Pure Hg Research Articles

Electrical conductivity of Na-Hg and Ag-Hg β″-alumina

The electrical conductivity of single crystal and polycrystalline Ag-Hg and Na-Hg β″-aluminas with varying Hg contents was measured. The conductivity of pure Hg β″-alumina, extrapolated from conductivity isotherms of single crystal Ag-Hg β″-alumina, showed Arrhenius behavior with an activation energy of 0.96 eV. At 315°C the conductivity of single crystal Hg β″-alumina was 3.3×10 -5 (ω·cm) -1, which is about three orders of magnitude lower than for Ca, Sr, Ba, and Cd β″-alumina. An upper limit for the conductivity of Hg in the polycrystalline β″-alumina was estimated as 1×10 -6 (ω·cm) -1 at 315°C.

Phase equilibria in Hg-He mixtures near the critical point of almost pure Hg

Abstract The paper presents new high pressure - high temperature experiments on the phase behavior of mercury-helium mixtures. Two distinct fluid phases are shown to exist in Hg-He-mixtures at temperatures and pressures higher than the critical temperature and pressure of pure mercury. Very accurate thermoelectric properties in the immediate vicinity of the critical point of pure fluid mercury show that profound chnages in the electronic structure in that region are manifest in a correspondingly strong thermodynamic state-dependence of the effective interparticle interaction. The latter noticeably influences the features of the phase behavior of pure fluid Hg and the Hg-He-mixtures.

Kariesprophylaxe and konservierende therapie

Mercury vapor release from amalgams during setting significantly decreases when the amalgams are prepared with binary Hg-In liquid alloys. The objective of this study was to compare the cytotoxicity of amalgams made with experimental Hg-In alloys with that of amalgam without In and a commercial In-containing amalgam.Amalgam specimens were prepared by triturating a high-Cu alloy powder (Tytin, Kerr) with pure Hg or Hg-In liquid alloy containing 5, 20 or 50% In and also by triturating an In-containing high-copper alloy powder (Indiloy, Shofu) with pure Hg. After the specimens were aged for 2 wk, a cylindrical specimen of each amalgam was immersed consecutively in cell culture medium for 0–8, 8–48 and 48–72 h. The cytotoxicity of the extracts was determined by placing them in contact with Balb/c 3T3 mouse fibroblasts for 24 h, after which the succinic dehydrogenase (SDH) activity was measured and expressed as a percentage of the Teflon negative controls. The results were statistically compared using ANOVA and Tukey's test (α = 0.05). The concentration of elements released into the extracts was determined by atomic absorption spectrophotometry and evaluated by Kruskal-Wallis and non-parametric multiple comparisons.For the 0–8 h and 8–48 h intervals, the 20% In amalgam was significantly (p < 0.05) less toxic than the other amalgams, and not different from the Teflon control. Results for the other amalgams were only slightly depressed compared to the Teflon control. For the 48–72 h interval, all amalgams were essentially no different from the control. Copper was the element dominantly released into the medium from all the amalgams tested.For amalgam tested after aging, alloying indium to mercury did not deleteriously affect the cytotoxicity of the resultant amalgam compared to the amalgam without indium.

On the quality of mercurous chloride crystals

Large, oriented single crystals of mercurous chloride were grown by the physical vapor transport (PVT) method. Crystal quality was evaluated by birefringent interferometry and scattering measurements. A total variation of 2.2 × 10 −4 in refractive index was estimated over the whole aperture (25 mm) of the crystal. A He-Ne laser beam 5 mm in diameter and with 40 dB dynamic range (from peak to sidelobes) showed that sidelobes are − 32 dB down for pure Hg 2Cl 2 crystals. The quality is suitable for Bragg cells which have the capability of long-term aperture, moderate resolution, good dynamic range, and reduced system volume compared to Bragg cells fabricated from other commercially available materials.

Thermodynamic properties of undercooled liquid metals

In the form of a droplet emulsion, a number of liquid metals and alloys have been undercooled by substantial amounts (0.3–0.4 T m) before crystallization. For example, pure Hg, In, Sn, and Bi can be undercooled by 90°C, 110°C, 187°C and 227°C respectively. Differential scanning calorimetry has been applied to determine the heat capacity difference, ∪Cp, between the undercooled liquid and crystalline solid. With decreasing temperature an increasing value of ∪Cp is observed which implies a reduction in configurational entropy of the liquid. In addition the heat capacity measurements allow for the determination of the free energy and the onset of the hypercooled regime which are useful in the evaluation of the crystallization kinetics.

