Optical Properties of ATO Sol-gel Coated Carbon Fibers

2012 ◽  
Vol 1454 ◽  
pp. 221-226
Author(s):  
Brandon Richard ◽  
Norma Alcantar ◽  
Andrew Hoff ◽  
Sylvia Thomas
Keyword(s):  
Heat Treatment ◽  
Optical Properties ◽  
Carbon Fibers ◽  
Sol Gel ◽  
Functional Materials ◽  
Additional Material ◽  
Heat Treated ◽  
Ft Ir ◽  
Recent Trends ◽  
Thermal Infrared Radiation

ABSTRACTRecent trends in composite research include the development of structural materials with multiple functionalities. In new studies, novel materials are being designed, developed, modified, and implemented into composite designs. Typically, an increase in functionality requires additional material phases within one system. The presence of excessive phases can result in deterioration of individual or overall properties. True multi-functional materials must maintain all properties at or above the minimum operating limit. In this project, samples of Sb-doped SnO2(ATO) sol-gel solutions are used to coat carbon fibers and are heat treated at a temperature range of 200 – 500 °C. Results from this research are used to model the implementation of sol-gel coatings into carbon fiber reinforced multifunctional composite systems. This research presents a novel thermo-responsive sol-gel/ (dopant) combination and evaluation of the actuating responses due to various heat treatment temperatures. While ATO is a well-known transparent conductive material, the implementation of ATO on carbon fibers for infrared thermal reflectivity has not been examined. These coatings serve as actuators capable of reflecting thermal infrared radiation in mid-range and near-range wavelengths (λ). By altering the ATO sol gel thickness and heat treatment temperatures, optimal optical properties are obtained. While scanning electron microscopy (SEM) is used for imaging, electron diffraction spectroscopy (EDS) is used to verify the compounds present in the coatings. Fourier transform infrared (FT-IR) spectroscopy was performed to analyze the reflectivity in the infrared spectra and analyze the crystal structures after heat treatments.

scholarly journals Tuning Green to Red Color in Erbium Niobate Micro- and Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 660
Author(s):  
Susana Devesa ◽  
Joana Rodrigues ◽  
Sílvia Soreto Teixeira ◽  
Aidan P. Rooney ◽  
Manuel P. F. Graça ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Optical Properties ◽  
Room Temperature ◽  
Sol Gel ◽  
High Energy ◽  
Site Symmetry ◽  
Photoluminescence Spectra ◽  
Heat Treated ◽  
Red Color ◽  
Optical Activation

Tetragonal Er0.5Nb0.5O2 and monoclinic ErNbO4 micro- and nanoparticles were prepared by the citrate sol–gel method and heat-treated at temperatures between 700 and 1600 °C. ErNbO4 revealed a spherical-shaped crystallite, whose size increased with heat treatment temperatures. To assess their optical properties at room temperature (RT), a thorough spectroscopic study was conducted. RT photoluminescence (PL) spectroscopy revealed that Er3+ optical activation was achieved in all samples. The photoluminescence spectra show the green/yellow 2H11/2, 4S3/2→4I15/2 and red 4F9/2→4I15/2 intraionic transitions as the main visible recombination, with the number of the crystal field splitting Er3+ multiplets reflecting the ion site symmetry in the crystalline phases. PL excitation allows the identification of Er3+ high-energy excited multiplets as the preferential population paths of the emitting levels. Independently of the crystalline structure, the intensity ratio between the green/yellow and red intraionic transitions was found to be strongly sensitive to the excitation energy. After pumping the samples with a resonant excitation into the 4G11/2 excited multiplet, a green/yellow transition stronger than the red one was observed, whereas the reverse occurred for higher excitation photon energies. Thus, a controllable selective excited tunable green to red color was achieved, which endows new opportunities for photonic and optoelectronic applications.

Preparation of La0.75Sr0.25Cr0.5Mn0.5O3-δ Nanometer Powders by Sol-Gel Method and Research about its Electrochemical Performance

2013 ◽  
Vol 712-715 ◽  
pp. 257-261
Author(s):  
Yin Lin Wu ◽  
Qing Hui Wang ◽  
Ling Wang ◽  
Hai Yan Zhao
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Electrochemical Performance ◽  
Heat Treatment Temperature ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Preparation Process ◽  
Gel Method ◽  
Sol Gel Method ◽  
Ft Ir

The La0.75Sr0.25Cr0.5Mn0.5O3-δnanometer powders were prepared by citric acid sol-gel method.The samples were characterized by DTA, FT-IR, XRD, TEM techniques. The preparation process, morphology of synthesized powders, the best heat-treatment temperature and the electrochemical performance had been studied. The results show that the spherical nanometer powders can be obtained and the best heat-treatment temperature is 800°C. The particle size is about 30nm and Ea is 0.071 eV.

Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 123-125 ◽  
Author(s):  
Yong Li ◽  
Qi Hong Wei ◽  
Ling Li ◽  
Chong Hai Wang ◽  
Xiao Li Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Heat Treatment Temperature ◽  
Bending Strength ◽  
Sol Gel ◽  
Negative Thermal Expansion ◽  
Treatment Temperature ◽  
Heat Treated

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.

Copper-alumina materials made by infiltration in boehmite

1995 ◽  
Vol 10 (9) ◽  
pp. 2271-2276 ◽  
Author(s):  
V. Pierre ◽  
D. Pierre ◽  
A.C. Pierre
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Phase Transformation ◽  
Sandwich Structures ◽  
Sol Gel ◽  
Copper Acetate ◽  
New Materials ◽  
Heat Treated ◽  
Direct Infiltration

New materials were made by infiltration of sol-gel boehmite thin films with copper acetate. The structure and phase transformation of these materials during heat treatment were studied. It was found that infiltration in the boehmite state did not end up in the same material as direct infiltration in the θ-alumina derived from boehmite, even after both types of materials were heat-treated at 900 °C. Infiltration in boehmite makes it possible to synthesize sandwich structures comprised of alternate layers of CuO and of γ-alumina.

Influence of Li2+ Doping on the Structural and Optical Properties of CaO Synthesized by Sol–Gel Process

2019 ◽  
Vol 07 (01n02) ◽  
pp. 1950002
Author(s):  
Nadir Lalou ◽  
Ahmed Kadari
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Sol Gel ◽  
Calcium Nitrate ◽  
Lithium Nitrate ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Sol Gel Process ◽  
Ft Ir ◽  
First Time

This work proposes the synthesis of nanocrystalline calcium oxide (CaO) pure and doped with different concentrations of lithium (Li[Formula: see text]) ions by sol–gel process. Calcium nitrate (Ca(NO[Formula: see text]4H2O; 99.99%) and lithium nitrate (LiNO3; 99.99%) were used as precursors. The synthesized powders were characterized by several techniques such as: UV-Vis transmission spectroscopy, Fourier Transform Infra-red spectroscopy (FT-IR) and X-ray diffraction (XRD). The main objective of this paper is to study the influence of lithium (Li[Formula: see text] ratio) on the structural and optical properties of synthesized powders. The band gap values decreased with the increasing of Li[Formula: see text] ions in CaO lattice; the slight change in the band gap was directly related to the energy transfer between the CaO excited states and the 2s levels of Li[Formula: see text] ions. The influence of Li[Formula: see text] doping on the physical properties of CaO nanocrystalline will be studied for the first time in this work; no literature has previously published this kind of impurities.

scholarly journals Structural characterization of heat-treated activated carbon fibers

1992 ◽  
Vol 7 (7) ◽  
pp. 1788-1794 ◽  
Author(s):  
A.M. Rao ◽  
A.W.P. Fung ◽  
M.S. Dresselhaus ◽  
M. Endo
Keyword(s):  
Heat Treatment ◽  
Activated Carbon ◽  
Raman Scattering ◽  
Carbon Fibers ◽  
Insulator Transition ◽  
Activated Carbon Fibers ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Sequence Of Events ◽  
Heat Treated

Raman scattering, x-ray diffraction, and BET measurements are used to study the effect of heat treatment on the microstructure of activated carbon fibers (ACFs) and to correlate the structural changes with the metal-insulator transition observed in the electronic transport properties of heat-treated ACFs. A sequence of events is identified, starting with desorption, followed by micropore collapse plus the stacking of basic structural units in the c-direction, and ending up with in-plane crystallization. The graphitization process closely resembles that depicted by Oberlin's model, except that the final material at high-temperature heat treatment remains turbostratic. Because the metal-insulator transition was observed to occur at heat-treatment temperature THT ≃ 1200 °C, which is well below the THT value (2000 °C) for in-plane crystallization, we conclude that this electronic transition is not due to in-plane ordering but rather to the collapse of the micropore structure in the ACFs. Raman scattering also provides strong evidence for the presence of local two-dimensional graphene structures, which is the basis for the transport phenomena observed in heat-treated ACFs.

