• Source: Europium(III) chromate

Europium(III) chromate is a chemical compound composed of europium, chromium and oxygen with europium in the +3 oxidation state, chromium in the +5 oxidation state and oxygen in the −2 oxidation state. It has the chemical formula of EuCrO4.




Preparation


To obtain europium(III) chromate, an equimolar solution of europium(III) acetate and chromium(IV) oxide is dried in a vacuum at 70 °C and then heated to 400 °C in air. Another way to obtain europium(III) chromate is by reacting stoichiometric amounts of europium(III) nitrate hexahydrate and chromium(III) nitrate nonahydrate for 30 minutes at 433 K (160 °C; 320 °F), 30 minutes at 473 K (200 °C; 392 °F) and then 1 hour at 853 K (580 °C; 1,076 °F). A constant stream of oxygen is passed over the reaction mixture. An oxygen flow is used to stabilise the +5 oxidation state of chromium.

Eu(NO3)3·6H2O + Cr(NO3)3·9H2O → EuCrO4 + 6 NO2 + 15 H2O + O2




Properties


Europium(III) chromate crystallizes tetragonally with space group I41/amd (No. 141) with lattice parameters a = 722.134(1) and c = 632.896(1) pm with four formula units per unit cell.
The Néel temperature of europium(III) chromate is 15.9 K (−257.2 °C; −431.0 °F). Above 700 °C, europium(III) chromate begins to decompose into europium chromite (EuCrO3).

2 EuCrO4 → 2 EuCrO3 + O2




References

Kata Kunci Pencarian:

• Europium(III) chromate
• Chromium
• List of inorganic compounds
• List of CAS numbers by chemical compound
• Bismuth
• Monazite
• Toxic heavy metal
• Solubility table
• Glossary of chemical formulae
• Arsenic