THERMODYNAMIC STUDIES OF IRON DOPED BETA"-ALUMINA BY COULOMETRIC TITRATION
Abstract
Thermodynamic studies of the nonstoichiometric iron doped beta''-alumina (ID(beta)'') phase were carried out by electrochemical measurements coupled with coulometric titration using the cell Na(,liq)/Li (beta)''-alumina/ID(beta)''. Hot pressing and glass sealing techniques were developed and employed to obtain a suitable and stable Li (beta)''-alumina/ID(beta)'' interface. The equilibrium emf of the cell was determined as a function of sodium concentration over the temperature range 444K to 523K. The range of sodium concentrations over which the ID(beta)'' phase is stable was also determined. Activity of sodium and the relative partial molar thermodynamic quantities of sodium, (DELTA)G(,Na),(' )(DELTA)H(,Na),(' )and(' )(DELTA)S(,Na) in ID(beta)'' alumina as a function of sodium concentration were obtained from cell emf data. A coulometer utilizing ID(beta)'' alumina as electrodes was fabricated and operated over the temperature range 399-523K.
Degree
Ph.D.
Subject Area
Materials science
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