Glass Aluminum Research Articles

Tantalum-lanthanum mixing effect on structural and mechanical properties of aluminate glasses

Aluminate glasses are known for their superior mechanical and optical properties. Here, we investigated the tantalum (Ta)-lanthanum (La) mixing effect on structural and mechanical properties of these glasses. Using the aerodynamic levitation and laser melting technique, we prepared a series of aluminate glasses with the molar composition 54Al2O3·(46-x)La2O3·xTa2O5, where x = 0.0, 9.2, 18.4, 23.0, 32.2, 36.8, and 46.0. The structural, thermal, and mechanical analyses revealed that substituting Ta for La strongly impacted the local Al environment in the glasses, thereby affecting their glass transition temperature and mechanical properties. The Vickers microhardness (HV) varied non-monotonically with the molar ratio R (defined as Ta/(Ta+La) = x/46), reaching a maximum HV value of 8.59 GPa at R = 0.8. This trend was explained in terms of both the average bond energy and the bond number density. Moreover, the crack initiation resistance of the studied glasses increased as R rose. This work aids in the design of oxide glasses with high crack resistance and hardness.

Hot press sintering of Y2O3-Al2O3 glasses: Impact of particle size on thermal behaviour, sintering ability and mechanical properties of sintered bodies.

The impact of grinding on particle size, thermal behaviour, and sintering ability of yttrium aluminate glass microspheres with eutectic composition (76.8mol % Al2O3 and 23.2mol % Y2O3) was studied. The work was conducted with the aim of determining the optimal particle size and grinding conditions of glassy powder used for hot-pressing of ceramic and glass-ceramic materials with desired mechanical properties. The flame synthesis was used for the preparation of glass microspheres (diameter∼40μm). Ball milling procedure under different conditions was applied to adjust of size of prepared microbodies. The milled powders were subsequently hot pressed. The prepared samples (raw, milled microspheres and hot-press sintered bodies were characterised by X-ray powder diffraction, and scanning electron microscopy. Thermal analysis and particle size analysis in combination with X-ray powder diffraction and high temperature X-ray diffraction was used for detailed inspection of thermal behaviour and phase changes in raw and milled systems in the temperature interval 25-1200°C. The samples after flame synthesis and after milling were found to be X-ray amorphous. The particle size measurements showed that the systems with a smaller average size D [0.9]∼25μm and a monomodal particle size distribution were prepared after 6h of milling. Thermal analysis in combination with X-ray and high temperature X-ray analysis indicated a difference in the crystallization mechanism of the yttrium aluminate garnet phase depending on the milling time. The bulk glass ceramic with fine lamellar eutectic microstructure and interesting mechanical properties (Vickers hardness HV=17.6±0.2GPa, indentation fracture toughness KIC=4.3±0.3MPa.m1/2) resulted from the sintering of microspheres milled for 6h under the "gentlest" conditions (milling speed - 200rpm, and milling balls size - 5mm in diameter).

Defect center–tailored calcium aluminate glasses for photonic applications: Unveiling structure–diffusivity correlation

AbstractCalcium aluminate (CA)‐based glasses have drawn significant attention owing to their pronounced optical, mechanical, and chemical properties for potential applications in IR photonics. Nonetheless, limitations related to their poor glass‐forming ability was addressed by incorporating ZnO that has formed negatively charged [ZnO4]2− and [AlO4]− units, thereby generating the oxygen‐excess defects. These defects impart a detrimental effect on the optical properties. Thus, the present study explores the impact of Li2O, Na2O, K2O, and GeO2 inclusion in the barium–zinc–calcium–aluminate (BZCA) glass to eliminate the oxygen‐excess defects. The molecular structure of the glass matrix was examined by Raman, NMR, and XPS along with the bulk diffusivity of the glasses through MD simulation and are correlated to elucidate the origin of the defect centers. Due to higher diffusivity, Li+ and Na+ cations decrease Al–O hole centers (Al–OHC) and defects but promote F+ (Farbe) centers while K+ ions having lower diffusivity and enhance the defects. Interestingly, all the defect centers are substantially reduced in GeO2‐containing glasses. Further, multivalent Cr ions are doped to optically probe the defect centers through UV–Vis–NIR absorption and photoluminescence spectra. Cr3+ and Cr4+ are found dominant in Li+‐and Na+‐containing glasses due to the presence of less defect, whereas excess converts all Cr3+ into Cr6+ for K+‐containing glasses. Additionally, broadband NIR emission from Cr4+ can functionalize selective glasses for laser and telecommunication applications.

