Optical Properties Of Titanium Dioxide Research Articles

Influence of Cu nanoparticles concentration on the electronic transition of pulsed laser deposited TiO2/ ZnO: Cu nanocoposite film

The decoration energy band gap of metal oxide material was a key issues for important applications which has remarkable effects on the electronic transition. in this work, the structure and optical properties of titanium dioxide, zinc oxide and copper nanocoposite were studied. TiO2, ZnO and Cu were successfully deposited on a suitable glass substrate at room temperature using a pulsed laser deposition (PLD) technique N d: YAG laser with = 1064 nm wavelength at energy 500 mJ was used, concentrations of Cu = (4%, 8%, 12%, 16%, 20%). The surface topography was studied using atomic force microscopy (AFM) to ensure that the films had a homogeneous surface and that the minimum grain size obtained was 50.06 nm at 20% of Cu. The absorption spectrum was studied and observed that it increases with increasing in the ratio of Cu, and the energy gap decreases with the percentage of Cu and direct possible transitions in the range of 2.74 to 3.21 eV. Also the electrical properties was studied such as Hall effect and found that these films had of the charge n-type negative charge carriers.

Study the Effect of Thickness on Optical Properties of Titanium Dioxide (TiO2) That Preparation of Via the Sol-Gel Process

This research, study the effect of the thickness on titanium dioxide (TiO2) , that prepared by the Sol-Gel Process method on the optical properties of (TiO2) thin film with different thickness (54, 64 and 89 nm), the thickness effect on optical properties (energy gap , absorbance spectrum, transmittance spectrum, reflectance, refractive index, extinction coefficient, absorption coefficient, real and imaginary dielectric constant) ,this study shows that thickness have an effect on all these parameters .

Synthesis and Characterization of Titanium (iv) Oxide Loaded with Silver Nano Particles Thin Films

This research investigates effect of annealing temperature on the optical properties of titanium dioxide loaded with silver nanoparticles (TiO2: AgNPs) thin films deposited on glass substrate by spin–coating technique. Silver nanoparticles was prepared using laguminosae-paplionodeae extracts as a reducing agent for silver nitrate and commercially available titanium (iv) oxide was used. Deposition of TiO2:AgNPs blend solution was done in different volume ratio. The blend solution volume ratio of (1:0.2) was deposited at 7 different thicknesses with different speed of revolution per minutes (rpm) for 30 seconds. Annealing of 16 samples deposited at 1000 rpm on the glass substrate was carried out at temperature range of 50°C to 425°C with 10°C interval in a tubular furnance. It is observed from the results that the peak absorption of photon energy occurred at 375°C in the visible range of the wavelength spectrum. Optimal thickness for peak absorbance of the TiO2:AgNPs blend layer occurred at 115 nm in the visible spectrum and at the corresponding spin speed of 1000 rpm. Optimized fabrication process with blend layer thickness of 115 nm yielded the best absorbance at annealed temperature of 375°C in the visible spectrum. The volume ratio of (1:0.2) gave the peak absorption at 0.75 a u. The band gap energy of the blend thin film is 3.58 eV at 375°C in the visible range of wavelength spectrum. It is revealed from the result that the light absorption, broadened absorption spectral range and thermal stability of titanium (iv) oxide film could be enhanced using silver nanoparticles. The results can be therefore used as a guideline for improving the design and fabrication of organic solar cells.

The generation of charge carriers in semi conductors – A theoretical study

A systematic study of electronic and optical properties of titanium dioxide under visible light was simulated using the first principles calculations. Both electronic and optical properties were studied. The findings support the application of TiO2 in photo energy generation after experimentally modifications. Our calculations were done using DFT with the GGA+U approach to mimic the experimental results and avoid underestimation of DFT. A theoretical band gap of 3.15eV complimented the experimentally obtained band gap of 3.2eV. Finally, our results revealed that upon protonation there is charge generation and this has the potential for application in photo energy generation.

Structural, electronic and optical properties of brookite phase titanium dioxide

Structural, electronic and optical properties of titanium dioxide (TiO2) in brookite phase were studied via first-principles calculations in the framework of density functional theory (DFT). The exchange-correlation functional from local density approximation (LDA) and generalized gradient approximation (GGA) were used to calculate the properties of brookite TiO2. The structural parameters of brookite in orthorhombic structure (Pbca space group) are in good agreement with the previous theoretical and experimental data. The obtained direct band gaps from GGA are slightly higher than LDA. Both LDA and GGA band gaps underestimate the experimental band gap due to the well-known limitation of DFT. The density of states (DOS) displays the hybridization of O 2p and Ti 3d states and Mulliken population analysis presents the net charge of Ti and O atoms in brookite. The dielectric function was also analyzed together with other optical properties such as refractive index, reflectivity, loss function and absorption coefficient. The first-principles calculations on the least studied TiO2 in brookite phase using different exchange-correlation functional from LDA and GGA provide theoretical understanding about its structural, electronic and optical properties. Besides, these results would give a better support for technological applications concerning TiO2 materials using brookite phase.

