Graphical This is a new method of producing nuclear material. ThO 2 NPs are synthesized by pyrolysis of an undiscovered thorium-based MOF. The MOF-derived ThO 2 NPs can easily be sintered to form ThO 2 ceramics. (Twitter: @yuting0437) A new method is demonstrated for synthesizing thorium dioxide (ThO 2 ) nanoparticles (NPs) by thermal decomposition of an undiscovered thorium-based metal-organic framework (MOF). Upon heating at 520 °C, the thorium-based MOF crystals, designated Th-MTB, are converted completely to ThO 2 NPs with an average size of 150 nm. The MOF-derived ThO 2 NPs are easily sintered to form ThO 2 ceramics which have good thermal conductivity. The crystalline grains of ThO 2 grow continuously during sintering.The method for the synthesis of ThO 2 NPs could have potential applications in the production of nuclear materials.
A simple and effective method for preparing ThO 2 ceramics with high density has been proposed. It mainly includes a positive precipitation approach and a conventional sintering process. The SEM images and laser particle size analysis show that the prepared powder exhibits a round-plated shape with a uniform and narrow particle size distribution, which is the key to the densification sintering of ThO 2 ceramics. The XRD analyses confirm that the ThO 2 ceramics sintered at 1590°C were composed of cubic fluorite phase. The effect of sintering temperature on the density of ThO 2 ceramics was also investigated, and a relative density higher than 95% were achieved after sintering at 1590°C for 6 h in an air atmosphere. Moreover, the Vickers hardness was up to 8.49 GPa, the average linear expansion coefficient within 40–800°C was low to 10.97 × 10 −6 /K, and the thermal conductivity and the thermal diffusivity were both higher than most of traditional ceramic materials (16.94–5.86 W/m K and 7.28–1.28 mm 2 /s, respectively, within the temperature range of 25–800°C). The previous great performances are closely related to its high density, which enables it to be a great candidate for nuclear fuels and other potential application fields.
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