SiOH Concentration Research Articles

High friction surface treatment with silicone resin materials (HFST-S): A preventive maintenance method of asphalt pavements

The skid resistance of asphalt pavements is the key to ensuring traffic safety. Silicone resin is often used as a maintenance material for fog seal because of its waterproof performance and weather resistance, but it is rarely mentioned in the field of skid resistance. In this paper, a high friction surface treatment with silicone resin (HFST-S) was prepared by adding skid-resistance aggregates to improve the skid resistance of pavements. Firstly, the curing time, chemical composition, group content, and hydrophobic performance of silicone resin were studied. Then the morphology characteristics and mechanical performance of skid-resistance aggregates were investigated. Finally, the type and particle size of skid-resistance aggregates, the ratio of silicone resin to skid-resistance aggregates (RSA), and silicone resin dosage were optimized by laboratory tests. The results indicate that silicone resin cured basically at 60 °C for 24 h and Si-OH content decreased during curing. The cured silicone resin was mainly composed of C, O, and Si elements and had remarkable hydrophobicity. In addition, emery sands had richer angularity and better mechanical performance than basalt sands. Therefore, the HFST-S prepared by silicone resin and emery sands has outstanding waterproof performance and skid resistance. The optimum formula of HFST-S was determined as 0.60 – 1.18 mm particle size of emery sands, 40:60 of RSA, and 800 g/m2 of silicone resin.

Improving the adhesion of diamond-like carbon films on glass substrate by chemical etching and oxygen plasma treatment

The weak adhesion of diamond-like carbon (DLC) films on glass has hindered their widespread application. Despite extensive research on interlayers to enhance adhesion, the challenge of poor DLC adhesion on glass surfaces remains unresolved. In this study, a new strategy is proposed to improve DLC adhesion on glass. Initially, the glass was chemically etched to generate continuous and micrometer-sized pits on the surface. Subsequently, oxygen plasma treatment was employed on the etched glass to increase the Si–OH content on the surface. SiO2, SiOC and DLC were then sequentially deposited on the etched glass using magnetron sputtering. The film materials were embedded into the pits, resulting in a wavy 3D morphology. This morphology facilitated the distribution of applied force on the inclined planes of the pits and increased the contact area between the film and the glass surface, thereby improving the chemical bonding between the film and the substrate. The adhesion strength, Vickers hardness and pencil hardness of the films on the glass were 135.37 mN, 751.8 HV and 8H, respectively. These results demonstrate the effectiveness of the proposed approach in addressing the issue of weak DLC adhesion on glass. The findings of this study have potential applications in various fields.

Quantitative hydrogen state analysis in the leached layer of soda-lime-silica glass by combination of nuclear reaction analysis and C60-X-ray photoelectron spectroscopy

The effects of acid treatment on the surface layer of soda-lime-silica glasses were investigated by nuclear reaction analysis (NRA) and C60-X-ray photoelectron spectroscopy (XPS) in a depth-resolved manner. As the time of treatment with HCl increased, the amount of H increased and was distributed in a region at a depth of almost 150 nm. In the near-surface region, however, the damage due to 15N2+ beam irradiation for conducting the NRA was found to be substantial as observed by the fast decay of signal intensity with increasing ion dose. The depletion of sodium, magnesium, and calcium in the surface layer was examined by C60-XPS. Sodium was depleted at a depth of 150 nm by the acid treatment, but the depletion of magnesium and calcium occurred at a depth within approximately 30 nm. Assuming the ion exchange reaction between the alkaline and alkaline earth elements with H3O+, the Si-OH concentration profile was evaluated from the depletion profiles of sodium, magnesium, and calcium. From the difference between the Si-OH profile and H distribution obtained by NRA, the H2O/Si-OH ratio in the leached layer was estimated at 1.3.

