Mixed-network former glasses have drawn considerable attention for their ability to combine the advantages of different glass formers. However, chemical incompatibilities among formers often lead to phase separation, hindering practical applications. In this work, glasses with the composition xAl2O3-(80-x)NaPO3-20SiO2 (x = 0, 10, 15, 20, 25 mol %) were synthesized via the melt-quenching method. The atomic-scale structure of these glasses was elucidated using advanced solid-state nuclear magnetic resonance (SSNMR) techniques, including single pulse Magic Angle Spinning (MAS), 31P refocused Incredible Natural Abundance Double Quantum Transfer Experiment (refocused INADEQUATE), Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction (DQ-DRENAR), 27Al{31P} Rotational Echo Double Resonance (REDOR), 31P{27Al} Rotational Echo Adiabatic Passage Double Resonance (REAPDOR). The results reveal that the 80NaPO3-20SiO2 glass predominantly contains homonuclear linkages (P-O-P, Si-O-Si), while heteronuclear P-O-Si bonds are less favored, leading to Na+ ions enrichment in phosphate-rich regions and evident phase separation. Incorporating Al2O3 promotes P-O-Al bond formation; when the average number of Al atoms bonded per phosphorus exceeds 2, further alumina incorporation promotes the formation of Si-O-Al linkages. Concurrently, Na+ ions begin to migrate from the vicinity of phosphate tetrahedra [PO4] toward silicate tetrahedra [SiO4]. This compositional evolution facilitates the progressive formation of Si-O-Al-O-P linkages, which effectively suppresses phase separation and yields a more homogeneous glass structure.

The bioactivity of glasses with the 45S5 composition is commonly attributed to the depolymerization of the silicate network and to dissolution-driven surface reactions. However, the structural mechanisms that connect glass formation, mechanical properties, and mineralization remain poorly understood. In this study, we show that the partial substitution of SiO2 with B2O3 reconfigures the glass structure, promoting phosphate ordering and the spontaneous formation of β-Na2Ca4(PO4)2SiO4 (silicorhenanite) crystalline phase without the need for post-thermal processing. Combined X-ray diffraction and multinuclear solid-state NMR techniques indicate that boron neither enters the calcium phosphate structure nor forms detectable borophosphate linkages. Instead, the results indicate a modifier-redistribution process in which boron preferentially stabilizes Na+ within the borate subnetwork, reduces Na–phosphate association, and promotes Ca-rich phosphate ordering. This facilitates the formation of β-Na2Ca4(PO4)2SiO4 crystalline phase during melt quenching. This crystalline phase is associated with enhanced hardness, while leaving the silicate network largely intact. Upon immersion in simulated body fluid, β-Na2Ca4(PO4)2SiO4 first converts into an amorphous phosphorus-rich intermediate before ultimately transforming into hydroxycarbonate apatite. Concurrently, the dissolution of borate species generates a transport-permeable, non-passivating interfacial layer enriched in protonated Q3H silicate species. This layer promotes ion exchange reactions and facilitates the conversion of the intrinsic β-Na2Ca4(PO4)2SiO4 crystals into fully developed hydroxycarbonate apatite. These results demonstrate a structure-based mechanism of boron's indirect control of phosphate ordering, interfacial changes, and hydroxycarbonate apatite formation in 45S5-based bioactive glasses.

The long-term structural evolution and sustained hydroxycarbonate apatite (HCA) mineralization of 45S5 bioglass under physiological conditions remain insufficiently explored, which ultimately limits the rational design of next-generation bioactive glasses. Here, we systematically studied the solution chemistry of 45S5 bioglass by examining its extended-time mineralization behavior and isolating the respective roles of simulated body fluid (SBF) components using a combined multimodal analytical approach and monitoring network restructuring, ion release, and phase changes over long immersion periods (7-30 days). Our findings demonstrate that specific ionic species in solution actively induce sustained glass transformation by continuously participating in ion exchange and network repolymerization, as evidenced by long-term atomic-scale structural evolution, persistent ion release, and stable hydroxycarbonate apatite formation. These species enable continuous growth of hydroxycarbonate apatite via coupled dissolution-repolymerization processes. On this basis, we propose a self-driven, solution-initiated mineralization cycle that captures the dynamic energetic interplay between glass structure and solution chemistry. These results redefine the role of physiological solutions as active regulators of bioactive glass mineralization and provide a fundamental framework for designing bioactive materials with controlled degradation and long-term functionality.

