Rare earth bromates

The James method has been modified to avoid both the preparation of the solid anhydrous sulfate and the use of large volumes of solution. It is desirable, although not 

In the directions to follow it will be assumed that 1 kg. of oxides of rare earths with average atomic weight equal to 128.25 (see synthesis 16) is to be transformed to bro-mates. For a smaller amount of material or for a different average atomic weight, proportionate amounts of reagents must be used. The rare earths must be cerium-free because cerium catalyzes a troublesome decomposition of bromate ion. 

Pkepakation of Rake Eakth Bkomates 3Ba(Br03)2 + (R.E.)2(S04)3 SBaSO + 2(R.E.)(Br03)3 

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Rare-earth alloys Rare-earth bromates... 

The mixed rare earth bromates are obtained in the form of colorless or faint-pink needlelike or feathery crystals. They are moderately soluble in cold water and very soluble in hot. The minimum in solubility among the various earths occurs at europium although the position of this minimum depends upon the crystallization temperature. 

If air is blown over the surface of rare earth bromate solutions during evaporation, care should be taken to ensure that it is entirely free from oil, which IS sometimes present in the compressed air lines. The oil causes reduction of bromate ion. 

The rare earth bromates are relatively stable in the absence of cerium or other reducing materials. Very little thermal decomposition occurs if overheating of the crystals and of the solution is avoided. To avoid such decomposition, the fractions should be heated carefully always on the steam bath and should be regularly mixed by gentle swirling during this operation. 

The physical properties of the rare earth bromate hydrates have been studied by several groups and can be sununarized as follows the melting points of the enneahydrates vary between 37 and 80°C (Petru and Dusek, 1968), the formation enthalpies between 3490 and 3590kJ/mol (Schumm et al., 1973). The specific heat of Gd(Br03)3 OHjO increases from 0.05 J/gK at 20 K to 0.32 J/gK at 100 K, exhibiting a clear jump at 66 K, where the structure changes (Poulet et al., 1975). The rare earth bromates are readily soluble in water the concentrations of the saturated solution vary between 1.2 and 2.3mol/kg H2O (Staveley et al.. 

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