Hydrogen isotope fractionation inside silicate melts and glasses studied by 1H and 2H MAS NMR spectroscopy – Molecular insights into deuterium exchange at the melt-fluid interface

Hydrogen isotope ratios (D/H) measured on geological samples are used to trace the pathways of water in magmatic and hydrothermal systems. Interpreting respective isotope data relies thereby on the theoretical and empirical constraints on hydrogen isotope fractionation. This study revisits a recently discovered hydrogen isotope fractionation effect between alkali-rich and alkali-poor regions within hydrous alkali silicate melts (Wang et al., 2015). In a series of experiments conducted at variable P-T-XH2O, D2O conditions, we studied this intramolecular isotope effect by 1H and 2H solid-state nuclear magnetic resonance (NMR) spectroscopy on quenched hydrous sodium tetrasilicate melts (Na2O⋅4SiO2 with 1:1 H2O and D2O).The results indicate a marked difference in the reactivity of the protonated and deuterated hydrous species. It is observed that c. 70% of deuterium concentrates as deuterated silanols (Si-OD) in proximity to the sodium cations in the silicate melt structure, while the remaining 30% occupy the Na-poor regions in the silicate melt in the form of Si-OD and presumably molecular water (HDOm). This distribution remains nearly constant under all experimental conditions. In contrast, the concentration of protonated hydrous species (Si-OH, H2Om) in the Na-rich and -poor regions of the silicate melt varies as a response to changing experimental P-T-XH2O and cooling rate, which is linked to common water speciation reactions taking place within the melt (Si-O-Si + H2Om = 2Si-OH). Previously considered insignificant, 1H NMR indicates that the speciation equilibrium is sensitive to pressure and correlates positively with Si-OH concentration. The significantly different reactivity of the isotope substituted hydrous species results in large molecular variations in the D/H ratio inside the sodium silicate melt. Measured intramolecular hydrogen isotope fractionation yields a 2- to 9-fold (in average 3-fold) enrichment of deuterium in Na-rich depolymerized regions in the silicate network, which translates to intramolecular fractionations of 1000ln(α) = 400 to 2200. Generally, intramolecular fractionation tends to increase when the melt evolves towards fluid-saturated conditions. The pre-concentration of deuterium in the depolymerized Na-rich regions of the silicate melt results in a higher local D/H ratio that may carry over when these regions disintegrate into a silicate saturated aqueous fluid. In this way, intramolecular isotope fractionation poses a potent way of enriching silicate saturated aqueous fluids in deuterium, potentially explaining previous experimental in-situ observations of large hydrogen isotope fractionations in the hydrous-melt – silicate-saturated fluid system. The observed affinity of deuterium to combine with alkali-associated silanols could comprise an important molecular sieving mechanism for deuterium that enhances the D/H fractionation between silicate-rich fluids (and hydrous melts) and the surrounding host rock. Consequently, intramolecular hydrogen isotope fractionation in hydrous silicate melts and silicate-rich aqueous fluids may be a very effective deuterium filter acting in the deep geological water cycle.

Novel acid-based geopolymer synthesized from nanosized tubular halloysite: The role of precalcination temperature and phosphoric acid concentration

Halloysite is a hydrated polymorph of kaolinite but possesses a distinctive nanosized tubular structure and surface reactivity. The microstructure and mechanical performance of geopolymers derived from calcined halloysite via acid-activation were investigated in this study. The acid-activation products were characterized using a combination of techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Acid-activation of halloysite calcined at 450 °C by 6 mol/L and 10 mol/L phosphoric acid solution produced metavariscite crystals. When the phosphoric acid concentration was increased to 14 mol/L, the acid-activation product became more compact due to the formation of geopolymer that were mainly composed of Al–O–P networks. Calcination of halloysite at 750 °C led to an active form of halloysite, which was favored by geopolymerization. Higher phosphoric acid concentration led to the incorporation of more Si and P in the geopolymer matrix with Si–O–P–O–Al networks, and thus greater compressive strength. Halloysites calcined at 1000 °C barely reacted with phosphoric acid, due to the nanocrystalline formation and the decreased Si–OH content in the calcined halloysite, which had low reactivity unfavorable for geopolymerization. These results indicated that the microstructure and mechanical performance of halloysite-based geopolymers are highly dependent on the precalcination temperature of halloysite and the phosphoric acid concentration. Suitable precalcination temperature and high concentration of phosphoric acid facilitate high degree of geopolymerization, which is conducive to the formation of an acid-activated halloysite-based geopolymer with excellent mechanical performance.

