Improving the optical properties of float glass

The nature of the defects that cause optical distortions in glass is analyzed. It was found that 70% of the optical defects in float glass is due to streak formation in the melt bath. Methods were developed for manufacturing float glass that increase its quality with respect to the optical indexes.     

Physical and optical properties of TeO2-WO3-GdF3 tellurite glass system

In the TeO₂-WO₃-GdF₃ glass system, 42 different proportions of glass have been prepared, showing the ideal forming area. The influence of proportions on the density was measured and several devitrified samples were analyzed by XRD. Discussed the internal structure changes and the variation of component concentration by Raman and Fourier transform infrared spectra. The properties and structural features of glasses were analyzed in terms of molar volume. TeO₂ and WO₃ act as glasses former while GdF₃ act as a modifier which forms mixed linkages Te–O–W, Te–F–W, etc. UV–Vis spectra were recorded to determine optical absorption/transmission and energy gap values. These results suggest that the TeO₂-WO₃-GdF₃ glass system could be potentially used as photonic devices and basic materials.     

Synthesis and optical properties of glass with cadmium sulfide nanoparticles

A new approach to the synthesis of silicate glass with cadmium sulfide (CdS) nanoparticles has been developed. It has been demonstrated that replacement of cadmium sulfide with cadmium oxide and zinc sulfide used as sources of cadmium and sulfur allows a substantial reduction of sulfur volatilization during the melting. The produced samples have been investigated by the methods of spectrophotometry in the ultraviolet and visible ranges of the optical range. Thermal treatment of the samples at temperatures exceeding the glass formation point initiates the growth of CdS nanoparticles, which results in the increase of their average size from 3 to 5.2 nm and a significant shift of the fundamental absorption edge to the longer wavelength range from 380 to 480 nm.     

HfO2-based refractory compounds and solid solutions: I. Phase diagrams of the systems HfO2M2O3 and HfO2MO

This paper is a review of works performed mainly in the USSR. The purpose of many of these works was the finding of new refractory compounds which could create the basis of high-refractory materials. The objects of the investigations were hafnium dioxide (HfO₂) and oxides of alkali-earth and rare-earth elements. The phase diagrams for the systems HfO₂Ln₂O₃ and HfO₂MO are given as well as the structures of the compounds and solid solutions formed in the systems.     

Preparation and optical properties of CdxHg1-xTe doped silica glass

In this paper, the Cd_xHg_1-xTe (x=1-0.7) doped silica glass was prepared through two step sol-gel process and in-situ growth technique from tetraethoxysilane (TEOS), cadmium acetate, mercury acetate and telluric acid. The influence of various factors on the glass was studied. The structure of the microcrystals was investigated by XRD. The absorption and transmittance spectrum of the composite showed that the shift of absorption edge was in conformity with the quantum size effect. The third-order nonlinear optical susceptibility χ⁽³⁾ was measured by the degenerate four wave mixing (DFWM). The values of χ⁽³⁾ was in the range of 10^-11-10^-12 MO esu at wavelength of 1.06 μm.     

Preparation and characterization of HfO2/VO2/HfO2 sandwich structures with low phase transition temperature,excellent thermochromic properties,and superior durability

In the last few decades, smart windows made from VO₂-based thermochromic films have attracted extensive attention, but their actual commercial applications are limited by low luminous transmittance (T_lum), low solar modulation ability (ΔT_sol), high phase transition temperature (T_c), and poor durability. In this study, glass/HfO₂/VO₂/HfO₂ tri-layer films were designed and deposited on glass substrates by pulse laser deposition. Crystal structures, surface morphology, surface roughness, electrical properties, and optical properties of as-prepared sandwich structure films were analyzed. Results showed that both HfO₂ buffer layer and antireflection layer (ARL) were monoclinic phase and grew along the (020) and (?111) crystal planes, respectively. HfO₂ buffer layer not only reduced T_c of VO₂ film by about 20 °C, but also played an important role in regulating crystal quality and surface morphology of VO₂ films. More importantly, by covering films with HfO₂ ARL, T_lum and ΔT_sol of VO₂ film were greatly improved. In particular, when the thicknesses of HfO₂ buffer layer and ARL were 80 nm and 120 nm, the obtained HfO₂/VO₂/HfO₂ tri-layer film reached a balance between high T_lum (～47.2%), high ΔT_sol (～9.1%) and low T_c (～49.1 °C). In addition, after 216 h of boiling water treatment, T_lum and ΔT_sol of HfO₂/VO₂/HfO₂ film covered with 120 nm thick ARL still remained at 49.3% and 7.0%, showing excellent durability. This research provides a new strategy for designing VO₂-based smart windows with high performance and good durability.     

