Kinetic study on the grain growth of PuO₂ nanocrystals

Abstract

Results on the kinetics of PuO2 nanocrystals are presented in the temperature range below 1100 °C showing the activation energy for the particle growth is ∼350 kJ mol−1. Particle growth proceeds from the nano- to the micrometer scale.

Probing the local structure of nanoscale actinide oxides: a comparison between PuO2 and ThO2 nanoparticles rules out PuO2+x hypothesis

“… 39,45–47 The broad XRD peaks observed for ThO 2 and PuO 2 powdered samples prepared at the lowest temperatures agree well with the presence of nanometric coherent domains (referred to as crystallites). 45,46,48 The selected electron diffraction patterns obtained with HR-TEM ( Fig. 2 ) confirm that the expected fluorite structure for all of the studied samples are in agreement with the PXRD observations.…”

“…Such observations are generally attributed to crystallite growth, elimination of amorphous domains and crystal defects, and to porosity closure. 39,[45][46][47] The broad XRD peaks observed for ThO 2 and PuO 2 powdered samples prepared at the lowest temperatures agree well with the presence of nanometric coherent domains (referred to as crystallites). 45,46,48 The selected electron diffraction patterns obtained with HR-TEM ( Fig.…”

Hydrothermal Conversion of Uranium(IV) Oxalate into Oxides: A Comprehensive Study

“…For higher temperatures of hydrothermal treatment, growth processes were activated and led to crystallites sizes up to 90 nm. Such a two-step behavior was usually observed during the thermal conversion of An­(IV)-based oxalates as well as for nanocrystals growth of AnO 2 . Moreover, no clear correlation was established between the variation of the oxide stoichiometry and that of the crystallites size.…”

“…For higher temperatures of hydrothermal treatment, growth processes were activated and led to crystallites sizes up to 90 nm. Such a two-step behavior was usually observed during the thermal conversion of An(IV)-based oxalates 53 as well as for nanocrystals growth of AnO2 54 .…”

“…Such a two-step behavior was usually observed during the thermal conversion of An(IV)based oxalates 53 as well as for nanocrystals growth of AnO 2 . 54 Moreover, no clear correlation was established between the variation of the oxide stoichiometry and that of the crystallites size. The O/U ratio was then probably a second-order parameter compared to temperature regarding crystallites growth.…”