Investigation on Stability and Optical Properties of Titanium Dioxide and Aluminum Oxide Water-Based Nanofluids

Water is regarded as a poor absorber of solar energy. This affects the efficiency of solar thermal systems. The addition of nanoparticles to heat transfer fluids used in solar thermal systems can enhance their optical properties. These new-generation heat transfer fluids are known as nanofluids. The present study investigates the stability and optical properties of three nanofluids, including aluminum oxide (13 nm and <50 nm) and titanium dioxide (21 nm) nanofluids. The stability of the nanofluids was observed through a photo-capturing method and zeta potential measurements. Ultraviolet–visible (UV–Vis) spectrophotometer was used to measure the absorbance and transmittance of the prepared nanofluids. The effect of factors such as type of particle, type of surfactant, and pH of the solution on the optical properties of the nanofluids was also investigated. We found that the titanium dioxide nanofluid had better optical properties but lower stability compared to aluminum oxide nanofluids.

Effect of N and F content on structural, optical and photocatalytic methylene blue degradation properties of TiO2

Photocatalytic systems based on fluorine- and nitrogen-doped titanium dioxide were obtained via the sol–gel method. Titanium tetraisopropoxide and ammonium fluoride were used as precursors. Transmission electron microscopy and measurement of Brunauer–Emmett–Teller surface area and porosity were used to establish that the concentration of ammonium fluoride has an impact on the structural parameters of titanium dioxide produced in the sol–gel process. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy revealed that the dopants (F and N) are not incorporated into the crystal lattice of titanium dioxide, but affect the optical properties of titanium dioxide due to the emergence of additional bands in the absorption spectra in the range of 380–450 nm. Sorption and photoactivity were found using methylene blue photodecomposition under visible light. It was found that dopant introduction increases both sorption ability and photoactivity of the materials.

Effect of Annealing Temperature on the Structural and Optical Properties of TiO&lt;sub&gt;2&lt;/sub&gt; Thin Film Prepared by Sol-gel Method

The effect of annealing temperatures on the surface morphology and optical properties of titanium dioxide (TiO2) thin films deposited by spin coating on Silicon substrate was studied. The TiO2 thin films deposited onto silicon substrates were annealed at different temperatures. The structural and optical properties were studied using scanning electron microscopy (SEM), X-ray diffraction technique (XRD) and optical ellipsometer. The results indicated that the structural properties of the TiO2 thin films were changed with the increase in annealing temperature. The SEM investigation showed that as annealing temperature was increased, the grain and pores size were increased. The XRD patterns of the studied samples showed that rutile phase were found in a sample annealed at high temperature. The ellipsometry investigation shows that the refractive index increased while energy band gap decreased with the annealing temperature. The results showed that surface porosity, optical properties and surface morphology of TiO2 could be affected by changing the annealing temperature.

First-Principles Study on Structural, Electronic and Optical Properties of TiO&lt;sub&gt;2&lt;/sub&gt; for Dye-Sensitized Solar Cells Photoanode

First-principles study based on density functional theory (DFT) framework for structural, electronic and optical properties of titanium dioxide (TiO2) in anatase and rutile phases are investigated. Anatase phase exhibits wide band gap compare to rutile phase. The partial and total density of states for TiO2 (anatase and rutile) describes the occupying of titanium (Ti) and oxygen (O) atoms at each energy level. TiO2 has a high dielectric constant to avoid the recombination process while its high refractive index provides the efficient of light diffusion. The optical absorption of TiO2 occurs in ultraviolet (UV) light of the wavelength photon. The results from the first-principles calculations will be helpful to give an understanding about the properties of TiO2 as promising photoanode in dye-sensitized solar cell (DSSC).

Hubbard U calculations on optical properties of 3d transition metal oxide TiO2

The optical properties of titanium dioxide (TiO2) in rutile, anatase and brookite phases were investigated via density functional theory (DFT) framework. The Hubbard U term in Ti 3d electrons of the TiO2 phases was introduced to observe the optical behavior with the effect of U parameter. The calculated structural parameters from the optimized TiO2 are in good agreement with the previous experimental and theoretical data. The values of static dielectric constant and refractive index from exchange-correlation functional in standard DFT are slightly higher than the DFT+U method. The energy peaks of reflectivity and loss function spectra show the good match with each other. The TiO2 with rutile, anatase and brookite phases have optical absorption in the ultraviolet (UV) light region. Thus, the inclusion of U parameters turn out to shift the wavelength photon towards the low region. Furthermore, this work provides a good theoretical understanding of the optical properties of TiO2 which helpful in a technological application such as photocatalysis and photovoltaics.

