Ternary Intercalation Compounds Containing Ammonia

Abstract

The behavior of metal-ammonia-graphite intercalation compounds subjected to deammoniation process was studied. Structures and chemical compositions were determined from the results of X-ray diffraction measurement and chemical analysis. The behavior of the cornpounds under deammoniation is classified to three groups as follows: ( 1 ) Caesium and rubidium compounds; which release all ammonia included in the compounds. ( 2 ) Potassium and sodium compounds; which release a greater part of ammonia included and change into new compounds. ( 3 ) Lithium and alkaline-earth metals compounds; which have a tendency to form amides and the decomposition processes are relatively complex. Na-NH3-graphite intercalation compounds synthesized from natural graphite, Grafoil, and an artificial graphite (petroleum eokes; HTT.2000°C) showed the same behavior regardless the graphite materials as for the deammoniation process. When the deammoniated samples are allowed to react with sodium, a sodium rich, secondary. intercalation compound was formed at 350°C. The identity period of the compound was 10.7A and the chemical composition was found to be Na₄(NE13)C₂₈. Using HOPG as a starting material, it was shown that a mixture of the graphite phase containing slight amount of sodium and a compound with the identity period of 9.1A was formed by the same treatment. The chemical analysis of the mixture showed that the composition was Na₁₆(NH₃)C₂₆₀. It should be noted that the compound with the identity period of 9.1A, as well as that with the identity period of 10.7A, has the chemical composition relatively rich in sodium, and that the compound Na4(N113)C28 is rather stable in air and it decomposed to Na, NHOC, in dilute HC1. The behavior of K-NH3-graphite intercalation compounds subjected to the deammoniation process is similar to that of the Na-NH₃-graphite compounds.