point of our formulation, some comments are made on pressure formulas derived previously and on a definition of pressure widely used.
High resolution miniature dilatometer based on AFM piezocantilever  [PDF]
J. -H. Park,D. Graf,T. P. Murphy,G. M. Schmiedeshoff,S. W. Tozer
Physics , 2009, DOI: 10.1063/1.3258143
Abstract: Thermal expansion, or dilation, is closely related to the specific heat, and provides useful information regarding material properties. The accurate measurement of dilation in confined spaces coupled with other limiting experimental environments such as low temperatures and rapidly changing high magnetic fields requires a new sensitive millimeter size dilatometer that has little or no temperature and field dependence. We have designed an ultra compact dilatometer using an atomic force microscope (AFM) piezoresistive cantilever as the sensing element and demonstrated its versatility by studying the charge density waves (CDWs) in alpha uranium to high magnetic fields (up to 31 T). The performance of this piezoresistive dilatometer was comparable to that of a titanium capacitive dilatometer.
Design and Theoretical Analysis of a Resonant Sensor for Liquid Density Measurement  [PDF]
Dezhi Zheng,Jiying Shi,Shangchun Fan
Sensors , 2012, DOI: 10.3390/s120607905
Abstract: In order to increase the accuracy of on-line liquid density measurements, a sensor equipped with a tuning fork as the resonant sensitive component is designed in this paper. It is a quasi-digital sensor with simple structure and high precision. The sensor is based on resonance theory and composed of a sensitive unit and a closed-loop control unit, where the sensitive unit consists of the actuator, the resonant tuning fork and the detector and the closed-loop control unit comprises precondition circuit, digital signal processing and control unit, analog-to-digital converter and digital-to-analog converter. An approximate parameters model of the tuning fork is established and the impact of liquid density, position of the tuning fork, temperature and structural parameters on the natural frequency of the tuning fork are also analyzed. On this basis, a tuning fork liquid density measurement sensor is developed. In addition, experimental testing on the sensor has been carried out on standard calibration facilities under constant 20 °C, and the sensor coefficients are calibrated. The experimental results show that the repeatability error is about 0.03% and the accuracy is about 0.4 kg/m3. The results also confirm that the method to increase the accuracy of liquid density measurement is feasible.
Miniature Dilatometer Based upon an AFM Piezocantilever  [PDF]
Liran Wang,George M. Schmiedeshoff,David Earl Graf,Ju-Hyun Park,Timothy P. Murphy,Stanley W. Tozer,Eric C. Palm
Physics , 2013,
Abstract: We report on the development of a sensitive dilatometer based upon a AFM piezocantilever. This dilatometer has been tested at temperatures down to 25 mK and in magnetic fields up to 16 T. The layered heavy fermion superconductor $CeCoIn_5$ and its non-magnetic analog $LaRhIn_5$ have been measured to demonstrate its use in detecting phase transitions and quantum oscillations. In addition, using this dilatometer, a simultaneous multi-axis dilation measurement has been done. This compact dilatometer has many advantages such as its ability to measure very small samples with lengths at sub-mm levels, low temperature and field dependence, ability to rotate, and works well irrespective of being in a changing liquid or gas environment (i.e. within a flow cryostat or mixing chamber).
Computational study of the effective three-ion interaction potentials in liquid metals with high density of electron gas  [PDF]
E. V. Vasiliu
Physics , 2002,
Abstract: Based on the many-body theory of metals in the third order of the perturbation expansion in electron-ion interaction pseudopotential, the potentials of pair and three-ion interactions are calculated in liquid lead, aluminium and beryllium at their melting temperatures. The reducible and irreducible three-ion interactions have an attractive nature on distances approximately equal to an average distance between ions in metals. It results in the shortening of average interatomic distance in an equilibrium state of metal. The potential landscapes created by a pair of fixed ions relative to the third ion are constructed. It is shown that with increasing of an electronic density the contribution as reducible, that and irreducible three-ion interaction is increased. It is shown also that the influence of reducible three-ion interaction on a potential landscape in a cluster of three ions is considerably larger than influence of irreducible three-ion interaction.
