Structural design of sealing glasses

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Requirements for enhanced component performance and reliability have led to the development of novel glass compositions for a variety of hermetic sealing applications. The development of technologically useful glass compositions was based on an understanding of the relationships between the molecular-level glass structure and important physical properties. The properties of the alkaline earth aluminoborate glasses for lithium batteries are sensitive to changes in B- and Al-coordination number, characterized by solid state nuclear magnetic resonance (NMR) spectroscopy. In general, the most useful compositions have structures that are dominated by tetrahedral B- and Al-sites. Mixed alkali aluminophosphate glasses were developed for aluminum electrical connectors. The properties of sodium aluminophosphate glasses depend on the O P ratio and significant property changes (e.g. maxima in T g and refractive index) occur when O P exceeds pyrophosphate limit at 3.5. Associated with these property changes is a decrease in the average Al-coordination number, from six to four, at O P > 3.5 . Raman spectroscopy provides additional information about the aluminophosphate network. Finally, zinc borophosphate glasses are developed for seals in flat panel displays. Boron-11 NMR shows that tetrahedral borons are preferred in xB 2O 3(1 - x)(PO 3) 2) and in yB 2O 3(1 - y)Zn 2P 2O 7 glasses for x < 0.4 and y < 0.2. Raman spectroscopy reveals the concomitant evolution from a phosphate to a borophosphate network with increasing x and y.