The petrographic characteristics of mud supported limestone samples from Egypt were examined before and after calcination at 950uC for 0?25, 0?5, 1 and 2 h. X-ray diffraction (XRD), X-ray fluorescence (XRF), transmitted light microscopy (TLM), scanning electron microscopy (SEM) and X-ray microcomputed tomography (m-CT) were used for technological samples characterisation. Both the free lime content and the hydration behaviour of the resulted quicklime after calcination were measured. The produced lime is unreactive at all applied firing conditions, except the Chalk lime at 1 and 2 h soaking, despite the high free lime content of the samples. The microstructure of the mud supported limestones is of significance on the resulted quicklime reactivity, where microfractures are formed along the cavities inside the microfossils. The mineralogical and the chemical compositions of the studied mud supported limestones are the main controlling variables on the degree of the quicklime crystallinity and consequently the reactivity. Samples enriched with P 2 O 5 show higher crystallinity of the resulted lime crystallites associated with lowest reactivity.

Synchrotron radiation diffraction studies of meteoritic (Fe,Ni)3P crystals have been performed to reveal the ordering of the elements Fe and Ni on the three metal sites M1, M2 and M3 of the unit cell. The delta synthesis technique, which is a two-wavelength method using anomalous dispersion effects, was applied. For (Fe,Ni) phosphide crystals with different Fe:Ni ratios extracted from different meteorites, it was found that Ni occupies the M3 site and also partially the M2 site, avoiding the M1 position, whereas the M1 site is preferentially occupied by Fe. In connection with earlier results known from the literature, this metal distribution seems to be characteristic of this compound, and is independent of thermodynamic formation conditions.

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The behavior of an oxide fiber at elevated temperatures was analyzed before and after thermal exposures. The material studied was a mullite fiber developed for high‐temperature applications, CeraFib 75. Heat treatments were performed at temperatures ranging from 1200°C to 1400°C for 25 hours. Quantitative high‐temperature X‐ray analysis and creep tests at 1200°C were carried out to analyze the effect of previous heat treatment on the thermal stability of the fibers. The as‐received fibers presented a metastable microstructure of mullite grains with traces of alumina. Starting at 1200°C, grain growth and phase transformations occurred, including the initial formation of mullite, followed by the dissociation of the previous alumina‐rich mullite phase. The observed transformations are continuous and occur until the mullite phase reaches a state near the stoichiometric 3/2 mullite. Only the fibers previously heat treated at 1400°C did not show further changes when exposed again to 1200°C. Overall, the heat treatments increased the fiber stability and creep resistance but reduced the tensile strength. Changes observed in the creep strain vs. time curves of the fibers were related to the observed microstructural transformations. Based on these results, the chemical composition of the stable mullite fiber is suggested.