Glass Physics and Chemistry最新文献

Nanosized precursor powders of (1 – x)ZrSiO₄‒xZrO(OH)₂ are synthesized by the sol-gel method with the separate precipitation of components to obtain (1 – x)ZrSiO₄‒xZrO₂ ceramic composites. The thermal behavior of precursor powders is studied by differential scanning calorimetry and thermogravimetry (DSC/TG). Ceramic composites with a high level of microhardness are obtained by sintering powders, preliminarily calcined at 850°C, in air in the temperature range 1000‒1300°C. In the future, such ceramic composites can be used as matrices for solidification and isolating high-level waste (HLW).

This paper discusses the technology of formation of photoresistive structures based on a composite of lead selenide and lead selenite. The structures are formed by the oxidation of n-PbSe polycrystalline films. Film The surface modification mechanism of n-PbSe films in the oxidation process is analyzed by a Zeiss Merlin scanning electron microscope (SEM). The new results of the authors on the oxidation mechanism of n-PbSe, together with their earlier publications, are summarized and their consistency with each other is examined. A theoretical model (hypothesis) of the potential profile of a photosensitive heterojunction is proposed, in which each crystal of the n-PbSe film during oxidation in an atmosphere of dry air forms a continuous shell on the p-PbSeO₃ surface. The hypothesis on the structural model of the photosensitive heterojunction proposed by other authors, which is based on the oxidation mechanism proposed by us, is practically confirmed in this study.

Crystals of a novel hybrid organo-inorganic borate, K[B₅O₆(OH)₄][B(OH)₃]₂(H₂O)(C₁₀H₂₀O₅)₂ (1), were obtained from aqueous solutions and characterized by single-crystal X-ray diffraction and IR spectroscopy. 1 is triclinic (a = 10.1567(4), b = 11.9941(6), c = 17.1893(9) Å, α = 75.280(4), β = 79.406(4), γ = 88.531(4)°, V = 1990.270369 ų, SG P-1; R₁ = 0.058). Its structure contains [K(C₁₀H₂₀O₅)₂]⁺ groups which behave as “hydrophobic” templates for the inorganic part comprised of ({{{text{B}}}_{{text{5}}}}{{{text{O}}}_{{text{6}}}}left( {{text{OH}}} right)_{4}^{ - }) anions and neutral B(OH)₃ molecules.

The features of the formation of a hidden lead-silicate insulating layer in silicon substrates are considered. To do this, ions of molecular oxygen and lead are sequentially implanted into them in an atomic ratio of 75 : 1 then annealing is carried out at a temperature of 1150°C in an environment of dry oxygen. The distribution of the implanted ions in the experimental samples is recorded by the method of secondary ion mass spectrometry. It is shown that the latent insulator is formed in the process of the spinodal decomposition of a solid solution of SiO_x–PbO_x in the form of a three-layer structure. Its middle part is silicon dioxide doped with lead ions and the side parts consist of a lead-silicate phase. A relaxation diffusion model is proposed to analyze the distribution profile of lead.

Information about new cesium-containing quartzoid glasses (QGs) obtained as a result of the heat treatment of high-silica porous glasses (PGs) impregnated with aqueous solutions of CsNO₃ is presented. Quartzoid glasses have been studied by SEM, X-ray diffraction, flame photometry, and energy-dispersive X‑ray spectroscopy. It has been established that the total content of cesium in the synthesized QGs increases with an increase in the concentration of the impregnating solution of cesium nitrate and an increase in the impregnation time of PGs for the selected synthesis conditions.

A series of Titanium-doped mesoporous bioactive glass with different Si-Ca ratios (MBG-Ti-1– MBG-Ti-5) were prepared by the sol-gel method. These materials were used to adsorb Norfloxacin (NOR) pollutant from aqueous solution. The morphology, microstructure and chemical properties of MBG-Ti-3 were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The N₂ adsorption-desorption isotherm and pore size distribution of MBG-Ti-3 were investigated by the Brunauer–Emmett–Teller (BET) method and Barret–Joyner–Halenda (BJH) method. The specific surface of MBG-Ti-3 was 126.68 m²/g and the pore size was about 15 nm. The effect of time, initial concentration, pH and temperature on the adsorption of NOR were investigated. The maximum adsorption efficiency was 68% at 30°C, pH 8.0. Moreover, adsorption of NOR onto MBG-Ti-3 could be well fitted with the pseudo-first-order model and the pseudo-second-order model. Furthermore, adsorption was spontaneous, exothermic process of reduced entropy by analyzing thermodynamic model. Through the analysis of adsorption model, plausible adsorption mechanism was proposed. MBG-Ti-3 exhibited better adsorption efficiency after recycle 3 times. Additionally, bioactive glass was eco-friendly attribute to biological suitability which could not cause secondly pollution for aquatic environment. As an environmentally friendly adsorbent, Titanium-doped mesoporous bioactive glass showed promising potential application in NOR antibiotics removal from aquatic environment.

In this paper, the transition metal oxoborate warwickite (Fe²⁺,Mg)Fe³⁺(BO₃)O is studied for the first time by low- and high-temperature X-ray diffraction in the temperature range from 93 to 513 K. The sharply anisotropic nature of its thermal expansion is revealed. A structural interpretation of the expansion mechanism is given both in terms of the contribution of cationic and oxocentered polyhedra.

Praseodymium incorporated Na₂O–ZnO–TeO₂ (NZT) glass materials were prepared through usual melt quenching technique. The temperature of glass transition and the melting point were obtained by using thermal analyses. The amorphous and ionic nature of the prepared samples was obtained from the recorded X-ray diffraction pattern and FTIR spectra respectively. The optical band gap energy was calculated using UV-Vis absorption spectra and was observed to be decreased from 2.86 to 2.46 eV due to the increasing concentration of Pr³⁺ ions. The peaks of absorption spectra were found. The intense emission was observed from the fluorescence measurement for the emission band of Pr³⁺ doped glass materials. The doping of higher concentrations of Pr³⁺ ions enhanced the intensity of the emission peaks. The CIE chromaticity coordinates were estimated from fluorescence spectra for pure and Pr³⁺ doped glass samples to know the suitability of laser emission of these glass samples. The dielectric constant of the glass materials was observed to be independent of frequency in the large range of frequency (500 Hz to 2 MHz). The variation of conductivity of the glasses was exposed the Arrhenius mechanism of conduction with the temperature.

This paper analyzes the experimental and theoretical studies of the problem of a diffuse phase transition (PTC) in a composite material xPbSe⋅(1 – x)PbSeO₃, in which x varies from 0 to 1. The decrease in stability in the virtual cubic phase of lead selenide (PbSe) is achieved by oxidizing it with atmospheric oxygen and forming a ferroelectric disordered monoclinic phase of lead selenite (PbSeO₃). The mechanism of lead selenide oxidation by air oxygen is studied by X-ray diffractometry, optical reflection in the infrared region of the spectrum, X-ray emission analysis (the chemical shift method), nuclear magnetic resonance, studies of AC and DC conductivity, differential scanning calorimetry, and other methods. The reason for the smearing of the phase transition in the xPbSe⋅(1 – x)PbSeO₃ composite, in which x varies from 0 to 1, is analyzed based on the previously obtained experimental results of its detection.