| 摘要 |
The invention comprises sols in which the particles, which are generally from 5 to 100 millimicrons in diameter, consist of an intimate mixture of one or more oxides of a rare earth (i.e. yttrium and the elements from lanthanum to lutetium in the Periodic Table), and one or more oxides of quadrivalent uranium, plutonium or an element of atomic number greater than that of plutonium. The particles may contain 0.5 to 90, preferably 40 to 80, mole per cent of the rare earth oxide and 99.5 to 10, preferably 60 to 20, mole per cent of the other oxide. The sol is prepared by autoclaving, at at least 100 DEG C. under a nonoxidizing atmosphere, a freshly prepared sol of the rare earth oxide with a freshly prepared sol of the other oxide. One or both of these sols may be prepared by peptizing the corresponding hydroxide with a non-oxidizing monobasic acid, e.g. acetic acid, or by removing the anions from a solution of a salt, e.g. chloride, of the element by electrodialysis or ion exchange. The autoclaved sol may be deionized by passing it over a mixed anioncation exchange resin. The particles of the autoclaved sol may be separated and redispersed in deionized water.
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