Synthesis and characterization of ureido-containing MQ silicone resin

Ureido-containing MQ silicone resin (U-MTQ) was synthesized by the hydrolysis and co-condensation reaction of ethyl silicate, ureido silane, hexamethyldisiloxane, and divinyltetramethyldisiloxane under the catalysis of hydrochloric acid. U-MTQ was characterized by FT-IR, 1H-NMR, 29Si-NMR, GPC and TGA. The influences of M/Q molar ratio and hydrochloric acid content on the yield and structure of U-MTQ were investigated. The results showed that the M/Q molar ratio of the product calculated from the 29Si-NMR spectrum was much smaller than that in the feed. As M/Q molar ratio in the feed increased, the molecular weight and its distribution index of U-MTQ decreased, and Si-OH content of U-MTQ also decreased, while the structural regularity of U-MTQ was enhanced. With HCl content increasing, the molecular weight and its distribution index of U-MTQ decreased, but the Si–OH content and structural regularity increased. Meanwhile, the yield first increased and then decreased, and reached the highest value of 71.9% when HCl content was 2.10%. Compared with MQ, the onset weight loss temperature of U-MTQ decreased from 237 °C to 158 °C, and the residue at 900 °C increased from 3.5% to 29.5%.

Measurement of Si―OH content in fused silica with extended dynamic range by Fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy Si―OH group is widely used in Si―OH content measurement of fused silica optics. However, the measurement accuracy is influenced by water molecular absorption bands in low Si―OH content samples and absorption saturation in high Si―OH content samples, leading to limited measurement range. FTIR spectroscopy is employed to measure 2500 cm-1 ~5000 cm-1 transmittance spectra of fused silica samples with different OH contents and thicknesses. The interference of water molecular absorption band to 3673 cm-1 is eliminated. Then Si―OH contents, corresponding measurement errors and limits of detection at 3673 cm-1 and 4522 cm-1 bands are calculated. Based on the experimental results and Beer’s law, a model to correlate Si―OH content, sample thickness, measurement error of transmittance, and measurement error of Si―OH content is established. From this model, by using 3673 cm-1 band for fused silica samples with Si―OH content less than 8.17×10-4 and 4522 cm-1 band for samples with Si―OH content more than 8.17×10-4 to measure the Si―OH content, a dynamic range from 0.4×10-6 to10-2 Si―OH can be achieved with optimized accuracy for fused silica samples with 2 mm thickness.

A simple method to ameliorate hierarchical porous structures of SiO2 xerogels through adjusting water contents

In this contribution, hierarchical micro-/meso-porous SiO2 xerogels were successfully prepared through a Stöber methodology coupled with following drying process. The SiO2 xerogels were consisted of nanoparticles of 20–40nm in size with different contents of water. Fourier transform infrared spectroscopy proved that SiOC2H5 and SiOH groups could be formed in SiO2 xerogels. Further analyses declared that the amount of the SiOC2H5 groups decreased while the concentration of SiOH was firstly increased and then suffered a decline with improving contents of water. Besides, the SiO2 xerogels was endowed with controllable micro-/meso-porous structure. Furthermore, the formation mechanism of the micro-/meso-porous SiO2 xerogels was tentatively put forward. As a consequence, SiO2 xerogels with controllable hierarchical micro-/meso-porous structure could act as the smart material for huge development in catalytic fields.

