The transformation of shell structure of the core-shell particles of poly(methyl methacrylate)-silica and hollow SiO2 particles undergoing heat treatment was studied by infrared (IR) spectroscopy using deconvolution of absorption bands in the wavenumber range 400–650 cm–1. It was revealed that the changes in the IR absorption spectra during annealing were caused by structural transformation of the particles’ material due to its restructuring, including the formation of silica ring clusters of different sizes and changes of their ratio during annealing. The used method of the spectra deconvolution made it possible to consider in more detail the parameters and contributions of the vibration modes of such clusters to the absorption spectra of SiO2. A modified structure of a polysiloxane, synthesized through hydrolysis of trimethoxy(vinyl)silane, which represents a polymer chain of repeating fragments containing four- and three-fold (Si–O) rings linked by a bridging oxygen atom, is proposed. It has been found that skeletal vibrations of 6-fold (Si–O) rings combined with transverse optical and longitudinal optic vibration modes of the Si–O–Si bonds make the principal contribution to total IR absorption of the studied samples both in amorphous and in crystal silica structures obtained after annealing.

Cd1-xZnxTe crystals are necessary for the production of ionizing radiation detectors widely used in science, technology, medicine and other fields. Internal stresses during crystallization lead to generation of dislocations and low-angle boundaries. Typical problem of melt crystal growth of Cd-Zn-Te compounds are tellurium inclusions, which deteriorate detector performance. Microgravity conditions provide unique opportunities for growing high-quality crystals due to the absence of convection, more equilibrium conditions of melt mixing, and a decrease in internal stresses. Since the properties of such crystals strongly depend on the production conditions, seeds and a feed ingot with specified compositions and structure are required. Ampoules with two compositions of materials have been prepared for the space experiment. Crystals of different compositions Cd0.96Zn0.04Te and Cd0.9Zn0.1Te were produced for two charges. They consist of an oriented seed, solvent, and feeding ingot, which are single-phased, single crystalline, have certain crystallographic orientation, meet demands for growth of Cd–Zn–Te crystals in microgravity. Ampoules containing these materials were sent to International Space Station for crystal growth on equipment already assembled at “Nauka” station.

The structure, IR absorption and luminescence spectra, and morphology of Lu 0.99-x Sm x Eu 0.01 BO 3 (0≤ x≤0.99) orthoborates synthesized at 970 o C were studied. With an increase in the Sm 3+ concentration, a successive change of five structural states is observed: calcite (0≤ x≤ 0.1)-> calcite + vaterite (0.1 vaterite (0.3≤ x≤ 0.95)-> vaterite + a triclinic phase (0.95 a triclinic phase (0.98

The structure, morphology, IR spectra, as well as luminescence spectra and luminescence excitation spectra of europium-doped borates formed during the interaction of lanthanum and scandium oxides with a potassium tetraborate melt at 970 o C with the general formula La 0.99-x Sc x Eu 0.01 BO 3 were studied. It is shown that with an increase in the Sc 3+ concentration, three compounds are successively formed: LaBO 3 , LaSc 3 (BO 3 ) 4 , and ScBO 3 . At 0≤ x≤ 0.26, the samples are single-phase and have the structure of LaBO 3 aragonite. Within the range of 0.26<x<0.75, the samples are two-phase and contain the structures of LaBO 3 aragonite and LaSc 3 (BO 3 ) 4 huntite. At 0.75≤ x≤0.85, LaSc 3 (BO 3 ) 4 is observed. Within the range of 0.85<x≤0.97, the samples are two-phase and consist of LaSc 3 (BO 3 ) 4 huntite and ScBO 3 calcite. At 0.97<x≤0.99, the ScBO 3 samples have a calcite structure. Correspondence between the structure and spectral characteristics of these compounds was established. Keywords: phosphors for LEDs, rare earth orthoborates, X-ray diffraction analysis, IR spectroscopy, luminescence spectra.

The structure, morphology, IR spectra, as well as luminescence spectra and luminescence excitation spectra of europium-doped borates formed during the interaction of lanthanum and scandium oxides with a potassium tetraborate melt at 970°С with the general formula La0.99-xScxEu0.01BO3 were studied. It is shown that with an increase in the Sc3+ concentration, three compounds are successively formed: LaBO3, LaSc3(BO3)4, and ScBO3. At 0 ≤ x ≤ 0.26, the samples are single-phase and have the structure of LaBO3 aragonite. Within the range of 0.26 < x < 0.75, the samples are two-phase and contain the structures of LaBO3 aragonite and LaSc3(BO3)4 huntite. At 0.75 ≤ x ≤ 0.85, LaSc3(BO3)4 is observed. Within the range of 0.85 < x ≤ 0.97, the samples are two-phase and consist of LaSc3(BO3)4 huntite and ScBO3 calcite. At 0.97 < x ≤ 0.99, the ScBO3 samples have a calcite structure. Correspondence between the structure and spectral characteristics of these compounds was established.

