Inert Matrices Research Articles

USE OF STABILIZING ADDITIVES FOR TARGETED MODIFICATION AND HARDENING OF Nd2Zr2O7 CERAMICS

This paper presents the results of experimental work related to the preparation of Nd2Zr2O7 ceramics stabilized by Y2O3, the choice of which is due to the great prospects for their use as materials for inert matrices of dispersed nuclear fuel. During the conducted experiments aimed at determining the effectiveness of the influence of stabilizing additives in the form of Y2O3 on the change of structural and strength parameters of Nd2Zr2O7 ceramics it was found that the increase in the concentration of stabilizing additives above 0.1 M leads to the formation of inclusions in the structure in the form of Y2Zr2O7 grains, the formation of which is associated with the effects of polymorphic transformations in zirconium dioxide during high-temperature annealing. It was determined that the substitution of zirconium cations by yttrium cations leads to an increase in the concentration of oxygen vacancies in ceramics composition, the change in the concentration of which is also associated with phase transformations in the structure, arising at high concentrations of stabilizing dopant. At the same time, the optimum concentration of stabilizing additives is the concentration of 0.15 M, at which the ratio of structural and strength parameters has optimum values, determining their potential use as materials of inert matrices of dispersed nuclear fuel with high strength characteristics.

STUDY OF THE INFLUENCE OF VARIATION OF PHASE COMPOSITION OF COMPOSITE CERAMICS ON RESISTANCE TO RADIATION DAMAGE

The paper presents the results of investigation of the influence of the variation of the phase composition of composite (1−x)Si3N4 – xAl2O3 ceramics on the stability of strength properties in the case of irradiation with heavy ions Xe23+ (230 MeV) at fluences1011–1014 ions/cm2 . The variation of the component concentration was chosen taking into account the possibility of obtaining composite ceramics with different phase ratio: Si3N4, Al2O3, as well as Al2(SiO4)O and SiO2, the formation of which in the composition of ceramics is associated with the processes of thermal decomposition of Si3N4 during high-temperature annealing in an oxygen-containing atmosphere and phase transformations by the type of solid solution formation. The choice of the type of ions for irradiation is conditioned by the possibilities of simulation of structural damage processes leading to unstrengthening of the damaged layer, comparable to the impact of nuclear fuel fission fragments in ceramics – materials of inert matrices of dispersed nuclear fuel. In the course of the conducted studies, it was established that at irradiation fluences of 1011–1012 ion/cm2 structural changes associated with the formation of single isolated structurally deformed inclusions do not lead to significant changes in the strength characteristics of ceramics, while small changes observed are associated with deformation distortions, the accumulation of which leads to destabilization of the damaged layer. In the case of higher irradiation fluences (above1012 ions/cm2 ), which are characterized by the formation of the effects of overlapping defect regions in the damaged layer, the ceramics of 0,4 Si3N4 – 0,6 Al2O3, in which, according to X-ray phase analysis data, the dominant phase is Al2(SiO4)O, the presence of which causes a large number of grain boundaries, which in turn leads to dislocation hardening and restraint of the disordering processes associated with deformation distortions of the damaged layer.

Matrix Isolation FT‐Raman Study of Acetylacetone D2‐Acetylacetone and Hexafluoroacetylacetone

ABSTRACTAcetylacetone, double‐deuterated acetylacetone and hexafluoroacetylacetone were isolated in inert matrices and investigated by means of Raman scattering and infrared absorption spectroscopic methods, combined with theoretical calculations. The ability of Raman spectroscopy to access low wavenumber modes enables the study of vibrational modes involved in internal hydrogen bonds that are challenging to observe with infrared absorption spectroscopy. An almost complete set of vibrational modes for the studied molecules was observed experimentally, facilitating a comprehensive assessment of different computational approaches. The large dataset obtained allowed for an improved assignment of vibrational bands and firmly confirmed the existence of only one chelated isomer of acetylacetone, double‐deuterated acetylacetone and hexafluoroacetylacetone in matrices. The experimental data also highlighted the effects of deuteration and fluorination.

