Synthesis of nanocrystalline NH4MnF3. A preparation route to produce size-controlled precipitates via microemulsion systems

TLDR: Using ammonium-substituted AOT as surfactant and n-heptane as dispersion medium, water in oil microemulsions with large contents of concentrated NH4F and manganese acetate aqueous solutions, respectively, have been stabilised as mentioned in this paper.

Abstract: Using ammonium-substituted AOT as surfactant and n-heptane as dispersion medium, water in oil microemulsions with large contents of concentrated NH4F and manganese acetate aqueous solutions, respectively, have been stabilised. After mixing, nanostructured NH4MnF3 precipitates, in spite of its comparatively high solubility in water. During the coagulation with acetone, CH3COONH4(s) is formed which, however, can quantitatively be removed by transformation into acetamide and subsequent solution in the organic medium. The resulting n-NH4MnF3 is immediately crystalline at room temperature without annealing procedures. Different mean crystallite sizes between 10 and 60 nm were obtained by appropriate variation of the synthesis parameters, i.e., aqueous phase content, salt concentration, synthesis temperature, and the period of time between the mixing of the two microemulsions and the coagulation with acetone.