VOL 97, No. 6 (2024)

Direct femtosecond laser writing of phase optical elements in glasses opens up new possibilities for controlling light beams and developing new functional devices that operate on the birefringence effect. In this work, phase plates were written in the volume of silica and nanoporous glasses using a laser beam, and for the first time, chromatic dispersion curves of birefringence were measured for them using several methods. This makes it possible to estimate the retardance of birefringent elements fabricated by the direct laser writing even using commercial birefringence analysis systems operating at a specific wavelength.

The optical properties and microstructure of composites based on yttrium aluminum garnet were studied. The composites were produced by vacuum sintering pre-formed compacts of nanocrystalline powder with the composition Y3Al4.995Cr0.005O12 in conjunction with a YAG single crystal. The light transmission spectra of composite samples showed absorption bands of Cr3+ after vacuum sintering and bands of Cr4+ after annealing in air. The effect of heating rate during vacuum sintering on the light transmission of composite samples was investigated. It was determined that the optimal heating rate during vacuum sintering of composites should not exceed 120 °C/h. The influence of vacuum sintering temperature on the optical properties and microstructure of YAG:Cr (ceramics)/YAG:Nd (single crystal) composite samples was also examined. The most transparent samples were obtained at a temperature of 1850 °C. Microstructure studies of the composites revealed the presence of regular residual porosity near the interface, primarily located in the YAG single crystal. It is hypothesized that the formation of these pores occurs during the fusion of ceramic grains with the single crystal during sintering.

In the paper presents the process of producing glass ceramics based on corundum modified with borosilicate glass with various additives. The described Al2O3/SiO2–B2O3–CaO–MgO–Na2O–K2O system has developed for LTCC technology and got a sintering temperature less than 950 ?. The influence of additive content on the sintering temperature, microstructure, ceramic and electrophysical properties of ceramics has been investigated. Developed composition has a dielectric constant of ?r = 6.73…6.82 and tangent of the dielectric loss angle tg ? = 8.0…8.6?10–3 at a frequency f = 1 MHz.

High-temperature thermal insulation materials are widely used in civil engineering as flame retardant materials, as well as in many industries. Rocks and industrial waste are used as raw materials for their production. The article confirms the possibility of using ceramovermiculite and keramoperlite materials on a wollastonite bond as high-temperature thermal insulation. The materials were obtained by firing a charge of chalk, diatomite and heat-resistant filler (expanded perlite, expanded vermiculite). The material of the fired samples with expanded vermiculite consists mainly of the crystalline phase of wollastonite and biotite with a small amount of quartz and ackermanite-helenite. When using expanded perlite as a heat-resistant filler, in addition to the crystalline phase of wollastonite, a small amount of plagioclases is present in the material of the burnt samples, and an amorphous phase also appears. The physicomechanical properties of the charge and the fired samples were determined, and the effect of the apparent density and phase composition of the developed materials on the change in their thermal insulation properties at high temperature was studied. The thermal insulation properties of materials at high temperature were determined by unilateral exposure of the sample to heat flow from the heating chamber of the muffle furnace. Samples from the developed materials have an apparent density from 375 kg/m3 to 630 kg/m3 and compressive strength from 0.95 MPa to 3.25 MPa. The developed keramoperlite materials on a wollastonite bond can be used as high-temperature thermal insulation up to +900 °C, and ceramovermiculite – up to +1050 °C. According to many physico-mechanical and thermophysical properties, the materials obtained are not inferior to known analogues.

Describes a method for determining the physico-mechanical properties of a synthesized batch of propants. Industrial waste is one of the sources of anthropogenic impact on the environment on a global scale, being formed in the process of coal and oil extraction as a by-product. With the decrease in stocks of high-quality natural raw materials and the accumulation of man-made products, the problem of use becomes urgent.

The ability of isovalent substitution of zinc and cobalt atoms in the structure of willemite Zn2SiO4 was studied, ceramic pigments with willemite structure of blue, violet and blue colors were synthesized. Samples of blue color were used in the manufacture of glazes. Synthetic silicon oxide was replaced by natural quartz sand in synthesizing the pigments. The pigments were synthesized by solid-phase reactions at a temperature of 1270 ?C. The physical and chemical properties of the synthesized blue pigment used in the composition of traditional glazes for coloring ceramic products were determined. It is established that the synthesized blue pigment has high aesthetic and decorative characteristics at a relatively low cost price.

In the present study, we review current progress in sol-gel techniques for synthesis of ferroelectric powders, thin films and rods in lead zirconate-titanate system, as well as methods for obtaining controlled particle morphology, primarily rod-like. Synthetic approaches in sol-gel process and heat treatment conditions for obtaining lead zirconate-titanate ceramics of pre-defined morphology are of primary focus in the present review.