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The effect of boron substitution for aluminium on the microstructure of calcium fluoro-aluminosilicate glasses and glass-ceramics
摘要： Calcium fluoro-aluminosilicate (4.5SiO2-3Al2O3-1.5P2O5-3CaO-2CaF2) glasses have significant applications in the medical and dental fields. However, due to the biological hazard of aluminium in the human body, this study focused on the influence of boron substitution for aluminium on the structure and properties of a series of substituted glasses and their correlated glass-ceramics. The results indicated that by increasing the amount of boron, the density of glasses and their glass-ceramics both decreased, whereas the number of bridging oxygens in the glasses increased. The glass transition temperature and the crystallization temperature remained almost unchanged for the glasses with a boron substitution of less than 25 mol%. Boron formed oxygen bridges in all glasses in the form of BO3 triangles and BO4 tetrahedra. Reducing the Al content in glasses, had an effect on the morphology and orientation of the fluorapatite crystal phase formed.
关键词： Mullite,Fluorapatite,Boron-Substitution,Calcium fluoro-aluminosilicate glasses
更新于2025-09-23 15:21:21
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Morphological characteristics of nanoholes induced by single-shot femtosecond laser ablation of borates and aluminate silicates
摘要： Single-shot femtosecond laser ablation experiments with linearly and circularly polarized light were conducted in order to investigate the morphological characteristics of surface nanostructures in lithium borate crystals and glasses, a strontium borate crystal, lanthanide containing borate crystals, and aluminate silicate crystals: Li2B4O7 (LTB) and LiB3O5 (LBO) crystals and Li2O?2B2O3 (LTB) and Li2O?3B2O3 (LBO) glasses; SrB4O7 (SBO) crystal; Li6Gd(BO3)3 (LGB) and LaSc3(BO3)4 (LSB) crystals; and Ca2Al2SiO7 (CAS) and CaSrAl2SiO7 (CSAS) crystals. In the present study, the material and laser polarization dependance of the morphology of nanoholes was examined in these crystals and glasses. A single nanohole or two holes (a primary hole and a secondary hole) were observed in the borate and aluminate silicate crystals. The size of the nanohole is not restricted by the diffraction limit but instead is dependent on the laser fluence and the materials. It is suggested that the formation of these secondary nanoholes in the studied crystals is attributed to a spontaneous reshaping of the incoming Gaussian pulse into a Gaussian–Bessel pulse. In the LTB and LBO crystals, nanoholes (both primary and secondary holes) with subwavelength sides exhibit a quadrilateral (approximately square or rectangular) morphology, regardless of linear or circular polarization. The sides of the quadrilateral nanoholes lie approximately in the {h h 0} planes on the LTB crystal and in the ({h 0 0} and {0 0 l}) planes on the LBO crystal. We found that the nanohole morphology did not reflect the spatial distribution of the laser intensity. These phenomena were the first observations on the anisotropic morphology of nanoholes. These morphologies do not correspond to the circular symmetric pattern of the Gaussian intensity distribution of the incoming laser beam. This is contrary to the expectations based on the generally accepted laser ablation mechanism. The quadrilateral nanoholes could be an inherent morphology in the LTB and LBO crystals. The morphology of the network structure in their quadrilateral holes in the LTB and LBO crystals is considered to reflect the continuous BO3 and/or BO4 3? 5? respective tetragonal or orthorhombic unit cells, in which self-tapped excitons are formed in an initial process under multiphoton excitation. In contrast, the SBO, LGB, LSB, CAS, and CSAS crystals and the LTB and LBO glasses exhibit circular nanoholes with subwavelength diameters independent of the laser polarization, the structure, or the composition. The isotropic morphology of nanoholes in these samples reflects the circular pattern of the Gaussian intensity profile of the focused laser beam.
关键词： borate,single pulse,aluminosilicate,scanning electron microscopy,crystal structure,nanohole morphology,femtosecond laser ablation,nanostructuring
更新于2025-09-23 15:19:57
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Kinetics of crystallization in 13.2Li2O-67.6SiO2-14.49Al2O3-3.3TiO2-0.4BaO-0.97ZnO glass ceramic powder: Part I: A model-free vs. model-fitting approach
摘要： Crystallization kinetics of lithium aluminosilicate glass powder has been investigated by model-free and model–fitting methods. Non-isothermal experiments were carried out using differential scanning calorimetry (DSC) to monitor crystallization behavior. Model-free activation energy has been calculated based on Ozawa-Flynn-wall (OFW), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods during crystallization progress. Although activation energy does not significantly differ between the models (400 to 470 kJ/mol), partial Avrami coefficient n(α) varies considerably with rate and crystallization progress. A better description of the crystallization behavior could be observed by the comparison of model-free and model fitting methods. The conformity of one model has been approved with comparison of theoretical DSC curve and experimental results. Finally, a model which can more accurately describe the crystallization behavior of this material was suggested.
关键词： aluminosilicate,Kinetics,model-free,model-fitting,lithium,crystallization.
更新于2025-09-19 17:15:36
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Effect of normal scratch load and HF etching on the mechanical behavior of annealed and chemically strengthened aluminosilicate glass
摘要： Micro-cracks generated by hard body scratch are a major cause of strength decrease for silicate glass. The influence of normal scratch load on the cracking patterns and flexural strength of annealed glass (AG) and chemically strengthened glass (CSG) were studied. With the increase of the normal load, the load capacity of scratched AG specimens decreased to about 40MPa at 20gf immediately. However, the residual strength of CSG decreased to a steady value of 145MPa as the scratch load increased to 500gf. Then the effect of hydrofluoric acid (HF) etching on the surface morphology and mechanical properties of the 500gf scratched glass were investigated. After 8min (for CSG) and 16 min (for AG) acid treatment, the flexural strength of CSG and AG increased to a considerable value of 900MPa, which is 3.6 and 5.5 times higher than the flexural strength of undamaged specimens. Microscopic observations show that the blunting and eliminating of median cracks as well as the formation of new surfaces are the main causes of strength enhancement.