Machine Learning for Deconvolution and Segmentation of Hyperspectral Imaging Data from Biopharmaceutical Resins.

Biopharmaceutical resins are pivotal inert matrices used across industry and academia, playing crucial roles in a myriad of applications. For biopharmaceutical process research and development applications, a deep understanding of the physical and chemical properties of the resin itself is frequently required, including for drug purification, drug delivery, and immobilized biocatalysis. Nevertheless, the prevailing methodologies currently employed for elucidating these important aspects of biopharmaceutical resins are often lacking, frequently require significant sample alteration, are destructive or ionizing in nature, and may not adequately provide representative information. In this work, we propose the use of unsupervised machine learning technologies, in the form of both non-negative matrix factorization (NMF) and k-means segmentation, in conjugation with Raman hyperspectral imaging to rapidly elucidate the molecular and spatial properties of biopharmaceutical resins. Leveraging our proposed technology, we offer a new approach to comprehensively understanding important resin-based systems for application across biopharmaceuticals and beyond. Specifically, focusing herein on a representative resin widely utilized across the industry (i.e., Immobead 150P), our findings showcase the ability of our machine learning-based technology to molecularly identify and spatially resolve all chemical species present. Further, we offer a comprehensive evaluation of optimal excitation for hyperspectral imaging data collection, demonstrating results across 532, 638, and 785 nm excitation. In all cases, our proposed technology deconvoluted, both spatially and spectrally, resin and glass substrates via NMF. After NMF deconvolution, image segmentation was also successfully accomplished in all data sets via k-means clustering. To the best of our knowledge, this is the first report utilizing the combination of two unsupervised machine learning methodologies, combining NMF and k-means, for the rapid deconvolution and segmentation of biopharmaceutical resins. As such, we offer a powerful new data-rich experimentation tool for application across multidisciplinary fields for a deeper understanding of resins.

Inactivation of Bacillus cereus Spores and Vegetative Cells in Inert Matrix and Rice Grains Using Low-Pressure Cold Plasma.

This study investigated the effects of low-pressure cold plasma on the inactivation of Bacillus cereus vegetative cells and spores in an inert matrix (borosilicate glass slide) and in rice grains, using oxygen as ionization gas. Greater reductions in B. cereus counts were observed in vegetative cells rather than spores. The experimental data obtained show that both the power of the plasma treatment and the matrix proved to be determining factors in the inactivation of both the spores and vegetative cells of B. cereus. To characterize the inactivation of B. cereus, experimental data were accurately fitted to the Weibull model. A significant decrease in parameter "a", representing resistance to treatment, was confirmed with treatment intensification. Furthermore, significant differences in the "a" value were observed between spores in inert and food matrices, suggesting the additional protective role of the food matrix for B. cereus spores. These results demonstrate the importance of considering matrix effects in plasma treatment to ensure the effective inactivation of pathogenic microorganisms, particularly in foods with low water activity, such as rice. This approach contributes to mitigating the impact of foodborne illnesses caused by pathogenic microorganisms.

Isolation and characterization of a two-coordinate phosphinidene oxide.

Nitroso compounds, R-N=O, are common intermediates in organic synthesis, and are typically amenable to storage and manipulation at ambient temperature under aerobic conditions. By contrast, phosphorus-containing analogues, such as R-P=O (R = OH, CH3, OCH3, Ph), are extremely reactive and need to be studied in inert gas matrices at ultralow temperatures (3-15 K). These species are believed to be key intermediates in the degradation/combustion of organic phosphorus compounds, a class of chemicals that includes chemical warfare agents and flame retardants. Here we describe the isolation of a two-coordinate phosphorus(III) oxide under ambient conditions, enabled by the use of an extremely bulky amine ligand. Reactivity studies reveal that the phosphorus centre can be readily oxidized, and that in doing so, the P-O bond remains intact, an observation that is of interest to the proposed reactivity of transient phosphorus(III) oxides.

