Europium selenates

The measurements of Serebrennikov and Tsybukova [79SER/TSY], which established the phase diagram of the system Eu2(Se04)3-La2(Se04)3-H20, indicate that Eu2(Se04)3 8H20 is the stable europium selenate in contact with water at 298.15 K. The reported solubility is accepted  

Smolyakova, Efremov, and Serebrennikov [73SMO/EFR] determined the enthalpy change of the reaction between Eu2(Se04)3 8H20(cr) and a solution of barium chloride with formation of BaSe04(cr) by a calorimetric measurement. The review calculated  

No other thermodynamic data have been found for europium selenates. 

Solid solutions Eu2(Se04)3-8H20-Eu2(S04)3 8H20 are treated in this section, without regard to the system number of S, a deviation from the usual Gmelin practice. 

The compound was prepared from EU2O3 (or preferably Eu(OH)3) and H2Se04, Rosso, Perret [3]. For the existence of Eu2(Se04)3 81120 in the system Eu2(Se04)3-La2(Se04)3-H20 at 25°C see Serebrennikov, Tsybukova [4]. 

The solubility in H2O at 25°C is 30.81 wt%. The compound forms mixed crystals with La2(Se04)3 5H20 (see below), Serebrennikov, Tsybukova [4], or Eu2(S04)3-8H20 (see below). Rosso, Ferret [3]. 

During the reduction of Eu2(Se04)3 with CO the pale brown Eu2O2SeO4 0.1 Se02 is observed at 380 C, Belik, Serebrennikov [1]. 

Eu2(Se04)3 8H20 forms a continuous series of mixed crystals with the isomorphous Eu2(S04)3 8H20 by crystallization of the salts in various proportions from aqueous solution at 25°C. As a function of composition the lattice parameters of the monoclinic crystals change according to Vegard s law  

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