Effect of feed solution composition and heat treatment conditions on the morphology of uranium oxide microspheres prepared by sol–gel process

Uranium oxide microspheres were prepared by internal gelation process (IGP) using selected feed solution compositions. In the feed, concentration of uranium was maintained at 1.25 M and hexamethylenetetramine (HMTA)-urea to uranium mole ratio (R) was varied between 1.2 and 1.5. The gel particles obtained from each batch were heated at 250 °C in air. The samples from each batch were heated under various heat treatment conditions, such as calcination to U3O8, reduction of calcined U3O8 and direct reduction of UO3 to UO2. The effect of feed solution composition and heat treatment conditions on the morphology of the uranium oxide microspheres was studied by measuring surface area, pore size distribution, pore volume, tap density and crush strength. The details of open and closed pores on the dried and heat treated products were studied by scanning electron microscope (SEM) analysis.