OH Absorption Peak Research Articles

Drying kinetics and energy efficiency of soot ash of smelting silicon manganese alloys under microwave heating

When smelting silicon manganese alloy in an industrial electric furnace, it will produce smoke and dust waste gas, which can be utilized again back to the furnace and improve the utilization rate of raw materials after a particular trapping device and collection treatment. However, at higher moisture levels, they are prone to explode. Effects of various initial masses, initial moisture contents, and microwave output powers on the soot ash of smelting silicon manganese alloy were studies. The findings indicate that the microwave drying rate increases with all three variables. The time for complete microwave drying is directly proportional to the sample's initial moisture content and the sample's initial mass, and the time for complete microwave drying is inversely proportional to the microwave output power. The results demonstrate that the Modified Page model can accurately describe the microwave drying process. The experimental data were fitted experimentally by drying kinetic models. Microscopic characterization of soot ash from refining silico‑manganese alloys before and after drying was carried out using FTIR and SEM. Through FTIR characterization, the peak value of the -OH absorption peak decreases upon drying, and SEM results in no agglomeration caused by microwave drying and better dispersion of the soot ash of the dried smelted silica‑manganese alloys, all of which proved that microwaves could effectively remove water. It was discovered that the diffusion coefficient increased gradually with increasing power when it was computed using Fick's second law. The diffusion coefficient increases and then decreases as the moisture content increases. The diffusion coefficient decreases as the initial mass increases. Activation energy of microwave drying of soot ash from the refining of silicomanganese alloys was calculated to be −1.4467 W/g. Its purpose is to offer a detailed guide for the industrial drying of soot ash from silicomanganese alloy refinement using microwave drying technology.

Study of precursor-solution purity for high-quality yttrium–barium–copper-oxide superconducting thin film

Trifluoroacetic acid-metal-organic deposition (TFA-MOD) is an effective method to prepare high-quality yttrium–barium–copper oxide (YBCO) superconducting thin films with a large area. Chemical reactions and purification are the keys to the preparation of the precursor solution in the TFA-MOD method. In this study, the process of preparing the precursor solution was examined by the infrared spectra systematically, and each infrared spectrum was determined by Fourier-transform-infrared spectroscopy (FTIR) to judge the possible side reactions. The results show that organic functional groups have no side effects at room temperature (20 ± 2°C). And the purification process can remove excess water, acid, and so on. The purity of the precursor solution would increase with distillation. When the relative height ratio of CF3− and the C−OH absorption peak in the spectra of solution 3, which has been purified three times, reaches 0.664, and the relative ratio of C−F and the C−OH absorption peak is 0.418, a YBCO thin film can be obtained with a perfectly uniform surface. Its transition-onset temperature is approximately 90.9 K, the value of critical current density (Jc) is 2.32 mA/cm2 (77 K, 0 T), and the growth of the superconducting film is strongly oriented to the c-axis. In addition, it was found that distillation removes excess water, acetic acid, and other small molecules, and determines the quality of YBCO thin films. For this performance, a superconducting film has been successfully applied to filter the fabrication. Therefore, this method is essentially an effective method to study the content of impurities in the precursor solution in order to form a superconducting film with good quality.

Polarized all-normal dispersion supercontinuum reaching 2.5 µm generated in a birefringent microstructured silica fiber.

We demonstrate a polarized all-normal dispersion supercontinuum generated in a birefringent silica microstructured fiber spanning beyond 2.5 µm. To our knowledge, this is the spectra reaching the furthest in mid-infrared ever generated in normal dispersion silica fibers. The generation process was studied experimentally and numerically with 70 fs pump pulses operating at different wavelengths on short propagation distances of 48 mm and 122 mm. The all-normal operation was limited by the zero-dispersion wavelength at 2.56 µm and spectral broadening was stopped by OH absorption peak at 2.72 µm. We identified the asymmetry between propagation in both polarization axes and showed that pumping along a slow fiber axis is beneficial for a higher degree of polarization. Numerical simulations of the generation process conducted by solving the generalized nonlinear Schrödinger equation (NLSE) and coupled NLSEs system showed good agreement with experimental spectra.

