The microstructures of BME-X7R ceramics have been investigated by imaging and analytical TEM. By varying the sintering conditions (pressing, sintering temperature and atmosphere), the microstructure changes drastically, and dislocation loops can be observed. These defects most probably are caused by an ordering of oxygen vacancies in the lattice, and the density appears to be correlated to the oxygen partial pressure applied during the reoxidation step. For pressed and unpressed ceramic foils, a model for different sintering behaviors according to liquid-phase assistance is given that is based on a kinetically determined microstructure rather than thermodynamic equilibrium.

Base metal technology, mainly using Ni electrodes in multilayer ceramic capacitors (MLCCs), is now well established. This technology requires a so‐called reoxidation treatment after sintering the MLCCs in a reducing atmosphere to guarantee a sufficient electrical reliability. Large numbers of electrodes, and production of physically larger components for high‐voltage components, are two technological trends that make the control of the reoxidation process rather difficult. The reoxidation process has been studied to determine oxygen diffusion pathways into commercial MLCCs, using 18O tracer diffusion and finite element calculations. In MLCCs oxygen diffusion mainly occurs along the Ni electrodes. Furthermore, the reoxidation process is mostly controlled by the thermodynamic potential of the Ni/NiO equilibrium in the interior of the capacitor, but it is the short circuit diffusion along the interface of the electrode that controls the kinetics of the oxygen transport into the interior of the capacitor device.

The present work is related to the upscaling of calcium manganite–based oxygen‐carrier materials, which have a perovskite structure, both with respect to the use of inexpensive raw materials, i.e., instead of pure chemicals, and the upscaling of production to multitonne batches. Results are presented from the two different stages of material development, i.e., raw material selection and upscaling. The evaluation involves both operation in chemical‐looping combustor units of 300 W and 10 kW, and material characterization. In the latter unit, the gas velocities in the riser and in the grid‐jet zone of the gas distributor come close to gas velocities of industrial‐scale units and, therefore, this unit is also used to assess particle lifetime. Results from the various chemical‐looping combustion units and oxygen‐carrier materials produced from various raw materials of both high and low purity show that very high degrees of fuel conversion can be reached while achieving very high oxygen‐carrier lifetimes. The composition of the oxygen‐carrier materials seems robust and flexible with respect to the precursors used in its manufacturing.

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