Self-reducing induced Eu2+/Eu3+ dual-emitting glasses for anti-counterfeiting and optical thermometry

Eu3+/Eu2+ co-doped glasses possess extensive application potential in diverse fields, including light-emitting diodes and sensors, due to their distinctive luminescent characteristics. To date, numerous strategies have been devised to facilitate the coexistence of Eu3+ and Eu2+ in materials. Among them, adjusting the composition of the glass matrix stands out as a straightforward and reproducible approach. Herein, a series of Eu2+/Eu3+ co-doped borosilicate aluminate glasses were successfully synthesized via a high-temperature melting method. By elevating the ratios of B2O3/MgO and Al2O3/BaO in the matrix, a remarkable self-reduction of Eu3+ in ambient air was achieved because of the structural weakness and lower optical basicity for the designed glass matrix. The reduction of Eu3+ is also related to the formation of EuZn• and VΖn′′ defects. Furthermore, by fine-tuning the melting duration and Eu content, we achieved comparable violet and red emission intensities for both Eu2+ and Eu3+ ions. Under UV irradiation with various wavelengths, anti-counterfeiting patterns fabricated from glass powder exhibited precise and pronounced color changes. Notably, the emission intensity ratio of Eu2+/Eu3+ exhibited a consistent decrease as temperature increased, enabling precise temperature determination with exceptional absolute sensitivity (1.22 % K−1) producibility, and discrimination. These findings hold significant implications for the design of Eu3+/Eu2+ co-doped inorganic multifunctional glasses.

Systematical investigations on the influence of Stark splitting of Er3+ on the potential wavelength-tunable of laser and optical amplification in several glasses

Er3+-doped glasses and fibers with broadband near infrared (NIR) emission have been widely applied in EDFA. Limited by optical gain band of Er3+-doped glasses and fibers, it was hardly meet to the demands of broadband amplification in the C + L band. In this work, six glass matrixes were employed for discussing the influence of glass matrix on the Stark splitting of Er3+ and the wavelength of laser output and amplification. The larger scalar crystal-field parameter NJ induce larger Stark splitting of Er3+-doped tellurite, germanate, and fluorophosphate glasses, which resulted in larger Δλeff. The Stark splitting of Er3+-doped tellurite, germanate, silicate, and phosphate glasses was mainly derived from homogeneous broadening, which be favor to obtain longer wavelength amplification and laser output. While that of Er3+-doped fluorophosphate and aluminate glasses was mainly derived from the inhomogeneous broadening, the amplification and laser output of Er3+ tend to operate in the shorter wavelength.

Deciphering the Nd3+ environment and energy-transfer mechanisms in thermally stable novel calcium aluminate glasses: elucidation of broadband high-gain performance for laser applications