Low temperature metal saturation of Hg1−xCdxTe(s)

The simultaneous fit to diverse phase diagram and thermodynamic data in the Hg-Cd-Te system using an associated solution model for the liquid phase is summarized. The calculated low temperature isotherms and solid isoconcentration lines near pure Hg are shown to agree well with experiment. The difference between the crystal temperature and the temperature of a Hg-reservoir required to give the mercury pressure for metal-saturation is tabulated for crystal temperatures of 250, 275, and 300°C and x-values between 0.1 and 0.9. The differences are all less than 0.6°C and at a given crystal temperature are smallest for x = 0.9.

Collision-induced Raman spectra of Hg-rare gas Van der Waals complexes

An absolute differential scattering cross section is calculated for the Hg-rare gas and pure Hg Van der Waals quasimolecules, taking into account both the free state and bound state contributions to the depolarized Raman spectra of these systems. The calculations are performed using the Maitland-Smith (MS) potential function fitted to available experimental data and assuming the simple dipole-induced dipole (DID) model of anisotropy of the polarizability tensor of a collisional atomic pair. The obtained cross sections are about 100 times greater than those for the pure rare gas calculated and measured by Frommhold et al.

New data on the mercury antimony mineral shakhovite: Chemical composition, unit cell and crystal structure

A new investigation of the mercury antimony mineral shakhovite yielded space groupIm witha=4.871(1),b=15.098(3),c=5,433(1) A and β=98.86(2)°. The determination of the crystal structure gave a cell content of Hg8Sb2O12. Since the presence of Hg2-groups indicates that shakhovite is a pure Hg(1) compound and the infrared spectrum shows an absorption band at 3440 cm−1 which is due to the OH-stretching frequency, it is assumed that there are six oxygen atoms and six OH-groups in the unit cell. Thus the chemical formula of shakhovite reads Hg4Sb(OH)3O3 with two formula units per unit cell. The Hg−Hg distance in the Hg2-group is 2.543 A, each mercury atom has a close oxygen neighbour at 2.160 and 2.135 A. Hg−Hg−O angles are 159.0 and 166.3°.

The Influence of Admixtures of Molecular Gases on the Efficiency of Radiation Production by ArHg Mixture Plasmas used in Fluorescent Lamps

AbstractStarting from former investigations of pure ArHg mixture plasmas in parameter ranges typical of fluorescent lamps we studied the influence of additional admixtures of molecular gases (N2, H2) on the energy transfer from the electrons heated by an electric field to the lowest excited states of Hg atoms which are the energy source for the resonance radiation production. By calculation of the different power loss rates via solving the appropriate Boltzmann equation for three component mixture plasmas it was found that already a threshold level of molecular impurities of about 10−4 Torr leads to a marked energy dissipation by the impurities and thus to a pronounced reduction of the efficiency of the resonance radiation production. This is caused by the great effectivity of vibrational excitation of molecules in electron collisions due to the great cross sections for such collisions and their low thresholds.

Unusual Thermodynamic and Electrical Properties of Metallic Solutions Near the Critical Point of the Almost Pure Solvent

AbstractThe paper presents experimental results of the electrical conductivity σ, the equation of state data and different related properties such as excess volumes of mixing VEx and partial molar volumes V̄In for dilute amalgams of In as a function of pressure p. temperature T and composition XIn to 2700 bar, 1900 K and 2.85 at‐% In, respectively. Particular attention is given to the behaviour of these properties in the metal‐nonmetal transition range and close to the critical point of pure Hg. It is found that the divergence of the compressibility χT of pure Hg at the critical point is reflected in the behaviour of VEx, V̄In and in the concentration dependence of the conductivity. The limiting values of the negative partial molar volume V̄In and of for infinitely dilute solutions become extremely large as the critical point of pure Hg is approached. — An attempt is made to separate the different effects of temperature, volume and concentration and to analyze the data in terms of existing models for the electrical transport in expanded Hg and the critical behaviour of fluid dilute solutions.

Evaluation of a Mixed Ag2S/AgI Membrane as Hg (II) Ion Selective Electrode

Abstract Molar ratios of Ag2S/AgI between 3:1 to 1:3 have been studied as Hg(II) ion selective electrode. It was found that the molar ratio 1:3 WBB the best ratio to be used as Hg(II) electrode after one hour conditioning in a solution of 10−2M Hg(II) ion and in the pH range between 1.5–4.5. Interferences from anions (Cl−, Br−, S− and CN−) were quite serious if concentration of the interfering ion exceeded that of Hg(II) ion. Cations except Ag+ ion did not interfere. Dynamic response of the electrode showed that the equilibrium response time of the electrode is between 30–50 seconds at different concentrations of Hg(II) ion. Potentiometric titrations and antomatic titrations using Cl− or Br− as titrants gave sharp end points down to 10−3M Hg(II) ion. Analysis of pure inorganic Hg(II) ion gave an error of 0.5% or less and a coefficient Of variation of better than 0.1%.