Eutectoid decomposition processes of solid solutions in the HfO2  PrO1.5 and HfO2  MgO systems and their influence on the physico-chemical properties of refractory materials

Microscopy and electron microprobe analysis were used to study the process of eutectoid decomposition of cubic solid solutions in the HfO₂  PrO_1.5 and HfO₂  MgO systems. In the first system this occurs by forming of a Pr-rich pyrochlore-type phase and monoclinic HfO₂ solid solution. In the HfO₂  MgO system, magnesium concentrates mainly at crystal boundaries yielding a MgO solid solution; the second, MgO-poor phase is a HfO₂-based monoclinic solid solution. As a result of decomposition the electrical conductivity of the cubic solid solutions is reduced by two orders of magnitude in the HfO₂  PrO_1.5 system and more than orders of magnitude in the HfO₂  MgO system.     

Mechanical properties and thermal conductivities of 3YSZ-toughened fully stabilized HfO2 ceramics

In this work, the 3 mol% yttria stabilized zirconia (3YSZ) composed of tetragonal phase has been introduced into the 10 mol% Er₂O₃ stabilized cubic hafnia (10ErSH) matrix to improve its fracture toughness. The effects of the addition of 3YSZ on the phase composition, microstructure, mechanical properties and thermal conductivities of the 10ErSH have been investigated. The results showed that all the 3YSZ-toughened 10ErSH samples were composed of cubic phase and a little (<10 mol%) monoclinic phase. The introduced tetragonal phase of 3YSZ fully disappeared even when the volume fraction of 3YSZ reached 50%, indicating that the phase transformation occurred during 1500 °C. The fracture toughness for the sample with 50% 3YSZ was improved by 60% compared with the pure 10ErSH ceramics owing to the sub-mico/micro hybrid structure, which changed the crack propagation mode and consumed part of the crack extension energy. Additionally, the thermal conductivity slightly decreased due to the mass and radius misfits induced by substitution atoms (Zr⁴⁺, Er³⁺ and Y³⁺). Considering the improved mechanical and thermal properties, the 3YSZ-toughened 10ErSH ceramics may be alternative TBC materials.     

Formation of CdS nanoparticles in the matrix of silicate glass and its optical properties

CdS nanoparticles of an average diameter of ~2.7 nm have been synthesized in silicate glass by two stage heat treatment. As was demonstrated using the methods of spectrophotometry and luminescence in the ultraviolet and visible optical ranges, semiconductor phase nuclei were formed at the first stage of thermal treatment, and they grew at the second stage. The image of the spatial distribution of CdS nanoparticles in the glass network has been obtained by computer simulation. The calculated pair distribution function revealed that the average distance between nanoparticles was ~15 nm, which appears sufficient to isolate them from each other in the dielectric matrix and to ensure reliable confinement of electrons inside each nanoparticle.     

Thermal Expansion of HfO2 and ZrO2

The thermal expansion of a low symmetry crystal can be much more interesting than the lattice parameter expansion would suggest. Here, the complete thermal expansion tensors for monoclinic and tetragonal phases of ZrO₂ and HfO₂ have been measured in air, by high‐resolution, high‐temperature X‐ray diffraction. These results reveal the highly anisotropic nature of thermal expansion in the monoclinic phase as well as a cooperative movement of ions and the existence of a zero thermal expansion plane.     

The nonlinear optical properties of silver nanoparticles decorated glass obtained from sintering mesoporous powders

Silver nanoparticles (Ag NPs) have excellent third-order nonlinear optical properties but it is still difficult to obtain silica glass containing Ag NPs with homogenous dispersion and small particle size. Herein, silica glass with homogenously distributed Ag NPs in its matrix was derived from sintering a famous type of mesoporous silica (FDU-12) encapsulated with Ag NPs (Ag NPs/FDU-12) through Spark Plasma Sintering (SPS) technique. Benefited from the low-temperature sintering property of the Ag NPs/FDU-12 powders (~930°C within 5 min), the Ag NPs can be directly trapped in the derived silica glass with small particle size (<3.0 nm) and without mass loss. The as-prepared Ag NPs/glass showed a typical reverse saturable absorption curve, which is measured via the Z-scan method by using a 532 nm nanosecond laser. The nonlinear coefficient and imaginary third-order susceptibility were calculated as 11.46 cm/GW and 2.22 × 10⁻¹² esu, respectively, indicating the excellent third-order nonlinear optical properties of the Ag NPs/glass. This study demonstrates a great potential for preparing silica glasses functionalized with well dispersed ultrafine functional particles, which is appealing in photonic field.     