Corrosion mechanism of minerals and glass is a critical study domain in geology and materials science, vital for comprehending material durability under various environmental conditions. Despite decades of extensive study, a core aspect of these mechanisms-specifically, the formation of amorphous alteration layers upon exposure to aqueous environments-remains controversial. In this study, the corrosion behavior of a boro-alumino-phospho-silicate glass (BAPS) was investigated using advanced solid-state nuclear magnetic resonance (SSNMR) and SEM techniques. The results are consistent with a uniform nanoscale phase separation into aluminum phosphrous -rich and aluminum silicate-rich domains. During corrosion, the aluminum phosphrous -rich domains undergo gelation, whereas the aluminum silciate-rich domains remain vitreous, forming a gel layer comprised of both phases. Although SEM images show a sharp gel/glass interface-suggestive of a dissolution-precipitation mechanism, multiple lines of evidence indicate that an in situ transformation mechanism is more consistent with our findings, even if dissolution-precipitation cannot be entirely excluded. This in situ transformation is governed by a series of coupled chemical reactions, involving: (i) preferential hydrolysis of aluminum phosphrous -rich domains leading to porous gel regions; (ii) retention of aluminum silciate-rich glass domains within the gel layer, with water infiltrating inter-network spaces; and (iii) selective leaching of phosphorus over aluminum, leading to reorganization of the gel network.

Some metal organic-inorganic complexes (MOICs) are known for their glass-forming ability. However, the composition range of glass-forming MOICs is rather limited as the mechanism of MOIC glass formation has not been well understood. Here, we uncover the structural factors controlling MOIC glass formation and thereby develop new MOIC glass formers. MOIC glass formation relies on the creation of a hydrogen-bonded structural network. By properly choosing metal centers, anions, and organic ligands of MOICs, a supramolecular structural network can be constructed, thereby allowing property modulation. Furthermore, MOIC systems with mixed crystals are generated by ligand-mixing and then vitrified by melt-quenching. The glass-transition temperature (T g) of the derived glasses can be linearly tuned through the substitution of benzimidazole for imidazole. Interestingly, vitrification led to disordering of hydrogen-bonded networks in MOICs at short-, medium-, and long-range scales. This work enables the expansion of the composition range of MOIC glasses with various functionalities.

This study investigates the structural evolution of sodium boro-alumino-phospho-silicate (BAPS) glasses with the composition (40-x)SiO2–20B2O3–33Na2O–7Al2O3–xP2O5 (mol %), where x = 0, 5, 10, 20, 30, using a suite of advanced solid-state NMR techniques. The 31P–31P DQ-DRENAR pulse sequence provided dipolar coupling strengths, corroborating P-species assignments derived from 31P MAS NMR chemical shifts, which indicate a compositional evolution from P0 toward P1 species. Through single-pulse 31P NMR, site-specific 31P{27Al} REAPDOR, 31P{11B} REDOR experiments, and 31P{27Al} J-HMQC spectroscopy, heteronuclear interactions were identified. The compositional evolution of the NMR data suggested a hierarchical connectivity preference in the order: Na+ > Al3+ > B3+. With increasing phosphorus content, both Al3+ and B3+ progressively accumulate around phosphate species. Ultimately, aluminum achieves nearly exclusive coordination with phosphate, whereas boron is partially incorporated via tetrahedral [BO4]¯ species that bridge phosphate and silicate species, forming P–O–B–O–Si linkages. Taken together, the data are consistent with the development of two structurally distinct sub-networks: a phosphate-centered region enriched with aluminum and sodium, and a B–Si-rich network in which the silicate framework increasingly polymerizes. This work highlights the governing role of phosphate in structuring BAPS glasses and provides a quantitative framework of local bonding connectivity—including the average numbers of Al–O–P, B–O–P linkages per network-forming species—and proposes a structural model for the resulting network heterogeneity.

