Lithium Aluminosilicate Research Articles

Mechanical Behavior of Ion-Exchanged Alkali Aluminosilicate Glass Ceramics

Glass is one of the oldest and most versatile manmade materials and has been used for centuries. One of the areas of significant research and progress is that of high-mechanical-resistance glass. Several processes can be used to maximize the mechanical strength of glasses, namely thermal or chemical treatments. Glass ceramics, obtained through controlled crystallization, can enhance the mechanical properties of these materials and, as long as the crystals remain small enough, transparent glass ceramics can be obtained. On the other hand, ion exchange can strengthen the glass surface and reduce failure. As a result, ceramization followed by ion exchange can further enhance the mechanical characteristics of the parent glass. Aluminosilicate glasses and glass ceramics are known to present excellent transparency and chemical durability, plus good mechanical behavior; therefore, a lithium aluminosilicate glass composition was studied in order to obtain transparent glass ceramics, followed by an ion exchange process, and its mechanical properties were studied. Transparent glass ceramics were obtained, with an increase of ~15% in hardness over the parent glass. The glass ceramics were then subjected to an ion exchange treatment in a KNO3 bath, in order to further enhance the mechanical properties, without hindering the optical transmittance. The combination of heat treatment and chemical treatment resulted in a cumulative hardness increase of ~25%, from 620 ± 10 HV, for the as-cast glass and from 773 ± 23 HV for the ion-exchanged glass ceramic. Regarding the indentation fracture toughness, values obtained for the glass ceramics were similar to those obtained for the cast glass, yielding no noticeable change. Indentation fracture toughness increased after the ion exchange treatment of the glass ceramic, since a much higher load was necessary to obtain a measurable indentation, indicating higher indentation fracture strength.

The effects of B2O3 on the structure, phase separation and crystallization of lithium aluminosilicate glass-ceramics with Y2O3 addition

The effects of B2O3 on the structure, phase separation and crystallization of lithium aluminosilicate glass-ceramics with Y2O3 addition

The effect of ZrO2 on the structure, properties and crystallization behavior of transparent lithium disilicate based glass-ceramics

The effects of ZrO2 on the parent glass network structure, crystallization behavior, and properties of lithium aluminosilicate glass-ceramics by various amounts of ZrO2 were investigated. The main crystalline phases of transparent glass-ceramics are quartz solid solution and Li2Si2O5. The increase of ZrO2 addition promotes an increasing of Q3(Zr) tetrahedral proportion in the glass network, resulting a reduction of ZrO2 nucleus. The increase of ZrO2 content also effectively improves the fracture toughness of glass-ceramics, but reduces the transmittance significantly. In this work, the glass with the 1 mol% ZrO2 nucleated at 545 °C for 2 h and crystallized at 800 °C for 2h possesses the excellent comprehensive properties, which exhibited the Vickers hardness of 6.91 GPa, the fracture toughness of ∼1.40 MPa·m1/2, and the transmittance at 550 nm of 90 %. It provides significant potential applications in the display protective cover.

Advancing the prediction of crystalline phases in glass-ceramics via machine learning

Lithium aluminosilicate (LAS) glass-ceramics are widely utilized in diverse application, owing to their outstanding properties such as high transparency, high fracture toughness and ultra-low thermal expansion. The development of LAS glass-ceramics has traditionally relied on the phase diagram to identify primary crystalline phases. However, this approach is limited by constrained composition ranges and unknown heating treatment parameters, hindering the efficient development of high-performance glass-ceramics. In this study, we establish a comprehensive small-scale database of LAS glass-ceramics, comprising 751 samples characterized by 27 compositions, nucleation temperature, nucleation time, crystallization temperature, crystallization time and 13 crystalline phases. We employ five algorithms, i.e. Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Classification and Regression Trees (CART), K-Nearest Neighbors (K-NN) and Multi-Layer Perceptron (MLP) Classifier to predict the potential crystalline phases. Our results demonstrate that RF achieves the best overall performance, with the highest accuracy of 0.8609, the lowest hamming loss of 0.0142, and the highest micro F1 score of 0.9234. This work advances the understanding and prediction of crystalline phases in LAS glass-ceramics, providing valuable insights for the development and optimization of these materials.

