Thermal Stability and Phase Transitions in WO3-ZrO2 and WO3-TiO2 Composites
Complex sol-gel process was applied to synthesize WO3-ZrO2 and WO3-TiO2 composites at
different ratio of oxides. These composites are used to obtain radionuclide W-Re generators important
due to applications in nuclear medicine.
The structure of above composites depends on annealing temperature. At 800 °C specimens are fully
crystalline containing separate oxides with crystallites of nanometric sizes. WO3 existing in
monoclinic form stabilizes tetragonal ZrO2 form. Long time annealing at 1000 °C causes martensite
type phase transition in ZrO2 from tetragonal to monoclinic form whereas in WO3-TiO2 composite in
the same conditions phase transitions do not occur.
Keywords: Phase transitions, sol-gel method, W-Re generators, WO3-TiO2, WO3-ZrO2 composites, X-ray diffraction.
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