Metal organic-inorganic complex (MOIC) glasses have emerged as a new family of hybrid glasses. However, the low thermal stability of MOIC glasses fabricated via crystallization suppression constrains their practical applicability under ambient conditions. Here, we report a novel approach for preparing the MOIC glasses that combines slow-solvent removal with subsequent quenching to avoid gel thermal decomposition and enhance the thermal stability of the obtained glass. Specifically, the new approach utilizes an aprotic solvent (acetone) to kinetically prevent the ordering of the metal-ligand complex molecules in solution, thereby suppressing crystallization and forming a gel. The subsequent gradual drying process leads to the removal of the solvent to enhance the connections between molecules through hydrogen bonds, thus causing the formation of a hydrogen-bonded network. The increased network connectivity lowers the mobility of the molecules, thereby enhancing the thermal stability of the system. A disordered network of dried gel is frozen-in via cooling from 130 degrees C to room temperature, and hence, MOIC glass forms. Structural analyses reveal that hydrogen bonds are responsible for connecting the tetrahedral units. The as-prepared MOIC glass exhibits an increase in glass transition temperature (Tg) during rapid room-temperature relaxation, enhanced CO2 uptake, and a red shift in photoluminescence. This work not only presents a novel strategy for fabricating large-sized, stable, functional MOIC glasses but also uncovers the critical role of hydrogen bonds in MOIC glass formation.

Molybdate crystals tend to precipitate in nuclear waste glasses, significantly compromising their chemical and thermal stability, thereby rendering them unsuitable for long-term storage. However, the mechanisms by which glass composition influences the precipitation of molybdate crystals remain poorly understood. This study investigated this influence by preparing three series of molybdenum-doped sodium-calcium mixed aluminum borosilicate glasses using the melt-quenching technique. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy, supplemented by Raman spectroscopy, was utilized to examine the glass structure at the atomic scale to reveal composition-dependent structural impacts on crystallization, while transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to identify the precipitated crystals. The results demonstrate that increasing the Al2O3 content effectively suppresses molybdate crystal precipitation. It has been proven that high-valence cations differ in their ability to capture free oxygen, with the order of strength being Al3+ > Mo6+ > B3+ and Si4+. It is the strong ability of Al3+ to capture free oxygen and the formation of Al[4]-Ca2+-Mo[6] linkages that are responsible for inhibiting molybdate crystallization in the glass. An intriguing and important abnormal crystallization behavior was observed: a slight substitution of Na2O with CaO resulted in CaMO4 crystal precipitation, whereas larger substitutions paradoxically suppressed it. The findings reveal that in CaO-Na2O mixed aluminum borosilicate glasses, Al[4] preferentially attracts Na+ over Ca2+ to compensate for its negative charge. Meanwhile, Ca2+ ions are capable of forming an Al[4]-Ca2+-Mo[6] linkage, which Na+ ions cannot achieve. This fundamental difference results in the abnormal precipitation of CaMO4 crystals.

