In this study SiCNO coatings with tunable carbon content were derived from a single preceramic polysilazane and deposited on AISI 441 steel. The carbon content was controlled through the annealing atmosphere. The coatings were annealed in argon, in argon followed by cooling in air, and entirely in air. As a result three coatings with different carbon concentrations were obtained. XPS together with Raman spectroscopy confirmed that the annealing atmosphere altered both the amount and nature of the free carbon phase. ToF-SIMS depth profiles revealed the outward diffusion of manganese and chromium notwithstanding the annealing conditions. During oxidation at 800°C for 100 h in air, the coatings inhibited the mass gain of steel but they did not act as perfect diffusion barriers, as evidenced by the formation of oxide scales above the coatings. The area specific resistance (ASR) of the coatings was too high for the application in SOFC interconnects, despite the presence of the free carbon phase. This is due to the fact the free carbon phase forming a discontinuous, non-percolating network. The annealing atmosphere modified the relative contributions of silica, and SiON/SiOC/SiOx environments within the coating, thereby affecting metal transport and the resulting oxide-scale composition. The coating annealed in argon developed a scale containing mainly (Mn,Cr)3O4 and Cr2O3, whereas the coatings exposed to air during annealing or cooling formed manganese-rich oxides and silicates together with smaller amounts of (Mn,Cr)3O4 and Cr2O3. Overall, the annealing atmosphere strongly controlled carbon structure, metal transport, and oxidation-product formation.

Lead-free K_0.5Bi_0.5TiO₃ (KBT) ceramics were prepared using a finely tuned convectional solid-state reaction method. Their phase transitions in unpoled and poled states were examined. The temperature-dependent evolution of the reflections sensitive to structural changes and their 2Θ-positions indicated two temperature-driven phase transitions: tetragonal–tetragonal at about 200 °C, and tetragonal–cubic at around 400 °C. These structural transformations are further corroborated by studies examining Raman spectroscopy, dielectric properties, and mechanical properties. It was demonstrated that a prior E-field poling process significantly influences the polar state, causing an increase in the local degree of order, as well as the transformation of the cubic phase into the tetragonal one. This stabilizes and widens the temperature range of the ferroelectric phase. It was found that phase transformations in KBT are accompanied by a softening of the mechanical behavior similarly to improper ferroelastic transformations. The results demonstrate that KBT possesses favorable structural, dielectric, and mechanical characteristics, making it a potential candidate for electronic applications. The present study provides a clear understanding of the multi-scale structural behavior in multi-phase KBT, bridging micro-heterogeneity behaviors and macro-properties, and demonstrates an effective method of tuning the properties of KBTs by E-poling with a low electric field.