Synthesis of Waste Cooking Oil-Based Polyol Using Sugarcane Bagasse Activated Carbon and Transesterification Reaction for Rigid Polyurethane Foam

This study was carried out to determine the potential of waste cooking oil (WCO) in preparation of rigid polyurethane (PU) foam. The raw WCO was first filtered and adsorbed by using sugarcane bagasse activated carbon in order to purify the oil. Next, the adsorbed WCO was used to synthesize polyol via transesterification reaction. The WCO-based polyol was then combined with other chemicals at various ratios to form PU rigid foam. The adsorbed WCO showed the decrease in both free fatty acid percentage and viscosity, from 4.3 % to 0.77 % and from 106 mPa.s to 72.5 mPa.s, respectively. No alteration of functional group observed after adsorption as proven by FTIR spectroscopy. The FTIR spectrum of WCO-based polyol showed the formation of OH absorption peak and supported by the increase in hydroxyl value from 0 to 148.79 mgKOH/g after reaction. The formation of urethane linkages (NHCO) backbone in PU foam was confirmed using FTIR. The properties of PU foam are highly dependent on the chemical composition. The density and compressive strength of 60:54:90:40 of glycerol:water:polyol:amine polyurethane foam are 277.7 kg/m3 and 0.10 MPa, respectively. This study showed that WCO exhibit promising potential as raw material for PU formation.

Growth and Holographic Storage Properties of Zr:Mn:Fe:LiNbO<sub>3</sub> Crystal

Doping different concentration of ZrO2in Mn:Fe:LiNbO3crystals, a series of Zr:Mn:Fe:LiNbO3crystals were grown by the Czochralski method. The infrared transmission spectra and the photo-damage resistant ability of the crystals were measured. The OH-absorption peak of Zr (2mol%):Mn:Fe:LiNbO3crystal shifts to ultraviolet. The photo-damage resistant ability of Zr (3mol%):Mn:Fe:LiNbO3crystal is about three orders of magnitude higher than that of Mn:Fe:LiNbO3crystals. The diffraction efficiency, response time of Zr:Mn:Fe:LiNbO3crystals were measured by two-wave coupling experiment. The response time of Zr (3mol%):Mn:Fe:LiNbO3crystal is only one tenth of that of Mn:Fe:LiNbO3. The mechanism of OH-absorption peak shifting and improvement of holographic storage properties was discussed.

Impact of optical and structural aging in As_2S_3 microstructured optical fibers on mid-infrared supercontinuum generation

We analyze optical and structural aging in As₂S₃ microstructured optical fibers (MOFs) that may have an impact on mid-infrared supercontinuum generation. A strong alteration of optical transparency at the fundamental OH absorption peak is measured for high-purity As₂S₃ MOF stored in atmospheric conditions. The surface evolution and inherent deviation of corresponding chemical composition confirm that the optical and chemical properties of MOFs degrade upon exposure to ambient conditions because of counteractive surface process. This phenomenon substantially reduces the optical quality of the MOFs and therefore restrains the spectral expansion of generated supercontinuum. This aging process is well confirmed by the good matching between previous experimental results and the reported numerical simulations based on the generalized nonlinear Schrödinger equation.

Effect of deposition temperature on the alignment of hexagonal laminates in turbostratic boron nitride thin film

The deposition behavior of turbostratic boron nitride (t-BN) films was investigated with the focus on its microstructure variation in relation to deposition temperature substrate bias voltage. BN films were deposited using the unbalanced magnetron sputtering method. Thin (100μm) Si strips (3×40mm2) coated with a nanocrystalline diamond thin layer were used as substrates. A BN target was used, which was connected to a radio frequency power supply set at 400W. A pulsed direct current power supply connected to a substrate holder was used for negative biasing. The deposition pressure was 0.27Pa with a flow of Ar (18sccm)–N2 (2sccm) mixed gas. Only t-BN films were deposited with the substrate bias less than −100V irrespective of the deposition temperature. The orientation of (0002) t-BN laminate alignment changed from normal to parallel to the substrate surface with increased deposition temperature. High resolution transmission electron microscopy and Fourier transform infrared spectroscopy confirmed such behavior. However, the application of bias voltage made the (0002) laminates align normal to the substrate surface even at high deposition temperatures. The films tended to react with moisture in an ambient atmosphere as confirmed by the appearance of OH absorption peak in the FTIR spectrum. The measured OH absorption intensity was not influenced by the variation of deposition variables.

Hydrogen production from CO2 reforming of methane over high pressure H2O2 modified different semi-cokes

H2O2 was used under different temperatures and pressures to activate three kinds of different semi-cokes. FTIR, BET, SEM and Boehm titration were used to analyze properties of the semi-cokes surfaces, finding that catalytic activities of these semi-cokes after modification by high temperature and high pressure H2O2 were improved. FTIR shows that the characteristic infrared absorption peak of functional groups on the semi-cokes surface does not change, but the absorption peak intensity of some functional groups is increased. The strength of OH absorption peak of Hongce lignite (HCL) semi-coke at 3444cm−1, carboxyl CO at 1598cm−1, aliphatic ether, cyclic ether and other organic functional groups at 1023cm−1 in the modified Shenmu bituminous(SMB) semi-coke and Jincheng anthracite (JCA) semi-coke are increased significantly. BET finds that the specific surface area and pore volume of three semi-cokes are increased after modification. Boehm titration shows that the basic functional group content in semi-coke is increased after modification, and the net alkali content is increased significantly. Compared with the raw semi-coke, SEM shows that the surface of semi-coke modified with H2O2 becomes rough. Modified JCA semi-coke surface pitted with holes, modified HCL and SMB semi-coke surface present porous.