Detailed near-infrared study of the ‘water’-related transformations in silcrete upon heat treatment

In archaeology, lithic heat treatment is the process of modifying a rock for stone tool production using fire. Although the earliest known cases of heat treatment come from South Africa and involved silcrete, a microcrystalline pedogenic silica rock, its thermal transformations remain poorly understood. We investigate the ‘water’-related transformations in silcrete using direct transmission near-infrared spectroscopy. We found that SiOH is noticeably lost between 250 and 450 °C and hydroxyl reacts with H2O, part of which is trapped in the structure of the rocks. This water can only be evaporated through heat-induced fracturing at high temperatures, imposing maximum temperatures for silcrete heat treatment of approximately 500 °C. Between 250 and 450 °C new siloxane bonds are formed according to the reaction 2SiOH → Si–O–Si + H2O, which can be expected to transform the rock’s mechanical properties. The tolerance of silcrete for relatively fast ramp rates can be explained by its pore volume and low SiOH content, ensuring good water evaporation. These results shed light on the processes taking place in silcrete during heat treatment and allow for a better understanding of the parameters needed for it.

Route to hydrophilic, hydrophobic and functionalized cross-linked polysiloxane microspheres

A new approach to the synthesis of all-polysiloxane functional microspheres is worked out. Simultaneous catalysis of four reactions of polyhydromethylsiloxane (PHMS) by a Pt(0) complex in an aqueous emulsion process is used to synthesize all-polysiloxane microspheres containing a large number of silanol groups. These reactions include (i) hydrosilylation of olefinic bond of a cross-linker with the SiH group on the polymer, (ii) hydrolysis, and in some cases alcoholysis, of the Si–H bond in the polymer and (iii) dehydrogenative condensation of the SiOH group formed in the hydrolysis with the SiH group. A solution of PHMS with divinyltetramethyldisiloxane (DVTMS) cross-linker together with the catalyst is mechanically emulsified with water. The polymer cross-linking and the silanol formation occur in the formed emulsion. In most cases preliminary hydrosilylation is carried out before emulsification, which leads to the grafting of vinylsiloxane on PHMS. In the emulsion process a large number of SiH groups on PHMS may be transformed into SiOH hydrophilic groups. This reaction occurs not only on the surface of microspheres but also in their bulk. The cross-linking of PHMS takes place as a result of hydrosilylation of vinyl groups grafted on the polymer and by dehydrogenative condensation of the SiH groups with the silanol groups which are formed on PHMS. The SiOH content, density of grafting and the particle size depend on the parameters of the process. The obtained microspheres, named here M–OH, are modified by reactions with reactive silanes containing organofunctional groups.

Synthetic control of cage/network ratio of poly(methylsilsesquioxane)s for storage stability, hardness, and weather resistance of coating films

AbstractPoly(methylsilsesquioxane) (PMSQ) was synthesized using a two‐step process consisting of hydrolysis of methyl trimethoxysilane (MTMS) with aluminum chelate catalyst and successive condensation reactions conducted at elevated temperatures. Results of nuclear magnetic resonance and Fourier transform infrared measurements show that all terminal functional groups were SiOH in PMSQ. Results show further that PMSQ has both a cage structure and a network structure, and a cage/network ratio is represented by a height ratio of −64.5/−66.6 ppm. PMSQ of different molecular weight but the same SiOH concentration is obtainable by varying the condensation reaction conditions such as the concentration, temperature, amount of aluminum chelate catalyst, and the solvent solubility parameter. A difference of the cage/network ratio occurs. A different cage/network ratio is dependent on the different reactivities of the intramolecular and intermolecular reactions. The relations of molecular structure of the obtained PMSQ molecular structure were characterized along with functions of storage stability, film hardness, and weather resistance. PMSQ designed with a larger cage/network ratio is necessary to obtain PMSQ with good storage stability and a coating film having good weather resistance. PMSQ designed with a smaller cage/network ratio should be prepared to obtain a coating film with high hardness. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

A case study on the impact of local material chemistry on the mechanical reliability of packaged integrated circuits: Correlation of the packaging fallout to the chemistry of passivation dielectrics