SENSOR OF OPTICAL WAVEGUIDE WITH LIQUID CORE FOR LIQUID DENSITY MEASUREMENT
液芯光波导溶液浓度传感器

Mat Yongxian,Zhou Zuoping,Fan Shiliang,
麦咏贤
,周佐平,范仕良

红外与毫米波学报 , 1995,
Abstract: A new system of large-diameter waveguide with liquid core for the measurement of liquid density is presented.The main advantage of this system is the relatively high measuring sensitivity. The principle of this system and the effect of construction parameters of the system on the sensitivity are discussed.The results of measurements are nearly in agreement with the theoretical analysis.
Ion density fluctuations in liquid metals: the strongly interacting ion-electron plasma  [cached]
L.E.Bove,C.Petrillo,F.Sacchetti
Condensed Matter Physics , 2008,
Abstract: An unified description of liquid metals dynamics based on an interacting two-component model for the ion-electron plasma is tempted. The propagation velocity of the collective modes in alkali and polyvalent metals, derived from inelastic neutron and x-rays scattering experiments, is compared with the estimates obtained by different theoretical approximations for the strongly-interacting plasma. Using accurate results for the electron gas correlation energy, and taking into account the ion finite size effects, a good overall description of a large set of liquid metals is obtained. The observed trend for the damping of the collective modes in liquid metals is also discussed within the framework of the two-component description.
A versatile and compact capacitive dilatometer  [PDF]
G. M. Schmiedeshoff,A. W. Lounsbury,D. J. Luna,S. J. Tracy,A. J. Schramm,S. W. Tozer,V. F. Correa,S. T. Hannahs,T. P. Murphy,E. C. Palm,A. H. Lacerda,S. L. Bud'ko,P. C. Canfield,J. L. Smith,J. C. Lashley,J. C. Cooley
Physics , 2006, DOI: 10.1063/1.2403088
Abstract: We describe the design, construction, calibration, and operation of a relatively simple differential capacitive dilatometer suitable for measurements of thermal expansion and magnetostriction from 300 K to below 1 K with a low-temperature resolution of about 0.05 angstroms. The design is characterized by an open architecture permitting measurements on small samples with a variety of shapes. Dilatometers of this design have operated successfully with a commercial physical property measurement system, with several types of cryogenic refrigeration systems, in vacuum, in helium exchange gas, and while immersed in liquid helium (magnetostriction only) to temperatures of 30 mK and in magnetic fields to 45 T.
Odd-Frequency Density Waves: Non-Fermi-Liquid Metals with an Order Parameter  [PDF]
Eugene Pivovarov,Chetan Nayak
Physics , 2000, DOI: 10.1103/PhysRevB.64.035107
Abstract: We consider states with a charge- or spin-density wave order parameter which is odd in frequency, so that the order parameter vanishes at zero frequency and there is a conventional Fermi surface. Such states break translational symmetry and, therefore, are not conventional Fermi liquids. In the odd-frequency spin-density wave case, there are Goldstone bosons and the low-energy spectrum is manifestly different from that of a Fermi liquid. We discuss a simple model which gives rise to such ordered states. The frequency-dependence of the gap leads to an unusual temperature dependence for various thermodynamic and transport properties, notably the resistivity.
Freezing of Simple Liquid Metals  [PDF]
A. R. Denton,G. Kahl,J. Hafner
Physics , 1999, DOI: 10.1016/S0022-3093(99)00108-8
Abstract: Freezing of simple liquid metals and the relative stabilities of competing crystalline solids are investigated using thermodynamic perturbation theory, the interactions between ions being modeled by effective pair potentials derived from pseudopotential theory. The ionic free energy of the solid phase is calculated, to first order in the perturbation potential, using classical density-functional theory and an accurate approximation to the hard-sphere radial distribution function. Free energy calculations for Na, Mg, and Al yield well-defined freezing transitions and structural free energy differences for bcc, fcc, and hcp crystals in qualitative agreement with experiment.
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