Matrix-formation dynamics dictate methyl nitrite conformer abundance.

Methyl nitrite has two stable conformational isomers resulting from rotation about the primary C-O-N-O dihedral angle: cis-CH3ONO and trans-CH3ONO, with cis being more stable by ∼5kJ/mol. The barrier to rotational interconversion (∼45kJ/mol) is too large for isomerization to occur under ambient conditions. This paper presents evidence of a change in conformer abundance when dilute CH3ONO is deposited onto a cold substrate; the relative population of the freshly deposited cis conformer is seen to increase compared to its gas-phase abundance, measured by in situ infrared spectroscopy. We observe abundance changes depending on the identity of the bath gas (N2, Ar, and Xe) and deposition angle. The observations indicate that the surface properties of the growing matrix influence conformer abundance-contrary to the widely held assumption that conformer abundance in matrices reflects gas-phase abundance. We posit that differences in the angle-dependent host-gas deposition dynamics affect the growing surfaces, causing changes in conformer abundances. Quantum chemistry calculations of the binding energies between CH3ONO and a single bath-gas component reveal that significant energetic stabilization is not observed in 1:1 complexes of N2:CH3ONO, Ar:CH3ONO, or Xe:CH3ONO. From our results, we conclude that the growing surface plays a significant role in trapping cis-CH3ONO more effectively than trans-CH3ONO, likely because cis-CH3ONO is more compact. Taken together, the observations highlight the necessity for careful characterization of conformers in matrix-isolated systems, emphasizing a need for further study into the deposition dynamics and surface structure of chemically inert matrices.

Steam cracking of sulfur containing compounds: A fundamental modelling study

Sulfur-containing additives are commonly used in industrial steam cracking to mitigate carbon monoxide (CO) formation. Their impact on solid coke deposition in reactors is well-studied but not fully understood. This study investigates the decomposition of five common sulfur compounds (DMDS, DMS, DMSO, CS2, COS) in both inert and hydrocarbon environments within the steam cracking industry. To achieve this, an in-house automated network generation tool called Genesys and a validated ab initio methodology at the CBS-QB3 level are used. This combination generates a comprehensive kinetic model with precise thermodynamic and kinetic parameters. The kinetic model is rigorously validated against experimental data from prior studies under various conditions, including inert nitrogen atmospheres and hydrocarbon matrices (using ethane and heptane). Experimental setups involve bench-scale annular quartz reactors and pilot-scale stainless steel reactors. Remarkably, the kinetic model accurately predicts primary products and captures secondary product trends across diverse conditions without parameter adjustments. Rate of production analyses reveal critical decomposition pathways during sulfur-containing additive pyrolysis and the influence of hydrocarbon matrices. Notably, these additives primarily yield H2S upon decomposition, with CS2, SO2 and thiophene as minor products. In conclusion, the developed fundamental kinetic model accurately predicts product formation during the pyrolysis of DMS, DMDS, DMSO, CS2 and COS, whether in nitrogen or a hydrocarbon matrix, without altering core thermodynamic and kinetic parameters.

Determination of the influence of the dose dependence of radiation damage on changes in the thermophysical parameters of oxide ceramics - materials of inert matrices of dispersed nuclear fuel

Determination of the influence of the dose dependence of radiation damage on changes in the thermophysical parameters of oxide ceramics - materials of inert matrices of dispersed nuclear fuel

Energetic processing of thioacetamide in cryogenic matrices.