In this paper, we use a variety of analytical techniques to examine the impact of local chemistry, and the mechanical properties, of the encapsulation dielectric films on the post-packaging device rejection rate of integrated circuit devices. A strong dependence of lot rejection rate (LRR) on the effective Young's modulus of the encapsulating dielectric stack is demonstrated; specifically, the device fall out rate increases with increasing Young's modulus. The increase in LRR with increasing stiffness of the encapsulating layer is attributed to the increase in thermal stress in the encapsulation dielectric stack layer and in the metal lines due to their increased constraint. This stems from the strong adhesion of the encapsulating dielectric material to the metal, thus fixing the loci of the surface planes of the metal, which could result in mechanical damage through voiding, cracking or delamination.It is also found that the increase in the local SiOH concentration leads to a decrease in the Young's modulus of the encapsulating SiO2. Thus, the engineering and optimization of the chemistry of the encapsulating dielectric are essential for improved post-packaging burn-in yields.

Natural hydrous amorphous silica: Quantitation of network speciation and hydroxyl content by 29Si MAS NMR and vibrational spectroscopy

Natural and synthetic hydrous amorphous silicas were investigated with single-pulse 29Si magic angle spinning (MAS) NMR and with vibrational spectroscopic methods. Samples included a volcanically derived silica coating on young basalt from Kilauea, Hawaii, as well as hyalite (opal-AN), silica sinters, and synthetic silica gels and silicic acid. Pulse delays of up to an hour were employed for silica samples with slow spin lattice relaxation rates, and nearly fully relaxed spectra (90-100%) were demonstrably achieved for all samples. 29Si NMR spectra consisted of two broad, overlapping peaks at -111 and -102 ppm and a smaller peak at -92 ppm, corresponding to Q4, Q3, and Q2 sites, respectively. The Hawaiian silica coating and silicic acid samples displayed high Q3 and Q2 contents; in particular, the structural Si-OH content of the coating was unusually high for a natural silica (5.4 ± 0.4 wt% H2O). Saturation-recovery spectra of the Hawaiian silica with increasing delay times were consistent with “stretched exponential” relaxation behavior and three-dimensional distribution of paramagnetic centers. Attenuated total reflectance infrared (ATR-IR) and Raman spectra of the silica powders indicated fully amorphous structures, and displayed hydrous (SiO3OH) and anhydrous silicate vibrational bands in positions consistent with previous work. Raman spectra of some samples indicated modest grain to grain heterogeneity. Inferred Si-OH contents from ATR-IR band ratios were strongly correlated with hydroxyl contents calculated from NMR spectra. The high Si-OH content of the Hawaiian silica coating suggests it is diagenetically immature and has not been exposed to elevated temperatures.

Study of the proton irradiation damage on Capsule type polarization-maintaining optical fibers made in China

A spacecraft running in the space environment would be irradiated by the proton, and the irradiation effects on the most important parts of the optical fiber gyroscope in the spacecraft -the optical fiber ring is the most. In order to investigate the irradiation damage induced by proton irradiation on the Capsule type polarization-maintaining optical fibers made in china, the variation of the transportation power at 1310 nm wavelength is measured by means of situ measurement for the 5 MeV and 10 MeV environments protons irradiation on the Capsule type polarization-maintaining optical fibers made in china. The irradiation induced loss is calculated by us. The Stopping and Range of Ions in Matter (SRIM) software was used to simulate the ionic and displacement damage of 5 MeV and 10 MeV energy protons irradiation on the optical fibers. The O 1s and Si 2p analytic spectrum of the before and after irradiation were obtained by means of X ray photoelectron spectroscopy (XPS). Using the Fourier transform infrared spectrometer (FTIR), we analyzed the before and after irradiation spectrum. The results show that at the 1310 nm wavelength, the rradiation induced loss of the of optical fibers increase with the increasing of the protons fluence due to the increase of the SiOH concentration in optical fiber core. The 5 MeV proton irradiation induced loss is worse than that of the 10 MeV mainly because the more worse displacement and the ironic damage induced by 5 MeV proton at the position of the optical fiber core than that of 10 MeV, i.e., the more amount of SiOH generation.

