Iron (II) Ammonium Sulfate Hexahydrate

Iron (II) Ammonium Sulfate, also known as Ferrous Ammonium Sulfate or Mohr’s salt, is a blue-green, water-soluble double salt of Ferrous Sulfate and Ammonium Sulfate. Compared to Iron (II) Sulfate, it is much more resistant to oxidation in air, giving it greater stability and shelf life, which makes it widely used as a chemical reagent. Named after the German chemist Karl Friedrich Mohr, who advanced titration methods in the 19th century, it is employed in laboratory analyses, as a fertilizer, in water treatment, and as a precursor for synthesizing Iron-containing materials.

For example, researchers at the Anhui Key Laboratory of Information Materials and Devices in China used Ferrous Ammonium Sulfate in the hydrothermal synthesis of Cobalt Ferrite (CoFe₂O₄) nanocomposite permanent magnets. The magnetic properties of these materials arise from super-exchange interactions between Cobalt and Iron ions, and varying the ratio of these ions allows tuning of the magnetic behavior. The Iron (II) Ammonium Sulfate was easily incorporated into the aqueous precursor solution, facilitating the hydrothermal reaction.

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