There is an ongoing debate on the apparent depletion of sulfur in the interstellar medium (ISM) compared to its universal abundance; therefore, the investigation of sulfurous compounds at low temperatures is of utmost importance. This work aims to study thioacetamide, H3C-C(=S)-NH2, in low-temperature inert Ar and para-H2 matrices by IR spectroscopy. The samples have been exposed to various sources of irradiation, such as Lyman-α or laser UV photons as well as energetic electrons. Using different host materials enabled assessing the matrix's impact on precursor decomposition. The response of the molecule to different types of irradiation has also been evaluated. The existence of three main decomposition channels were deduced: formation of (i) CH3, CH4, and HNCS; (ii) H2S and H2C=C=NH; and (iii) NH3 and H2C=C=S. The H3C-CN and H3C-NC isomers of H2C=C=NH could also be identified. Secondary products such as HNC and HCN were also detected in the quantum solid para-H2 in contrast to the more rigid Ar matrix. The listed decomposition products have been observed in the ISM, with the exception of H2C=C=NH and H3C-NC. The results point to the potential sensitivity of the precursor molecule to energetic radiation in space environments. Finally, the findings of this work will serve as a foundation for future irradiation experiments using the astrochemically more relevant pure thioacetamide ice.

Study on damage of Gd2O3-CeO2 under electronic energy loss: comparison between bulk-like and nanostructure.

To understand the physical phenomena responsible for radiation damage of the materials used in nuclear reactors, and thus study their operation life and/or efficiency, it is required to simulate the conditions by exposing the materials to energetic ions. Ceria (CeO2) has been proposed as one of the inert matrices for the transmutation of minor actinides in the futuristic inert matrix fuel (IMF) concept. The inert matrix should also contain burnable poison to compensate for the initial reactivity of fuel. In this context, gadolinium (Gd) is an excellent burnable poison with a high neutron absorption cross-section. In view of this, Gd2O3-CeO2 nano-powders were synthesized and sintered at 800 °C and 1300 °C to obtain different grain sizes and morphologies. FESEM and TEM were carried out to study the grain size of pristine pellets. The sintered pellets were irradiated with 80-MeV Ag ions (electronic energy loss (Se) regime) at room temperature to emulate the effect of fission fragments. For analysis of the effect of grain size on the irradiation-induced structural degradation at different fluences, GIXRD and Raman spectroscopy were performed. Significantly large damage has been observed for the smaller grain-sized samples (sintered at 800 °C) as compared to the large grain-sized sample (sintered at 1300 °C). Neither of the samples amorphized under the present experimental conditions as indicated by the presence of the Raman-active T2g mode (centred at 462 cm-1) and all the XRD peaks of fluorite cubic structure up to the highest fluence employed (1 × 1014 ions cm-2). X-ray photoelectron spectroscopy results demonstrate that Ce4+ to Ce3+ and vacancy-related isolated clusters are the main defects produced in the systems. The radiation tolerance behaviour of the samples is understood with the help of thermal spike simulation, which indicates higher transient lattice temperatures with longer duration in the smaller grain-sized sample upon irradiation. Gd-doped ceria thus possesses good radiation stability in the Se regime, indicating its potential for application in IMFs.

Dopant-Matrix Afterglow Systems: Manipulation of Room-Temperature Phosphorescence/Thermally Activated Delayed Fluorescence Afterglow Mechanism via Mismatch/Match of Intermolecular Charge Transfer between Dopants and Matrices.

Dopant-matrix organic afterglow materials exhibit ease of fabrication and intriguing functions in diverse fields. However, a deep and comprehensive understanding of their photophysical behaviors remains elusive. Here we report manipulation of a room-temperature phosphorescence/thermally activated delayed fluorescence (RTP/TADF) afterglow mechanism via the mismatch/match of intermolecular charge transfer between dopants and matrices. When dispersed in inert crystalline matrices, the luminescent dopants show RTP lifetimes up to 2 s. Interestingly, when suitable organic matrices are selected, the resultant dopant-matrix materials display a TADF-type afterglow under ambient conditions due to the formation of dopant-matrix intermolecular charge transfer complexes. Detailed studies reveal that reverse intersystem crossing from dopants' T1 states to charge transfer complexes' S1 states, which features a moderate kRISC of 101-102 s-1, is responsible for the emergence of a TADF-type organic afterglow in rigid crystalline matrices. Such less reported delicate photophysics reveals a new aspect of the excited state property in dopant-matrix afterglow systems.