To overcome the challenges associated with conventional ultraviolet-C (UV-C) light-emitting devices-such as toxic mercury, aging of organic adhesives, and various stability concerns-an efficient UV-C emitting nano-glass composite (nano-GC) has been developed. The transparent nano-GCs embedded with Pr3+-doped Li(Al7B4O17) nanocrystals (NCs), achieved through precise modulation of the fluoride content in the glass matrix network. The unique architecture of these nano-GCs synergistically combines the high luminescence efficiency characteristic of a crystalline phase with the robustness of glass. Upon excitation by deep-UV, X-ray and high energy electron-beams, the nano-GCs exhibit pronounced 5d-4f interconfigurational emissions of Pr3+, with their emission profile closely aligning with the germicidal effectiveness curve. Although the transmittance of nano-GCs is reduced compared to that of precursor glass (PG), their UV-C luminescence output is significantly enhanced-e.g., a sixfold increase under e-beam pumping. These nano-GCs achieve an impressive photoluminescence quantum yield of up to 25.93%, surpassing most previously reported Pr3+ doped glasses and nano-GCs. Moreover, the nano-GCs exhibit robust X-ray excited luminescence, with an intensity more than twice that of the commercial Bi4Ge3O12 (BGO) crystal, and exhibit a highly linear response to X-ray dose, accompanied by a decay time of 24.13 ns under gamma-ray excitation. Collectively, this study presents a novel approach to the development of disinfection phosphors and fast scintillators.

Joint doping with trivalent and monovalent ions is a widely adopted strategy to enhance the ionic conductivities of NASICON-type solid-state electrolytes (SSEs) with the general formula Na1+x Zr2Si x P3-x O12, but the underlying microscopic mechanism remains unclear. In this study, we synthesized a series of Na3+x La x Zr2-x Si2PO12 (NLZSPx, 0 <= x <= 0.4) ceramics and characterized their electrical properties and structures by using electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and advanced solid-state nuclear magnetic resonance (SSNMR). Among all of the samples, the composition with x = 0.2 exhibited the highest ionic conductivity, achieving 1.05 x 10-3 S/cm at 25 degrees C, which is 3.65 times higher than that of the undoped sample. XRD and SSNMR results prove that La3+ ions did not integrate into the main phase lattice to replace Zr4+ ions. Instead, they formed a heterogeneous phase predominantly composed of Na3La(PO4)2 at the grain boundaries. The content of Na3La(PO4)2 and the composition of the NASICON main phase were accurately determined by SSNMR. This impurity resulted in changes in the Si/P and Na/Zr ratios within the main phase. Some comparison experiments are carried out and prove that these changes were not the principal drivers of the increased conductivity. SEM results further indicated that doping with an appropriate amount of La3+ ions significantly increased the sample densification, thus promoting Na+ ions transport between grain boundaries-this being the key factor driving the observed improvement in ionic conductivity.

Metal inorganic-organic complex (MIOC) crystals are a new category of hybrid glass formers. However, the glass-forming compositions of MIOC crystals are limited due to lack of both a general design principle for such compositions and a deep understanding of the structure and formation mechanism for MIOC glasses. This work reports a general approach for synthesizing glass-forming MIOC crystals. In detail, the principle of this approach is based on the creation of hydrogen-bonded structural network by substituting acid anions for imidazole or benzimidazole ligands in the tetrahedral units of zeolitic imidazolate framework crystals. By tuning the metal centers, anions, and organic ligands of MIOCs, supramolecular unit structures can be designed to construct supramolecular networks and thereby enable property modulation. Furthermore, mixed-ligand synthesis yielded a mixed-crystal system in which the glass-transition temperature (Tg) can be linearly tuned from 282 K to 360 K through gradual substitution of benzimidazole for imidazole. Interestingly, upon vitrification, MIOCs were observed to undergo reorganization of hydrogen-bonded networks, with retention of tetrahedral units, short-range disorder, and the freezing of multiple conformations. This work offers a new strategy to systematically expand the glass-forming compositional range of MIOCs and to develop functional MIOC glasses.

