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The preferred adsorption sites of xenon in the recently synthesized metal-organic framework MFU-4l(arge) possessing a bimodal pore structure (with pore sizes of 12 Å and 18.6 Å) were studied via the combination of low temperature thermal desorption spectroscopy and in situ X-ray powder diffraction. The diffraction patterns were collected at 110 K and 150 K according to the temperature of the desorption maxima. The maximum entropy method was used to reconstruct the electron density distribution of the structure and to localize the adsorbed xenon using refined data of the Xe-filled and empty sample. First principles calculations revealed that Xe atoms exclusively occupy the Wyckoff 32f position at approximately 2/3 2/3 2/3 along the body diagonal of the cubic crystal structure. At 110 K, Xe atoms occupy all 32 f positions (8 atoms per pore) while at 150 K the occupancy descends to 25% (2 atoms per pore). No Xe occupation of the small pores is observed by neither experimental measurements nor theoretical studies.

The oxidation behavior of Cr–Cr3(Si1−XGeX) alloys with the composition range Cr85GeXSi1−X (0 < X < 15) was studied at 1350 °C. Thermogravimetric measurements showed improved oxidation kinetics by alloying up to 2 at% of Ge, but a significant weight loss was observed when higher Ge was added. Phase analysis and composition of the spalled oxide scales and subscale alloy substrates revealed that eskolaite (Cr2O3) forms the protective scale, while SiO2 (cristobalite) is locally formed below the chromia scale. Addition of up to 2 at% altered the morphology of locally formed silica and subsequently affected the spallation of chromia scale. The morphological observations of the different chromia scales are discussed for all alloys oxidized at 1350 °C.

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