Glass-crystalline Materials Research Articles

Vitrification as a Key Solution for Immobilisation Within Nuclear Waste Management

AbstractVitreous materials in the form of both relatively homogeneous glasses and composite glass crystalline materials (GCM) incorporating disperse crystalline phases are currently the most reliable wasteforms effectively used on industrial scale for nuclear waste immobilisation. Glasses are stable solid-state materials with a topologically disordered atomic structure in the form of solid solutions, i.e. solutions frozen via vitrification to a solid state without forming regular crystalline phases. Nuclear waste vitrification is attractive because of technological and compositional flexibility enabling hazardous elements to be safely immobilised and providing a glassy material characterised by high corrosion resistance, mechanical and radiation durability, as well as effectively reducing the volume of the resulting wasteform.

STUDY OF THERMAL COEFFICIENT OF LINEAR EXPANSION OF BIOCOMPATIBLE GLASS CRYSTALLINE MATERIALS BASED ON THE SYSTEM Li2O–СaO–ZrO2–TiO2–MgO–ZnO–Al2O3–B2O3–P2O5–SiO2

The prospect of using biocompatible scaffolds with bone tissue architecture to replace large areas of bone tissue has been established. The necessity of creating reinforced porous bioactive glass-crystalline materials, which are operated under conditions of variable loads and characterized by high osteoconductive and osteoinductive properties, has been established. The main criteria for the formation of a reinforced hierarchical porous structure of bioactive glass-crystalline materials under the conditions of heat treatment have been determined. The choice of the system is justified Li2O–СaO–ZrO2–TiO2–MgO–ZnO–Al2O3–B2O3–P2O5–SiO2, within which the compositions of the OS series glasses with the content of the main components and modifying additives are selected, wt. %. %: CaF2 0,5–2,5; CeO2 0,01–0,05; SrO 0,01–0,05; Nb2O3 0,01–0,1; SrO 0,01–0,1 and with the ratio Са:P = 1,67 and SiO2:Li2O = 4,0 and glass-crystalline materials were developed, which are characterized by the content of crystalline phases of hydroxyapatite and lithium disilicate for the formation of a bioactive reinforced structure. The influence of the chemical and phase composition of model glasses on the crystallization ability and thermal properties of glass-crystalline materials based on them was analyzed. It was determined that the indicator TСLЕ indicator for experimental glass materials in the temperature range of 25–600 °С is 78–130,2·10-7°С-1 and is recognized by the type and content of crystalline phases and the composition of the glass phase. It was established that the formation of a sytalized interconnected structure with the presence of 50 vol. % hydroxyapatite and 10 об. % lithium with TСLЕ about 100·10-7°С-1, determines the possibility of obtaining high-quality durable and defect-free porous biocompatible materials and coatings on titanium alloys based on calcium-silicophosphate glass-crystalline materials for creating a single endoprosthesis design. The creation of reinforced nanostructured glass-crystalline materials with a hierarchical porous structure, the ability to withstand thermal loads and the formation of a strong connection with titanium alloys will allow solving the urgent problems of replacing significant areas of bone tissue.

