Revised Calibration for High Pressure Electrical Resistance Cell
01 Nov 1970-Review of Scientific Instruments (American Institute of Physics)-Vol. 41, Iss: 11, pp 1667-1668
About: This article is published in Review of Scientific Instruments.The article was published on 1970-11-01. It has received 111 citations till now. The article focuses on the topics: Electrical resistance and conductance & Calibration.
Citations
More filters
••
TL;DR: A diamond-anvil type optical cell of improved design has produced static pressures in gasketed samples up to 500 kilobar as measured by the ruby fluorescence technique as discussed by the authors.
Abstract: A diamond‐anvil type optical cell of improved design has produced static pressures in gasketed samples up to 500 kilobar as measured by the ruby fluorescence technique. The ruby R1 line pressure shift is linear to 291 kilobar, and the maximum measured shift is extrapolated to 500 kilobar assuming continued linearity of the pressure dependence. The ultimate pressure capability of this diamond cell has not been established. Transition pressures in the semiconductors Si, ZnSe, ZnS, and GaP measured by the ruby method indicate that the revised 1970 fixed point scale and the ruby (NaCl) scale diverge above 135 kilobar and disagreement may be by as much as a factor of 2 in the 500 kilobar range with the ruby scale defining the lower pressure.
486 citations
••
TL;DR: In this paper, a two-band model was proposed to describe and predict the ionization potentials and electronic interband gaps of binary compounds and their alloys, and a revised method of calculating the excess heat of mixing of a substitutional alloy was presented.
Abstract: Electronegativity difference was redefined in Paper I of this series as a scaling parameter which combines the concepts of valence and size differences. A procedure has been developed for its evaluation in terms of a two-band model. In Paper II of this series it was shown that this model describes and predicts the ionization potentials and electronic interband gaps of binary ${A}^{N}{B}^{8\ensuremath{-}N}$ compounds and their alloys. Here the energy of this model semiconducting-insulating solid is evaluated relative to a free-electron gas, i.e., an idealized metal, as a function of composition, pressure, and temperature. Using this highly simplified scaling approach, we obtain suprisingly accurate predictions for the heat of fusion, melting point, and pressure-temperature phase diagrams of these materials. A revised method of calculating the excess heat of mixing of a substitutional alloy is presented. This calculation is extended to the case of an arbitrary dilute impurity in an arbitrary semiconducting host; the distribution coefficient at the melting point of the host is obtained.
358 citations
••
TL;DR: In this article, it was shown that the intra-atomic interaction in cerium is considerably smaller than seems to have been believed in the past, and it is argued that in metallic cerium, U is only of the order of a few electron volts.
Abstract: The α-γ transition in cerium is considered as a Mott transition. From spectroscopic data it is concluded that the intra-atomic interaction, U, is considerably smaller than seems to have been believed in the past. Here it is argued that in metallic cerium, U is only of the order of a few electron volts. Current band calculations of the width of a 4f band state are presumably very unreliable, and correlation effects on the ionic crystal potential are probably of considerable importance. Still, some conventional band calculations seem to imply a width of nearly one electron volt for densities appropriate for the dense a phase in cerium. Several experimental facts on the properties of γ and α cerium lead us to assert that metallic cerium cannot promote its f electron into the (sd) configuration. This is most clearly seen from its cohesive energy properties, and it is shown that if cerium were to attain an (sd)4 configuration, say in the a or a phase, this would lead to a totally unacceptable behaviou...
353 citations
••
TL;DR: In this paper, X-ray diffraction studies on silicon at pressures up to 250 kbar (25 GPa) were conducted and the structure of the β-Sn structure was tentatively assigned as primitive hexagonal with c / a = 0.941 ± 0.002 at 250 k bar.
253 citations
••
TL;DR: Ritsema et al. as mentioned in this paper presented a phase diagram for the MgSiO3-FeSiO4-SiO2 system at 800 and 1,000°C.
221 citations
References
More filters
••
TL;DR: In this paper, the authors present a review of the experimental approaches to the problem of determining the pressure-compression states behind shock waves and a summary of the published experimental data for solids is given.