Fabrication and Characterization of Ce3+-Doped Lithium Alumino-Silicate Scintillating Glass-Ceramic and Fiber.

Ce3+-doped lithium alumino-silicate (Li-Al-Si) scintillating glass was prepared using a melting method and crystallized via heat treatment. X-ray diffraction and transmission electron microscopy confirmed the presence of nanocrystals in the materials. Radioluminescence spectra, obtained by X-ray excitation, and luminescence spectra, obtained by 338 nm excitation, showed that the luminescence intensity increased after crystallization. The glass was combined with pure silica as the inner cladding to fabricate a hybrid fiber core using a melt-in-tube technique. The composition of the fiber core was examined using an electron probe microanalyzer. The glass fiber produced strong blue luminescence under UV excitation. After a micro-crystallizing heat treatment of the hybrid fiber at 850 °C in a reducing atmosphere, a Ce3+-doped lithium alumino-silicate glass-ceramic scintillating hybrid fiber was obtained. The nanocrystal structure of the fiber core was examined using micro-Raman spectroscopy. Excitation and luminescence spectra of the hybrid fiber before and after micro-crystallization were measured using microspectrofluorimetry. The results demonstrated that the fiber remained luminous after micro-crystallization. Hence, this work provides a new way to prepare scintillating glass-ceramic hybrid fibers for neutron detection.

Synthesis and characterization of lithium alumina silicate (LiAl(SiO3)2) from naturally sourced silica: a comparative study

This study investigates the synthesis and characterization of lithium aluminosilicate (LiAl(SiO3)2) using naturally sourced silica (NSS) from the Djamâa region in Algeria and compares it with laboratory-sourced silica (LSS). The synthesis was conducted using the sol–gel method and solid-state reactions with lithium carbonate, aluminum oxide, and SiO2. Characterization techniques included X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). XRD analysis confirmed the crystalline structure of the synthesized lithium aluminosilicate, revealing distinct crystal phases: the NSS material exhibited a tetragonal spodumene-II phase. In contrast, the LSS material showed a hexagonal spodumene-III phase. The crystallite sizes were 21.96 μm for NSS and 22.14 μm for LSS, with crystallinity percentages of 60.77% and 57.55%, respectively. FTIR spectroscopy verified the successful incorporation of lithium and aluminum into the silica framework. SEM analysis provided detailed insights into surface morphology and particle size distribution, highlighting the uniformity of the materials. Specifically, the LSS material exhibited cylindrical spaces between particles, whereas the NSS material displayed spherical spaces.

Effect of glazing and thermocycling on the fracture toughness and hardness of a New fully crystallized aluminosilicate CAD/CAM ceramic material

BackgroundThe mechanical properties of fully crystallized lithium aluminosilicate ceramics may be influenced by intraoral temperature variations and postmilling surface treatment. The purpose of this study is to explore the interplay among glazing, thermocycling, and the mechanical characteristics (namely, fracture toughness and hardness) of fully crystallized lithium aluminosilicate ceramics.MethodsBending bars (n = 40) cut from LisiCAD blocks (GC, Japan) were randomly assigned to glazed or unglazed groups (n = 20) and subjected to the single edge v-notch beam method to create notches. A glazing firing cycle was applied to the glazed group, while the unglazed group was not subjected to glazing. Half of the specimens (n = 10) from both groups underwent thermocycling before fracture toughness testing. The fracture toughness (KIC) was evaluated at 23 ± 1 °C using a universal testing machine configured for three-point bending, and the crack length was measured via light microscopy. Seven specimens per group were selected for the hardness test. Hardness was assessed using a Vickers microhardness tester with a 1 kg load for 20 s, and each specimen underwent five indentations following ISO 14705:2016. The Shapiro–Wilk and Kolmogorov-Smirnov tests were used to evaluate the normality of the data and a two-way ANOVA was utilized for statistical analysis. The significance level was set at (α = 0.05).ResultsRegardless of the thermocycling conditions, the glazed specimens exhibited significantly greater fracture toughness than did their unglazed counterparts (P < 0.001). Thermocycling had no significant impact on the fracture toughness of either the glazed or unglazed specimens. Furthermore, statistical analysis revealed no significant effects on hardness with thermocycling in either group, and glazing alone did not substantially affect hardness.ConclusionsThe impact of glazing on the fracture toughness of LiSiCAD restorations is noteworthy, but it has no significant influence on their hardness. Furthermore, within the parameters of this study, thermocycling was found to exert negligible effects on both fracture toughness and hardness.

