Showing papers on "Calcium aluminates published in 1979"

Substructure and properties of sodium beta alumina solid electrolytes. Final report

Abstract: About ten years ago sodium beta aluminas were identified as useful solid electrolytes for high-energy-density sodium/sulfur storage batteries. The ionic conductivity, the mechanical strength, and the lifetime of the electrolytes in operating cells was found to depend significantly on a number of factors. These factors included impurities and microstructure of the electrolytes. Because of the important economical benefits that could result from the use of long-life, high-energy-density batteries in load leveling, a study was conducted at Cornell to determine the relationship between the impurities and microstructure and the properties of sodium beta alumina solid electrolytes. Part of this study involved an investigation of certain aspects of the electrolyte fabrication, since the sintering process by which the electrolyte is made determines to a large extent the microstructure and impurity distribution. The methods used in this study include high-resolution transmission electron microscopy and measurement of the response of the electrolyte to ac signals between 10 hertz and 10 megahertz (complex admittance). Specifically, the importance of transient liquids during the sintering process was clarified. The effects on ionic conductivity of the presence of silicon (as silicates), calcium (as calcium aluminates), and zinc (in solid solution) were quantified. The importance of the microstructure and,more » in particular, the role of the grain boundaries in the sodium ion conduction process were elucidated. 89 figures, 7 tables.« less