Oxygen-deficient perovskites exhibit promising ionic conductivity for electrochemical applications, but understanding their structure-property relationships requires detailed knowledge of local atomic environments. In this study, we employ multinuclear (17O, 45Sc, and 71Ga) solid-state NMR spectroscopy to investigate the local structure of cubic Sr2ScGaO5 (c-SSGO). 17O NMR signals were assigned based on 17O{45Sc} transfer of population double resonance experiments (TRAPDOR) and ab initio chemical shift calculations using the CASTEP code. Our results provide compelling evidence that despite its cubic average structure determined by X-ray Bragg diffraction, the local atomic arrangement in c-SSGO closely resembles the orthorhombic brownmillerite structure, as previously proposed from neutron diffraction pair distribution (PDF) analysis. Furthermore, we demonstrate how solid-state NMR, together with DFT calculations of 17O NMR chemical shifts can serve to discriminate between alternative structural scenarios for defect perovskite structures. The study highlights the power of solid-state NMR in elucidating local structural details in complex oxides with local variations in their crystal structures.

This study investigated the atomic-scale structure of Sc2O3-xKPO3 glass series to model the local environments of rare-earth ions in phosphate glasses. A combination of advanced solid-state nuclear magnetic resonance (SSNMR) techniques, including single-pulse, 1D refocused INADEQUATE, 1D HMQC, 2D J-resolved, WURST-TQMAS, REDOR, and REAPDOR, was employed to characterize the glass structure. The structural analysis demonstrated that Sc3+ ions adopt a six-coordinate configuration in phosphate glasses, forming corner-sharing connections with six [PO4] tetrahedra. Nine distinct phosphate structural species-categorized as Pn mSc (n = 0, 1, 2; m = 0, 1, 2, 3)-were identified in this glass system. Notably, the simultaneous presence of abundant P13Sc and P20Sc species within individual samples strongly indicates significant local clustering of Sc3+ ions. A structureconnectivity model was developed to quantitatively assess the distribution probabilities of different Pn mSc species surrounding Sc3+ ions. The analysis revealed pronounced spatial aggregation of Sc3+ ions within a 5.5 & Aring; radius.

HfO2-based mixtures, such as HfO2-Al2O3, play an important role in high-power laser optics and metal oxide semiconductor devices due to their high laser damage resistance and high dielectric constant. However, comprehensive insights into the microstructure and chemical state of HfO2-based mixtures at the atomic level are limited, partly because the extremely large fourfold coupling constant of hafnium makes it difficult to characterize. Herein, the Al structures in HfO2-Al2O3 mixtures were investigated and compared with that of Al2O3 using solid-state nuclear magnetic resonance (NMR) spectrometry, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and conventional spectroscopic and microscopic techniques. 27Al NMR spectra show that the Al coordination resonances in HfO2-Al2O3 mixtures change with the Al content. The content of five-coordinate Al (AlV) is positively correlated with the content of ternary compounds, indicating that the Al–O bonds in ternary compounds tend to be connected at the five-coordinated Al site, which is further demonstrated through annealing experiments of HfO2-Al2O3 mixtures. Further, the impact of the above microscopic properties on the macroscopic performance, such as wettability and optical bandgap, has also been explored. Our insights into Al coordination resonances and ternary compounds in HfO2-Al2O3 mixtures may help understand the structure–function relationship of mixture coatings.

HfO2-based 2-based mixtures, such as HfO2-Al2O3, 2-Al 2 O 3 , play an important role in high-power laser optics and metal oxide semiconductor devices due to their high laser damage resistance and high dielectric constant. However, comprehensive insights into the microstructure and chemical state of HfO2-based 2-based mixtures at the atomic level are limited, partly because the extremely large fourfold coupling constant of hafnium makes it difficult to characterize. Herein, the Al structures in HfO2-Al2O3 2-Al 2 O 3 mixtures were investigated and compared with that of Al2O3 2 O 3 using solid-state nuclear magnetic resonance (NMR) spectrometry, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and conventional spectroscopic and microscopic techniques. 27 Al NMR spectra show that the Al coordination resonances in HfO2-Al2O3 2-Al 2 O 3 mixtures change with the Al content. The content of five-coordinate Al (AlV) V ) is positively correlated with the content of ternary compounds, indicating that the Al-O bonds in ternary compounds tend to be connected at the five-coordinated Al site, which is further demonstrated through annealing experiments of HfO2-Al2O3 2-Al 2 O 3 mixtures. Further, the impact of the above microscopic properties on the macroscopic performance, such as wettability and optical bandgap, has also been explored. Our insights into Al coordination resonances and ternary compounds in HfO2-Al2O3 2-Al 2 O 3 mixtures may help understand the structure-function relationship of mixture coatings.