The CdHg (a) state: Fluorescence kinetics and absorption

The molecular fluorescence of CdHg has been studied following excitation of Hg2 at 266 nm. The fluorescence is modeled by giving the CdHg (a) state a lifetime of 2.4 μsec and including a reservoir of metastable Cd2Hg molecules. The transmission of this system has been monitored at wavelengths between 390 and 514 nm as a function of cadmium density and temperature yielding results consistent with the Cd2Hg hypothesis. Excited state absorption has been measured for CdHg (a), Cd2Hg, pure Hg, and pure Cd. The absorption intrinsic to CdHg (a) has a peak cross section of 5×10−19 cm2 at 450 nm and a width of 90 nm at half-maximum.

Nuclear Radiation Detected Optical Pumping of neutron-deficient Hg isotopes

The extension of the Nuclear Radiation Detected Optical Pumping method to mass-separated samples of isotopes far off stability is presented for a series of light Hg isotopes produced at the ISOLDE facility at CERN. The isotope under investigation is transferred by an automatic transfer system into the optical pumping apparatus. Zeeman scanning of an isotopically pure Hg spectral lamp is used to reach energetic coincidence with the hyperfine structure components of the 6s 2 1 S 06s6p 3P1,λ=2,537 A resonance line of the investigated isotope and the Hg lamp. The orientation built up by optical pumping is monitored via the asymmetry or anisotropy of the nuclear radiation. Nuclear spins, magnetic moments, electric quadrupole moments and the isotope shifts are obtained for181Hg-191Hg using theβ asymmetry as detector. The extension of the method using theγ anisotropy is discussed and test measurements on193Hg are presented. This paper describes the experimental procedure, results, and discussion are given in a following publication.

Resonant level in semiconducting Hg 1− xCd xTe

In pure n-type Hg 0.8Cd 0.2Te we have observed an anomalous peak in the transverse magnetoresistance and in the Hall coefficient at low temperatures. Moreover the same samples show an absorption line at far infrared frequencies. Tentatively we have proposed a resonant state at an energy of 7.5 meV above the conduction band which might be generated by a tellurium vacancy. This model yields a good description of the experimental results.

The upper critical field of quenched condensed Sn, Tl, In and Hg with extremely short mean free path

Quenched condensed films of Sn, Tl, In and Hg are fine crystalline and have very short mean free path. The upper critical field of these disordered superconductors is measured. The initial slope,dB c 2/dT is compared with a strong coupling calculation. We use α2F(ω) which is measured for these superconductors in the pure state and for Sn in the quenched state. The strong coupling behavior enhances the upper critical field by 15–20%. We find a fair (about 10%) agreement between the experimental and theoretical values ofdB c 2/dT except for Hg. In Hg one has either to consider band structure effects or the α2F(ω) of quenched condensed Hg is quite different from that of pure Hg.

The compressibility of liquid sodium alloys

Abstract The velocity of sound at 7·5 Mhz and the density have been measured as functions of temperature for a number of liquid alloys based on Na. The results cover the whole concentration range for the Na-Hg system and the range from 0 to about 5 atomic % of the solute for Na + Au. Cd, In, Pb and Sn. From the results the adiabatic compressibility and the mean molar volume have been deduced. The behaviour of these quantities provides no convincing evidence for compound formation in the liquid phase of Na-Hg. There is, however, a substantial volume contraction on mixing and, apparently because of this contraction, the compressibility when plotted against composition falls well below the straight line linking the values in pure Na and pure Hg. The results for the dilute Na alloys suggests that this contraction and the associated reduction of the adiabatic compressibility are not peculiar to Na-Hg. The effects of all the different solutes used are, indeed, remarkably similar.

Modulated Spectra of ac Arc Lamps

Light emanating from ac arcs operating on 60-Hz power exhibits a 120-Hz modulation of intensity. Although time-averaged spectra of such arcs are usually reported, the instantaneous light spectrum and its dependence on the oscillating plasma temperature is a more valuable source of spectroscopic information. An experimental technique is described for scanning the spectrum of an ac discharge at any fixed phase in the arc operating cycle. Spectra were recorded at phases corresponding to maximum and minimum light output for a pure Hg arc, a Hg–Na, Sc, Th metal-iodide arc, a Hg high-pressure Na arc, and a Hg–SnI2 arc. Intensity ratios Imax/Imin of spectral lines generally increased with increasing upper-state energy. Many of the dominant lines also exhibited sizable changes of line profile with variations of phase. In the Hg–Na, Sc, Th metal-iodide arc, the intensity variations of optically thin lines were used to obtain estimates of upper-state energies and relative gA values of some Th lines for which these quantities were previously unknown.