The structure, IR absorption and luminescence spectra, and morphology of Lu0.99xSmxEu0.01BO3 (0 ≤ x ≤ 0.99) orthoborates synthesized at 970°С were studied. With an increase in the Sm3+ concentration, a successive change of five structural states is observed: calcite (0 ≤ x ≤ 0.1) → calcite + vaterite (0.1 < x < 0.3) → vaterite (0.3 ≤ x ≤ 0.95) → vaterite + a triclinic phase (0.95 < x ≤ 0.98) → a triclinic phase (0.98 < x ≤ 1). A wide range of Sm3+ concentrations at which the vaterite phase (0.3 ≤ x ≤ 0.95) exists and a very narrow region of triclinic phase formation (0.98 < x ≤ 1) are important distinctive features of this system. Correspondence between the structure and spectral characteristics of these compounds was established. It is shown that the vaterite phase appears in the bulk of the microcrystals of the samples that have a calcite structure.

The structure, IR, luminescence, and luminescence excitation spectra of Ce3+, Tb3+, and Eu3+ ions in Lu1-2xCexEuxBO3 and Lu0.91-2xCexTb0.09EuxBO3 solid solutions were studied. The minimum "threshold" distance between Ce3+ and Eu3+ ions was estimated, at which there is no charge transfer between these ions, leading to the quenching of Ce3+ and Eu3+ luminescence. It is shown that in Lu0.91-2xCexTb0.09EuxBO3 compounds, the range of Ce and Eu concentrations of 0.2-0.25 at.% is optimal for obtaining the maximum luminous intensity of this compound. Keywords: phosphors for LEDs, rare earth orthoborates, X-ray diffraction analysis, IR spectroscopy, luminescence spectra.

The structure, IR absorption, luminescence, and luminescence excitation spectra of La 0.99-x Y x Eu 0.01 BO 3 orthoborates synthesized at 970 o C were studied at 0≤ x≤0.99. An increase in x leads to a sequential change of the structural state of these compounds. At 0≤ x≤0.1, the samples are single-phase and have the aragonite structure. Within the range of 0.1^7F 0 electron transition, as well as 469 nm-band in the LES, can be an indicator of the structural state of the sample. Keywords: rare earth orthoborates, X-ray diffraction analysis, crystal structure, IR spectroscopy, luminescence spectra.

The structure, infrared (IR) absorption spectra, luminescence spectra (SL), and luminescence excitation spectra (LES) of La 0.99-x Tb x Eu 0.01 BO 3 orthoborates synthesized at 970 o C at 0≤ x≤ 0.99 were studied. An increase in x leads to the successive emergence of three structural states of these compounds. At 0≤ x≤0.2, orthoborates have an aragonite structure; then, at 0.2 5 D 2 ) in the LES and the band in the wavelength range of 577-582 nm ( 5 D 0 -> 7 F 0 ) in the SL of these compounds can serve as indicators of the structural state of the sample. In the SL of the samples containing the aragonite and vaterite phases, two bands corresponding to these structures were simultaneously observed for the first time. It was established that the luminescence of Eu 3+ ions in La 0.99-x Tb x Eu 0.01 BO 3 orthoborates, which occurs when the sample is excited by light in the absorption bands of Tb 3+ ions, is due to the transfer of the electron excitation energy from Tb 3+ ions to Eu 3+ ions. The efficiency of this process in La 0.9 Tb 0.09 Eu 0.01 BO 3 samples with an aragonite structure is 86%. Keywords: rare earth orthoborates, crystal structure, X-ray diffraction analysis, IR spectroscopy, luminescence spectra, phosphors for LEDs.

The structure, IR absorption and luminescence spectra of Pr0.99xLuxEu0.01BO3 orthoborates synthesized at 970°C were studied at 0 ≤ x ≤ 0.99. An increase in the concentration of lutetium leads to a sequential change of the structural state of the orthoborates. At first, the orthoborates are single-phase and have an aragonite structure (0 ≤ x ≤ 0.1). Then, they become two-phase and contain the aragonite and vaterite phases (0.1 < x < 0.6). With a further increase in х (0.6 < x ≤ 0.8), the compounds are single-phase with a vaterite structure, then they contain the vaterite and calcite phases (0.8 < x ≤ 0.95), and, finally, they become single-phase with a calcite structure (0.95 < x ≤ 0.99). An unambiguous correspondence between the structural modification and IR spectra of these compounds was established. It is shown that the emission of Eu3 + ions is observed in samples where the concentration of europium exceeds that of praseodymium.

