Influence of Topology Structure on the Stability of Konjac Glucomannan Nano Gel Microfibril

Konjac glucomannan nano gel microfibrils were prepared by using electrospinning method. Topology structures were analyzed by Fourier transform infrared spectroscopy （FT-IR） and Field emission scanning electron microscopy （FESEM）, while the differential scanning calorimetry （DSC） was carried out to check the thermal stability of the structure. Results reveal that the interaction of KGM intermolecular hydrogen bonds and topological tangle rate are increased by electrospirming, while stable structures of nano gel microfibrils are formed without altering the molecular groups of origin, These structures compose of topological networks of clustered nano fibers with lower porosity and higher density.

Development of Modified Glasses by Transparent, Functional Hybrid Sol-Gel Nano-Ceramic Coatings, a Comparative Study

This paper concentrates on the development of glasses with self-cleaning surfaces exhibiting high water contact angles. In this study, we prepared super-hydrophobic nano-ceramic coated glass based on titania & silica using simple sol-gel & dip coating methods and studied the best composition of the coatings by altering ratios of titanium tetraisopropoxide (TTIP)/tetraethyl orthosilicate (TEOS) with different homogenizing agents. We characterized the coatings by surface roughness measurement, percentage of optical transmission, static contact angle, near-infrared (NIR) transmission, and diffuse reflectance. The fabrication of coatings on glass substrates played an important role in increasing the water contact angle of about 95° and visible & NIR transmission of about 90%. We compared our modified glass substrate with commercial low emissivity (Low E) glass using X-ray diffraction (XRD) analysis, which showed pure amorphous surface claiming excellent wettability and thus the prepared glass substrate could have a variety of applications in different fields.

Microstructure of nano precursors of La-Mg hydrogen storage alloy synthesized by sol-gel technology at different pH values

Sol-gel technology was employed to synthesize nanosized precursors of La-Mg hydrogen storage alloy at different pH values (0.5, 1.5, 8.0 and 9.0) of reaction solution. The effect of pH value on microstructure of the nano precursors of La-Mg hydrogen storage alloy was studied by infrared radiation (IR), thermo-gravimetric and differential thermal analysis (TG/DTA), X-ray diffraction analyzer (XRD) and transmission electron microscopy (TEM). IR results indicate that the chelating agent, citric acid, is not fully ionized, and carboxyl groups are not entirely used to complex metal ions in acidic solutions. The efficiency of complexing metal ions is enhanced in basic solutions. TG/DTA results show that the combustion may take place with low rate of the flame propagation that causes the longer combustion time when pH<1.5. On the contrary, the dry gel synthesized in basic solution combusts at low ignition temperature and combustion reaction is violent; it is easy to form fine particles. XRD and TEM results reveal that the precursor powders are mainly two-phase mixture of La 2 O 3 and MgO. The morphology of the particles is almost flake with the size of ~30 nm when pH is 8.0.

The Preparation of Perovskite Nano Powder by Sol-gel from DTPA and the Mechanism of Thermal Decomposition

Dy0.8Sr0.2FeO3 nano powder, a synthetic oxide, is made by sol-gel method from metal nitrate and diethylenetriaminepentaacetic acid (DTPA), and the processing parameters are optimized. The process of the preparation, thermal decomposition and the property of the powder are studied by TG-DTA, IR, TEM, and XRD. The diameter of the average grain is about 70 nm. This new technique can be used in the preparation and the studying of na'no materials in the complex oxide system.

Preparation and Characterization on Nano- Sized Barium Titanate Powder Doped with Lanthanum by Sol-Gel Process

The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900℃and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43 .34 nm.

Study on Extended Gate Field Effect Transistor with Nano-TiO-2 Sensing Membrane by Sol-Gel Method

The nano-titanium dioxide (nano-TiO_2) sensing membrane,fabricated by sol-gel technology,was used as the pH-sensing layer of the extended gate field effect transistor (EGFET) device.The objective of this research is the preparation of titanium dioxide materials by sol-gel method using Ti(OBu)_4 as the precursor.In this study,we fabricated a nano-titanium dioxide sensing layer on the ITO glass by dip coating.In order to examine the sensitivity of the nano-TiO_2 films applied to the EGFET devices,we adopted the ITO glass as substrate,and measured theⅠ_(DS)-Ⅴ_G curves of the nano-titanium dioxide separative structure EGFET device in the pH buffer solutions that have different pH values by the Keithley 236 Instrument.By the experimental results,we can obtain the pH sensitivities of the EGFET with nano-TiO_2 sensing membrane prepared by sol-gel method,which is 59.86mV/pH from pH 1 to pH 9.

