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Europium(III) chromate(V)
Names
	IUPAC name Europium(III) chromate(V)
	Other names Europium chromate; Europium(3+) chromate;
Identifiers
CAS Number	60746-51-2;
3D model (JSmol)	Interactive image;
	InChI InChI=1S/Cr.Eu.4O/q;+3;;3*-1 Key: QYGFCRGOCJDKFZ-UHFFFAOYSA-N;
	SMILES [O-][Cr](=O)([O-])[O-][Eu+3];
Properties
Chemical formula	EuCrO4
Molar mass	267.956 g·mol−1
Density	5.39 g/cm−3
Melting point	700 °C (1,292 °F; 973 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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.^[4]^[3] It has the chemical formula of Eu Cr O₄.

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.^[2]^[5] 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.^[4]

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.^[2]

The Néel temperature of europium(III) chromate is 15.9 K (−257.2 °C; −431.0 °F).^[4] Above 700 °C, europium(III) chromate begins to decompose into europium chromite (EuCrO₃).^[3]

2 EuCrO₄ → 2 EuCrO₃ + O₂

References

^ G. Buisson, E. F. Bertaut, J. Mareschal (1964), "Etude cristallographique des composes TCrO₄ (T = terre rare ou Y)", Comptes rendus hebdomadaires des séances de l'Académie des Sciences (in German), vol. 259, pp. 411–413{{citation}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b ^c Hidetaka Konno, Yoshitaka Aoki, Zoltán Klencsár, Attila Vértes, Makoto Wakeshima (2001-12-01). "Structure of EuCrO₄ and Its Electronic and Magnetic Properties". Bulletin of the Chemical Society of Japan. 74 (12): 2335–2341. doi:10.1246/bcsj.74.2335. ISSN 0009-2673.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b ^c J. Thakur, R. Shukla, N. Raje, D. Ghonge, H. Bagla (2011-10-01). "Synthesis, Structural Characterization and Thermal Stability of Nanocrystalline Rare-Earth Chromates (RECrO₄) and Rare-Earth Chromites (RECrO₃)". Nanoscience and Nanotechnology Letters. 3 (5): 648–654. doi:10.1166/nnl.2011.1233.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b ^c E Jiménez, J Isasi, R Sáez-Puche (2000-11-01). "Synthesis, structural characterization and magnetic properties of RCrO₄ oxides, R=Nd, Sm, Eu and Lu". Journal of Alloys and Compounds. 312 (1–2): 53–59. doi:10.1016/S0925-8388(00)01079-3.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Yoshitaka Aoki, Hidetaka Konno, Hiroto Tachikawa, Michio Inagaki (2000-05-01). "Characterization of LaCrO₄ and NdCrO₄ by XRD, Raman Spectroscopy, and ab Initio Molecular Orbital Calculations". Bulletin of the Chemical Society of Japan. 73 (5): 1197–1203. doi:10.1246/bcsj.73.1197. ISSN 0009-2673.{{cite journal}}: CS1 maint: multiple names: authors list (link)