Barium ferrate


Barium ferrate is the chemical compound of formula BaFeO4. This is a rare compound containing iron in the +6 oxidation state. The ferrate ion has two unpaired electrons, making it paramagnetic. It is isostructural with BaSO4, and contains the tetrahedral Ferrate|2− anion.

Structure

The ferrate anion is paramagnetic due to its two unpaired electrons and it has a tetrahedral molecular geometry.
X-ray diffraction has been used to determine the orthorhombic unit cell structure of nanocrystalline BaFeO4. It crystallized in the Pnma space group with lattice parameters a=0.8880 nm, b=0.5512 nm and c=0.7214 nm. The accuracy of the X-Ray diffraction data has been verified by the lattice fringe intervals from High-Resolution Transmission Electron Microscopy and cell parameters calculated from Selected Area Diffraction.

Characterization

absorbance peaks of barium ferrate are observed at 870, 812, 780 cm−1.
BaFeO4 has a magnetic moment of x Am2 with a Weiss constant of -89 K.

Preparation and Chemistry

There are two methods for producing ferrate : dry and wet synthetic methods.
The dry synthetic method is usually performed using a thermal technique. The wet method employs chemical and electrochemical techniques. Addition of a soluble barium salt to an alkali metal ferrate solution produces a maroon precipitate of barium ferrate, a crystal which has the same structure as barium chromate and has approximately the same solubility. Barium ferrate, BaFeO4, can be prepared by adding barium oxide to a mixture NaClO and ferric nitrate at room temperature.
Primary experiments indicate an improvement in the purity of the synthesized barium ferrate by performing the reaction at low temperature in the absence of carbon dioxide and by rapidly filtering and drying the precipitate.

Uses

Barium ferrate is an oxidizing agent and is used as an oxidizing reagent in organic syntheses. Its other applications include removal of color, removal of cyanide, killing bacteria and contaminated and waste water treatment.
Salts of ferrate are energetic cathode materials in “super-iron” batteries. Cathodes containing ferrate compounds are referred to as “super-iron” cathodes due to their highly oxidized iron basis, multiple electron transfer, and high intrinsic energy. Among all ferrate salts, barium ferrate sustains unusually facile charge transfer, which is important for the high power domain of alkaline batteries.

Reactions

Barium ferrate is the most stable of the ferrate compounds. It can be prepared in its purest state and has the most definite composition. Barium ferrate can be easily decomposed by all soluble acids, including carbonic acid. If carbon dioxide is passed through water on which hydrated barium ferrate is suspended, barium ferrate will decompose completely to form barium carbonate, ferric hydroxide and oxygen gas. Alkaline sulfates decompose barium ferrate that has not been dried, forming barium sulfate, ferric hydroxide and oxygen gas.