Chapters authored
Synthesis and Investigation of Ceramic Materials for Medium-Temperature Solid Oxide Fuel Cells
Finely dispersed (СeO2)1-x(Sm2O3)x (x = 0.02; 0.05; 0.10); La1-xSrxNiO3, La1-xSrxCoO3 and La1-xSrxFe0.7Ni0.3O3 (x = 0.30; 0.40) mesoporous xerogel powders are synthesized by co-crystallization of the corresponding nitrates with ultrasonic processing and used to obtain nanoscale ceramic materials with cubic fluorite-like, orthorhombic, and perovskite-like tetragonal crystal structure, respectively, with CSR ∼ 64–81 nm (1300°C). Physicochemical characterization of the obtained ceramics revealed that (СeO2)1-x(Sm2O3)x features with open porosity 2–6%, while for La1-xSrxNiO3, La1-xSrxCoO3, and La1-xSrxFe0.7Ni0.3O3, this value is about 21–29%. Ceria-based materials possess a predominantly ionic conductivity (ion transport numbers ti = 0.82–0.71 in the temperature range 300–700°C, σ700°С = 1.3·10−2 S/cm) determined by the formation of mobile oxygen vacancies upon heterovalent substitution of Sm3+ for Се4+. For solid solutions based on lanthanum nickelate and cobaltite, a mixed electronic-ionic conductivity (σ700°С = 0.80·10−1 S/cm) with ion transport numbers (te = 0.98–0.90, ti = 0.02–0.10) was obtained. The obtained ceramic materials are shown to be promising as solid oxide electrolytes and electrodes for medium-temperature fuel cells.
Part of the book: Smart and Advanced Ceramic Materials and Applications
Fractal Characterization of Microstructure of Materials and Correlation with Their Properties on the Basis of Digital Materials Science Concept
The concept of Digital Materials Science supposes that materials are designed, fabricated, tested, studied, characterized, and optimized on the basis of digital technologies, including the analysis of fractal parameters (fractal dimension, lacunarity, scale invariance, Voronoi entropy, etc.) of materials’ microstructure. Many classes of materials may be considered as composites: polymer composites with inorganic fillers, alloys containing nonmetallic inclusions (oxides, carbides, nitrides, intermetallic ones, etc.), ceramic materials with pores and sintering additives, etc. The analysis of composition-technology-structure-properties relationships for such non-ordered composite materials requires the development of numerical tools for the characterization of their structure, including the interposition of phases. This chapter presents several examples of the implementation of this concept, including the study of filler distributions in dielectric composites, interposition of phases in special ceramic materials, distribution of nonmetallic inclusions in additively manufactured stainless steel, and structural features of tungsten oxide-based electrochromic materials. Based on the analysis of such characteristics as lacunarity and surface functionality, interrelations are established between technical properties of the studied materials and their structure providing approaches to the prediction and optimization of their target performances.
Part of the book: Fractal Analysis - Applications and Updates