Synthesis of Nano-sized Yttria via a Sol-Gel Process Based on Hydrated Yttrium Nitrate and Ethylene Glycol and Its Catalytic Performance for Thermal Decomposition of NH_4ClO_4

Nano-sized yttria particles were synthesized via a non-aqueous sol-gel process based on hydrated yttrium nitrate and ethylene glycol. The effects of the molar ratio of ethylene glycol to yttrium ion and calcination temperature on crystallite size of the products were studied. The catalytic performance of the as-prepared yttria for the ammonium perchlorate （AP） decomposition was investigated by differential scanning calorimetry （DSC）. The results indicate that the nano-sized cubic yttria particles with less than 20 nm in average crystallite size can be obtained after 2 h reflux at 70℃, dried at 90 ℃, forming xerogel, and followed by annealing of xerogel for 2 h, and that the addition of the nano-sized yttria to AP incorporates two small exothermic peaks of AP in the temperature ranges of 310 - 350 ℃ and 400 - 470 ℃ into a strong exothermic peak of AP and increases the apparent decomposition heat from 515 to over 1110 J·g^- 1. It is also clear that the temperature of AP decomposition exothermic peak decreases and the apparent decomposition heat of AP increases with the increase of the amount of nano-sized yttria. The fact that the addition of the 5 % nano-sized yttria to AP decreases the temperature of AP exothermic peak to 337.7℃ by reduction of 114.6℃ and increases the apparent decomposition heat from 515 to 1240 J·g^-1, reveals that nano-sized yttria shows strong catalytic property for AP thermal decomposition.

High temperature oxidation of chromium with nanometric ceria sol-gel coating

Isothermal oxidation behavior of chromium with and without nanometric sol-gel CeO2 coating is studied at 1000℃ in air. Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） are used to examine the surface morphology and microstructure of their oxide films. It is found that ceria coating greatly improves the anti-oxidation property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer （XRD） are also used to study the stress level in oxide films formed on ceria-coated and ceria-free Cr. The difference in oxidation behavior is mainly attributed to the fact that ceria greatly reduces the growth speed and grain size of Cr2O3 film, and this fine grain-sized Cr2O3 film probably has better high temperature plasticity, i.e. oxide film can relieve parts of compressive stress by means of creeping. XRD and Raman testing results both show the stress declination due to nano-CeO2 application, and their deviation is analyzed conceming to the rare earth effect.

Effect of Bi3+ Ion Substitution on Magnetic Properties of Cobalt Nano Ferrites Prepared by Sol-Gel Combustion Method

Bismuth substituted cobalt nano ferrites with the chemical composition Co Bix Fe2-x O4 (x = 0.00, 0.05, 0.10, 0.15, 0.20 & 0.25) were prepared by sol-gel combustion method. The phase identification of prepared samples is characterised by X-ray powder diffraction (XRD) method, which confirms the formation of a single phase fcc spinal structure. The mean crystallite sizes of all prepared samples were obtained within the range of 21 (±5) nm. Transmission Electron Microscopy (TEM) images also confirmed the crystallite size of all the synthesised samples was in nano range. With the effect of Bi3+ ion substitution on spinal cobalt ferrite, the magnetic properties were investigated by using Vibration Sample Magnetometer (VSM). The obtained hysteresis (M-H) curves of all the samples were analysed under the applied magnetic field of range ± 10 K Oe at 300 K. The magnetic properties such as saturation magnetisation (Ms), remnant magnetization (Mr) and coercivity (Hc) values are tabulated, which show a decrease in trend as the bismuth ion concentration increases. This is due to the addition of Bi3+ ion in the place of Fe3+ ion (octahedral site) and hence the Bi3+-Fe3+ ion interaction predominates as compared with the Fe2+-Fe3+ ion interaction. The data obtained from magnetic studies, the variation among the magnetic properties have been investigated for all the prepared samples.

