High pressure X-ray nano-tomography and fractal microstructures in the Ce γ-α transition

Abstract

Among the reported descriptions of the electronic structure of the γ-α transition, the Mott and the Kondo volume collapse (KVC) models are widely debated. In spite of the existing calculations and experimental efforts probing the 4f electron properties, no consensus was achieved between the two models. Actually, valence bond changes are different in the Mott and in the KVC scenarios, where the transition is driven by the delocalization or the hybridization of 4f electrons, respectively. However, instead of probing 4f electrons directly as done earlier, we propose to discriminate these models by investigating microstructures sensitive to valence bonds. In this contribution, we characterized the isostructural cerium γ-α phase transition by using the high-pressure nanotomography technique. This work monitors the formation of inner microstructures under in situ high pressure, paving the way to investigate similar processes, such as martensitic transformations. Experimental data show that nucleation and growing of the α-phase are indeed analogous to a martensite transition, and the occurrence of microstructures with fractal features is in good agreement with the KVC model.