Morphology control and optical properties of SiGe nanostructures grown on glass substrate

With the rapid progress of nanotechnology, nanostructures with different morphologies have been realized, which may be very promising to enhance the performance of semiconductor devices. In this study, SiGe nanostructures with several kinds of configurations have been synthesized through a chemical vapor deposition process. By controlling growth conditions, different SiGe nanostructures can be easily tuned. Structures and compositions of the nanostructures were determined by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The optical properties of various SiGe nanostructures revealed some dependence with their morphologies, which may be suitable for solar cell applications. The control of the SiGe morphology on nanoscale provides a convenient route to produce diverse SiGe nanostructures and creates new opportunities to realize the integration of future devices.     

The influence of ultraviolet radiation on the optical properties of glass fibre reinforcements for polyurethane matrix composites

Polyurethanes represent one of the most frequently used polymeric matrixes in composites. Although there have been many studies focused on the weather resistance of polyurethanes, this important property is unheeded during the reinforcing phase. In this article, the effects of ultraviolet (UV) radiation on the changes in optical properties of commercially available glass fibre reinforcements containing various polymeric binders used as compatibilising agents for the polymeric matrix in the final composite products were studied. The standardised experiments were performed using accelerated ageing equipment, q‐lab ultraviolet tester, in dry mode. Chemical modification of the binder in the form of polyesters or silanes by UV irradiation was studied using Fourier Transform–infrared spectroscopy. Changes in the optical properties caused by the degradation processes of polymeric components due to UV irradiation were evaluated based on colour changes in the examined samples using the yellowness index; statistical evaluation of the data obtained was conducted with an Anderson–Darling test of normality and an ANOVA test. It was demonstrated that both the amount of the binder and the glass fibre reinforcement's construction play a more important role than the chemical structure of the binder.     

Tuning of dielectric properties in Ti-Doped granular HfO2 nanoparticles for high-k applications

An array of titanium (Ti) doped HfO₂ [(Hf_1-xTi_xO₂) (x = 0.0–1.0)] nanoparticles (NPs) synthesis and the study of their structural, spectroscopic, and dielectric properties is reported. The Hf_1-xTi_xO₂ NPs were synthesized by a sol-gel type wet chemical process. The crystal structure of pure HfO₂ and TiO₂ NPs revealed by structural analysis is monoclinic (m) and tetragonal (t), respectively. The crystallinity of the doped samples was found to be dopant concentration-dependent. The microstructure of the obtained NPs was investigated along with their spectroscopic and dielectric characteristics. The tunable dielectric properties of Hf_1-xTi_xO₂ NPs make them ideal for high frequency, high-k applications.     

Effect of Zr ions on the structure and optical properties of lithium borosilicate molybdate glass system

The glass system with the composition [(20-x) MoO₃– x ZrO₂–15 SiO₂– 65 Li₂B₄O₇, x = 0, 1, 2, 3, 4, and 5 mol %] was successfully synthesized using the melt quenching method. The XRD results of this glassy system confirmed the glassy nature of the prepared glasses. The density of this glassy system presented higher values while the molar volume provided lower values with increasing ZrO₂ content. The FTIR result showed that the spectrum of each sample consisted of broad bands that de-convoluted into several peaks. These peaks were characterized and the structure of each sample was recognized. Additionally, the optical measurements showed that sample x = 0 mol% provided a sharp ultra-violet cut-off at 380 nm, while the other samples showed a transition peak in the (210–230) nm range. The energy of optical band gaps of these glass samples decreased and the Urbach energy increased by increasing ZrO₂ content. Moreover, the different optical parameters of these glass samples were calculated and showed that the studied glasses could be considered promising materials to be used in different optical applications such as nonlinearity and optoelectronics.     

Condensation and hydrophobicity of the surface hydroxyl groups between organosilane modified water glass and microsilica

As one of the novel green foundry binders, the bonding strength of two-component inorganic binder system (water glass-microsilica) under wet conditions needs to be further improved. In this work, γ-(methacryloxypropyl) trimethoxy silane (MPS) was added to water glass. The effect of MPS on the storage stability of sand core was studied, based on which the mechanisms of condensation and hydrophobicity of water glass-microsilica were discussed. The results showed that the maximum bonding strength of 1.0 wt% MPS modified sand core was increased by 15.5% at 80–85% RH. MPS promoted the dehydration condensation between water glass and microsilica, which will make its three-dimensional network more complex. Moreover, it formed a hydrophobic organosilane layer on the surface of the bonding bridge, which can play a role in shielding hydrophilic Na⁺ and prevent the destruction of bonding film by forming Si–O–R bonds, preventing the external water from damaging.