DETERMINATION OF PROSPECTIVE DIRECTIONS FOR THE IMPROVEMENT OF MATERIALS FOR INDIVIDUAL ARMOR PROTECTION

An analysis of world experience in the direction of modern developments of high-strength aluminosilicate glass-crystalline materials, in particular, in the creation of lightweight armor, was carried out. The trends and current state of the glass-ceramics market from 2019 to 2023 have been determined, and an increase in demand for glass-crystalline materials for technical purposes has been established. It was determined that the orientation of the global glass-ceramic market towards fragmentation will allow domestic manufacturers to reduce import dependence and increase the competitiveness of domestic glass-ceramic materials on the world market. The prospect of using high-strength aluminosilicate glass-crystalline materials as a basis for the production of armor protection elements has been established. The criteria for the synthesis of high-strength armored steels have been selected. The choice of oxide systems for the production of protective glass-crystalline materials is substantiated, model glasses are synthesized and the technological parameters of production of impact-resistant sitals, which include cooking, forming, annealing and heat treatment, are determined. Model glasses were synthesized and their structure under thermal treatment conditions was investigated in relation to the physical and chemical properties of the materials based on them. It was established that the developed glass-crystalline materials based on lithium disilicate are characterized by high operational properties and can be used in the creation of modern armor. It was established that the developed high-strength spodumene glass-crystalline materials under the conditions of low-temperature two-stage heat treatment are characterized by high operational properties and can be used as a basis for the development of a composite element of individual armor protection. A comparative assessment of the operational properties and technical and economic indicators of known ceramic and glass-ceramic materials for armor protection made it possible to establish the competitiveness of the developed domestic spodumene-containing materials as elements of individual protection.

Synthesis of Lead-Containing Glass Crystalline Materials with Various Crystallization Nucleators

Synthesis of Lead-Containing Glass Crystalline Materials with Various Crystallization Nucleators

Glass-Containing Matrices Based on Borosilicate Glasses for the Immobilization of Radioactive Wastes

Glass-containing materials are widely considered among the most reliable materials for the immobilization of radioactive waste materials. The present work considers the synthesis of glass–ceramic and glass crystalline composite materials based on borosilicate glasses. The synthesis of glass–ceramic materials was carried out by a gradual temperature decrease, followed by crystallization for several hours. Sintering of crushed samples with crystalline components was carried out as an alternative procedure. Porous glasses were produced from glass melts by quenching. After impregnating the resulting porous materials with aqueous solutions of cesium nitrate, compaction of the glass was carried out to form glass crystalline composites. The thermochemical characteristics of the parent glasses were determined using the differential scanning calorimetry method. The phase composition and structure of the glass-containing materials were determined using X-ray phase analysis, X-ray spectral microanalysis, and Raman spectroscopy.

Characterization of calumite-modified melaphyre glass in terms of mineral fibres and glass-ceramic materials production

The possibility of utilizing calumite (BSF) in the glass-ceramic industry was analyzed in this study. The properties of melaphyre glasses modified with 25 % and 50 % of calumite were determined after the post-melting and directional crystallization process. The produced glasses were subjected to microstructural analysis using light LM and scanning electron microscopy SEM. Their chemical composition was determined using XRF spectroscopy. After melting and directional crystallization, the glasses' structural tests were performed using FTIR spectroscopy and XRD phase analysis. The characteristic temperatures and the thermal stability of the glasses were determined with thermal analysis (DTA/TG) and dilatometric tests, which analysis was also valuable to determine the parameters of the directional crystallization process of melaphyre glasses. The results showed that unmodified melaphyre glasses demonstrate a low crystallization ability and do not crystallize even at 900 °C, while incorporating calumite into their composition increases their crystallization ability. The study showed that calumite significantly influences the chemical and structural characteristics of melaphyre glasses, which gives it the chance to be successfully used as a raw material for producing glass crystalline materials or mineral fibres. Notably, the findings underscore the potential utility of calumite as a proficient raw material for fabricating glass crystalline fibrous or insulating materials.

TRANSPARENT GLASS-CERAMICS BASED ON LITHIUM ALUMINOSILICATE SYSTEM

Methods of laser micro- and nanomodification structure of transparent dielectrics open promising prospects for the creation of a new type glass-crystalline materials and new applications. In this work, after a brief excursion into the history of glass-ceramics, transparent aluminosilicate glass-ceramics are discussed, mainly using the example of the Li2O–Al2O3–SiO2 system, and the areas of their new applications. The recently discovered possibilities of laser micromodification of structures and direct laser writing of elements photonics and integrated optics in their volume are considered. In this case, special attention is paid to transparent glass-ceramics with coefficient of thermal expansion close to zero.

