Abstract

The reaction of aqueous solutions of strontium nitrate and stannous fluoride results in the formation of a precipitate which is SrSn$\sb2$F$\sb{6\cdot}$H$\sb2$O, or Sr$\sb2$Sn$\sb2$NO$\sb3$F$\sb{7\cdot}$2H$\sb2$O, or a mixture of both, depending on the conditions. The reaction has been studied as a function of various reaction parameters, such as molar ratio, order of addition of reagents, mixing speed, time and temperature. The preparation of these materials is described here. The nature of the products was investigated by various analytical techniques, such as atomic absorption spectrophotometry, fluoride ion electrode analysis, infrared spectroscopy, X-ray diffraction, thermal analyses and Mossbauer spectroscopy. Recrystallization of SrSn$\sb2$F$\sb{6\cdot}$H$\sb2$O and Sr$\sb2$Sn$\sb2$NO$\sb3$F$\sb{7\cdot}$2H$\sb2$O from nitric acid was performed in primarily an effort to obtain single crystals that could be used for crystal structure determination by X-ray single crystal diffraction. In addition, it was also used to investigate if any new materials are formed by this method, since it is known to happen if PbSnF$\sb4$ is recrystallized in nitric acid. Furthermore, highly oriented samples and higher purity of both materials are obtained by recrystallization. Reactions between strontium chloride and stannous fluoride in aqueous solutions were also investigated under similar conditions.