Freeze-casting to create create directional micro-channels in regenerators for magnetic refrigeration

We present the engineering of directional porosity in the form of lamellar micro-channels in the magnetocaloric ceramic of La0.66Ca0.27Sr0.06Mn1.05O3 (LCSM) by freeze-casting. Freeze-casting is a templating technique based on the anisotropic growth of ice crystals in aqueous suspensions upon directional freezing, which, when applied to a suspension of LCSM results in hierarchical structures of aligned porosity in the form of micro-channels with widths of 5 μm to 20 μm. Channel sizes and tortuosity are measured and calculated from analysis of SEM images obtained at cross sections perpendicular and parallel to the freezing direction, respectively, while freezing conditions are monitored by temperature measurements. We propose that freeze-casting demonstrate apparent applicability within processing of ceramic materials for application as regenerator for magnetic refrigeration.