Rare-earth-doped barium calcium aluminate (BCA) glasses, having extended infrared (IR) transmission (6 μm), are attractive materials for near IR (NIR) photonic applications. Nd2O3-doped BCA glasses display broadband emission at 1.07 µm, but they are limited, with poor glass-forming ability (GFA) and low emission cross sections. In the present study, four different barium zinc calcium aluminate (BZCA) glasses are synthesized with varied ZnO concentrations (from 9.5 to 24.5 mol%) and doped with 0.5 mol% Nd2O3 to decipher the effect on GFA and spectroscopic properties. The addition of ZnO enhances the GFA, and the NdBZCA20 glass shows the maximum GFA. Ultraviolet (UV)–visible (Vis)–NIR absorption spectra reveal a decreasing trend in the nephelauxetic effect, while J–O parameters, emission, and gain properties lead to no significant alteration with increasing ZnO, and the structure–properties correlation is established accordingly. However, the emission cross sections for all ZnO concentrations are found ∼4.5 × 10−20 cm2 accompanied by broadband emission (Δλ eff ∼ 40 nm), which ensures the potentiality of these glasses for low-threshold high-gain laser applications as well as ultrashort pulse laser applications. Furthermore, a thorough analysis of 1.06 µm emission as a function of Nd concentration in the BZCA20 glass is reported here. The emission spectra and decay time indicate that 0.5 mol% is the optimized doping concentration. Inokuti–Hirayama and Burshtein equations are adopted to study the decay kinetics and energy-transfer mechanisms, which confirm that the energy-transfer process due to cross-relaxation is dominant up to 0.5 mol% concentration, whereas, beyond that concentration, excitation energy migration via the hopping mechanism supersedes.

Broadband ∼2 μm luminescence properties and energy transfer in Tm3+/Ho3+ co-doped TeO2–Al2O3–BaF2 glass

Tm3+/Ho3+ co-doped tellurite aluminate glasses were prepared using the melt-quenching technique. Under 808 nm laser diode (LD) excitation, these glasses exhibit intense 2 μm band luminescence, with a full width at half-maximum (FWHM) of 144 nm. The energy transfer mechanism between Tm3+ and Ho3+ was explored to investigate the luminescence behavior further. Furthermore, the forward energy transfer coefficient (Tm3+→Ho3+) is greater than the backward energy transfer coefficient (Ho3+→Tm3+), indicating that Tm3+ can effectively sensitize Ho3+. As mentioned above, Tm3+/Ho3+ co-doped tellurite aluminate glass is a competitive material in the laser field.

Enhancing glass-forming ability and mechanical properties of barium-calcium-aluminate glasses through ZnO inclusion

Calcium aluminate (CA) glasses have garnered attention in the field of infrared photonics due to their low phonon energy. Nonetheless, the poor glass-forming ability (GFA) and strong crystallization tendency have hindered their utilization in various technological applications. Therefore, we demonstrate here that the substitution of ZnO for CaO enhances the GFA of 29Al2O3–(66X)CaO–5BaO–(X)ZnO (X = 0,7,10,15,20,25) glasses and improves their mechanical properties. The structural characterization using Raman, 27Al MAS-NMR spectroscopy and MD simulations reveal that, Zn2+ ions adopt tetrahedral coordination and contribute as network formers along with Al3+ ions. Notably, MD simulations indicate a preference of ZnO4 units for the CaO6 sites to convert non-bridging oxygens to bridging oxygens. The decrease in glass transition temperature and the increase in elastic modulus is noticed which correlated with the structural changes in the studied glasses. These findings provide valuable insights into the design and development of stable multicomponent CA glasses for photonic applications.

Surface-silanized glass nanofibers and aluminate nanoparticles as reinforcing agents for acrylic emulsion toward multifunctional stimuli-responsive composite coatings

