The paper reviews the history and present understanding of protons in oxides; their defect chemistry, thermodynamics, and transport. Focus is put on correlations between hydration thermodynamics and other materials properties which may help to predict proton uptake and proton conduction in oxides. Also effects of defect association and the particular problem of high grain boundary resistance in high temperature proton conductors are addressed. In the second part, a number of experimental observations attributed to the presence of hydride ions under mildly reducing conditions are discussed in relation to the unlikelihood that general thermodynamic considerations predict of finding these species under such conditions.

Chemical-looping with oxygen uncoupling (CLOU) is a novel method to burn fuels in gas-phase oxygen without the need for an energy-intensive air separation unit. The carbon dioxide from the combustion is obtained separated from the nitrogen in the combustion air. The technique is based on chemical-looping combustion (CLC) but does not involve any direct reaction between the fuel and oxygen carrier. Instead, the CLOU process uses three steps in two reactors, one air reactor where a metal oxide captures oxygen from the combustion air (step 1), and a fuel reactor where the metal oxide releases oxygen (step 2) and where this oxygen reacts with a fuel (step 3). This means that the fuel burns directly with gaseous O 2 . In this work CaMn 0.875 Ti 0.125 O 3 will be used as oxygen carrier. Experiments were first performed with a thermogravimetric analyzer (TGA). Here the sintering temperature, and thereby the porosity, for the produced granulates was varied and optimized. The substitution of Ti on Mn sites in CaMnO 3 was chosen since this material showed no coke formation even in dry CH 4 at high temperatures. This was followed by fluidized bed experiments with both methane and petroleum coke as fuel. The CaMn 0.875 Ti 0.125 O 3 particles showed promising results both for the tests performed in TGA and in fluidized bed experiments. CaMn 0.875 Ti 0.125 O 3 released O 2 both in inert and reducing atmosphere, making it a possible candidate as oxygen carrier in CLOU.

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The degradation of the interface between Plansee Ducrolloy alloy (Cr-5 wt % Fe-1 wt %Y 2 O 3 ) (PD) and (La 0.85 Sr 0.15 ) 0.91 MnO 3 (LSM) ceramic was studied by means of electrical resistance measurements at 900ЊC in air humidified with 2% H 2 O and with a dc load of 100 mA/cm 2 and by scanning electron microscopy/energy-dispersive spectroscopy of cross sections of the samples. One sample of PD alloy with plasma-sprayed La 0.9 Sr 0.1 CrO 3 and a contacting layer of La 0.8 Sr 0.2 CoO 3 exhibited little degradation, estimated to be 0.066 ⍀ cm 2 after 10,000 h. Other samples of PD were coated by different spinel-forming slurries pretreated in H 2 /H 2 O/Ar mixtures at 950 and 1000ЊC. Coatings forming MnCr 2 O 4 spinel and using La 0.8 Sr 0.2 CoO 3 as a contacting layer showed a low estimated degradation of 0.04-0.06 ⍀ cm 2 after 10,000 h. Another spinel (Co,Mn) 3 O 4 appeared to reduce Cr diffusion significantly, and when used together with a mixed perovskite made of 1:1 of LSM and La 0.8 Sr 0.2 CoO 3 as a contacting layer, exhibited estimated degradation of 0.024 ⍀ cm 2 for 10,000 h.

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