Effect of pH on the Dispersion Characteristics of Fumed Silica

The effect of pH on the particle distribution and zeta potential of the fumed silica(SiO2) suspended in H2SO4 or NaOH aqueous solution and their relationship were investigated with laser dynamic light scattering(DSL).The experiment showed that the isoelectric point(IEP) and titration end(TE) of silanol were at pH(IEP)=2.09 and pH(TE)=7.47,respectively,and a simple method was given for the determination of Si-OH concentration on SiO2 particle surface based on pH(TE).The dispersed phase particle size measurement showed that between IEP and TE,the hydration radius of SiO2 was stabilized near 230 nm;in H2SO4 medium,when pHpH(IEP),the apparent hydration radius of SiO2 increased with the increased H2SO4 concentration due to the coalescence of dispersed SiO2 aggregates;in NaOH medium,when pHpH(TE),the SiO2 aggregates decomposed and the apparent size of the dispersed phase decreased with increasing the NaOH concentration,which showed that NaOH can promote the dispersion stability of fumed silica in aqueous.

Visible to vacuum-UV range optical absorption of oxygen dangling bonds in amorphous SiO2

Synthetic silica glass with an optical absorption spectrum dominated by oxygen dangling bonds (nonbridging oxygen hole centers, or NBOHCs) and having negligible (1%) contribution from the usually copresent Si dangling bonds (E\ensuremath{'}-centers), was prepared by room temperature ultraviolet photobleaching of high SiOH content (``wet'') silica, irradiated by F${}_{2}$ laser (7.9 eV) at $T$ = 80 K. This allowed us to obtain the up-to-now controversial optical absorption spectrum of NBOHC in the ultraviolet and vacuum-ultraviolet (UV-VUV) region of the spectrum and to show that it is semicontinuous from 4 to 7.8 eV and cannot be represented by a pair of distinct Gaussian bands. Since NBOHC is one of the main UV-VUV range optical absorbers in silica, its spectral shape provides a tool to disentangle contributions of different color centers to optical losses in this spectral region.

Structural organization of silanol and silicon hydride groups in the amorphous silicon dioxide network

We present a study on the effects of an isothermal annealing treatment on a-SiO2 having a significant content of silanol hydride groups (Si-H). We examined the properties of the IR absorption bands of silanol (Si-OH) and silicon hydride groups as a function of the duration of the thermal treatment. We showed that the Si-OH and Si-H groups contents decrease in a linearly correlated way. The annealing dynamics suggest that the two species are close to each other in the amorphous network. We showed that the profile of the silanol groups absorption band is the same as that observed in other commercial a-SiO2 materials, irrespectively of the concomitant presence of nearby Si-H groups, and, moreover, it does not change during the annealing treatment. This set of evidences supports the conclusion that silanol groups are organized in clusters in the a-SiO2 network. Finally, present data provide an unprecedented characterization of the Si-H IR absorption band. It results that the profiles of the IR and Raman activities of silicon hydride groups closely coincide.

Exchange between interstitial oxygen molecules and network oxygen atoms in amorphousSiO2studied byO18isotope labeling and infrared photoluminescence spectroscopy