Smart waterborne coatings have shown various functions, such as afterglow photoluminescence, antimicrobial activity, water resistance, ultraviolet blocking, and anti-counterfeiting properties. However, photoluminescent organic agents have shown poor photostability and high cost. Additionally, waterborne acrylic coatings have shown poor mechanical properties. Herein, nanoparticles of rare-earth strontium aluminate (NRESA) and electrospun glass nanofibers (EGN) were used to strengthen the bulk of acrylic (ACR) coatings to develop smart products with mechanical reliability, hydrophobicity, ultraviolet blocking, and persistent photoluminescence. By physically integrating nano-scaled particles of RESA, colorless smart coatings of EGN@ACR were produced. Photoluminescence spectra showed that the transparent EGN@ACR changed its appearance to greenish when exposed to ultraviolet rays. Hybrids of EGN@ACR with trace amounts of NRESA showed fluorescence emission with instant reversibility. As the phosphor concentration in the EGN@ACR hybrids increased, afterglow photoluminescence with delayed reversibility was detected. When excited at 370 nm, the hybrid coatings displayed an emission band at 519 nm. The morphological analysis of NRESA by transmission electron microscopy (TEM) displayed diameters of 9–21 nm. After being prepared using electrospinning technology, glass nanofibers were introduced into acrylic emulsion coatings as a reinforcement agent. Scanning electron microscopic (SEM) analysis of EGN showed diameters of 70–120 nm. The smart coatings had better resistance to scratches as compared to the control sample of NRESA-free acrylic paint. A higher concentration of NRESA resulted in enhanced hydrophobicity and ultraviolet blocking.

A new Topp-Leone Kumaraswamy Marshall-Olkin generated family of distributions with applications

We aim in this paper to propose a novel class of distributions that was created by merging the Topp-Leone distribution and the Generated families of Kumaraswamy and Marshall-Olkin. Its cumulative distribution function characterizes it and includes rational and polynomial functions. In particular, the following desirable properties of the new family are presented: Shannon entropy, order statistics, the quantile power series, and several associated measures and functions. Then, using a specific family member identified before, we create a parametric statistical model with the basic distribution being the inverse exponential distribution. Finally, a thorough investigation has been made to implement this new distribution with three data sets: the glass fibers data set, the glass Alumina data set and the hailing times data set. In comparison to six prominent competitors, the new model performs favorably on all statistical tests and criteria that were examined.

Single-mode lasing in diode-pumped passive Q-switch lasers based on neodymium-doped yttrium aluminate and ytterbium-erbium glass active elements

Single-mode lasing in diode-pumped passive <i>Q</i>-switch lasers based on neodymium-doped yttrium aluminate and ytterbium-erbium glass active elements

Investigation of mechanical properties of aluminum–glass fiber-reinforced polyester composite joints bonded with structural epoxy adhesives reinforced with silicon dioxide and graphene oxide particles

In this work, to investigate the mechanical properties of aluminum–glass fiber-reinforced polyester composite joints bonded with structural epoxy adhesives reinforced with silicon dioxide (SD) and graphene oxide (GO) particles, firstly, SD and GO particles were added to epoxy adhesive in varied weight percentages. After the surface treatment made by sanding aluminum and composite sheets with abrasive sandpaper, aluminum sheets and glass fiber-reinforced polyester composite sheets were bonded. Adhesives containing 0.2% SD and 0.25% GO had tensile strengths that were approximately 15.89% and 14.03% greater than neat epoxy, respectively. The lap shear strength of neat epoxy was improved with the addition of filler in all samples, and 0.2% SD and 0.25% GO-reinforced adhesives increased the shear strength of the neat epoxy by 66.57% and 125%, respectively. The adhesion, thin-layer cohesive and light-fiber tear were noted, as well as cohesive and fiber-tear failures based on the damaged surfaces of the samples.

Transparent glaze containing high-alumina glass frit: Batch-to-melt conversion

The use of high alumina (HA) glass frits in the production of transparent glazes is of potential technological interest due to their excellent mechanical properties. However, their strong tendency to crystallize limits their practical application. A transparent glaze was obtained by adding 30% by weight of the HA frit to a low-melting glaze fired at 1453 K for 30 min with a hardness between 5.92 GPa and 6.46 GPa. The crystallization and melting behavior of an HA frit mixed with a low-melting glaze model batch is investigated by studying the interaction between a compacted raw low-melting glaze placed on the polished surface of bulk HA glass. With increasing temperature, the low-melting glaze batch melts while CaAl2Si2O8 and MgAl2O4 crystallize in the HA frit. The melt surrounding the HA frit decreases the number of active nucleation sites weakening surface crystallization. In addition, the alkali cations in the melt tend to diffuse into the crystallized HA frit, reducing the viscosity of the layer surrounding the crystals, which accelerates their dissolution. The results provide information on the batch-to-melt conversion mechanism of high alumina content transparent glazes.