Growth and Characterization of High Homogeneity Heavily MgO-doped Lithium Niobate Crystals

High homogeneity heavily MgO-doped lithium niobate(MgLN for short) single crystals were grown by Czochralski method.The as-grown crystals were poled at high temperature,so as to obtain single ferroelectric domain structure.UV absorption edge,OH absorption peak,optical homogeneity of the crystal were tested,respectively.Micro-compositions along the radial direction were analyzed by EDS method and "line scan" of the distribution of Mg element along the radial direction was investigated by WDS method.The results showed that high homogeneity MgLN crystals were obtained with proper starting composition and improved growth process of Czochralski technology.UV absorption edge at 308 nm and OH absorption peak at 2828 nm were observed.The optical homogeneityΔn5.11×10~(-5). Finally,ferroelectric domain structure was observed by optical microscope by chemical etching method.High uniformity single ferroelectric domain structure was obtained by applying an external electric field at 1200℃.

Influence of Nd:Zn codoping in near-stoichiometric lithium niobate

Near-stoichiometric lithium niobate (SLN) crystals doped with up to 1.6 mol % Zn and codoped with various Nd concentrations in the melt (0.2, 0.5, 0.9, and 1.5 mol %) (Nd:Zn:SLN) are grown from 58.6 mol % Li(2)O using conventional Czochralski technique. Crystals are pulled at the rate of 0.35 mmh with seed rotation at 9 rpm. Concentrations of Zn and Nd in the crystal are varied by adding appropriate amounts of ZnO and Nd(2)O(3) to the starting composition. Unit cell parameters of the grown crystals are calculated by Rietveld refinement method using FULLPROFF software. Domain structure studies are carried out by chemical etching followed by microscopic examination. Dielectric studies reveal the existence of piezoelectric resonance at high frequencies. Enhancement in dielectric constant and tan delta in Nd doped samples has been attributed to the space charge polarization. Nd doped samples exhibit reduction in the relative permittivity after oxygen annealing. Transmission spectra of Nd:Zn:SLN crystals in the UV region exhibit blueshift in the cutoff wavelength. In Mid Infrared (MIR) region crystals doped with 1.6 mol % Zn have shift in the OH absorption peak from 2873 to 2833 nm. Judd-Ofelt analysis carried out on the absorption spectra of codoped crystal yields the lifetime of 104 mus for the metastable state (4)F(32). The branching ratio for the electronic transition from (4)F(32) to (4)I(112) is high compared to that for (4)F(32) to (4)I(132), indicating a higher emission cross section for the former transition. Laser damage threshold evaluated using 532 nm, 5 ns pulsed neodymium doped yttrium aluminum garnet laser, shows an increase by two orders of magnitude for crystals doped with 1.6 mol % Zn. Photorefractive damage threshold for these crystals shows an enhancement of four orders of magnitude due to increase in the photoconductivity.

In situ cyclization reactions during the preparation of high‐performance methacrylic acid/acrylonitrile/acrylamide ternary copolymer foam

AbstractA new high‐performance methacrylic acid/acrylonitrile/acrylamide ternary copolymer foam was prepared by radical bulk copolymerization, and the reaction mechanism of in situ cyclization taking place during copolymer foaming as well as the heat treatment was examined too. Then, the crucial mechanism was validated via optical microscopy, infrared absorption spectroscopy (Fourier transform infrared), differential thermal analysis (differential scanning calorimetry), and thermogravimetric analysis. The results showed a weak exothermic peak at 149.17°C and a strong endothermic peak at 270.85°C in differential scanning calorimetry curves of the methacrylic acid/acrylonitrile/acrylamide copolymer after the foaming and heat treatment at 160°C for 2 h and at 200°C for 2 h. The peak temperature of the differential thermogravimetry curve was 175.87°C, whereas the weight‐loss rate was less at 276.58°C in the thermogravimetry curves. In the case of the Fourier transform infrared curves, the OH absorption peak at 930–970 and 1480 cm−1 weakened, and the CN absorption peak of the imide increased. The >CO absorption peak at 1700 cm−1 occurred as an excursion phenomenon toward the low‐frequency field; at the same time, the second absorption peak increased. Furthermore, the CN absorption peak at 2240 cm−1 weakened, and a new CN absorption band appeared. All these data revealed that in situ cyclizations had taken place in the copolymer molecule chains, so some rigid ring structures appeared in the copolymer molecule chains, such as six‐membered imide rings and ladder polymer structures. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Crystal growth of Sc-doped near-stoichiometric LiNbO 3 and its characteristics

