Synthesis and characterization of ultra-fine well-dispersed thoria nano spheres through reduction reactions in nitrate bath

Abstract

In most applications we need to use thoria with sintered density of 95% TD which is usually achieved at temperatures above 2073 K. Thus, it is an expensive and energy consuming process. Recent researches have shown that the nanocrystalline phase of thorium oxide can be sintered to a density of 9.6 × 106 g m−3 at low temperature (1573 K). Therefore, the synthesis of thoria nanostructures obviously is attracting increasing attention recently. The strategy developed in this study, offers significant advantages (simplicity and cleanness of method and also a phase purity and new morphology of the product) over the conventional routes for the synthesis of ThO2 nanostructure. Electrochemical preparation of nanocrystalline thorium oxides based on base generation at the electrode surface in aqueous solutions containing thorium nitrate was studied. Subsequent heat treatment under air atmospheres leads to formation of the pure phase of nanocrystallineThO2 at 1000 °C. The synthesized powder was characterized by means of Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Transmission Electron microscopy (TEM, Phillips EM 2085) Brunauer–Emmett–Teller (BET) and Fourier transform Infrared (FT-IR) spectroscopy. The obtained product consisted of uniform nanospheres from 20 to 50 nm in diameter with narrow size distribution. To the best of our knowledge, this is first attempt to quantitatively synthesize ThO2 nanosphere by the base generation procedure.