Effect of striae on the high temperature dielectric and electrical properties of lithium aluminosilicate glass-ceramics

Lithium Aluminosilicate glass-ceramics with striae (LAS-WS) and without striae (LAS-WoS) were processed using melt casting technique. LAS-WS and LAS-WoS samples were characterized and found stress birefringence >10 nm/cm and <10 nm/cm, respectively. LAS-WS and LAS-WoS samples were subjected to structural, microstructural, high temperature dielectric and electrical characterization. The presence of striation did not significantly affected the formation of β-spondumene structure during crystallization heat treatment. TEM image confirms the formation of nanocrystals in the glass matrix of lithium aluminosilicate glass-ceramics. The homogeneous distribution of LAS nanocrystals of average size of 3–6 nm is evident from TEM results. Stress birefringence distribution in lithium aluminosilicate glass-ceramic clearly shows the striae formation. Shadowgraphy images confirmed the striae free and striae containing regions in the glass-ceramic. The effect of striae on dielectric properties and AC conductivity was analysed using impedance spectroscopy and it was found that the value of the relative permittivity decreased from 415 (1.2 Hz) to 9.76 (1.2 MHz) for LAS-WoS and from 401 (1.2 Hz) to 10.3 (1.2 MHz) for LAS-WS, respectively. It was found that striae in LAS glass-ceramics influence the electrical impedance and AC conductivity relaxation process rather than relative permittivity. The effect of striae on crystallization and morphology are presented. Both the samples have shown crystallinity of more than 75 %. The electrical conductivity of σ = 2.0 × 10−3 S/cm for LAS-WoS and 2.7 × 10−3 S/cm for LAS-WS at 300 °C as well as σ = 4.6 × 10−3 S/cm for LAS-WoS and 6.9 × 10−3 S/cm for LAS-WS at 700 °C are found to be in good agreement due to increase in the electrical conductivity with temperature. The ionic conductivity of the material due to Li-ion mobility with respect to temperature and electric field and possible mechanism of AC conductivity are discussed. The results presented indicates the potential application of this material that demands high temperature operation of lithium aluminosilicate glass-ceramics.

Structural features and thermal expansion of zinc aluminosilicate quartz solid solutions

Zinc aluminosilicate (ZAS) glasses were synthesized along the peraluminous join (SiO2 contents between 95 and 50 mol%) by melt-quenching or sol-gel spray-drying and subjected to controlled heat treatments to obtain ZAS quartz solid solutions (Zn-Qz-ss). The precipitation of Zn-Qz-ss is non-stoichiometric with respect to their parent glass and the crystals undergo a compositional evolution during annealing, even in absence of secondary crystalline phases. Near-hexagonal high-quartz-like crystals with negative thermal expansion (down to −3 × 10−6 K−1) can be obtained in the range 50–80 mol% SiO2, while SiO2-richer crystals exhibit positive thermal expansion at room temperature (up to 29 × 10−6 K−1). Zn2+ ions occupy two distinct positions within the structural channels of quartz, with a strong preference for 4-fold coordination. In analogy to lithium aluminosilicate quartz solid solutions (Li-Qz-ss), the low-to-high phase transition exhibits a linear correlation to the composition of the crystals.