Study of the Effect of Variation in the Phase Composition of ZrO2/MgO Ceramics on the Resistance to Radiation Damage during Irradiation with Kr15+ Ions

Interest in the modification of zirconium-containing ceramics is rooted in their great prospects for application as materials for creating inert matrices of dispersed nuclear fuel, which can replace traditional fuel containing uranium dioxide, as well as increase the degree of its burnup. Moreover, among the variety of different types of ceramics offered, zirconium dioxide is the most promising, since it has higher thermal conductivity values compared to other types of ceramics, as well as low volumetric thermal expansion. Moreover, the key limitations in the application of these types of ceramics as materials for creating inert matrices are polymorphic transformations, which have a negative impact on changes in the properties of ceramics under external influences. The evaluation results of the impact of change in the ZrO2 ceramics’ phase composition on the radiation damage resistance when subjected to irradiation with heavy ions, comparable in energy to fission fragments, are presented. The objects of study were samples of ZrO2 ceramics doped with MgO, the variation in the concentration of which leads to an acceleration of the processes of polymorphic transformations during thermal sintering, as well as the formation of a ZrO2/MgO-type structure with inclusions in the form of MgO grains. The results of the irradiation effect on the stability of the crystal structure of ceramics to deformation swelling due to the accumulation of deformation inclusions showed that ceramics with a monoclinic structure type are the least stable, for which, in the case of high irradiation fluences, the accumulation of deformation distortions leads to polymorphic transformations of the m—ZrO2 → t—ZrO2 type. During the evaluation of the irradiation effect on the change in mechanical properties and the softening degree, it was found that phase transformations of the m—ZrO2 → t—ZrO2 and t—ZrO2 → c—ZrO2 types lead to an increase in crack resistance by 1.5–2.0 times. Meanwhile, the formation of a structure of the ZrO2/MgO type with inclusions in the form of MgO grains in the interboundary space results in a softening resistance growth by over 7-fold. During tests for determining thermophysical parameters, as well as maintaining stability to crystal structure thermal expansion during prolonged thermal exposure, it was found that phase transformations associated with polymorphic transformations of the t—ZrO2 → c—ZrO2 type led to the preservation of the stability of thermophysical properties, even in the case of high irradiation fluences.

High-Conductive CsH2PO4 Membranes with PVDF-Based Polymers Additives.

The study is devoted to one of the important problems of hydrogen energy-the comparative analysis and creation of novel highly conductive and durable medium-temperature proton membranes based on cesium dihydrogen phosphate and fluoropolymers. The proton conductivity, structural characteristics and mechanical properties of (1 - x)CsH2PO4-x fluoropolymer electrolytes (x-mass fraction, x = 0-0.3) have been investigated and analyzed. UPTFE and PVDF-based polymers (F2M, F42, and SKF26) with high thermal stability and mechanical properties have been chosen as polymer additives. The used fluoropolymers are shown to be chemical inert matrices for CsH2PO4. According to the XRD data, a monoclinic CsH2PO4 (P21/m) phase was retained in all of the polymer electrolytes studied. Highly conductive and mechanically strong composite membranes with thicknesses of ~50-100 μm were obtained for the soluble fluoropolymers (F2M, F42, and SKF26). The size and shape of CsH2PO4 particles and their distribution have been shown to significantly affect proton conductivity and the mechanical properties of the membranes. The thin-film polymer systems with uniform distributions of salt particles (up to ~300 nm) were produced via the use of different methods. The best results were achieved via the pretreatment of the suspension in a bead mill. The ability of the membranes to resist plastic deformation increases with the growth of the polymer content in comparison with the pure CsH2PO4, and the values of the mechanical strength characteristics are comparable to the best low-temperature polymer membranes. The proton-conducting membranes (1 - x)CsH2PO4-x fluoropolymer with the optimal combination of the conductivity and mechanical and hydrophobic properties are promising for use in solid acid fuel cells and other medium-temperature electrochemical devices.