Abstract: Publisher Summary For most solids, shock wave pressures in the range extending from 100 kilobars to 400 kilobars are attained easily. Pressures in excess of 1000 kilobars can be obtained by the slight modification of the simple in contact explosive–solid geometry. The task of determining the associated pressure–compression data derives part of its appeal from the fact that precise static compressibility studies have been limited to pressures below 100 kilobars. The experimental approaches to the problem of determining the pressure–compression states behind shock waves are reviewed and a summary of the published experimental data for solids is given in the chapter. The experimental data that consist of a known pressure P, volume V, energy E locus for each material are extended to a complete thermodynamic description of states neighboring the experimental curves. These calculations are based upon the Mie–Gruneisen equation of state and the Dugdale–MacDonald relation, the latter being used to determine the volume dependence of the Gruneisen ratio. The Dugdale–MacDonald relation is tested at zero pressure, where sufficient thermodynamic data exist to permit the comparison with Gruneisen's ratio as calculated from the usual thermodynamic relations.
520 citations
••
01 Jan 1952
305 citations
••
TL;DR: In this article, a high pressure electrical cell is described consisting of tapered Carboloy pistons supported by a pyrophyllite pellet, and a calibration is obtained based on the barium transition at 59 kb, the bismuth transition at 90 kb and an extrapolation of Bridgman's data.
Abstract: A high pressure electrical cell is described consisting of tapered Carboloy pistons supported by a pyrophyllite pellet. The pistons are heavily work hardened. A calibration is obtained based on the barium transition at 59 kb, the bismuth transition at 90 kb, and an extrapolation of Bridgman's data. The pressure range is to 500 kb under favorable circumstances. New fixed points include a discontinuous rise in resistance of lead at 161 kb, a discontinuous rise in resistance of barium at 147 kb, a discontinuous rise in the resistance of rubidium at 193 kb, a maximum in the resistance of calcium at 370–75 kb, and a maximum in the resistance of rubidium at 425 kb. In addition, there is a discontinuous rise in resistance of iron at 133 kb which is consistent with the shock wave pressure point found at 131 kb and 37°C.
213 citations
••
TL;DR: The effect of pressure to several hundred kilobars has been measured on the compressibilities of seven substances having the NaCl (fcc) or CsCl (sc) structure as discussed by the authors.
Abstract: The effect of pressure to several hundred kilobars has been measured on the compressibilities of seven substances having the NaCl (fcc) or CsCl (sc) structure. These include NaCl, KCl, CsCl, MgO, CaO, CaS, and TlI. For the first four crystals a Born—Mayer treatment involving the Madelung energy, van der Waals' terms, and an exponential repulsion (with constants evaluated from initial volume and compressibility) gave a quantitative fit throughout the range. CaO has a measurable lower compressibility at high pressure than predicted from the theory. This effect is exaggerated in CaS. An interesting feature of the behavior of TlI is that although it exhibits metallic conductivity above 160 kbar, there is no measurable discontinuity in the compressibility near this point.
204 citations
••
TL;DR: In this article, the authors used the Mie-Gruneisen equation of state with Born-Mayer type repulsion terms between first and second nearest neighbors to calculate the pressure as a function of lattice parameter and temperature for NaCl over a pressure range of 0 to 500 kbar for temperatures between 0° and 1500°C.
Abstract: The pressure as a function of lattice parameter and temperature has been calculated for NaCl over a pressure range of 0 to 500 kbar for temperatures between 0° and 1500°C. The calculation used the Mie‐Gruneisen equation of state with Born‐Mayer type repulsion terms between first and second nearest neighbors. The Gruneisen constant was expanded about its value at room temperature and atmospheric pressure; the first coefficient in the expansion being evaluated by forcing the calculated thermal expansion at atmospheric pressure to fit the experimental results of Enck. The two empirical parameters in the repulsion terms were evaluated using the experimental lattice parameter and isothermal compressibility at atmospheric pressure. The calculated pressure vs volume agrees with Bridgman's room‐temperature measurements in NaCl below 100 kbar to within 3% and with high‐pressure high‐temperature shock data to better than 2%. It is proposed to use the numerical results to calibrate the pressure in high‐pressure high‐temperature apparatus.
201 citations