Mechanochemical synthesis of ion-exchange silver forms of polyantimonic acid

The possibility of synthesising ion-substituted forms of hydrated silver antimonates $\mathrm{Ag_{2\gamma} H_{2-2\gamma} Sb _{2} O_{6} \cdot 2H_{2}O}$ has been studied. For the synthesis, the method of mechanochemical activation of the components of an inorganic mixture consisting of polyantimonic acid (PAA) with $\mathrm{H_{2} Sb _{2} O _{6} \cdot 2H _{2} O}$ composition and silver nitrate with the concentration range $(\gamma)$ from $0.0$ to $1.0$ has been applied. The results of studies of the phase composition of the synthesized compounds and their structural features are presented. Using the Rietveld method, the parameters of the crystal lattice of PAA hydrated ion-substituted silver forms with a pyrochlore-type structure have been refined. The model for the occupation of metal ions by crystallographic positions has been proposed: the framework of the structure of the compounds is formed by $16c$- and $48f$-positions, in which $\mathrm{Sb}^{5+}$ and $\mathrm{O}^{2-}$ are statistically located; hydrated oxonium ions ($\mathrm{H_{3}O}^+$) and silver ions occupy $16d$- and $8b$-positions respectively. It has been shown that the synthesis of silver forms of PAA is preferably carried out by the mechanochemical synthesis, which results in the complete substitution of proton groups by silver ions in the structure of the compounds.