High-temperature electron microscopy study of ThO 2 microspheres sintering

Early stages of UO2+x sintering by in situ high-temperature environmental scanning electron microscopy

“…Associated crystallite sizes equaled 80 to 90 nm range depending on the conditions considered ( Table 2). This indicated that the crystallite growth and/or the mechanical rearrangement phenomena competed with the elaboration of a neck upon heat treatment during the first step of sintering, as already evidenced for other systems such as CeO 2 and ThO 2 [15,16].…”

“…Images of the two-grain systems recorded during isotherm thermal treatments were processed in order to achieve direct determination of quantitative data. The protocol employed followed image processing reported in our previous publications [15,16]. Trainable Weka Segmentation plugin [25] available in the Fiji software [26] first led to the automatic extraction of grain contours.…”

“…These samples were selected as model compounds for real UO 2+x powders used in the fabrication of nuclear fuel as well as for the systems generally used in numerical simulations, composed of two spheres in contact. This approach, which allows the determination of quantitative geometrical data describing the formation then the growth of a neck between spherical particles was already developed and tested on model compounds free from redox reactions [15,16]. In the case of the present study, this methodology has been adapted to various atmospheres in order to stabilize different uranium oxide phases.…”

Synthesis of size-controlled UO2 microspheres from the hydrothermal conversion of U(iv) aspartate

“…Lastly, polycrystalline spherical particles can be used as model samples to investigate the early stages of oxide ceramics 8,9 .…”

First Stage of Sintering of ThO2 Microspheres: a HT-ESEM and HT-HRTEM Study

“…The behavior of ThO 2 microspheres [1] during heat treatments at high temperature (1000-1300°C) was investigated by electron microscopy, including in situ and ex situ ESEM [2] as well as HT-HRTEM with high temporal resolution, and further advanced image processing.…”