Structures of Liquid Mercury and Dilute Liquid Mercury Alloys

The structures of liquid Hg and the dilute liquid Hg alloys with 0.5 and 2 atomic percent Cd, and 0.5 and 1 atomic percent Pb have been studied by x-ray diffraction using a theta-theta diffractometer with monochromator in the diffracted beam. The addition of 0.5 or 2 atomic percent Cd into Hg did not produce any detectable change in the interference function I (K), where K=4π (sin Θ)/λ, whereas small additions of Pb seem to reduce the asymmetry of the first peak of 1(K) which is observed in pure Hg. Small additions of Pb also cause a slight shift of the second peak of l (K) to smaller K-values. The present results have been used to offer a possible interpretation of the structure of Hg as observed in the liquid state.

Interference Functions, Pair Distribution Functions and Electron Transport Properties of Liquid Mercury-Indium Alloys

X-ray diffraction patterns of liquid Hg-In alloys with 5, 12, 25, 35, 42, 50 and 62 atomic percent In were measured at room temperature (25°C). The interference and radial distribution functions, I(K) and 4 π r2 ρ(r), respectively, were refined by an error analysis program. The position K1=4π sin Θ1/λ of the first peak maximum of I(K) does not change upon alloying, i. e., K1=2.29 A-1. The interference function of In plotted in reduced coordinates K/K1 agrees with that calculated from the hard sphere model with a packing density of 45%. A small asymmetry of the first peak towards larger K values might be discernible in In, whereas the Hg and Hg-In interference functions show a relatively large asymmetry, and their subsequent peaks appear at larger K/K1 values than those of the hard sphere model and In. The interatomic distances r1 and the numbers of electrons ηE in the first coordination shell show only a small deviation from a linear relationship when plotted as a function of concentration. Since 1(K) for K&lt;2 kF, where kF is the FERMI radius, are rather similar for Hg, In and all measured alloys, the electrical resistivity and thermoelectric power were evaluated using the random model and ANIMALU and HEINE pseudopotentials. The predicted resistivity was found to increase from 30µΩcm for pure Hg to 43 µΩcm for 35 atomic per cent In alloy and then to decrease to 24 µΩcm for pure In. The measured values of the resistivity decrease from 96 µΩcm for Hg to 30 µΩcm for pure In. Beyond the first eutectic composition, i. e., about 35 atomic per cent In concentration, the predicted resistivity curve decreases similarly to the measured resistivity curve. The discrepancy is attributed to the low density of states for Hg at the FERMI level. The predicted thermoelectric power decreases gradually from 1.22 µV/°K for pure Hg to 0.23 µV/°K for 62 atomic per cent In alloy, the value for pure In being 0.59 µV/°K. The measured values of thermoelectric power at 100°C decrease first from -6.5 µV/°K for pure Hg to -7.1 µV/°K for 5 atomic per cent In alloy and then increase to -0.7µV/°K for pure In. The discrepancy in the predicted values has been attributed to the energy dependence term of the pseudopotentials near the FERMI surface, particularly for pure Hg.

Atomic Distribution and Electrical Properties of Liquid Mercury—Thallium Alloys

The x-ray-diffraction patterns of liquid binary Hg–Tl alloys have been measured using a theta—theta diffractometer and quartz crystal monochromatized Mo Kα radiation. Pure mercury and five alloys of 5, 8.5, 16, 28.6, and 40 at. % thallium were studied at room temperature (25°C), whereas pure thallium was studied at 350°C. Since mercury and thallium are next to each other in the periodic table, the contribution of the Laue monotonic scattering to the scattered intensity should be negligible. The radial distribution functions were refined by an error-analysis program and then the refined interference functions were computed and used to calculate the electron transport properties of the alloys. The general equation for the scattering cross section of the electrons in liquid metals has been used and expressed in terms of the matrix elements of the pseudopotentials and the interference functions of the respective elements. Assuming that the atomic distribution is random, the resistivity and thermoelectric power of the alloys and the pure elements were calculated. There is some disagreement between the calculated or predicted and measured values of the resistivity. The predicted value of resistivity of mercury and thallium are 30 and 60 μΩ·cm, respectively. The interatomic distances were found to vary linearly from 3.05 for pure Hg to 3.28 Å for Hg−40 Tl alloy. The value for pure Tl is 3.30 Å. This linear variation is not in agreement with previous results. The positive deviation from Vegard's law has been attributed to the electrochemical and valence difference of the two elements. The behavior of the coordination number with concentration, the change being from 10.0 to 11.5 for pure Hg to pure Tl, is similar to that of the interatomic distance with the concentration.