Electric Conductivities of Molten Salts of Some Binary Fluoride Systems

The specific electric conductivities of binary molten salts of NaF-BaF_2, NaF-CaF_2, KF-BaF_2 and KF-CaF_2 systems were measured at 1000℃. 1) In these binary molten salts, the specific electric conductivities decrease almost parabolically with the increase of barium fluoride or calcium fluoride contents. 2) The specific electric conductivities of these four binary molten salts were calculated by "Taniuchi\u27s modified formula", which is a modification of "Markov\u27s formula", and the calculated values agreed well with the measured values. 3) From above-mentioned results, we conclude that the ionic species of these molten salts which take part in the electric conduction are Na^+, K^+, Ba^, Ca^ and F^- respectively. 4) We are of the opinion that sodium fluoride cannot be replaced by potassium fluoride in the aluminum refining electrolytes, because the latter is less electrically conductible and more hygroscopic

Sequential Nature of (p,3p) Two-Proton Knockout from Neutron-Rich Nuclei

Twenty-one two-proton knockout (p,3p) cross sections were measured from neutron-rich nuclei at ∼250  MeV/nucleon in inverse kinematics. The angular distribution of the three emitted protons was determined for the first time, demonstrating that the (p,3p) kinematics are consistent with two sequential proton-proton collisions within the projectile nucleus. Ratios of (p,3p) over (p,2p) inclusive cross sections follow the trend of other many-nucleon removal reactions, further reinforcing the sequential nature of (p,3p) in neutron-rich nuclei

Melting and metallization of silica in the cores of gas giants, ice giants and super Earths

The physical state and properties of silicates at conditions encountered in the cores of gas giants, ice giants and of Earth like exoplanets now discovered with masses up to several times the mass of the Earth remains mostly unknown. Here, we report on theoretical predictions of the properties of silica, SiO$_2$, up to 4 TPa and about 20,000K using first principle molecular dynamics simulations based on density functional theory. For conditions found in the Super-Earths and in ice giants, we show that silica remains a poor electrical conductor up to 10 Mbar due to an increase in the Si-O coordination with pressure. For Jupiter and Saturn cores, we find that MgSiO$_3$ silicate has not only dissociated into MgO and SiO$_2$, as shown in previous studies, but that these two phases have likely differentiated to lead to a core made of liquid SiO$_2$ and solid (Mg,Fe)O.Comment: 5 pages, 4 figure

Electrical Conductivities of Quaternary Molten Salts in the Sodium Fluoride-Calcium Fluoride-Barium Fluoride-Aluminum Fluoride System

Molten salts in the sodium fluoride-calcium fluoride-barium fluoride-aluminum fluoride quaternary system are known as Hurter\u27s bath and Sumitomo\u27s bath for electrolytic refining of aluminum. The specific electrical conductivities of this quaternary molten salt system have been measured. 1) The specific conductivities of NaF-AlF_3 binary molten salts are found to be 5.17～2.33 ohm^ cm^ up to the composition range of 50 wt.% AlF_3 at 1000℃, and these values agree fairly well with the values reported in other works. 2) In these quaternary molten salts, the measured values of specific conductivity are 4.13～0.73 ohm^ cm^ in the composition range of 5～20 wt.% CaF_2 and 30～50 wt.% BaF_2 at 950℃. 3) When the weight percent of added CaF_2 and BaF_2 is kept constant, the specific conductivities of this quaternary molten salt system decrease almost linearly with an increase in AlF_3 content. Similarly, the values decrease with increase in the contents of CaF and BaF_2 4) In this quaternary molten salt system, such compounds as Na_3AlF_6, NaAlF_4, Na_5 Al_3F_ NaCaAlF_6 NaBaAlF_6, CaAlF_5 and BaAlF_5 are formed and several complex ions including AlF_6^ and AlF_4^- are considered to exist. The structures of the molten state are not clearly known. The validity law in the electrical conductivity by each component are questioned. 5) The specific conductivities of Hurter\u27s and Sumitomo\u27s baths have been measured at 750～950℃ as 0.96～1.25 ohm^ cm^ and 0.87～1.10 ohm^ cm^, respectively. 6) Experimental evidence shows the possibility that some other composition range in this quaternary system can be used as an electrolyte of aluminum refining, besides Hurter\u27s or Sumitomo\u27s bath

Nonclassical symmetry and Riemann invariants

In this paper it is shown that Riemann invariants are invariant under nonclassical symmetries of a hyperbolic system. As a specific example, we study the one-dimensional shallow water equations on the flat and present another type invariance under nonclassical symmetries.Comment: 7 pages. Submitted t