Machine learning approaches have shown remarkable potential in elucidating the complex, nonlinear relationships between compositional effects, structural configurations, and macroscopic properties in materials science. Nevertheless, their application within glass science for guiding the inverse design of formulations with properties tailored for high-performance applications remains limited. In the present work, we report the implementation of an autoencoder within glass science. To address scenarios where the dimensionality of the input exceeds that of the output, a case study was selected wherein 34-dimensional formulations were projected into a 4-dimensional latent space through an autoencoder's encoder. This strategy thereby enabled the prediction of formulations (with up to 34 different elements) from four material parameters (Young's modulus, hardness, glass transition temperature, and specific mass), whereby an artificial neural network (ANN) links these parameters to the latent representation, and the decoder subsequently reconstructs the formulation in its original 34-dimensional form. Two promising candidate compositions generated through this framework, upon synthesis and experimental characterization, yield glasses that rank among the stiffest, hardest yet light large-scale inorganic, non-metallic systems amongst reported literature, exhibiting a unique combination of high Young's modulus (E = 155 GPa) and hardness (H = 12.2 GPa) at a comparatively low specific mass (rho = 3.62 g.cm(-3)). These findings emphasize the potential of machine learning methodologies for the systematic quantification and subsequent rationalization of composition-property trends based on physicochemical descriptors, offering novel insights both within and across chemical systems - demonstrated here for oxynitride glasses, where the processing- and content-dependent incidence of nitrogen is revealed.

Oxynitride glasses are glasses wherein two-fold oxygen atoms are substituted by three-fold nitrogen atoms. This results in increased physical and mechanical properties, which have long driven the development of such materials. This article examines the reactivity of oxynitride melts, with the aim of deepening our knowledge of the formation of oxynitride glasses, of the reasons for their opacity, and of the influence of the often-overlooked redox state. The functionalization of oxynitride glasses through the crystallization of oxynitride and nitride crystals, and by the control of the particles size of the precipitating metal and nitride species (from the nano-to the micro-scale), is also discussed in the light of recent advances in the fields of optical and photonic materials. Our main objective is to provide insights and a renewed momentum to this field by providing new guidelines for future fundamental and applied investigations.

Mechanoluminescent materials exhibit a broad spectrum of controllable light-emission responses to mechanical stimuli of varying types and magnitudes. Yet progress toward high-performance systems remains constrained by an incomplete and often contradictory mechanistic understanding. Here, density functional theory (DFT) calculations optimized for the quantitative treatment of point defects are used to systematically investigate the interplay between stress type (hydrostatic vs. shear) and active-phase dimensionality (1D vs. 3D), using SrAl_2O_4:Eu^2+, Dy^3+ and Ba_4Si_6O_16:Eu^2+, Ho^3+ as representative model systems. Two distinct emission-driving mechanisms are identified: a piezoelectric contribution, and a second, apparently universal, mechanism arising from stress-induced structural reorganization at point defects sites. These results establish a design framework for mechanoluminescent materials in which crystal dimensionality, stress type and stress-sensitive point defects are deliberately matched to tune emission behavior and overall performance.

A bulk (cm 3 ‐large) and homogeneous Ba 4 Si 6 O 16 :Eu 2+ , Ho 3+ ‐containing glass‐ceramic was previously obtained from the congruent crystallization of an oxynitride glass. We show in the present work that the europium oxidation state can be controlled by the incorporation of silicon nitride (<6 mol. %). The elastico‐mechanoluminescence (EML) is investigated by means of experiments involving different mechanical loading modes, including pure hydrostatic loading, uniaxial compression, torsion, three‐point bending and dynamic loading (ball drop). The effect of the loading parameters on the EML response is examined, both during the loading and the unloading stages. A model is proposed, which is based on thermoluminescence investigations and on the physics of persistent luminescence. An optimal fitting of the EML intensity is obtained under the assumption of a linear dependence of the depth of the energy level on the applied stress. A value of 1.37·10 –3 eV·MPa –1 is determined from uniaxial compression experiments. The EML phenomenon is found to chiefly stem from the hydrostatic part of the stress. Unlike the SrAl 2 O 4 :Eu 2+ , Dy 3+ crystal, (i) there is no EML signal under pure shear (torsion experiments) for the studied active phase and (ii) the EML intensity weakens upon unloading in uniaxial compression.

This study investigates the structural, thermal, and mechanical properties of Mg–Al–Si–O–N glasses. Six compositions with increasing nitrogen content from 1.7 to 6.2 at.% were synthesized by melting mixtures of high‐purity oxide and nitride precursors, followed by quenching and annealing. Structural analysis via X‐ray diffraction and Raman spectroscopy confirms the amorphous nature of the glasses and highlights distinct spectral features based on the Mg/Al ratios, providing insight into the changes of the Si‐O and Al‐O bond concentration with the nitrogen content. The effects of nitrogen incorporation on density, molar volume, atomic packing density, glass transition temperature, and thermal expansion were systematically examined, revealing strong correlations. Measurements of elastic moduli, hardness, and fracture toughness underscore the role of nitrogen and the Mg/Al ratio in enhancing the mechanical properties. The findings demonstrate that by increasing the nitrogen content, the glass becomes stiffer and denser, and the mechanical properties are improved.