Transparent aluminoborosilicate glass-ceramics containing Al4B2O9 nanorods

Transparent glass-ceramics containing nanorods are attractive for many applications. In this work, transparent aluminoborosilicate glass-ceramics containing aluminum borate nanorods are reported. Effects of Al2O3 and SiO2 concentrations on the thermal properties and crystallization of aluminoborosilicate glasses are studied. It is found that lithium aluminosilicate nanocrystals and Al4B2O9 nanorods are co-precipitated in glasses with Al2O3/SiO2 molar ratios of 0.29 and 0.33, and only Al4B2O9 nanorods are precipitated in glasses with Al2O3/SiO2 molar ratios of 0.375 and 0.42. Precipitation of these nanocrystalline phases leads to the enhancement in Vickers hardness. Glass-ceramics with Al2O3/SiO2 molar ratios of 0.375 and 0.42 are highly transparent in the visible region due to the small size of the Al4B2O9 nanorods precipitated inside.

PROSPECTIVE LITHIUM ALUMINOSILICATE GLASS-CERAMIC MATERIALS FOR PULSE RANGEFINDERS

The relevance of creating multi-functional nanosecond pulsed laser devices with a generation wavelength that lies in the conditionally eye-safe region of the spectrum of 1.5÷1.6 μm has been established. The prospects of using the mode of passive Q-switching when receiving powerful nanosecond laser pulses with a radiation divergence close to the diffraction one have been determined. Materials for shutters that function in the mode of passive Q-switching were analyzed: solid-state nonlinear optical materials based on single crystals of yttrium-aluminum garnet doped with cations of neodymium, chromium, vanadium and other Nd- or Yb-doped crystals in the wavelength range of 0.8–1.2 μm. The promising use of oxide single crystals activated by Co2+ ions in four-coordinated oxygen positions for MgAl2O4, LiGa5O8, LaMgAl11O19 has been confirmed. The feasibility of developing transparent glass-ceramics based on aluminomagnesium and lithium gallium spinel for pulsed ranging was determined, taking into account its commercial availability, the simplicity of the production technology, as well as the homogeneity of the distribution of the activator in the volume. The feasibility of creating a new type of nonlinear optical materials based on nanostructured heat-resistant lithium aluminosilicate glass ceramics with spinel nanocrystals activated by Co2+ ions under low-temperature heat treatment conditions, has been determined. The purpose and tasks of the work are formulated, which consist in justifying the choice of the system and compositions of glasses for obtaining glass-ceramic materials as a passive laser shutter for powerful lasers that operate at a wavelength of 1.54 μm and are characterized by high heat resistance. The choice of the lithium aluminosilicate system R2O – RO – RO2 – P2O5 – R2O3 – SiO2 based on phase-forming SiO2, Al2O3, Li2O, modifying K2O is substantiated; RO – MgO, ZnO, CaO, SrO, BaO components and a complex crystallization catalyst of P2O5, CeO2, TiO2, SnO2, ZrO2 and ZnO. The structural criteria for the glass matrix were formulated. Compositions of model glasses were designed taking into account the calculated parameters fSi &gt; 0.22, Kсr ≥ 3.5, Ktr ≥ 2.1, and the probability of obtaining transparent glass-ceramic materials with a sitallized structure for pulse rangefinders was established on their basis.

Amorphous LiAlSiO4 coating modifies the crystal structure stability and electrochemical behaviors of nanocrystalline LiCoO2 at 4.6 V