A density functional study of structural, electronic and optical properties of titanium dioxide: Characterization of rutile, anatase and brookite polymorphs

Study of fundamental physical properties of titanium dioxide (TiO2) is crucial to determine its potential for different applications, such as study of electronic band gap energy is essential to exploit it for optoelectronics and solar cell technology. We present here investigations pertaining to structural, electronic and optical properties of rutile, anatase and brookite polymorphs of TiO2 by employing state of the art full potential (FP) linearized (L) augmented plane wave plus local orbitals (APW+lo) approach realized in WIEN2k package and framed within density functional theory (DFT). To incorporate exchange correlation(XC) energy functional/potential part into total energy, these calculations were carried out at the level of PW–LDA, PBE–GGA, WC–GGA, EV–GGA, and mBJ–GGA which are exploited as the manipulated variables in this work. From our computations, the obtained structural parameters results were found to be consistent with the available experimental results. The analysis of electronic band gap structure calculations point to TiO2 as a semiconducting material in all three phases, whereas band gap character around Fermi level was found to be indirect for anatase, and direct for rutile and brookite phases. Density of state (DOS) profiles showed a substantial degree of hybridation between O 2p and Ti 3d in conduction and valence band regions, illustrating a strong interaction between Ti and O atoms in TiO2 compund. In addition, our investigations of the optical properties also endorse the interband transitions from O 2p in valence band to Ti 3d in conduction band.

Transition from anatase to rutile phase in titanium dioxide (TiO2) nanoparticles synthesized by complexing sol–gel process: effect of kind of complexing agent and calcinating temperature

In this work, the structural and optical properties of titanium dioxide (TiO2) nanopowders are studied. The TiO2 nanoparticles were synthesized by complexing sol–gel process and effect of complexing agents on transition of the anatase phase to rutile phase during the heat treatment have been investigated. In addition, we have studied the grain size of TiO2 powders and their dependence on the type of complexing agent. The analysis of the XRD patterns, FT-IR and UV–Vis spectroscopy, BET surface area and TEM images show that the synthesis of nanoparticles with acetyl acetone (AcAc) as complexing agent yielded the smallest size of nanoparticles about 22–35 nm. Our results indicate that with increasing the calcinating temperature, the size of the nanoparticles is increased and the energy gap reduced, too. Also, the optical band gap was obtained in the range of 3.4–4.1 and 3.06–3.74 eV for anatase and rutile phases, respectively.

Dye-Sensitized Solar Cells Based on a Natural Low Cost Halochromic Sensitizer

ABSTRACTSince their re-introduction as new generation solar cells in 1991, dye-sensitized solar cells (DSSCs) have been studied extensively to improve their efficiency and their stability. Few papers have reported the usage of natural dyes in the fabrication of DSSCs. We are most interested in these dyes being easy to extract, low cost and with tunable absorption. For example, Anthocyanin is extracted from red cabbage and is present in a multitude of colors ranging from red to yellow to violet according to the pH. In this study, two industrial types of titanium dioxide powders, the Degussa P 25 and the Crystal 128 with different particle sizes 21 and 200 nm respectively, were used to prepare DSSCs. The dye used is anthocyanin and its color is varied by varying the pH of the medium. The pH effect on the light absorption of anthocyanin in the visible range and the optical properties of titanium dioxide dyed with anthocyanin and coumarin 102 are investigated using UV-Vis spectroscopy. The open-circuit voltage of all the samples is tested and it if found out that it is dependant on the dye color.

Investigation of the Effect of Titanium Dioxide on Optical Aspects and Physical and Mechanical Characteristics of ABS Polymer

Acrylonitryl-butadiene-styrene (ABS) is an engineering polymer with intrinsic yellowness and translucency due to blue wavelength absorption and partial light transmission, respectively. Generally, using titanium dioxide pigment helps to whiten ABS polymer and reduce its intrinsic yellowness. Also, it can impart opacity to polymeric parts. However, it must be considered that this pigment may cause some unfavorable effects in ABS parts. In this article, effects of surface treatment type and content of TiO2 pigment on optical aspects of a general purpose ABS have been investigated. In addition, physical and mechanical characteristics including tensile strength, izod impact strength and Rockwell hardness of the polymer have been studied. By adding titanium dioxide pigment opacity and whitening index increased and yellowness index decreased. It is important to note that surface treatment type of titanium dioxide pigment had no considerable effect on optical properties of titanium dioxide pigmented ABS polymer. The results showed that arising content of organic and inorganic surface treated TiO2 pigments up to 0.5% and 1.5%, respectively, causes to increase impact strength and decrease yield stress and maximum strain of pigmented ABS samples. Above these percentages, impact strength decreased due to agglomeration and decreasing inter-particle spacing. Also hardness of all the ABS samples reduced in the presence of inorganic and organic treated titanium dioxide pigments.