The Correlation of LVI Parameters and CAI Behaviour in Aluminium-Based FML.

An experimental analysis of mechanical behaviour for aluminium-based fibre metal laminates under compression after impact was conducted. Damage initiation and propagation were evaluated for critical state and force thresholds. Parametrization of laminates was done to compare their damage tolerance. Relatively low-energy impact had a marginal effect on fibre metal laminates compressive strength. Aluminium-glass laminate was more damage-resistant than one reinforced with carbon fibres (6% vs. 17% of compressive strength loss); however, aluminium-carbon laminate presented greater energy dissipation ability (around 30%). Significant damage propagation before the critical load was found (up to 100 times the initial damaged area). Damage propagation for assumed load thresholds was minor in comparison to the initial damage size. Metal plastic strain and delaminations are dominant failure modes for compression after impact.

Harnessing Brillouin interaction in rare-earth aluminosilicate glass microwires for optoelectromechanic quantum transduction

Quantum transduction, the process of converting quantum signals from one form of energy to another is a key step in harnessing different physical platforms and the associated qubits for quantum information processing. Optoelectromechanics has been one of the effective approaches to undertake transduction from optical-to-microwave signals, among others such as those using atomic ensembles, collective magnetostatic spin excitations, piezoelectricity and electro-optomechanical resonator using Silicon nitride membrane. One of the key areas of loss of photon conversion rate in optoelectromechanical method using Silicon nitride nanomembranes has been those in the electro-optic conversion. To address this, we propose the use of Brillouin interactions in a fiber mode that is allowed to be passed through a fiber taper in rare-earth Aluminium glass microwires. It suggests that we can efficiently convert a 195.57 THz optical signal to a 325.08 MHz microwave signal with the help of Brillouin interactions, with a whispering stimulated Brillouin scattering mode yielding a conversion efficiency of ∼45%.

Preparation and photochromic behavior of borosilicate aluminate glass for smart window and curtain wall applications

Sunlight-induced photochromic glass exhibits attractive application prospects in the field of architecture materials. In this work, a series of borosilicate aluminate photochromic glasses containing AgCl nanocrystals were prepared. The photochromic property and mechanisms were systematically investigated. The color of the glass turned from transparent to black (or dark grey) under the irradiation of 365 nm ultraviolet light (or sunlight). Placing in a dark environment, the color of photochromic glass gradually restores to its initial state. From the results of in situ TEM and XPS measurement, it is found that the photochromic and self-bleaching behavior of borosilicate aluminate glass originated from the formation and decomposition of silver nanoparticles. Utilizing the photochromic and self-bleaching properties of the glass, the transmittance of the glass could be reversibly modulated. The cycle measurement shows excellent repeatability, demonstrating the potential application of AgCl-contained borosilicate aluminate photochromic glass in the fields of smart building windows and curtain walls.

Development and Investigation of a Fire-Resistant Aluminum–Glass Fiber Reinforced Plastic for a Helicopter Engine Cowl

Development and Investigation of a Fire-Resistant Aluminum–Glass Fiber Reinforced Plastic for a Helicopter Engine Cowl

Coordination Changes in Densified Aluminate Glass upon Compression up to 65 GPa: A View from Solid-State Nuclear Magnetic Resonance.

