The relationship between yttria concentration and the unit cell parameters in partially and fully stabilized zirconia has been reassessed, motivated by the need to improve the accuracy of phase analysis upon decomposition of t′-based thermal barrier coatings. Compositions ranging from 6 to 18 mol% YO 1.5 were synthesized and examined by means of high-resolution Xray diffraction. Lattice parameters were determined using the Rietveld refinement method, a whole-pattern fitting procedure. The revised empirical relationships fall within the range of those published previously. However, efforts to achieve superior homogeneity of the materials, as well as accuracy of the composition and lattice parameters, provide increased confidence in the reliability of these correlations for use in future studies. Additional insight into the potential sources for scatter previously reported for the transition region (~12-14 mol% YO 1.5 ), where tetragonal and cubic phases have been observed to coexist, is also provided. Implications on the current understanding of stabilization mechanisms in zirconia are discussed.

New and facile wet chemistry based synthesis method for the preparation and processing of MAX phase Cr2GaC.

Perovskite oxides with mixed ionic and electronic conductivities are very promising candidates for their application as energy materials related to fuel cell and metal air battery integration.

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A pinch of oxygen: incorporation of small additional oxygen introduces partly square planar coordination into BaCoO2+δ.

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Metal dusting attack is a serious problem in processing industries using carbonaceous gases and high temperatures. Ni-based alloy 699 XA was recently developed as an alloy for these types of environments with high resistance against metal dusting. In this study, different surface treatments of this chromium-and aluminum-rich alloy are shown to have an important influence on the metal dusting onset behavior. It was found that surface treatments that are traditionally considered to be helpful for fatigue performance, for example, shot peening, and pickling were detrimental to the metal dusting performance of alloy 699 XA.Additionally, the shot peening surface treatment promoted Fe surface contamination, resulting in a negative impact on the metal dusting pitting resistance of the alloy. Deformation accompanied by apparent BCC α-Cr precipitation in the bulk microstructure, but a comparison with cold-rolled materials shows that the surface treatment dominates the metal dusting resistance.

Perovskite oxides exhibiting mixed protonic and electronic conductivities have interesting applications in protonic ceramic fuel cells. In this work, we report on a hydrated phase of BaCoO1.80(OH)0.86 synthesized using nebulized spray pyrolysis. Structural analysis based on X-ray and neutron powder diffraction data showed that the compound is isotypic to BaFeO2.33(OH)0.33. The water loss behaviour was studied using simultaneous thermal analysis and high temperature X-ray diffraction, indicating that protons (respectively water) can be stabilized within the compound up to temperatures significantly above 673 K, confirmed by ex situ Fourier transform infrared spectroscopy studies. Impedance spectroscopy was used to determine the conductivity characteristics of BaCoO1.80(OH)0.86, finding and a total electrical conductivity in the order of 10-4 S cm-1 at ambient temperature with an activation energy of 0.28 eV.