Optical and Electrical Properties of TiO2 Nanotubes Grown by Titanium Anodization

AbstractIn this work we investigated the structural, electrical, and optical properties of titanium dioxide (TiO2) nanotubes (NTs) formed by electrochemical anodization of Ti metal sheets in NH4F+glycerol electrolyte at different anodization voltages (Va) and acid concentrations. Our results revealed that TiO2 NTs can be grown in a wide range of anodization voltages from 10 V to 240 V. The maximum NH4F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for Va&lt;60V, and decreases to 0.1% at Va =240 V. Glancing angle X-ray diffraction (GAXRD) experiments show that as-grown amorphous TiO2 transforms to anatase phase after annealing at 400 oC, and further transforms to rutile phase at annealing temperatures above 500 oC. Samples grown in 30-120 voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with Va concentration and increases by eight orders of magnitude when Va increases from 10 V to 240 V. This is consistent with cathodoluminescense studies which showed improved optical properties for samples grown in this voltage range. Optical properties of samples were also studied by low temperature photoluminescence. Temperature dependent I-V and photo-induced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.

Nanocrystalline TiO&lt;sub&gt;2&lt;/sub&gt; Coated-Fabric for UV Shielding and Anti-Bacterial Functions

Due to excellent photocatalytic and optical properties of titanium dioxide (TiO2), it has been applied in several products such as food packaging plastics, materials for vehicles or for buildings and sunscreen-protecting cosmetics. In this present work, the synthesized as well as commercial TiO2 was coated onto a household curtain fabric for anti-microbial and ultraviolet (UV) shielding functions. The coating was performed by inducing the deposition of TiO2 layer from the Ti precursor onto the fabric surface pre-treated with silane adhesive agent so as to improve the adhesion. Ag nanoparticles were also incorporated in some samples to further improve the antibacterial function. Anti-bacterial activities of the coated fabric were evaluated by standard qualitative test (the Kirby-Bauer test (AATCC 147)). Efficiency for UV shielding was evaluated by measuring a UV-Vis reflection of the coated fabrics both before and after subjecting to several washing cycles. The result showed that the TiO2-coated fabrics developed had potential as antibacterial and UV shielding for the curtain industry.

Investigation on microstructure and optical properties of titanium dioxide coatings annealed at various temperature

TiO2 coatings were prepared on fused silica with conventional electron beam evaporation deposition. After TiO2 thin films were annealed at different temperatures for 4 h, several properties were investigated by X-ray diffraction (XRD), spectrometer, photoelectron spectroscopy (XPS) and AFM. It was found that with the annealing temperature increasing, the transmittance of TiO2 coatings decreased, and the cutoff wavelength shifted to long wavelength in near ultraviolet band. Especially, when coatings were annealed at high temperature, the optical loss is very serious, which can be attributed to the scattering and the absorption of TiO2 coatings. XRD patterns revealed that only anatase phase was observed in TiO2 coatings regardless of the different annealing temperatures. XPS results indicated that the fine chemical shift of TiO2 2p1/2 should be attributed to existence of oxygen vacancies around Ti+4 ion. The investigation on surface morphology by AFM showed that the RMS of titania thin films gradually increases from less than 0.40 nm to 5.03 nm and it should be ascribed to the growth of titanium dioxide grain size with the increase of annealing temperature.

Optical properties of pigmented coatings taking into account particle interactions

Abstract A T-matrix approach is used to obtain the orientation-averaged scattering and absorption cross sections of randomly oriented particle clusters, and the average angular distribution of the radiation scattered by them. The coefficients involved in the expansion of the phase function are obtained from this T-matrix approach, and used in a multiple scattering formalism to characterize the angular distribution of the diffuse radiation propagating through a particulate coating perpendicularly illuminated with collimated visible radiation. Asymmetry between forward and backward propagating diffuse radiation intensities is taken into account by means of this multiple scattering approach, which is based on solving the radiative transfer equation for successive scattering order contributions. A four-flux model is applied to compute the reflectance in terms of wavelength of the incident radiation and particle concentration. An application of the formalism is carried out to predict the optical properties of titanium dioxide pigmented polymer coatings, in terms of the pigment volume fraction and the degree of aggregation.

Optical properties of titanium dioxide in the rutile structure.

We present first-principles calculations for the optical properties of titanium dioxide in the rutile structure. The electronic band structure has been calculated self-consistently within the local-density approximation using ab initio pseudopotentials and a plane-wave basis. Optical properties are determined from the imaginary part of the dielectric function and compared to experiment. Although our local-density calculation underestimates the band gap, our results show that the optical properties for this early-transition-metal oxide are in surprisingly good agreement with experiment away from the fundamental absorption edge. We attribute this good agreement to the ability of the local-density approximation to yield accurate matrix elements between occupied and empty states.