The formation mechanism of crystalline phases within the corrosion layer of glasses has attracted considerable attention, but research on the microscopic chemical process of their formation has rarely been studied. This study focuses on investigating potassium aluminum phosphate glass with a nominal molar composition of 41.6K(2)O-16.7Al(2)O(3)-41.7P(2)O(5). Liquid- and solid-state nuclear magnetic resonance (NMR) techniques are employed to investigate the evolution of the aluminum species and phosphorus units of the corroded glasses, leachates, and sediments derived from immersing the glass for various durations. Our findings provide compelling evidence that the formation of the crystalline phases during the phosphate glass immersion process is a result of leached glass elements saturating in the solution and subsequently precipitation onto the glass surface. Furthermore, we have identified two distinct dissolution modes in this process, which include the overall dissolution of large molecular units presented in the initial stage and the continuous dissolution of small molecular units that persists throughout the entire corrosion process. The coexistence of these two dissolution modes leads to the formation of crystalline phases on the glass surface even before both the glass and the solution have fully reached dissolution saturation. This study sheds light on the glass corrosion mechanism at the molecular level, providing new insight into comprehending the corrosion process of glass.

In this work, a novel series of oxyfluoride glasses‐ceramics (GCs) is developed by enhancing the phase separation through the substitution of LaF 3 for La 2 O 3 . The thus‐derived GCs exhibit a remarkable 2700‐fold increase in up‐conversion (UC) luminescence of Er 3+ ions compared to the precursor glass. From the 19 F Nuclear Magnetic Resonance analysis, this enhancement is attributed to the structural disorder‐to‐order transition in the fluoride‐rich phase. Upon isothermal heat treatment, the translucent GCs transform into transparent ones, making UC luminescence even stronger. The enhanced UC luminescence leads to strong temperature‐sensing ability of the studied glasses. The nano‐micro phase separation is clarified by atomistic simulations and scanning electron microscopy. This study implies that phase separation engineering is a powerful way to achieve superior photonic performances.

One major factor impeding the design of nuclear waste glasses with enhanced waste loadings is our insufficient understanding of their composition-structure-durability relationships, specifically in the environments the waste form is expected to encounter in a geological repository. In particular, the high field-strength cations (HFSCs) are an integral component of most waste streams. However, their impact on the long-term performance of the glassy waste form remains mostly undeciphered. In this context, the present study aims to understand the impact of some HFSCs (i.e., Nb5+, Zr4+, Ti4+, and La3+) on the dissolution behavior of alkali/alkaline-earth aluminoborosilicate-based model nuclear waste glasses in hyper-alkaline media. At pH = 13, the studied glasses dissolve through the dissolution-reprecipitation mechanism, with Ca precipitation being the most vital step to passivation. In Ca-free glasses, although the HFSCs slow down the forward rate, they do not seem to impact the residual rate behavior of glasses. The presence of Ca2+, however, initiates the rapid precipitation of network polymerizing HFSCs (i.e., Nb5+, Zr4+, and Ti4+) into a Ca2+/HFSCs-based passivating layer, thus suggesting a synergy between Ca2+ and HFSCs that contributes to the enhanced long-term durability of the glasses. Such synergy is not strongly evident for La3+, but instead, a potential La/Si affinity is observed upon the formation of the alteration layer.