Thermodynamic properties of liquid magnesium-bismuth alloys
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A detailed description of the experimental arrangement was given in the paper. 1 The same type of cells was used by lkeuchi and Krohn s for the study of molten MgClz-AlkC1 mixtures. Here the following cell was employed: Mg(Bi) (l) I (MgCI~-AlkCI) (l) I CI~ (g) (graphite) To increase the density of the liquid magnesium electrode, and to lower the solubility of magnesium in the electrolyte, the magnesium was alloyed with bismuth. The same cell was employed in the present f o r m a tion cell investigation of the Mg-Bi system, taking MgCla activity data for the 32 mole pct MgCI~-NaC1 electrolyte from the data by Ikeuchi and Krohn. s Since the experimental arrangement has been described elsewhere, l's only the experimental procedure will be given here. The proper amounts of Mg, Bt, MgCI~ and NaC1 were weighed-in in a glove-box flushed with dry nitrogen. MgC1z was dried by passing dry HC1 f i r s t over solid analytical grade magnesium chloride hexahydrate. The hexahydrate then gradually was heated and melted, and finally HC1 was passed through the molten magnesium chloride. After purging the melt with purified Ar, the molten chloride was filtered into ampoules which were sealed off and then transported to the glove-box. The crucible with the weighed-in amounts of metal and salt then quickly was t r a n s f e r r e d to the preheated furnace with an inert atmosphere. After heating the cell to about 900"C to ensure a proper mixing of the Mg-Bi alloy in the electrode, the anode compartment with the diaphragm and the Ta lead to the magnesium electrode was lowered into place. After stabilization of the t e m perature and the cell potential, the measurements were started. Measurements were c a r r i e d out both at continuously decreasing and increasing temperature, respectively, in the range from 973 to 1123 K. The EMF of the cell and T was recorded simultaneously on a Varian G-2000 potentiometric r e c o r d e r with suppressed zero point. Temperature was measured by a calibrated P t / P t 10 Rh thermocouple. The EMF values were corrected for the thermoelectric EMF which a r i s e s in the measuring c i r cuit due to the application of Pt and Ta leads to the r e spective electrodes. VOLUME 5, MAY 1974-979
Concentration Cells
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