The mechanically stable and Li+-conducting solid solution of lithium aluminosilicate (LiAlSiO4 or Li2O·Al2O3·2SiO2, LASO) has been regarded as one of effective coating materials to suppress the adverse transformation of well-crystallized LiCoO2 (LCO) into Li-insulating Co3O4, but its functional mechanism is still ambiguous so far. In this study, as-prepared LCO nanocrystallites are previously dispersed in the formation system of amorphous LASO, and the resulting LCO@LASO is applied as Li+-ion battery cathodes to elaborate a reinforcing mechanism of the amorphous coating for the Li+-ion insertion/extraction behaviors of 4.6 V LiCoO2. Aside from a synergistic effect of the three components (i.e., Li2O, Al2O3 and SiO2) in coating layer, the much higher high-rate capability (i.e., 149.1 mAh g−1, 2.0 C) and long-term cycling stability (160.1 mAh g−1, 0.5 C, the 360th cycle) of LCO@LASO than those (50.5 mAh g−1, 2.0 C; 142.4 mAh g−1, 0.1 C, the 100th cycle) of the uncoated counterpart suggests a potential application of the amorphous LASO in achieving the high-voltage electrochemical properties of nanocrystalline LiCoO2 in future.

Formation of a zirconium oxide crystal nucleus in the initial nucleation stage in aluminosilicate glass investigated by X-ray multiscale analysis

Understanding the nucleation mechanism in glass is crucial for the development of new glass-ceramic materials. Herein, we report the structure of a commercially important glass-ceramic ZrO2-doped lithium aluminosilicate system during its initial nucleation stage. We conducted an X-ray multiscale analysis, and this analysis was used to observe the structure from the atomic to the nanometer scale by using diffraction, small-angle scattering, absorption, and anomalous scattering techniques. The inherent phase separation between the Zr-rich and Zr-poor regions in the pristine glass was enhanced by thermal treatment without changing the spatial geometry at the nanoscale. Element-specific pair distribution function analysis using anomalous X-ray scattering data showed the formation of a liquid ZrO2-like local structural motif and edge sharing between the ZrOx polyhedra and (Si/Al)O4 tetrahedra during the initial nucleation stage. Furthermore, the local structure of the Zr4+ ions resembled a cubic or tetragonal ZrO2 crystalline phase and formed after 2 h of annealing the pristine glass. Therefore, the Zr-centric periodic structure formed in the early stage of nucleation was potentially the initial crystal nucleus for the Zr-doped lithium aluminosilicate glass-ceramic.

Preparation of some selective glass–ceramics from nano-silica within the Li2O–SiO2 system with ZrO2 for future dental applications

Many recent studies have indicated that some modified silicate glass–ceramics are considered and recommended to be part of the process of dental applications. Examples from the recommended glass–ceramics include modified lithium silicate with various dopants (ZrO2, CeO2), mica-based glass–ceramics, and leucite-based glass–ceramics. The present study employs a new direction of research in the preparation of modified lithium silicate glasses containing varying dopant percents of ZrO2 to produce the parent glasses using nano-silica as an essential chemical component in comparison with silica. The ZrO2-doped glass–ceramic reveals the crystalline phase of lithium aluminosilicate (Li5AlSi2O8) due to the effect of ZrO2. The modified lithium silicate glasses doped with ZrO2 prepared from nano silica indicate their high mechanical properties and can be primarily recommended for dental applications.

Ion-exchange induced mechanical properties enhancement and microstructural modifications of transparent lithium aluminosilicate glass-ceramics

Alkali-aluminosilicate glass and glass-ceramics can be effectively strengthened by ion-exchange if compression is introduced into the surface, which have been widely used in many electronic devices, especially for mobile phones. In this work, the transparent lithium aluminosilicate glass-ceramics with eucryptite crystalline phase were ion-exchanged in the mixed x NaNO3 + (100－x) KNO3 (wt%, x = 60, 70, 80, 90, 100) molten salts at 420 °C for 4 h. With the increase of NaNO3 concentration in the molten salts from 60 to 100 wt%, the depth of stress layer increase from 98 to 104 μm, and the surface compressive stress increase to the maximum ∼500 MPa at x = 80 and then decrease. In addition, there is also a K+-rich layer observed with the depth of ∼25 μm. The ion-exchange takes place in both crystalline and residual glassy phases, and thus leads to the microstructural modifications, including the amorphization of eucryptite and the presence of lithium phosphate. Upon ion-exchange, the Vickers hardness of glass-ceramics increase from 7.03 GPa to the maximum ∼7.62 GPa (x = 80), and the bending strength from 198 MPa to the maximum ∼510 MPa (x = 90). The improvement in mechanical properties is mainly related to the generation of surface compressive stress layer. Meanwhile, the amorphization and transformation of crystalline phase during the ion-exchange process are probably conductive for the reduction of surface cracks and defects, leading to the enhancement of mechanical properties, especially for the bending strength.