NANOCRYTALLINE GLASS CERAMICS BASED ON PERLITE: SYNTHESIS AND RESEARCH

From a cheap perlite as the basic raw material an opaque glass-crystalline material was synthesized containing nanosized crystals of wollastonite and gehlenite with an average size of 100 nm. The phase composition, microstructure and strength properties of the material were investigated. Changes in the composition and size of crystal grains caused by varying the amount of catalyst and the content of quartz in the initial mixtures make it possible to control the physico-mechanical properties of the obtained material. High strength and hardness allow using this material for protection against high-speed impact, including small arms bullets.

APPLICATION OF THERMAL PLASMA ENERGY FOR PRODUCING GLASS-CRYSTALLINE MATERIALS

The characteristics of glass-ceramic materials obtained using thermal plasma have been studied. The effect of TPP ash on the properties of glass-ceramic materials should be taken into account. Samples with a mass content of ash of 70 % were obtained. They have the following characteristics: compressive strength 530 MPa, flexural strength 110 MPa, density 3000 kg/m3.

Determination of the influence of temperature, concentration of ferric oxides and oxidative conditions of glass boiling on the displacement of the equilibrium of ferric oxides Fе2O3↔FеO

The object of research is the state of equilibrium of ferrum(II) and ferrum(III) oxides in glass melts at temperatures of 1000–1400 °С, welded in oxidizing, neutral and reducing conditions with a content of ferrum oxides up to 1.5 %. This problem is relevant in the following aspects. The first aspect of this problem is the unwanted coloring of the glass: FeO colors the glass blue, and Fe2O3 – yellow. The combined presence of ferrum(II) oxide and ferrum(III) oxide determines the gradations of glass shades that fall on the green spectrum. The second aspect concerns the thermophysics of processes of boiling glasses containing iron oxides. Ferrum(II) oxide causes a strong absorption band of infrared radiation in the region of 1.1 μm. This becomes an obstacle to the volumetric heating of glass in the processes of cooking, forming, and annealing. The third aspect of the problem concerns the structure of glasses and glass-crystalline materials with an increased content of iron oxides. Iron oxides significantly affect the processes of glass structuring, as ferrum(III) oxide is a typical network former, and ferrum(II) oxide is a typical modifier. The state of FeO↔Fe2O3 equilibrium in glass is significantly influenced by the glass cooking environment, the total amount of iron oxides, and the temperature of the melt. The glass brewing environment has the greatest influence on the balance of iron oxides in the glass. The share of FeO oxide in the total amount of iron oxides (FeO+Fe2O3) increases sharply when moving from an oxidizing medium to a neutral one and then to a reducing one. During thermostating at a temperature of 1400 °С, the proportion of FeO in the glass increases by 1.4–1.7 times during cooking in an oxidizing environment, by 1.2–1.3 times in a neutral environment, and by approximately 1.1 times in a reducing environment. At the same time, this growth is more noticeable in glasses with a lower iron content. Thus, the equilibrium state of FeO↔Fe2O3 in glass significantly affects the technological and operational properties of silicate melts and the final glass. The ratio of formed oxides of trivalent and divalent ferrum was studied by chemical (titrometric) analysis. The research results can be used in practice to develop the composition of glasses with an increased content of iron oxides.

Uranium Retention in Silica-Rich Natural Glasses: Nuclear Waste Disposal Aspect

Uranium-containing glass samples with an age of 140–145 million years were collected within the volcanic rocks of the largest volcanic-related uranium ore deposit in the world. Main features of their composition are high concentrations of silica and uranium, the largest for the rocks of this type. In contrast to this, the ages of fresh (unaltered) low-silica natural glasses of a basic composition (basalts) usually do not exceed a few million years. The volcanic low-silica glass is unstable at longer times and in older ancient rocks is transformed into a crystalline mass. The geochemistry of uranium including the behavior in solids and solutions is similar to that of long-lived transuranic actinides such as radioactive Np and Pu from high-level radioactive waste. This allows uranium to be used as a simulant of these long-lived hazardous radionuclides both at the synthesis and for the study of various nuclear wasteforms: glasses, glass crystalline materials and crystalline ceramics. The data obtained on long-term behavior of natural glasses are of importance for prognosis and validation of stability of nuclear wasteforms disposed of in geological disposal facilities (GDF).