Preparation and Characterization of Nano-hydroxyapatite/polyvinyl Alcohol Gel Composites

Nano-hydroxyapatite reinforced poly（vinyl alcohol） gel（nano-HA/PVA gel） composites has been proposed as a promising biomaterial,especially used as an articular cartilage repair biomaterial.In this paper,nano-HA/PVA gel composite was prepared by in situ synthesis method and incorporation with freeze-thaw cycle process.The microstructure and morphology were investigated by X-ray diffraction,TEM,SEM and FTIR.The results showed that the size of HA particles synthesized in PVA solution was on the nanometer scale.Both the size and crystallinity of HA particles synthesized in PVA solution decreased compared with that of HA synthesized in distilled water.The nano-HA particles were distributed in PVA matrix uniformly due to the effect of PVA solution as a dispersant while low content of HA particles in the composites.On the contrary,with high content of nano-HA particles in the composites,the particles tended to aggregate.The result of FT-IR analysis indicated that the chemical bond between nano-HA particles and PVA matrix existed.The conformation and degree of tacticity of PVA molecule changed because of the addition of HA particles.Furthermore,the interfacial strength of the composites was improved due to the interaction between nano-HA particle and PVA matrix and this was beneficial to improving the mechanical properties of the composites.

Preparation of Scratch-Resistant Nano-Porous Silica Films Derived by Sol-Gel Process and Their Anti-reflective Properties

Structural strengthening of the nano porous silica films has been reported. The films were prepared with a base/acid two-step catalyzed TEOS-based sol-gel processing and dip-coating, and then baked in the mixed gas of ammonia and water vapor. The silica films were characterized with TEM, AFM, FTIR, spectrophotometer, ellipsometer, and abrasion test, respectively. The experimental results have shown that the films have a nanostructure with a low refractive index and can form an excellent scratch-resistant broadband anti-reflectance. The two-step catalysis noticeably strengthens the films, and the mixed gas treatment further improves mechanical strength of the silica network. Finally the strengthening mechanism has been discussed.

Structure,room-temperature magnetic and optical properties of Mn-doped TiO_2 nano powders prepared by the sol-gel process

TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 ℃ are of pure anatase and rutile, respectively. The scanning electron microscope （SEM） observations reveal that the crystal grain size increases with the annealing temperature, and the high resolution transmission electron microscopy （HRTEM） investigations further indicate that the samples are well crystallized, confirming that Mn has doped into the TiO2 crystal lattice effectively. The room temperature ferromagnetism, which could be explained within the scope of the bound magnetic polaron （BMP） theory, is detected in the Mn-TiO2 samples with Mn concentration of 2 at%, and the magnetization of the powders annealed at 500 ℃ is stronger than that of the sample treated at 800 ℃. The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.

Synthesis of Yb³⁺Doped TiO₂Nano Particles Powder as IR Filter via Sol-Gel

Ytterbium doped TiO2 nano-particles were prepared via Sol-Gel Technique under varying conditions to investigate the effects of Ytterbium ion doping on the Titania optical properties in MID IR range. X-ray diffraction analyses show that prepared Yb3+ doped TiO2 samples have polycrystalline structure in Anatas phase. FTIR spectrums for pure and doped samples after annealing process show a single transmission peak at wave number around 1145 cm-1. Transmission rate of this peak depends on Yb3+ concentrations and its value rises from 1.82% (for pure TiO2) to 58.1% (for doped with 1.13 wt% Yb3+). Slightly peak shift occurs at a lower doping rate with no further response to higher concentration rate. FTIR spectra gives a good indication in direction of preparation of optical band-pass filter at a wavelength around 8.733 μm (~1145 cm-1).

Prepared of Nd: TiO₂Nano Particles Powder as IR Filter via Sol-Gel

Doped and undoped nanostructured titanium dioxides were prepared via Sol-Gel method under varying conditions to investigate the effects of neodymium ion doping on the titania optical properties in MID IR range. X-ray diffraction analyses show that the amorphous structure of the prepared samples turns to anatas polycrystalline structure after annealing process at 500°C. FTIR spectrums for pure and doped samples after annealing show a single transmission peak at wave number around 1200 cm-1. The transmission rate of the peak depends on Nd3+ concentrations and its value rises from 1.82% (for pure TiO2) to 86.9% (for doped with 12%wt Nd3+). Shifting on the peak occurs with a maximal shift at 7%wt Nd3+ and then becomes stable at higher concentration. FTIR spectra give a good indication in the direction of preparation of optical band-pass filter at a wavelength around 8.34 μm (~1200 cm-1).