The effect of nucleating temperature on the crystallization, phase formation and properties of lithium aluminum silicate (LAS) glass-ceramics

To study the influence of the nucleation mechanism in lithium aluminosilicate glass, a composition similar to commercially produced glass was used. The glass-ceramics was obtained as a result of two-stage heat treatment, differing in the nucleation temperature and coinciding in the temperature and time of crystal growth. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to study the formed nanocrystals. It was shown that the change of nucleation temperature in the glass transition interval Tg ±15 °C significantly affects the coefficient of thermal expansion, which is due to the formation of a different number of nanocrystals of the general composition LixAlxSi1-xO2 with x = 0.33 with the size less than 50 nm.

Tuning the Coefficient of Thermal Expansion of Transparent Lithium Aluminosilicate Glass-Ceramics by a Two-Stage Heat Treatment

Transparent glass-ceramics with a Li2O–Al2O3–SiO2 (LAS) system have been extensively utilized in optical systems in which thermal stability is of utmost importance. This study is aimed to develop thermal treatment routes that can effectively control the structure of transparent LAS glass-ceramics and tune its thermal expansion coefficient within a wide range for novel applications in photonics and integrated optics. The optimal conditions for the nucleation and crystallization of LAS glass were determined by means of differential scanning calorimetry and a polythermal analysis. XRD, Raman spectroscopy, and TEM microscopy were employed to examine the structural changes which occurred after heat treatments. It was found that the second stage of heat treatment promotes the formation of β-eucryptite-like solid solution nanocrystals, which enables effective control of the coefficient of thermal expansion of glass-ceramics in a wide temperature range of −120 to 500 °C. This work provides novel insights into structural rearrangement scenarios occurring in LAS glass, which are crucial for accurately predicting its crystallization behavior and ultimately achieving transparent glass-ceramics with desirable properties.

Effect of Na+ Ions on the Mechanical Properties of Lithium Aluminosilicate Glass

Effect of Na+ Ions on the Mechanical Properties of Lithium Aluminosilicate Glass

Microstructure, Dielectric Properties and Bond Characteristics of Lithium Aluminosilicate Glass-Ceramics with Various Li/Na Molar Ratio

The advent of 5G technology presented new challenges regarding the high-frequency characteristics of electrical signals and their impact on the cover glass properties of electronic devices. This study aimed to analyze the effect of the Li/Na molar ratio on the dielectric and mechanical properties, as well as the structural characteristics, of lithium aluminosilicate glass-ceramics. Using the melting method, we prepared lithium aluminosilicate base glasses and subsequently crystallized them by adjusting the molar ratio. XRD and TEM analyses were employed to investigate the resultant structures and crystal formation in the five base glasses. It was observed that Li2Si2O5 and LiAlSi4O10 crystals precipitated, exhibiting varying degrees of crystallinity and crystal ratios. Through a comparison of dielectric properties before and after crystallization, it was found that the dielectric constants of the glass-ceramics were consistently reduced. This decrease can be attributed to the lower dielectric constants exhibited by both crystalline phases compared to the parent lithium aluminosilicate glasses. Furthermore, the presence of glass crystals effectively immobilized the alkali metal ions within the glass phase, impeding their movement under an electric field. Consequently, the dielectric loss value of the glass-ceramics decreased with the increasing amount of precipitated crystals. By carefully adjusting the composition and optimizing the crystallization process, we successfully produced lithium aluminosilicate glass-ceramics, demonstrating excellent mechanical and optical properties, coupled with low dielectric properties.

Synthesis and Sorption Properties of Lithium Aluminosilicate

Synthesis and Sorption Properties of Lithium Aluminosilicate