Indium-Sensitized UV Photocatalysts Made from Alkali Titanate Microfibers

2009 ◽  
Vol 620-622 ◽  
pp. 651-654
Author(s):  
Leticia M. Torres-Martínez ◽  
Cecilia Sánchez-Trinidad ◽  
Vicente Rodríguez-González ◽  
Ricardo Gómez
Keyword(s):  
Heat Treatment ◽  
Annealing Time ◽  
Uv Light ◽  
Sol Gel ◽  
Dichlorophenoxyacetic Acid ◽  
Sem Images ◽  
Uv Light Irradiation ◽  
Heat Treated ◽  
Munk Function ◽  
Sol Gel Process

Indium-alkali microfibers doped ceramic were prepared by the sol-gel process. The gels preparation samples, were heat treated at 700°C for different length of time. The products were characterized by means of XRD, SEM-EDS and UV–Vis-DRS. The XRD showed the formation of the Na2Ti6O13 phase whose crystallinity depends on the annealing time. The band gap calculated from the UV–Vis Kubelka-Munk function shows very similar values (3.53-3.55 eV). The SEM images of the indium-alkali titanates show microfiber clumps morphologies of about 5 µm, and the EDS spectra show that In2O3 is on the Na2Ti6O13 surface. The results of the evaluation of the In-Na2Ti6O13 semiconductors in the 2, 4-dichlorophenoxyacetic acid (2, 4-D) photodecomposition under UV light irradiation, show that the photoactivity depends on the time of heat treatment of the samples.

Mechanical Properties of Sol-Gel Inorganic-Organic Hybrid Films in Nanoindentation

2006 ◽  
Vol 317-318 ◽  
pp. 317-322 ◽  
Author(s):  
J.Q. Zhang ◽  
Atsunori Matsuda ◽  
Hiroyuki Muto ◽  
Mototsugu Sakai
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Treatment Time ◽  
Sol Gel ◽  
Heat Treatment Time ◽  
Nanoindentation Test ◽  
Glass Substrates ◽  
Organic Hybrid ◽  
Elastoplastic Properties ◽  
Heat Treated

Methylsilsesquioxane films were formed on glass substrates by dropping a sol prepared from methyltriethoxysilane and then heat-treated in an oven. Nanoindentation test was performed to assess the elastoplastic properties of the films, including the relative residual depth ξr, Meyer hardness HM, work-of-indentation WI and the elastic modulus E’. The values of ξr, HM and WI were obtained by a Berkovich indenter and E’ was determined by a spherical indenter on the basis of Hertz elastic theory. ξr decreased with the increase in the heat treatment time, whereas HM , WI and E’ significantly increased with the time. The changes in the mechanical properties with the heat treatment time well reflected the evolution of the Si-O-Si network structure in methylsilsequioxane film.

Effect of Surfactants on Stability of Colloidal Sols as Precursors in Sol-Gel Encapsulation

2009 ◽  
Vol 415 ◽  
pp. 57-60 ◽  
Author(s):  
Ioana Lacatusu ◽  
Nicoleta Maria Badea ◽  
Aurelia Meghea
Keyword(s):  
Sol Gel ◽  
Functional Materials ◽  
Flavonoid Compound ◽  
Quaternary Salts ◽  
Bioactive Properties ◽  
Nir Fluorescence ◽  
Scattering Measurements ◽  
Ft Ir ◽  
Preparation Route ◽  
Gel Preparation

This paper aims to study the effect of three alkyl quaternary salts on stability of colloidal sols further used as water-insoluble oligomers for encapsulation of an active flavonoid compound – quercitin. The preparation procedure is described and practical remarks on silica-based sol-gels are included. It is also demonstrated how to exploit the sol-gel preparation route in order to improve the thermal resistance of quercitin and to increase an optical function - fluorescence. The evolution in time of competitive hydrolysis and condensation processes has been observed by dynamic light scattering measurements. The sol-gel materials with entrapped quercitin molecule have been characterised by spectral methods (FT-IR, UV-VIS-NIR), fluorescence and by thermal analysis as well. Sol-gel materials doped with active flavonoid compound may be used in preparation of some functional materials with bioactive properties.

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