Stability and morphology of cerium oxide surfaces in an oxidizing environment: A first-principles investigation

Abstract

We present density functional theory investigations of the bulk properties of cerium oxides ͑CeO 2 and Ce 2 O 3 ͒ and the three low index surfaces of CeO 2 , namely, ͑100͒, ͑110͒, and ͑111͒. For the surfaces, we consider various terminations including surface defects. Using the approach of "ab initio atomistic thermodynamics," we find that the most stable surface structure considered is the stoichiometric ͑111͒ surface under "oxygen-rich" conditions, while for a more reducing environment, the same ͑111͒ surface, but with subsurface oxygen vacancies, is found to be the most stable one, and for a highly reducing environment, the ͑111͒ Ce-terminated surface becomes energetically favored. Interestingly, this latter surface exhibits a significant reconstruction in that it becomes oxygen terminated and the upper layers resemble the Ce 2 O 3 ͑0001͒ surface. This structure could represent a precursor to the phase transition of CeO 2 to Ce 2 O 3 .

First-principles study of surface properties of PuO2: Effects of thickness and O-vacancy on surface stability and chemical activity

“…Considering that a half oxygen vacancies can usually induce the significant surface reconstruction, here we first carry out the first-principles molecular dynamic (FPMD) simulations based on GGA+U within the micro-canonical ensemble to sufficiently optimize the defect- To briefly summarize our results in this section, we give the relative order of stability for low-index PuO 2 surfaces, namely, (111) > (110) > defect-(001) > polar-(001), which is well consistent with that of CeO 2 [44,45] and UO 2 [46], which are of the same fluorite structure as PuO 2 .…”

Ab initioinvestigation of defect formation at ZrO2-CeO2interfaces

“…In previous work, some of the present authors analyzed the thermodynamic stability of CeO 2 surfaces, concluding that, under oxygen-rich conditions, the (111) surface is stabler than the (100) and (110) surfaces. 20 After calculating the surface energies of the (111) and the (100) surfaces for ZrO 2 under oxygen-rich conditions (see Table I), the Wulff construction suggests that ZrO 2 crystal nanoparticles host a mixture of these two surfaces. From this analysis we can assume that a growing film would preferentially have a (111) orientation for CeO 2 and a mixture of (111) and (100) orientations for the ZrO 2 phase.…”

Communication: Different behavior of Young's modulus and fracture strength of CeO2: Density functional theory calculations

“…The electronic structures for core electrons are described by the effective core potential. We employed DMol 3 software package for these DFT calculations, which has been used for various investigations of CeO 2 such as surface defects, 31 water adsorption, 32 and catalytic reduction. 33 The validity of DMol 3 was already confirmed by the previous studies.…”