Amorphous ${\mathrm{SiO}}_{2}$ ($a$-${\mathrm{SiO}}_{2}$) thermally annealed in an oxygen atmosphere incorporates oxygen molecules (O${}_{2}$) in interstitial voids. When the thermal annealing is performed in $^{18}\mathrm{O}$${}_{2}$ gas, interstitial $^{18}\mathrm{O}$${}_{2}$ as well as interstitial $^{16}\mathrm{O}$$^{18}\mathrm{O}$ and $^{16}\mathrm{O}$${}_{2}$ are formed due to the oxygen exchange with the $a$-${\mathrm{SiO}}_{2}$ network. The ${a}^{1}{\ensuremath{\Delta}}_{g}(v=0)\ensuremath{\rightarrow}{X}^{3}{\ensuremath{\Sigma}}_{g}^{\ensuremath{-}}(v=1)$ infrared photoluminescence band of interstitial ${\mathrm{O}}_{2}$ was utilized to quantitatively analyze the oxygen exchange, taking into account the influences of common network modifiers in synthetic $a$-${\mathrm{SiO}}_{2}$ (SiOH, SiF, and SiCl groups). The presence of network modifiers does not significantly change the average rate of $^{18}\mathrm{O}$ transfer from interstitial ${\mathrm{O}}_{2}$ to the $a$-${\mathrm{SiO}}_{2}$ network and its activation energy, suggesting that the network modifiers themselves do not serve as preferential oxygen exchange sites. When the concentration of SiOH groups is low, the oxygen exchange rate is distributed, indicating that only a small part of the network oxygen atoms participates in the oxygen exchange. However, the distribution of the oxygen exchange rate is distinctly narrow in the sample with high SiOH concentration. It is attributed to the redistribution of the network $^{18}\mathrm{O}$ atoms and the modification of the $a$-${\mathrm{SiO}}_{2}$ network topology caused by reactions with mobile interstitial water molecules, which are transiently formed by dehydroxylation of paired SiOH groups. The activation energy for the average oxygen exchange rate is larger than that of the permeation of interstitial ${\mathrm{O}}_{2}$ in $a$-${\mathrm{SiO}}_{2}$. Furthermore, the average exchange-free diffusion length of interstitial ${\mathrm{O}}_{2}$ below 900 ${}^{\ifmmode^\circ\else\textdegree\fi{}}$C ($\ensuremath{\gtrsim}$1 $\ensuremath{\mu}$m) is far larger than the scale of the interstitial voids in $a$-${\mathrm{SiO}}_{2}$ ($\ensuremath{\lesssim}$1 nm). These observations confirm that the oxygen exchange is not necessarily involved in the permeation of interstitial ${\mathrm{O}}_{2}$.

Correlation between radiation-induced defects, and optical properties of pure fused silica-core optical fiber, under gamma-ray irradiation in air at 1273 K

Radiation-induced effects on optical properties such as thermoluminescence and optical absorption of pure fused silica-core optical fibers were investigated in situ under gamma-ray irradiation at 0.16mGy/s and 1273K in air. The intensities of broad optical transmission peaks below 900nm decreased due to appearances of non-bridging oxygen hole center (NBOHC), oxygen deficiency centers (ODCs), and optical leakage with increasing annealing time. The intensities of optical absorption and luminescence characteristics peaks at 1390nm were enhanced by the increment of Si–OH concentration due to the reaction of water vapor or hydrogen with NBOHC, ODCs, and SiO2 glass network. In addition, high resolution-transmission electron microscopy (HR-TEM) showed that SiO2 crystals approximately 10nm in diameter were formed in the clad and core of the irradiated optical fiber. The crystallization of the SiO2 glass network had greater influence on the optical transmission and luminescence properties.

SiO2 Films Deposited by APCVD with a TEOS/Ozone Mixture and Its Application to the Gate Dielectric of TFTs

Silicon dioxide films were deposited using atmospheric pressure chemical vapor deposition (APCVD) with tetraethyl orthosilicate (TEOS) and ozone as reactant gases. These films were used as the gate dielectric of low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs). gas was chosen instead of oxygen gas because the latter is not compatible with the low temperature processing of LTPS TFTs. films deposited at low temperatures have low Si–OH contents and electrical properties desirable for gate insulator materials. Although the LTPS TFTs were fabricated using low cost films deposited by APCVD as the gate dielectric, the fabricated devices exhibited a field-effect mobility of and a subthreshold swing of 490 mV/dec. The results demonstrate that deposited by APCVD with TEOS and is a promising material for low cost and high quality gate insulators for LTPS TFTs.