VOL 98, No. 11 (2025)

Yttrium aluminum garnet (YAG) powders were synthesized via chemical precipitation, both with and without the addition of ammonium sulfate as a dispersant. The impact of the dispersant on the particle size distribution of YAG powders calcined at various temperatures was investigated. Powder morphology was analyzed using scanning electron microscopy (SEM), revealing significant differences in both morphology and particle size depending on whether the dispersant was present. The kinetics of phase transformations in the ceramic powders, with and without ammonium sulfate, were thoroughly examined using X-ray diffraction (XRD) and simultaneous thermal analysis (STA). Based on the data obtained, a novel mechanism was proposed for reducing agglomeration in YAG ceramic powders through the use of ammonium sulfate as a dispersant. This mechanism entails the formation of intermediate phases, namely yttrium sulfate and yttrium oxysulfate, followed by their gradual decomposition to yield the garnet phase.

Nanocrystalline powders of yttrium scandium aluminum garnet (YSAG) doped with neodymium Nd3+ and samarium Sm3+ cations were synthesized by chemical precipitation. Their morphology, phase and granulometric composition have been studied. Three types of samples were produced from the obtained ceramic powders using various pressing methods: standard non-composite reference samples, samples with a composite structure of the same composition, and samples of composite ceramics with different layer compositions. The samples of the first and second types demonstrated high transparency and uniformity of the microstructure. A slight decrease in the light transmission of samples of the third type is due to the presence of a certain number of residual pores and inclusions near the interface of the layers, the probable nature of the formation of which is associated with differences in the kinetics of sintering compositions. The influence of the parameters of uniaxial and cold isostatic pressing of composite compacts on the microstructure and optical properties of YSAG:Nd3+/YSAG:Sm3+ composite ceramics was also investigated. It is shown that at the interface between the YSAG:Nd and YSAG:Sm layers there is a region of gradient doping with samarium cations, the extent of which may presumably depend on the pressing conditions and sintering parameters of composite compacts.

Yttrium aluminum garnet doped with ytterbium (YAG:Yb) ceramic powders were synthesized using the chemical precipitation method, from which optical ceramic samples were fabricated. Dispersants, namely polyvinylpyrrolidone and ammonium sulfate, were employed during powder synthesis, washing, and milling. The results presented include data on the phase composition, specific surface area, scanning electron microscopy, and particle size distribution of the ceramic powders. It was noted that the addition of polyvinylpyrrolidone and ammonium sulfate to the reaction mixture, as well as to the washing and milling solutions, alters the particle size distribution and specific surface area of the powders, while also influencing the kinetics of phase transformations. Furthermore, the influence of these dispersants on the optical properties of YAG:Yb ceramics and the number of macrodefects was revealed.

A study was conducted on obtaining powders for microwave dielectrics from zinc oxide using deep eutectic solvents. As a result of using various solvents, a monophase ZnO powder is formed, the particle size and phase composition of which can be controlled by changing the calcination temperature. Deep eutectic solvents make it possible to obtain zinc oxide precursors by interacting the corresponding deep eutectic solvent with water, without using alkalis or ammonium hydroxide, which gives reason to consider such synthesis more environmentally friendly. Zinc nanoparticles obtained at 500 °C have a pronounced antimicrobial effect on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).

Abstract. In recent years, the issues of obtaining clinker ceramics have become as relevant as possible, including – this is due to the tasks of import substitution. Clinker ceramics is a product that is used in aggressive environments and its characteristics are as close as possible to high-strength concrete. For production, it is necessary to maintain a balance between the cost of production and the achievement of characteristics corresponding to clinker ceramics. This article discloses the relationship between the composition of the raw components of ceramics, their granulometric composition, firing mode and its strength characteristics obtained in laboratory conditions from low-melting and refractory raw materials Siberian region, as well as the introduction of the sintering additive albitofir. The purpose of the work is to develop a composition for the production of clinker ceramics with water absorption indicators W not more than 4 %.

The effect of a combination of water-soluble magnesium and aluminum salts on the physicochemical properties of the obtained aluminomagnesium spinel was studied. It was shown that the formation of aluminomagnesium spinel occurs in the range of 800…1050 ? from synthesized xerogels based on different ratios of magnesium and aluminum chlorides and nitrates. It was found that the crystalline structure of the spinel is completely formed during heat treatment of xerogels from synthesized pairs of AlCl3 + MgCl2 salts at 900 °C and holding for 60 minutes, while they have smaller crystallite sizes compared to other heat-treated xerogels. It was revealed that a higher temperature of 1050 ? is required to obtain spinel from xerogels synthesized on the basis of pairs of Al(NO3)3 + MgCl2 and Al(NO3)3 + Mg(NO3)2 salts.