Sc-doped near-stoichiometric LiNbO 3 (Sc:SLN) crystals were grown from Li-rich solutions with Sc concentrations of up to 1.3 mol% by a top-seeded solution-growth method. We investigated the Sc-doping effects on the effective distribution coefficient, photorefractive damage (optical damage), the OH-absorption peak position, transmittance spectra, the ordinary and extraordinary refractive indices ( n o and n e), and the electric field needed for domain inversion. The Sc:SLN crystals doped with a Sc-doping concentration of 0.4 mol% or more showed no photorefractive damage. This critical Sc-doping concentration in the SLN crystal was one-fifth that in a congruent-melt composition LN (CLN) crystal which requires at least 2 mol% Sc (1 mol% Sc 2O 3) to suppress photorefractive damage. The 0.4 mol% Sc doping needed to suppress photorefractive damage in the SLN crystal was also low compared to the 1 mol% required for Mg doping. Except for n o and n e, all of the measured properties were influenced by the Sc-doping effect.

Advantages of TOF-SIMS Analysis of Hydroxyapatite and Fluorapatite in Comparison with XRD, HR-TEM and FT-IR

The chemical analysis of hydroxyapatite and fluorapatite was carried out using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Hydroxyapatite and fluorapatite were synthesized at 80 +/- 1 degrees C and pH 7.4 +/- 0.2. Fluorapatite was better crystallized, with its (300) reflection shifted to a slightly higher angle. High-resolution transmission electron microscopy clearly revealed a typical, regular hexagonal cross section perpendicular to the c-axis for fluorapatite and a flattened hexagonal cross section for hydroxyapatite. FT-IR spectra of fluorapatite confirmed the absence of OH absorption peak--which was seen in hydroxyapatite at about 3570 cm(-1). TOF-SIMS mass spectra showed a peak at 40 amu due to calcium. In addition, a peak at 19 amu due to fluorine could be clearly seen, although the intensities of PO, PO2, and PO3 were very low. It was confirmed that TOF-SIMS clearly showed the differences between positive and negative mass spectra of hydroxyapatite and fluorapatite, especially for F-. We concluded that TOF-SIMS exhibited distinct advantages compared with other methods of analysis.

Effect of glycerin on structure transition of PVA/SF blends

AbstractBlend films of silk fibrion (SF) and poly(vinyl alcohol) (PVA), with glycerin as an additive, were made, and the structure and properties of the blends were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD) and with an Instron Material Tester. The results showed that SF and PVA are principally incompatible and the blends made by the two polymers were phase‐separated. The results, however, also demonstrated that the blend structure could be changed to some extent by addition of 3–8% glycerin. The boundary of the PVA and SF phases became indistinct, as reported by SEM, a new peak appeared in the WAXD curves, the width of the OH absorption peak in the FT‐IR spectra increased, and the melting points changed in the DSC curves. In particular, the mechanical properties obviously increased, from 350 kg/cm2 and 10% of PVA/SF (80/20) film to 832 kg/cm2 and 39% of PVA/SF (80/20) film because of the increase in glycerin. It was suggested that glycerin plays a role in building the relationship between PVA and SF, strengthening the interaction between them and improving their compatibility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2342–2347, 2002

A model for estimating the peak attenuation due to OH in an optical fiber

A model for estimating the OH absorption peak in optical fibers given the attenuation values at 1.3, 1.4, and 1.55 μm has been developed. The model has been tested against the experimental data of a monomode fiber, and found to be within 5% of the experimental data. An attempt has been made to identify the cause of the deviation between the experimental and mathematical model. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 18: 310–312, 1998.

