Europium(III) oxalate (Eu<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub>) is a chemical compound of europium and oxalic acid. There are different hydrates including the decahydrate, hexahydrate and tetrahydrate. Europium(II) oxalate is also known.
An excess of oxalate is added to a hot solution of Eu<sup>3+</sup> cations. The resulting precipitate of Eu<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub> â 10H<sub>2</sub>O is dried in a desiccator.
Europium(III) oxide (Eu<sub>2</sub>O<sub>3</sub>) can be prepared by calcining europium(III) oxalate.
The dehydration of Eu<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub> ÷ 10H<sub>2</sub>O occurs below 200 ðC:
The decomposition of this compound takes place in two stages, the first at 350 ðC and the second at about 620 ðC.
In the Mössbauer spectrum, Eu<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub> ÷ 10H<sub>2</sub>O shows an isomer shift of +0,26 mm/s with a line width of 2,38 mm/s, in reference to EuF<sub>3</sub>. The Debye temperature of Eu<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub> is 166ñ15 K.
Eu<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub> ÷ 10H<sub>2</sub>O crystallizes monoclinically in the space group of P21/c (space group no. 14) with the lattice parameters a = 1098, b = 961, c = 1004 pm and ò = 114.2ð with four formula units per unit cell.
Nanoparticles show a line emission when excited by a light source of 393 nm, the transitions <sup>5</sup>D<sub>0</sub>âÂÂ<sup>7</sup>F<sub>1</sub> (592 nm) and <sup>5</sup>D<sub>0</sub>âÂÂ<sup>7</sup>F<sub>2</sub> (616 nm) can then be found in the spectrum. This can be used as a red phosphor for white LEDs.