Glass, ceramic, and glass-crystalline matrices for HLW immobilisation

We briefly overview the utilisation of glasses, ceramics and glass crystalline materials (GCMs) composed of both vitreous and crystalline phases focusing on nuclear waste immobilisation and potential use of some advanced waste forms for incorporation of the rare earth elements (REE) and minor actinide (MA: Am, Cm) fraction of high-level waste (HLW).

Glass–crystalline materials with high iron oxide concentration: Phase composition, redox ratio and magnetic properties

The synthesis of glass–crystalline materials in the system Na2O/CaO/SiO2/Fe2O3 with high concentrations of Fe2O3 (20, 25 and 30mol%) by applying the melt-quenching technique is reported. The melts spontaneously crystallize during pouring and the formation of magnetite (Fe3O4), hematite (α-Fe2O3) and ɛ-Fe2O3, as identified by X-ray diffraction (XRD) is observed. The microstructure and the elemental composition of the prepared materials are further investigated by scanning electron microscopy (SEM) and two different morphological types of Fe-containing crystals – needle-like and dendrite-shaped are detected. Mössbauer spectroscopy showed the presence of Fe3+ and Fe2+, as well as the existence of iron ions both in tetrahedral and octahedral coordination and the precipitation of hematite, ɛ-Fe2O3 and magnetite. The magnetic measurements on the prepared samples reveal ferrimagnetic properties with well defined hysteresis curves, although due to relatively small volume fraction of the iron-rich crystalline phases, the net magnetic moment is quite low compared to the bulk values for magnetite.

Composite Glass-Crystalline Material Based on Cullet and Colemanite

Composite Glass-Crystalline Material Based on Cullet and Colemanite

Reactivity of Amorphous Rocks from the Point of View of Their Interaction in Charges for Glass-Crystalline Materials

Reactivity of Amorphous Rocks from the Point of View of Their Interaction in Charges for Glass-Crystalline Materials

Effects of borosilicate glass on pollucite crystallization and Cs+ immobilization in geopolymer materials

Since Fukushima nuclear power plant accident there have been many publications on immobilization of radioactive 137Cs in the crystalline structure of pollucite (CsAlSi2O6). In this article, we report a novel method where Cs-polluted soil (metakaolin) and a specially formulated borosilicate glass power are sintered together to form a pollucite-based glass crystalline materials. Fine pollucite crystals are uniformly distributed in the matrix of glass phase. This is equivalent to pollucite being encapsulated by the borosilicate glass and theoretically this should enhance the chemical durability. Extensive characterizations of this material with differential scanning calorimetry (DSC), r-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and electronic differential system (EDS) reveal optimum glass content and that the formation temperatures of pollucite in the glass matrix was as low as 900 ℃, which is significantly lower than those used in forming Cs-pollucite by conventional sintering methods. Test showed that the Cs+ leaching rate of sample with 20 wt% glass content was only 4.19×10–4 g·m–2·d–1, lower than the sample without glass addition almost by an order of magnitude. This study not only presents an improved technique for 137Cs immobilization but may also provide a methodology for immobilization of other potential radioactive species.

