Abstract
UO2 powders were prepared from uranium oxalate and ammonium diuranate by reduction with hydrogen at various temperatures ranging from 600°C to 1300°C. Their morphological properties were determined by optical microscope, electron microscope, and X-ray diffraction techniques.
Observation by electron microscope showed that the UO2 particles prepared, in all cases, consisted of the small unit particles which were linked with each other resulting formation of aggregates. The size determinations of unit particle were undertaken by carrying out direct measurement on the electron microphotographs and also by the X-ray method by means of line broadening of Debye-Scherrer ring. Results obtained show fairly good agreement, and the size of unit particles increased with increasing temperature of reduction. The aggregates of UO2 particles, we obtained, resembled in shape with original crystals of their mother salts and, thus, the shape of aggregates prepared from oxalate was square plate like and from ammonium diuranate which was obtained by homogeneous precipitation method with urea, was irregulare plate like. The size of these aggregates decreased with increasing temperature of reduction.
The crystal of ammonium diuranate obtained by heterogeneous precipitation method with ammonia, was so fine crystal, that we could not observe the shape of mother salt maintained on the aggregate of UO2 prepared from this salt.