The structure, IR absorption and luminescence spectra of Pr 0.99-x Lu x Eu 0.01 BO 3 orthoborates synthesized at 970 o C were studied at 0≤ x≤0.99. An increase in the concentration of lutetium leads to a sequential change of the structural state of the orthoborates. At first, the orthoborates are single-phase and have an aragonite structure (0≤ x≤0.1). Then, they become two-phase and contain the aragonite and vaterite phases (0.1<x<0.6). With a further increase in x (0.6<x≤0.8), the compounds are single-phase with a vaterite structure, then they contain the vaterite and calcite phases (0.8<x≤0.95), and, finally, they become single-phase with a calcite structure (0.95<x≤0.99). An unambiguous correspondence between the structural modification and IR spectra of these compounds was established. It is shown that the emission of Eu 3+ ions is observed in samples where the concentration of europium exceeds that of praseodymium. Keywords: rare earth orthoborates, X-ray diffraction analysis, crystal structure, IR spectroscopy, luminescence spectra.

Changes in the morphology and structure of the core-shell particles of polymethyl methacrylate-silicon dioxide and hollow SiO2 particles during their heat treatment were studied by electron microscopy, infrared spectroscopy, and X-ray diffraction. The polymeric core of the PMMA-SiO2 hybrid particle was found to undergo an unusual transformation when exposed to the electron microscope beam: its shrinkage occurs through the formation of a spherical cavity. It was shown that the process of silica-shell formation occurs in the temperature range of 200–600 °C and is accompanied by the loss of vinyl- and OH-groups. It was determined by the method of X-ray diffraction, that in the place of the interaction of PMMA and the shell, the degree of ordering of the polymer is higher than that in the volume of the polymer core. It was shown that the frequency of the TO3-vibrational mode (asymmetric stretching vibrations of the Si–O–Si bonds) increases with an increase in the annealing temperature, which is associated with the densification of the silicon dioxide shell.

The structure, IR absorption spectra, luminescence spectra (SL), and luminescence excitation spectra (LES) of La0.99хTbxEu0.01BO3 orthoborates synthesized at 970°С at 0 ≤ x ≤ 0.99 were studied. An increase in x leads to the successive emergence of three structural states of these compounds. At 0 ≤ x ≤ 0.2, orthoborates have an aragonite structure; then, at 0.2 <x< 0.89, they become two-phase and contain the aragonite and vaterite phases. At 0.89 ≤ x ≤0.99, the compounds have a vaterite structure. A correspondence between the structure and spectral characteristics of these compounds was established. It is shown that in La0.99хTbxEu0.01BO3 orthoborates, as well as in La0.99хYxEu0.01BO3, the band with λex= 369 nm (7F0 → 5D2) in the LES and the band in the wavelength range of 577 – 582 nm (5D0→7F0 ) in the SL of these compounds can serve as indicators of the structural state of the sample. In the SL of the samples containing the aragonite and vaterite phases, two bands corresponding to these structures were simultaneously observed for the first time. It was established that the luminescence of Eu3+ ions in La0.99хTbxEu0.01BO3 orthoborates, which occurs when the sample is excited by light in the absorption bands of Tb3+ ions, is due to the transfer of the electron excitation energy from Tb3+ ions to Eu3+ ions. The efficiency of this process in La0.9Tb0.09Eu0.01BO3 samples with an aragonite structure is 86%.

The structure, IR absorption, luminescence, and luminescence excitation spectra of La0.99xYxEu0.01BO3 orthoborates (0 ≤ x ≤ 0.25) synthesized at 970°С were studied at 0 ≤ x ≤ 0.99. An increase in х leads to a sequential change of the structural state of these compounds. At 0 ≤ x ≤ 0.1, the samples are single-phase and have the aragonite structure. Within the range of 0.1 < x ≤ 0.8, the samples are two-phase: the vaterite phase is observed along with the aragonite structure. At 0.8 < x ≤ 0.99, the samples are single-phase and have the vaterite structure. Correspondence between the structure and spectral characteristics of these compounds was established. It is demonstrated that with an increase in the Y3+ concentration, the vaterite phase is formed first in the bulk of microcrystals having the aragonite structure and then in the entire sample. It is shown for the first time that a band with the maximum of 469 nm is observed in the luminescence excitation spectrum (LES) of samples having the vaterite structure and is absent in samples having the aragonite structure. It is revealed that a band in the luminescence spectrum, corresponding to the 5D0→7F0 electron transition, as well as 469-nm-band in the LES, can be an indicator of the structural state of the sample.