关键词： morphology,aluminosilicate glass,scratch,flexural strength,HF etching
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Study of Tm-Doped Aluminosilicate Films for Integration of Lasers on a SOI Silicon Photonics Platform
摘要： Thulium-doped glass has recently been highlighted as a potential candidate for amplifiers in a new telecommunications window, due to its potential for strong gain across a broad bandwidth in the 2-micron regime. However, the use of such technology in a silicon or planar platform has received much less attention. Lack of on-chip lasers is an obstacle to progress in silicon photonics with much research focused on mounting processed III-V lasers, bonding gain material, or the deposition of gain material onto SOI wafers. Here we report the preparation and study of Tm-doped aluminosilicate glass, which has been demonstrated as an efficient laser/amplifier in fibre-technology covering a 1.7-2.1 μm window. To achieve efficient operation the Tm3+ doping concentration is typically optimised for enhancing cross relaxation energy exchange between the 3H4 and 3F4 energy levels allowing an efficient “two-for-one” pumping approach. Fluorescent emission and gain can then be achieved by pumping with readily available ~795 nm sources diode-lasers. As such we have started preliminary investigations of higher concentrations to attempt to obtain enhanced gain per unit length devices.
关键词： silicon photonics,2-micron regime,Tm-doped aluminosilicate,on-chip lasers,cross relaxation energy exchange
更新于2025-09-11 14:15:04
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Transparent Conductive Films Derived from Single-Walled Aluminosilicate Nanotubes
摘要： This study reports on an approach to enhancing the performance of silver nanowire (AgNW)-based transparent conducing films (TCFs) via introducing an emerging class of nanotubes, aluminosilicate nanotubes (AlSiNTs), which can reduce silver ions to form silver nanoparticles (AgNPs). This reaction was carried out in a suspension of AlSiNTs and AgNO3(aq) under ambient conditions, i.e., without the need for additional reducing agents. The results of material characterization suggest that the AlSiNTs collapse after the formation of AgNPs. Computation based on density functional theory (DFT) was used to gain insight into the reducing capability of AlSiNTs. The computational results suggest that octahedral aluminum plays a key role in the transfer of charge from AlSiNTs to adsorbed silver ions. A solution of AlSiNT-AgNP was mixed with a commercial AgNW suspension and deposited on a flexible PET substrate to form TCFs. The addition of AlSiNT-AgNP was shown to improve the connectivity of AgNWs and thus enhance the overall transparency as well as the conductivity of the TCFs. In fact, the TCFs proposed in this work outperform most existing metal oxides- or AgNW-based TCFs.
关键词： aluminosilicate nanotube,transparent conducing film,flexible TCF,imogolite,density functional theory
更新于2025-09-11 14:15:04
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Standard and modified Judd-Ofelt theories in Pr3+-doped calcium aluminosilicate glasses: A comparative analysis
摘要： The small energy difference between the fundamental level and the first opposite parity configuration of Pr3+-doped hosts is particularly challenging for the characterization of radiative transitions using the Judd-Ofelt theory, although modified versions of the theory have been proposed in the past for the investigation of praseodymium doped materials. Here, we present a detailed spectroscopic investigation on two sets of calcium aluminosilicate glasses, with 34 wt.% of SiO2 (CAS) and with 7 wt.% of SiO2 (LSCAS), doped with different concentrations of Pr3+ (0.5, 1.0 and 2.0 wt.%). We use the standard Judd-Ofelt theory to characterize the glasses and the results and derived spectroscopic quantities — such as transition probabilities, radiative lifetimes and branching ratios — are compared to results obtained by the modified Judd-Ofelt theories. The analysis showed that the modified theories could lead to smaller values of root mean square deviations. However, a better agreement between experimental data and the standard theory was achieved when the derived spectroscopic quantities are taken into account. Moreover, the branching ratios of the 3P0 → 3H4 and 1D2 → 3H4 transitions were over 60% for both glass hosts, suggesting its potential use as solid-state laser devices.
关键词： Standard Judd-Ofelt theory,Aluminosilicate glass,Modified Judd-Ofelt theory,LSCAS:Pr3+,CAS:Pr3+
更新于2025-09-10 09:29:36
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Structural, Optical and Magnetic Properties of Ultramarine Pigments: A DFT Insight
摘要： The ultramarine pigments are among the most widely used coloring materials since the antiquity till present times. Despite many experimental studies, the characterization of ultramarines is still incomplete. In this work we reported for the first time the density functional theory results obtained for realistic periodic and large cluster models of ultramarines with blue S3- and yellow S2- chromophores. Periodic calculations provided insight into Sn- siting inside aluminosilicate cages, normally not resolved well in experimental structural data. All electron calculations performed on large cluster models showed that the optical properties of S3- ions depend little on their orientation within cavities, unless strong distortion from free S3- ion C2v symmetry is enforced by the lattice. No magnetic coupling between S3- species occupying adjacent cages was found. Upon the present results observed differences in the averaging of electron resonance signals should be rather ascribed to different S3- dynamical effects. Though the quantitative computational treatment of S2- systems is more challenging, due to near orbital degeneracy, the qualitative results show that the electronic structure and spectroscopic properties of embedded S2- radicals are more sensitive to the environment than in the case of S3- species.
关键词： S3- chromophores,density functional theory,S2- chromophores,magnetic properties,aluminosilicate cages,ultramarine pigments,optical properties
更新于2025-09-10 09:29:36