In situ application of alginate hydrogels containing oxidant or natural biocides on Fortunato Depero's mosaic (Rome, Italy)

Stone monuments in outdoor environments are subjected to biodeterioration due to the growth on their surfaces of biofilms responsible of aesthetic, physical and chemical damages. In recent years, the encapsulation of antimicrobial agents into inert matrices has aroused considerable interest thanks to the drastic reduction of the biocide amount needed to counteract the growth of biopatinas. In this study, two biocidal hydrogels containing thyme essential oil (thyme EO) or sodium dichloroisocyanurate (NaDCC), previously tested in the laboratory, were applied on three selected areas of the Depero's mosaic located in the EUR district of Rome (Italy). A simple method to prepare the biocidal hydrogels directly in situ and their easy application on large and vertical surfaces were developed. Before and after the treatment, photographic, colorimetric, and microscopic analyses were performed to highlight the hydrogels' biocidal effectiveness in removing all colonizers. Only one treatment was enough to completely remove the microbial patina constituted of various prokaryotic and eukaryotic microorganisms.This paper is dedicated to the memory of Laura Bruno, who passed away during the peer-reviewed.

Bottom-up gas phase construction of carbon coated Fe7Se8 nanosheet/carbon nanotube hybrid as ultrastable anode material for sodium-ion half/full batteries

Transition metal selenide/carbon nanotube (TMS/CNT) composites as one important category of anode material for rechargeable alkali metal ion batteries are always troubled by the high-quality combination between active matter and inert CNT matrices. Herein, a bottom-up gas phase pyrolysis strategy is introduced to avoid the tedious and time-consuming loading process of active nanostructures. With ferrocene and selenium powders as the raw materials, a carbon coated Fe7Se8 nanosheet/carbon nanotube (Fe7Se8@C/CNT) hybrid is synthesized. The critical role of selenium in the mass growth of CNTs at low deposition temperature is demonstrated for the first time. Benefiting from the molecular-level synthesis process, the carbon coated Fe7Se8 nanosheets are uniformly anchored on CNTs, and a porous hybrid network architecture is constructed. When tested in sodium-ion batteries (SIBs), the Fe7Se8@C/CNT electrode exhibits high reversible capacity (485 mA h g−1 at 0.1 A g−1), high initial Coulombic efficiency (97.4 %), superior long-term cycling stability upon 1000 cycles and excellent rate capability (397 mA h g−1 at 10.0 A g−1). Moreover, the full cell that coupled with a Na3V2(PO4)3 cathode also retains an undiscounted long-term cycling ability and high rate performance, reflecting its great potential for practical SIBs. The detail kinetics analyses including capacitive contribution, EIS and GITT are carried out. This work provides a new avenue for developing high-performance TMS/CNT electrode materials in electrochemical energy storage applications.

Thermal Conductivity of Fine-Grained Nd:YAG/SiC Composite Ceramics for Inert Fuel Matrices

Thermal Conductivity of Fine-Grained Nd:YAG/SiC Composite Ceramics for Inert Fuel Matrices

INVESTIGATION OF PHASE FORMATION PROCESSES IN COMPOSITE Al<sub>2</sub>O<sub>3</sub>-Si<sub>3</sub>N<sub>4</sub> CERAMICS WITH VARIATIONS OF SINTERING TEMPERATURE