Deciphering the structural evolution in irreversibly densified oxide glasses is crucial for fabricating functional glasses with tunable properties and elucidating the nature of pressure-induced anomalous plastic deformation in glasses. High-resolution NMR spectroscopy quantifies atomic-level structural information on densified glasses; however, its application is limited to the low-pressure range due to technical challenges. Here, we report the first high-resolution NMR spectra of oxide glass compressed by diamond anvil cells at room temperature, extending the pressure record of such studies from 24 to 65 GPa. The results constrain the densification path through coordination transformation of Al cations. Based on a statistical thermodynamic model, the stepwise changes in the Al fractions of oxide glasses and the effects of network polymerization on the densification paths are quantified. These results extend the knowledge on densification of the previously unattainable pressure conditions and contribute to understanding the origin of mechanical strengthening of the glasses.

Development of Photoluminescent and Photochromic Polyester Nanocomposite Reinforced with Electrospun Glass Nanofibers.

A polyester resin was strengthened with electrospun glass nanofibers to create long-lasting photochromic and photoluminescent products, such as smart windows and concrete, as well as anti-counterfeiting patterns. A transparent glass@polyester (GLS@PET) sheet was created by physically immobilizing lanthanide-doped aluminate (LA) nanoparticles (NPs). The spectral analysis using the CIE Lab and luminescence revealed that the transparent GLS@PET samples turned green under ultraviolet light and greenish-yellow in the dark. The detected photochromism can be quickly reversed in the photoluminescent GLS@PET hybrids at low concentrations of LANPs. Conversely, the GLS@PET substrates with the highest phosphor concentrations exhibited sustained luminosity with slow reversibility. Transmission electron microscopic analysis (TEM) and scanning electron microscopy (SEM) were utilized to examine the morphological features of lanthanide-doped aluminate nanoparticles (LANPs) and glass nanofibers to display diameters of 7-15 nm and 90-140 nm, respectively. SEM, energy-dispersive X-ray spectroscopy (EDXA), and X-ray fluorescence (XRF) were used to analyze the luminous GLS@PET substrates for their morphology and elemental composition. The glass nanofibers were reinforced into the polyester resin as a roughening agent to improve its mechanical properties. Scratch resistance was found to be significantly increased in the created photoluminescent GLS@PET substrates when compared with the LANPs-free substrate. When excited at 368 nm, the observed photoluminescence spectra showed an emission peak at 518 nm. The results demonstrated improved hydrophobicity and UV blocking properties in the luminescent colorless GLS@PET hybrids.

Determination of the Pressure Dependence of Raman Mode for an Alumina–Glass Pair in Hertzian Contact

Optimising the performance of materials requires, among other things, the characterisation of residual stresses during the design stage. Raman spectroscopy offers access to these residual stresses at the micrometre scale when this inelastic light scattering is active in these materials. In this case, the relationship between the Raman mode shift and the pressure must be known. High-pressure cells with diamond anvils or bending instruments coupled to Raman spectrometers are habitually used to determine this relationship. In this article, we propose a new method that involves a Hertzian contact to obtain this relationship. A device that compresses an alumina ball against a transparent glass plane is connected to a Raman spectrometer. Under these conditions, the contact pressure can be as high as 1.5 GPa. The contact between the glass plane and the ball is observed through a diaphragm. Several hundred Raman spectra are recorded depending on the contact diameter. The spectral profiles obtained represent the shift in the Raman modes of alumina and glass along the contact diameter. Hertz's theory accurately describes the pressure profile as a function of position for elastic materials. Therefore, the contact diameter can be measured by fitting the spectral profile with a function identical to the Hertz profile. We then deduce the maximum pressure. Next, the calculated pressure profile along the contact diameter is correlated with the spectral profile. We obtain a pressure dependence of the Raman mode with a coefficient equal to 2.07 cm-1/GPa for the Eg modes of alumina at 417 cm-1, which is in good agreement with the literature. In the case of glass, we refine the measurement of the Q3 mode shift at 1096 cm-1 in the studied pressure range compared to the literature. We find a coefficient of 4.31 cm-1/GPa. This work on static contacts opens up promising prospects for investigations into dynamic contacts in tribology.