Europium(III) oxalate

Europium oxalate 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.

Preparation

An excess of oxalate is added to a hot solution of Eu³⁺ cations. The resulting precipitate of Eu₂₃ ⋅ 10H₂O is dried in a desiccator.

Europium(III) oxide can be prepared by calcining europium oxalate.
The dehydration of Eu₂₃ · 10H₂O occurs below 200 °C:
The decomposition of this compound takes place in two stages, the first at 350 °C and the second at about 620 °C.
In the Mössbauer spectrum, Eu₂₃ · 10H₂O shows an isomer shift of +0,26 mm/s with a line width of 2,38 mm/s, in reference to EuF₃. The Debye temperature of Eu₂₃ is 166±15 K.
Eu₂₃ · 10H₂O crystallizes monoclinically in the space group of P21/c with the lattice parameters a = 1098, b = 961, c = 1004 pm and β = 114.2° with four formula units per unit cell.
Nanoparticles show a line emission when excited by a light source of 393 nm, the transitions ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ can then be found in the spectrum. This can be used as a red phosphor for white LEDs.