Physical Properties of Nano-Composite Silica-Phosphate Thin Film Prepared by Sol Gel Technique

A series of silica-phosphate nano-composites prepared as a host thin films Physical Properties of Nano-Composite Silica-Phosphate Thin Film Prepared by Sol Gel Technique and doped with different concentrations of Er3+ ions have been synthesized using tetraesoxysilane TEOS, triethylphosphate TEP and erbium nitrate as precursor sources of silica, phosphorus and erbium oxides. The structural properties of pure silica-phosphate thin films and doped with different concentrations of Er3+ ions were studied, using x-ray diffraction (XRD) and Fourier Transform Infrared (FTIR). The morphology of silica-phosphate was characterized by Scanning electron microscope (SEM).

Characterization of Chromium Substituted Cobalt Nano Ferrites Synthesized by Citrate-Gel Auto Combustion Method

Co-Cr nano-ferrites, having the chemical formula CoCrxFe2-xO4 (where x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0), were synthesized by the Citrate-gel auto combustion method. Synthesized powders were sintered at 500°C for 4 hours in an air and were characterized by XRD, SEM and EDS. XRD analysis showed cubic spinel structure of the ferrites and the crystallite sizes (D) were found in the range of 6 - 12 nm. The values of lattice parameter (a) decreased and X-ray density (dx) increased with the increase of Cr content. Scanning Electron Microscopic (SEM) studies revealed nano crystalline nature of the samples. An elemental composition of the samples was studied by Energy Dispersive Spectroscopy (EDS). The observed results can be explained on the basis of composition and crystal size.

RHEOLOGICAL MODIFICATION OF EPOXY RESINS WITH NANO SILICA PREPARED BY THE SOL-GEL PROCESS

Nano silica-modified epoxy resins were synthesized by the sol-gel process, The materials have the morphological structure of nano particales dispersed in the epoxy matrix. The dispersed phase formed a physical network in the resin and thus influenced the rheological behavior greatly. However, the nano silica did not show a significant influence on the mechanical properties of the cured resins.

Determination of A.C. Conductivity of Nano-Composite Perovskite Ba_{(1- x - y)}Sr_(x)TiFe_(y)O₃Prepared by the Sol-Gel Technique

Nano-composite, perovskite Ba(1- x - y)Sr(x)TiFe(y)O3, denoted as (BSTFe) in powder form was derived via sol-gel (SG) method followed by sintering at fixed temperature 750℃ for one hour. The chemical composition, morphology and structure of the powder samples were investigated by using X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). The XRD characterization indicates formation of a cubic crystalline phase in the pure BST. A well defined perovskite phase with nano-crystallite sizes equal to about 34 nm was achieved from XRD for B10ST3F sample, while TEM study confirmed the obtained XRD results giving the following crystallite size value about 33.75 nm for the same sample. The dielectric A.C. conductivity was evaluated as a function of temperature and frequency ranging from 42 Hz up to 1 MHz.

MESOPOROUS TIO_2 NANO-SPHERES: ELECTROSPRAY COMBINED SOL-GEL FABRICATION AND APPLICATION TO ORGANIC PHOSPHORUS DEGRADATION

In this work, electrospray technique combined sol-gel method was used to prepare porous TiO2 film. X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), and Scanning Electron Microscope (SEM) analyses were conducted to examine the chemical composition, phase structure, and surface morphology of the sprayed TiO2 film. After calcined at 450℃ in air atmosphere for 2 h, mesoporous TiO2 nano-spheres clusters were formed on the surface of silicon wafer and the average size of nano-spheres was 250 nm. Ti presented as Ti 4+ oxidation state in TiO2 film, and the TiO2 film exhibited the anatase phase. The sprayed porous TiO2 films were employed as photocatalyst to degrade organic phosphorus in water samples. Compared with the TiO2 film prepared by Sol-Gel spin-coating method, the porous TiO2 film deposited by electrospray combined sol-gel method showed higher photocatalytic activity.

Preparation Nano-Diamond Film by Sol-Gelled Coating Method for Field Emission Display

The mixture of Nano-graphite and organic vehicles doped to Nano-diamond paste. The suitable paste proportion was found. Nano-diamond film (NDF) was prepared by sol-gel coating method on ITO glass at 3000/min. The field emission characteristics of luminance-current, luminance-voltage and luminance-power of Nano-diamond film were analyzed and tested. Comparing these tested curves, the luminance was well proportional to current was got. Theoretic, the inner resistance of NDF field emission display (FED) consumes electric energy and real voltage change between the cathode and the anode of NDF-FED was very small after electrons emit. So the characteristic of NDF-FED was preferable to describe by luminance-current linear relationship, which was advantageous to device tested and designed.