Preparation of ultrafine fibrous uranium dioxide by electrospinning

Abstract

We are introducing for the first time a robust method for the preparation of uranium oxide nanofibers with extraordinary thin diameters. We have studied the preparation of U 3 O 8 and UO 2 nanofibers by the electrospinning method from uranyl acetylacetonate in mixed organic solvents. Polyvinylpyrrolidone (PVP) was used as a supporting polymer. Besides studying and optimizing the solution systems, we have also examined the effects of collector material on the properties of the fiber mat. We have found that calcination of electrospun green composite fibers deposited on aluminum foil produces U 3 O 8 nanofibers with the lowest average diameter of 20 ± 5 nm as their adhesion prevents fiber shrinking. We have also studied calcination of fibers on ashless paper and freestanding composite mats. Reduction of U 3 O 8 fibers in H 2 /N 2 atmosphere at various temperatures provided uranium dioxide nanofibers with an average diameter of 90 nm.

Encapsulation of Uranium Oxide in Multiwall WS2 Nanotubes

“…Conveniently, the WS 2 nanotubes are satisfyingly stable in the forming gas atmosphere at 800 °C, which is a suitable temperature for the reduction of both uranium and tungsten oxides. [46,47] This process is represented by the (unbalanced) Equation (3):…”

Nanofibers of solid-solution thorium(IV)-uranium(IV) oxides by electrospinning

“…Polyvinylpyrrolidone (PVP, M w = 360 kDa) was purchased from Sigma Aldrich and used as received. Uranyl acetylacetonate was synthesized according to the literature [21] , and the typical procedure was already described in the previous study [18] . Thorium acetylacetonate was synthesized according to the literature [22] from thorium nitrate tetrahydrate (98%, Lachema, CZ).…”

“…The process was conducted on a custom-designed set-up [18] based on two high-voltage power sources capable of an output of 0 to + 25 kV and 0 to −15 kV and on a New Era Scientific syringe pump. The syringe with a blunt-tip needle of 1 mm diameter was used as a carrier of the spinning solution.…”

“…Recently, we introduced the electrospinning route to nanofibrous uranium [18] and thorium [19] oxides. Others used the same method to prepare nanofibers containing uranium carbide [20] .…”

Quantification of STEM Images in High Resolution SEM for Segmented and Pixelated Detectors

“…Standard STEM detectors, which are formed of several segments for imaging in BF and DF modes, consist of many photodiodes. This detector has a wide range of applications, for example, in material analysis [ 16 , 17 , 18 , 19 ], in life science [ 20 ] and in semiconductors [ 21 ]. Conversely, the full annular distribution is not resolved because the signal incident on the inactive areas between the individual segments is lost.…”