Spodumene-containing glass-crystalline materials for technical purposes

The trends and current state of the glass-ceramic market from 2019 to 2024 have been analyzed, and an increase in demand for glass-crystalline materials for construction and technical purposes has been established. It has been determined that the orientation of world glass-ceramic market towards fragmentation will allow domestic producers to reduce import dependence and increase the competitiveness of domestic glass-ceramic materials in the world market.
 The aim of this work is to assess the technical and economic indicators of the technology developed spodumene-containing glass-ceramic materials for technical purposes and to conduct pilot laboratory tests.
 The study of the structure and phase composition of glass-ceramic materials was carried out using complementary methods of physicochemical analysis. The physicochemical properties of the materials were determined in accordance with the requirements of the current regulatory documents in silicate materials. Ballistic properties are determined according to GOST 8782: 2018.
 Compositions and technologies for the production of spodumene-containing glass-ceramic materials based on lithium-aluminum silicate glasses were selected for the production of domestic elements of armor protection, heat engineering and radio engineering, taking into account the aspects of energy and resource saving. The study of the developed materials structure made it possible to establish differences in mechanical, thermal, and optical properties, which makes it possible to select the recommended areas of their application.
 A comparative assessment of the performance properties and technical and economic indicators of known ceramic and glass-ceramic materials for body armor made it possible to establish the competitiveness of the developed domestic spodumene-containing materials as elements of individual protection.

PRODUCTION OF POROUS GLASS-CRYSTALLINE MATERIALS BASED ON GLASS CULLET AND CONVERTER SLAG

The study conducted the research aimed to obtaining a porous glass-crystalline materials based on glass cullet and converter slag, which was used as a gas-forming additive. In this work, the chemical and phase compositions of the studied slag were analyzed, and a differential thermal analysis of its sample was carried out. Converter slag was added to the composition of the masses in an amount of 2.5 to 30 wt%, the rest was glass cullet. Вurning of the samples was carried out in the temperature range of 850-925 ° C. For the samples under study, using a sand volumetric meter, the volume was determined and the swelling coefficient was calculated, the compressive strength was determined, and the type of structure, which depends on the average diameter of the prevailing pores, was analyzed. The dependence of the swelling coefficient of the investigated materials on the burdening composition and burning temperature has been established. To obtain porous materials with a swelling coefficient of 2.16-2.67 and uniform fine-porous structure (predominant pore size less than 0.5 mm), it is optimal to introduce converter slag into the composition of the masses in an amount of 10-15 wt%, and the recommended temperature range their burning 850-900 ° C. Analysis of the phase composition of the materials obtained indicates the presence of wollastonite as the main crystalline phase, which, due to the acicular structure of the crystals, has a reinforcing effect and contributes to an increase in strength characteristics. The developed porous glass-crystalline materials can be used as thermal insulation and aggregates in lightweight concrete.

Anorthite-reducing glass-crystalline materials synthesized in plasma

The paper presents the experimental results of the glass-ceramic material production using the low-temperature plasma. The dependences are suggested for the main physical-and-mechanical properties (compressive and flexural strengths, density, linear thermal expansion coefficient) of products and the mixture compositions. The centers of secondary recrystallization are identified for the anorthite phase (CaAl2Si2O8). These inclusions chaotically locate on the surface of the synthesis products and resemble dendritic microinclusions up to 90 nm in size. A comparative analysis is given to the properties of glass-ceramic materials produced by the low-temperature plasma and traditional methods.

ON THE POSSIBILITY OF OBTAINING EFFECTIVE PHOSPHORIC FERTILIZERS AS A RESULT OF INTERACTION OF PHOSPHORITE-CONTAINING WASTE WITH ACTIVATED GLAUCONITE SANDS

The aim of the study is to synthesize technical glass ceramics containing magnesium oxide and fluoride in boroaluminosilicate systems. As a result of the work, the range of compositions was determined, in which it is possible to obtain transparent sitalls with the required physicochemical characteristics. The optimal ratio of oxides for the synthesis of the initial glass has established, and the temperature ranges of nucleation and growth of crystals in glass for the formation of a cordierite crystalline phase have been determined. The processes of crystallization of glasses of cordierite composition, containing B2O3, have studied by a one-stage mode of heat treatment of glasses at 1000-1200 oC. The sequence of crystallization of phases in glasses and their effect on the properties of glass-crystalline materials of the system (MgO•Al2O3)-B2O3-SiO2, the compositions were in the region of metastable segregation of the system along the section of 2MgOꞏ2Al2O3∙5SiO2-2(MgO∙Al2O3)5B2O3, were determined