The purpose of this work is to establish regularities in the processes of phase formation in Al2O3-Si3N4 ceramics in the annealing temperature range from 800 to 1500 °C, as well as to determine the effect of the phase composition of ceramics on strength properties. Interest in this class of composite ceramics is due to the possibility of using them as materials for inert matrices of dispersed nuclear fuel. The evaluation of the phase composition as a result of thermal annealing of the samples was carried out using the method of X-ray phase analysis. In the course of the analysis, the following phase transformations were established: Si3N4/Al2O3 → Si3N4/Al2O3-M/Al2O3-R → Si3N4/Al2O3-R/Al2SiO5 → Al2SiO5/SiO2, according to which a change in the annealing temperature leads to polymorphic transformations of aluminum oxide with an increase in the annealing temperature, as well as the formation of a complex oxide phase of the Al2SiO5 type. At the same time, at an annealing temperature above 1400 °C, a transformation of the Si3N4 → SiO2 type is observed, associated with the processes of decomposition of silicon nitride and its transformation into silicon oxide upon interaction with air during annealing. It was found that the primary processes during annealing of ceramics are the processes of structural ordering of samples, without a significant change in the phase ratio.

Study of the influence of radiation-induced damage accumulation during the interaction of heavy Xe22+ ions on changes in the thermophysical parameters of zirconia ceramics

The aim of this paper is to evaluate the influence of the processes of radiation-induced damage formation in the form of point defects, dislocations and vacancies, as well as their accumulation and the formation of locally disorderedregions in the near-surface layer of zirconia ceramics under irradiation with heavy Xe22+ions with an energy of 230 MeV, on the change in the thermophysical properties of ceramics. The choice of the ion type for irradiation is due to the possibilities ofmodeling radiation damage processes comparable to the impact of uranium nuclei fission fragments during nuclear reactions in nuclear fuel. The choice of materials for irradiation in the form of ZrO2ceramics is due to the prospects for their use as the main material for inert matrices of dispersed nuclear fuel for new generation reactors. This choice is due to the physicochemical, thermophysical and strength properties of ZrO2ceramics, which are more resistant than other types of oxide ceramics. During research, it was found that the formation of isolated locally heterogeneous regions at low irradiation fluences does not lead to significant changes in the thermophysical properties of the damaged ceramic layer. However, polymorphic transformations of the t-ZrO2 → c-ZrO2type, which occur at irradiation fluences above 1012ion/cm2, lead to a decrease in thermal conductivity and the appearance of heat losses associated with the disruption of the phonon heat transfer mechanisms in the damaged layer.

Luminescence mechanisms in the 2V2O5–xLi2O–(98 − x)B2O3 glass matrices developed for creation of glass–ceramic materials

The oxide glass–ceramics is a promising class of solid state materials because they are using thermally stable and chemically inert glass oxide matrices. Development of such efficient glass matrices suitable for creation of glass–ceramic materials for several purposes is an important practical task. The xLi2O–yV2O5–(100 − x − y)B2O3 undoped glass and 47Li2O–2V2O5–50B2O3–1La0.3Eu0.7VO4 glass samples with crystalline nanoinclusions were synthesized and investigated using XRD, IR and UV–Vis spectroscopy and UV band-to-band excitation of luminescence. The synthesized glass samples are characterized by wide band photoluminescence emission with maximum at 570 nm and intensity increased with increase of Li2O concentration. The excitation spectra consist of three bands with maxima located at 270, 320 and 365 nm. The observed concentration dependencies of spectral distributions in the absorption and excitation spectra are explained by influence of the lithium ions on a ratio between triborate and tetraborate groups in the glass networks. The assumption is made that the observed wide band photoluminescence emission of the glass matrix can appear as a result of recombination processes between the defects in borate networks and the broken vanadate groups. The crystalline component in the doped glass samples is found to not affect the luminescence properties of the glass matrix. Intensity of narrow band photoluminescence emission of the crystalline component is up to 10 times more intense than that of the glass matrix wide band emission. The synthesized type of the glass matrices has promising characteristics for the use of developed materials in lighting devices, as it allows improving the spectral distribution of light emission towards the white light.