The structure, IR, luminescence, and luminescence excitation spectra of Ce3+, Tb3+, and Eu3+ ions in Lu1−2xCexEuхBO3 and Lu0.91−2xCexTb0.09EuхBO3 solid solutions were studied. The minimum "threshold" distance between Ce3+ and Eu3+ ions was estimated, at which there is no charge transfer between these ions, leading to the quenching of Ce3+ and Eu3+ luminescence. It is shown that in Lu0.91−2xCexTb0.09EuхBO3 compounds, the range of Ce and Eu concentrations of 0.2 – 0.25 at. % is optimal for obtaining the maximum luminous intensity of this compound.

The structure, IR absorption, luminescence, and luminescence excitation spectra of La 0.98-x Lu x Eu 0.02 BO 3 orthoborates synthesized at 970 o C were studied at 0≤ x≤0.98. An increase in x leads to a sequential change of the structural state of the orthoborates. At first, the compound has the aragonite structure. Then, it becomes two-phase and contains the aragonite and vaterite phases. With a further increase in x, the compounds have the vaterite structure, then the vaterite and calcite structure, and, finally, the calcite structure. Correspondence between the structure and spectral characteristics of these compounds was established. Luminescence spectra were investigated at different wavelengths of exciting light. This allowed obtaining information on the structure of a near-surface layer and the bulk of microcrystals of the investigated samples. It is shown that the vaterite phase arises in the bulk of microcrystals of samples that have the aragonite structure. Keywords: phosphors for LEDs, rare earth orthoborates, X-ray diffraction analysis, IR spectroscopy, luminescence spectra.

The structure, IR absorption and luminescence spectra of solid solutions of Lu0.99 ‒ xGdxEu0.01BO3 at 0 ≤ x ≤ 0.15 were studied. The correspondence between the structure and spectral characteristics of these compounds was established. It is shown that at x ≤ 0.05, the orthoborates Lu0.99 ‒ xGdxEu0.01BO3, consisting of lutetium borate LuBO3, which has two stable structural modifications (calcite and vaterite), and gadolinium borate GdBO3, which has only one structural modification (vaterite), form a solid solution with a calcite structure and a microcrystal size of 15–20 μm. As x increases, the amount of vaterite phase increases sequentially, and at x ≥ 0.1, the entire volume of the sample has a vaterite structure. At Gd3+ concentration in the range of 0.05 < x ≤ 0.1, the samples of Lu0.99 – xGdxEu0.01BO3 are two-phase. It is shown for the first time that at x > 0.05, the vaterite phase appears both in the volume of large microcrystals (15–20 μm) and in the form of small microcrystals (1–2 μm).

The structure, IR absorption, luminescence, and luminescence excitation spectra of La0.98xLuxEu0.02 BO3 orthoborates synthesized at 970°C were studied at 0 ≤ x ≤ 0.98. An increase in х leads to a sequential change of the structural state of the orthoborates. At first, the compound has the aragonite structure. Then, it becomes two-phase and contains the aragonite and vaterite phases. With a further increase in х, the compounds have the vaterite structure, then the vaterite and calcite structure, and, finally, the calcite structure. Correspondence between the structure and spectral characteristics of these compounds was established. Luminescence spectra were investigated at different wavelengths of exciting light. This allowed obtaining information on the structure of a near-surface layer and the bulk of microcrystals of the investigated samples. It is shown that the vaterite phase arises in the bulk of microcrystals of samples that have the aragonite structure.

The structure, IR absorption and luminescence spectra of solid solutions of Lu 0.99 ‒ x Gd x Eu 0.01 BO 3 at 0 ≤ x ≤ 0.15 were studied. The correspondence between the structure and spectral characteristics of these compounds was established. It is shown that at x ≤ 0.05, the orthoborates Lu 0.99 ‒ x Gd x Eu 0.01 BO 3 , consisting of lutetium borate LuBO 3 , which has two stable structural modifications (calcite and vaterite), and gadolinium borate GdBO 3 , which has only one structural modification (vaterite), form a solid solution with a calcite structure and a microcrystal size of 15–20 μm. As x increases, the amount of vaterite phase increases sequentially, and at x ≥ 0.1, the entire volume of the sample has a vaterite structure. At Gd 3+ concentration in the range of 0.05 < x ≤ 0.1, the samples of Lu 0.99 – x Gd x Eu 0.01 BO 3 are two-phase. It is shown for the first time that at x > 0.05, the vaterite phase appears both in the volume of large microcrystals (15–20 μm) and in the form of small microcrystals (1–2 μm).