Glasses and glass–ceramics from the BaO–TiO2–SiO2 systems have potential applications in piezoelectric and photonic devices. However, more studies on their crystallization and mechanical properties are needed to put the materials into service. In this work, seven grades of glasses with 30BaO–xTiO2–(70-x)SiO2 (mol

The aim of this work is two-fold: i) elaborating dense and transparent inorganic glass composites with improved fracture properties, and ii) testing the theoretical analysis proposed in [1] and based on Poisson's ratio mismatch. Particulate composites, consisting of glass or ceramic particles embedded in a soda-lime-silica glass matrix, were synthesized and their fracture behavior was studied by means of the Single-Edge Precraked Beam (SEPB) and Double Cleavage Drilled Compression (DCDC) methods, using in situ experiments with X-ray tomography where possible. An important effect of the T-stress on the fracture toughness (KIc) was observed in the case of DCDC experiments. KIc is increased by about 40 % by incorporating 7 vol. % amorphous silica beads or SrAl2O4:Eu,Dy ceramic particles (SAED) with a 40 mu m mean particle size. It is suggested that toughening results from the crack front trapping and pinning at particle sites and from the tortuous crack path in the case of a-SiO2 particles, and from the contribution of the intrinsic fracture surface energy of the ceramic particles, which are cleaved by the propagating crack, in the case of the SAED particles. The thermally induced stress field is believed to play a major role in the case of a-SiO2 particles. Two glass grades possessing Young's moduli similar to the one of the matrix but much larger Poisson's ratios were used to produce glass beads. However, the incorporation of these latter beads in the matrix was found to have a minor incidence on the fracture behavior.

The elastic moduli and the indentation behavior of glasses from the xLi2O-5Al2O3-(95−x)B2O3 system, with x = 35, 40, and 50 were characterized. Glasses become softer and less resistant to indentation cracking as the lithium content is increased, as a result of increasing the numbers of 3-fold coordinated boron and non-bridging oxygen atoms in this composition range. In parallel, the ionic conductivity at 25 °C is increased from 3.7 10–10 to 5.5 10–8 S∙cm–1, and the activation energy, as measured in the 10 to 90 °C ranges is between 55 (50 % Li2O) and 65 (35 % Li2O) kJ∙mol–1, which shows that the ionic diffusion of lithium is easier in Li-rich compositions. Measurements of the conductivity under a compressive load aligned with the electric field revealed a mechanical-electrical coupling. The change of the activation energy with the stress is associated with an activation volume, and thus a stress sensitivity, that is increased with the lithium content.

The luminescence properties of green Ba4Si6O16:Eu2+, rare-earths (RE) (RE = Sc, Y, La and Lu except Pm) phosphors are reported. Their long-lasting phosphorescence is discussed in view of trap depths and concentrations determined from thermally stimulated luminescence experiments. A second emission band centered at 439 nm was evidenced at low temperatures, which stems from the substitution of Eu2+ in the two non-equivalent Ba2+ sites of Ba4Si6O16. The mechanoluminescence properties of Ba4Si6O16:Eu2+, RE phosphors are described, and a new mechanoluminescence mechanism is proposed, in the case where RE = Ho3+, involving a trap distribution from 0.694 to 0.924 eV. Mechanical loading (post UV irradiation) induces a decrease in depth of the trap distribution, leading to an increase of the luminescence intensity, whereas a drop of the luminescence intensity is observed upon unloading, following the faster release of the charge carriers.

Mechanoluminescence is observed in oxynitride glass-ceramics from the BaO-SiO2-Si3N4 chemical system, doped with Eu and Ho. Light emission was investigated by means of uniaxial compression experiments on disks and parallelepipedic bars with constant loading rates ranging from 0.3 to 300 MPa s−1 up to about 500 MPa. In agreement with previous reports on SrAl2O4-based materials [Dubernet et al., Appl. Phys. Lett. 107, 151906 (2015) and Dubernet et al., Sci. Rep. 10, 19495 (2020)], the mechanoluminescence intensity is found proportional to the mechanical power. Nevertheless, in contrast with SrAl2O4, no gain in the intensity is observed at the onset of the unloading stage, but a drop of the photoluminescence intensity during unloading. This stems from different electron trapping populations and associated energy levels for the Ba4Si6O16 phase (the dominant crystallized phase in the present glass-ceramics), which are discussed in light of density functional theory calculations.

Oxynitride glasses are glasses where threefold coordinated nitrogen atoms substitute for twofold oxygen ones, hence resulting in a larger interatomic cross-linking degree. Such glasses were first observed at the grain boundary in silicon nitride ceramics, where they govern the high-temperature behavior. Later, they were prepared as bulk materials and motivated numerous researches, thanks to their large viscosity, glass transition range, elastic moduli, hardness, and fracture toughness among inorganic and non-metallic glasses. In different chemical systems that were investigated, the synthesis routes and the sources for these exceptional mechanical properties are reviewed. Oxynitride glasses are not easy to process and suffer from the loss of transparency as nitrogen is incorporated over some critical content. Nevertheless, they are attractive "specialty" glasses in various niche areas, thanks to their large refractive index and dielectric constant, improved chemical durability, high softening point, etc., and majorly to their exceptional mechanical properties.

Stress corrosion cracking is a well-known phenomenon in oxide glasses. However, how amorphous phase separation (APS) alters stress corrosion cracking, and the overall mechanical response of an oxide glass is less known in literature. APS is a dominant feature concerning many multicomponent systems, particularly the ternary sodium borosilicate (SBN) glass systems. Its three constituent oxides have significant industrial relevance, as they are the principal components of many industrial oxide glasses. Simulations and experimental studies demonstrate the existence of a two-phase metastable miscibility gap. Furthermore, theory suggests the possibility of three-phase APS in these oxide glasses. Literature already details the mechanisms of phase separation and characterizes SBN microstructures. Realizing that glasses are structurally sensitive materials opens a number of other questions concerning how the mesoscopic APS affects the continuum behavior of glasses, including dynamic fracture and stress corrosion cracking. This paper reviews current literature and provides a synthetic viewpoint on how APS structures of oxide glasses alter physical, mechanical, dynamic fracture, and stress corrosion cracking properties.