Nitridation of sol-gel derived DMDEOS-TEOS copolymer gels to silicon carboxynitride (SiCNO)

The need to synthesize glasses with improved mechanical and thermal properties has initiated research on the synthesis of glasses where anion substitutions are made in the glass network. The anion substitution increases the thermomechanical properties and also enhances the stability of the glass toward chemicals [1–4]. Incorporation of nitrogen and carbon offers the possibility of threeand fourco-ordinated bonds, which are different from the two-co-ordinated bonds in the glass network that consist of oxygen anion only [5]. Sol–gel technology is much sought after, due to better chemistry control, for the preparation of these glasses, which otherwise require high temperature and drastic conditions [6]. This letter reports the synthesis of Si, C, N, O glass network (silicon carboxynitride) via the hydrolysis–condensation process of dimethyldiethoxy silane (DMDEOS) tetraethoxy silane (TEOS). The hydrolytic polycondensation of DMDEOS and TEOS produced a copolymer which, when subjected to nitridation, yielded SiCNO glass network. Copolymer gels were prepared by taking TEOS and DMDEOS in the molar ratios of 1:2 and 1:4. The preparation details were as follows: for ‘‘Part A’’, TEOS, water, acetonitrile and HCl in the molar ratio of 1:4:4:0.05 were stirred for 30 min to partially hydrolyze the TEOS; for ‘‘Part B’’, DMDEOS, water, ethanol and HCl in the molar ratio of 1:4:4:0.05 were stirred for 10 min at 30 8C. Part A was then slowly added to Part B under vigorous stirring and the temperature was maintained at 30 8C, then 0.5 vol % liquid ammonia (of concentration 25%) was added to the mixture while stirring. This homogeneous mixture was then stirred for another 3 h and set for gelation. The nitridation of gels was carried out in a carbolite furnace at 1400 8C [7]. The heating schedule was adjusted to 5 8C miny1 up to 800 8C, 4 8C miny1 from 800 to 1200 8C, 2 8C miny1 from 1200 to 1400 8C and maintained at 1400 8C for 2 h. The copolymer gels were white and the colour changed on nitridation depending upon the temperature at which they were heat treated. At 600 8C they turned brown and at 1400 8C they became tinted black. The product obtained after nitridation was thermally stable and did not lose the black colour even after heating at 1200 8C in air. The product would have been converted to silica and turned white if nitrogen and carbon had not been incorporated into the silica network. The gels and the nitrided product were characterized by Fourier transform infrared (FTIR) spectroscopy (Nicolet 5DX), X-ray diffraction (XRD) (Siemens D-500) and thermal analysis (Mettler TA3000 with TG 30 and TMA 40). Chemical analysis was carried out to determine the carbon, nitrogen and silicon content by the methods reported earlier [6, 7]. The weight percentages of carbon, nitrogen and silicon are shown in Table I. Gelation in DMDEOS resulted in the separation of the sol into two phases. FTIR spectra of these two phases are shown in Fig. 1. The presence of absorption bands related to OH groups around 3300 cmy1 and Si–OH at 940 cmy1 in the top phase may indicate that it is a mixture of low silicon content linear polymer, with Si–OH groups as the end groups. The bottom phase does not have an Si– OH absorption peak, which may indicate that it contains condensed oligomer units with only methyl groups directly bonded to Si atoms in the siloxane chains. However, it was observed that gel network formation takes place, leaving no liquid phase, on addition of TEOS during hydrolytic polycondensation of DMDEOS. This shows the formation of copolymer gel by the cross-polycondensation of Si– OH units of DMDEOS and TEOS origin. FTIR spectra of copolymer gels, as shown in Fig. 1c and d, show characteristic absorption peaks of Si–O–Si and Si–OH at 1070 cmy1, 800 cmy1, 460 cmy1 and 960–940 cmy1, respectively. Peaks relating to Si– CH3 groups were observed at 3000 cmy1, 1270 cmy1, 1130 cmy1 and 780 cmy1. FTIR spectra of D-2 and D-4 gels heat treated to 800 and 1200 8C under nitrogen atmosphere are shown in Fig. 2. The major change observed in the

Low-loss compound-glass optical fibre

Progress has been made in reducing the losses of optical fibres made from multicomponent glasses by using the doublecrucible technique. This has been achieved by reducing the absorption loss caused by water and transition-metal impurities. The intensity of the OH absorption peak at 960 nm has been reduced to 5 dB/km, and a minimum total loss in fibre form of 3.4 dB/km at 840 nm has been achieved.

Low-loss silica core-borosilicate clad fiber optical waveguide

A low-loss fiber optical waveguide has been constructed having a pure fused silica core of 40-μm diameter and a chemical-vapor-deposited cladding layer of borosilicate glass 15–20 μm thick. This core-clad structure has an outer jacket of fused silica which serves to strengthen and protect the waveguide. Fabrication procedures and evaluation techniques are described. One fiber has been found to have a minimum optical attenuation of 13 dB/km at a wavelength of 0.7 μm. In the range 0.8–1.1 μm, where optical communications appear most promising, the attenuation varies between 18 and 22 dB/km with the exception of the OH absorption peak at 0.95 μm.