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In recent years, many efforts have been made to introduce reversible alkali metal anodes using solid electrolytes in order to increase the energy density of next‐generation batteries. In this respect, Na₃.₄Zr₂Si₂.₄P₀.₆O₁₂ is a promising solid electrolyte for solid‐state sodium batteries, due to its high ionic conductivity and apparent stability versus sodium metal. The formation of a kinetically stable interphase in contact with sodium metal is revealed by time‐resolved impedance analysis, in situ X‐ray photoelectron spectroscopy, and transmission electron microscopy. Based on pressure‐ and temperature‐dependent impedance analyses, it is concluded that the Na|Na₃.₄Zr₂Si₂.₄P₀.₆O₁₂interface kinetics is dominated by current constriction rather than by charge transfer. Cross‐sections of the interface after anodic dissolution at various mechanical loads visualize the formed pore structure due to the accumulation of vacancies near the interface. The temporal evolution of the pore morphology after anodic dissolution is monitored by time‐resolved impedance analysis. Equilibration of the interface is observed even under extremely low external mechanical load, which is attributed to fast vacancy diffusion in sodium metal, while equilibration is faster and mainly caused by creep at increased external load. The presented information provides useful insights into a more profound evaluation of the sodium metal anode in solid‐state batteries.

Flash spark plasma sintering (flash SPS) is an attractive method to obtain Nd–Fe–B magnets with anisotropic magnetic properties when starting from melt‐spun powders. Compared to the benchmark processing route via hot pressing with subsequent die upsetting, flash SPS promises electroplasticity as an additional deformation mechanism and reduced tool wear, while maximizing magnetic properties by tailoring the microstructure—fully dense and high texture. A detailed parameter study is conducted to understand the influence of Flash SPS parameters on the densification and magnetic properties of commercial MQU‐F powder. It is revealed that the presintering conditions and preheating temperature before applying the power pulse play a major role for tailoring grain size and texture in the case of hot deformation via Flash SPS. Detailed microstructure and magnetic domain evaluation disclose the texture enhancement with increasing flash SPS temperature at the expense of coercivity. The best compromise between remanence and coercivity (1.37 T and 1195 kA m⁻¹, respectively) is achieved through a combination of presintering at 500 °C for 120 s and preheating temperature of 600 °C, resulting in a magnet with energy product (BH)max of 350 kJm⁻³. These findings show the potential of flash SPS to obtain fully dense anisotropic nanocrystalline magnets with high magnetic performance.

Shaping of dense ceramics is difficult due to their inherent brittleness. Nanograined ceramics like tetragonal zirconia (TZP) can be superplastically deformed and shaped at high temperatures owing to grain boundary sliding (GBS). Herein, the enhanced plasticity of gadolinium-doped ceria (GDC) ceramics under mild and strong AC electric current in terms of steady state creep rate under both compressive and tensile loading is demonstrated. A current density of 25 and 200 mA mm−2 is used for the creep deformation. The creep rate increases by up to two orders of magnitude under electric current. The stress exponent remains unchanged for creep experiments at 1200 °C with and without electric current, suggesting a GBS mechanism of plastic deformation in both cases. The field-enhanced creep rate is attributed to the interaction of space–charge layer and the electric field resulting in enhanced GBS. A higher current density results in enhanced ductility of GDC even when the Joule heating effect is compensated by reducing the furnace temperature.

Proton-conducting barium zirconate ceramics have shown large potential for efficient electrochemical conversion and separation processes at intermediate operation temperatures. The high energy efficiency, robustness, and intermediate-temperature operation (500-650 °C) make proton-conducting cells promising candidates for future energy conversion systems. However, the major disadvantages of these materials are the inevitable high-sintering temperatures (>1500 °C), leading to Ba-evaporation and formation of high-resistance grain boundaries, which dominate the electrochemical performance. Here, we introduce a novel processing route for proton-conducting barium zirconates, which, on the one hand, significantly lowers the maximum processing temperature and, on the other hand, overcomes the dominating influence of grain boundaries on total conductivity. The key step of this novel processing route is the cold sintering of the powder using pure water as a sintering aid to consolidate BaZrCeYO (BZCY) at 350 °C. We show that clean grain boundaries with a high acceptor-dopant concentration are preserved thanks to the recovery of the perovskite phase during thermal treatment at 1300 °C. This compensates the interfacial core charge, resulting in highly conductive grain boundaries, which do not limit the total conductivity. Consequently, dense BZCY electrolytes produced by our novel approach outperform the conductivity of conventionally sintered BZCY irrespective of the significantly lower maximum processing temperature and its nanocrystalline microstructure. Our presented approach opens up new possibilities for grain boundary engineering and might facilitate novel co-sintering pathways for barium zirconate-based components.