L. V. Morozova

Mechanochemical Synthesis of ZrO2–CeO2 Solid Solutions

ZrO2–CeO2 solid solutions (12 and 13 mol % CeO2) were prepared by mechanochemical synthesis in different media. The mechanical activation medium was shown to have a significant effect on the phase composition and particle size of the resultant powders. The conditions for sintering the powders were optimized.

Mechanochemical synthesis and sintering of (ZrO2)0.97(Y2O3)0.03

The (ZrO2)0.97(Y2O3)0.03 tetragonal solid solution was prepared by solid-state reaction from mechanically activated powder mixtures. The effects of the activation medium and particle size on the sintering behavior of the material was examined.

Influence of cryochemical and ultrasonic processing on the texture and thermal decomposition of xerogels and properties of nanoceramics in the ZrO2〈Y2O3〉–Al2O3 system

We have studied the influence of cryochemical and ultrasonic processing on the formation, structure, particle size, and thermal decomposition of xerogels in the ZrO2〈Y2O3〉–Al2O3 (20 wt %) system. Nanopowders of tetragonal-zirconia-based solid solutions with a high degree of tetragonality (c/a = 1.4366) have been synthesized. Al2O3 has been shown to slow down t-ZrO2 crystallite growth in the temperature range 600–1400°C. We have optimized nanopowder consolidation conditions, obtained nanoceramics stable to low-temperature “aging” in a humid medium, and investigated their physicochemical and mechanical properties.

Electroconducting ceramics based on In2O3, CdO, and LaCrO3

The possibility of fabricating electroconducting (101–104 S cm–1) ceramics based on In2O3, CdO, and LaCrO3 by liquid-phase synthesis methods has been demonstrated. The results of studies of the effect of temperature, dopants, and partial oxygen pressure on the specific electroconductivity of ceramic composites are presented.

Preparation and Properties of a Ceramic in the ZrO2 – CeO2 System

The ZrO2 – CeO2 solid solution (88 mol.% – 12 mol.%) is synthesized by coprecipitation. The effect of dry mechanical grinding on the dispersity of the solid solution is studied. Combining methods of coprecipitation and mechanical grinding intensifies the sintering process and allows preparation of compact ceramic materials in the ZrO2 – CeO2 system.

Preparation and Characterization of Nanoceramics for Solid Oxide Fuel Cells

Precursor powders in the ZrO2–HfO2–Y2O3–CeO2, In2O3–ZrO2, and NiO–Nd2O3 systems for components of solid oxide fuel cells have been prepared by liquid-phase synthesis. We have determined formation conditions and the particle size of ZrO2- and In2O3-based solid solutions and neodymium nickelate (Nd2NiO4), demonstrated the feasibility of producing nanocrystalline powders (10–30 nm) of tailored chemical composition in the temperature range 500–900°C, and optimized powder consolidation conditions. Nanoceramics with a crystallite size from 60 to 90 nm have been obtained and their microstructure and phase composition have been investigated. We have studied the electrical properties of the ZrO2- and In2O3-based solid solutions and the Nd2NiO4 compound and established the range of their electrical conductivity at temperatures from 300 to 1000°C: 2.27 × 10–3 to 2.51 S/cm for the ZrO2-based solid solution, 8.91 × 101 to 6.59 × 103 S/cm for the In2O3-based solid solution, and 3.98 × 102 to 5.02 × 102 S/cm for Nd2NiO4.

Synthesis and Investigation of Solid Solutions Based on Indium Oxide in In2O3–MeO2 (Me = Zr, Sn, Ti) Systems

Solid solutions in In2O3–MeO2 (Me = Zr, Sn, Ti) systems based on indium oxide are synthesized by the coprecipitation method. It is found that the ultrasound treatment of the coprecipitation products reduces the degree of agglomeration of the initial particles by a factor of 3 and initiates the crystallization process of the precipitates. Nanocrystal (5–8 nm) precursor powders are obtained at 400°C. The optimal regime for sintering powders based on In2O3 to form a ceramic with a dense microstructure is chosen. The influence of the temperature, alloying additives, and the partial pressure of oxygen on the specific conductivity of indium oxide solid solutions is studied.

Preparation and properties of porous ceramics based on alumomagnesium spinel and zirconium dioxide

The foundations of the technology for the preparation of porous nanoceramics based on alumomagnesium spinel (MgAl2O4) and zirconium dioxide stabilized in the tetragonal structure (t-ZrO2) with an open porosity of >40% are developed. It is revealed that the cocrystallization of salt solutions with subsequent mechanochemical activation of crystallohydrates can be used for the production of nanosized MgAl2O4 and t-ZrO2 powder precursors (<20 nm). A possible way to control the open porosity and the pore size by choosing the optimal sintering temperature and the kind and the amount of pore-forming additives is shown. The width of the pore size distribution increases with increasing volume fraction of the blowing agent in the initial powder. Nanoporous ceramic materials with pores 25–100 nm in size for MgAl2O4 and 100–300 nm for t-ZrO2 are produced. The technological scheme for applying an α-Al2O3 membrane layer on a t-ZrO2 porous matrix is developed.

Synthesis of the study of solid solutions based on the ZrO2–HfO2–Y2O3(CeO2) system

The results of the studies of the conditions of the liquid-phase synthesis of highly dispersed xerogels with a low degree of agglomeration and precursor nanopowders (~10–12 nm) based on zirconium dioxide in the ZrO2–HfO2–Y2O3(CeO2) system are presented. The thermal decomposition of xerogels and formation of crystalline solid solutions with the structure of fluorite are investigated. The optimal conditions for the solidification of nanodispersed powders for fabricating compact ceramics based on solid solutions of ZrO2 and the physical–chemical properties of these ceramics are studied.