A Modified Chemical Route for Synthesis of Zirconia Thin Films Having Tunable Porosity

2008 ◽  
Vol 1074 ◽  
Author(s):  
Manish Kumar ◽  
G. B. Reddy
Keyword(s):  
Thin Films ◽  
Average Pore Size ◽  
Sol Gel ◽  
Dip Coating ◽  
Porous Films ◽  
Average Pore ◽  
Chemical Route ◽  
Porous Microstructure ◽  
Chemical Synthesis Route ◽  
Deposited Films

ABSTRACTA new chemical synthesis route is reported for deposition of zirconia thin films having adjustable porosity with average pore size in nanometer range. Deposition method is simply a sol-gel dip coating in which HCl is used as catalyst. TEM and FTIR studies of deposited films show porous microstructure, which depends critically on ageing of sol used. The shift in binding energy of Zr 3d5/2 (at 182.4 eV) attributes the formation of zirconia. Optical results show high transmittance (> 80%) in VIS-NIR region and effective refractive indices values (neff) tend to decrease for films prepared with higher aged sol. Porosity enhancement from 15-52% is observed by neff comparing with refractive index of non porous films (nz).

Substrate Influenced Nucleation and Crystallization of LiNbO3 Thin Films Made by Sol-Gel

1993 ◽  
Vol 310 ◽  
Author(s):  
Vikram Joshi ◽  
Debasis Roy ◽  
Martha L. Mecartney
Keyword(s):  
Thin Films ◽  
Amorphous Carbon ◽  
Room Temperature ◽  
Sol Gel ◽  
Dissipation Factor ◽  
Dip Coating ◽  
Polycrystalline Films ◽  
Heteroepitaxial Growth ◽  
Oriented Polycrystalline ◽  
Deposited Films

AbstractLithium niobate films were deposited on amorphous carbon, silicate glass, (0001) sapphire, and (100) silicon by spin or dip coating double metal ethoxide sols. The crystallinity and microstructure of the deposited films were examined by XRD and TEM. Crystallization behavior and resulting microstructure were strongly influenced by the type of substrate. The formation of crystalline LiNbO3 on amorphous carbon was detected at room temperature. Randomly oriented polycrystalline films were obtained on glass at 400°C. Choice of one mole of water per mole of ethoxide generated heteroepitaxial growth of LiNbO3 thin films on (0001) sapphire. Oriented but polycrystalline films were obtained on silicon. The electrical behavior of film on silicon was evaluated in metal-ferroelectric-semiconductor configuration. A dielectric constant of 35 and a dissipation factor of 0.004 was measured at 100 KHz.

Sol-Gel Processing of Low Dielectric Constant Nanoporous Silica Thin Films

2001 ◽  
Vol 703 ◽  
Author(s):  
Deok-Yang Kim ◽  
Henry Du ◽  
Suhas Bhandarkar ◽  
David W. Johnson
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Dielectric Constants ◽  
Gelling Agent ◽  
Porous Films ◽  
Average Pore

ABSTRACTTetramethyl ammonium silicate (TMAS) is known as a structuring agent in zeolite synthesis. We report its first use to prepare porous silica films for low k dielectric applications in microelectronics. A solution of TMAS 18.7 wt. % was spin coated on silicon substrates with a 3000 Å thick thermal oxide. The spin coated films were subsequently heat-treated at 450°C to obtain porous silica. The use of TMAS solution without gelation led to films of only moderate porosity value of 10%. The addition of methyl lactate, a gelling agent, significantly increased film porosity and improved the pore size distribution. For example, 50% porosity and uniform pore size distribution (average pore size ∼ 40 Å) has been achieved. Dielectric constants (k) of our porous films are as low as 2.5.

Photocatalytic Degradation of Methylene Blue by NiO Thin Films under Solar Light Irradiation

2019 ◽  
Vol 56 ◽  
pp. 152-157 ◽  
Author(s):  
Abdelouahab Noua ◽  
Hichem Farh ◽  
Rebai Guemini ◽  
Oussama Zaoui ◽  
Tarek Diab Ounis ◽  
...  
Keyword(s):  
Thin Films ◽  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Sol Gel ◽  
Visible Region ◽  
Optical Transmittance ◽  
Dip Coating ◽  
Light Irradiation ◽  
Solar Light ◽  
Solar Light Irradiation

Nickel oxide (NiO) thin films were successfully deposited by sol-gel dip-coating method on glass substrates. The structural, morphological and optical properties in addition to the photocatalytic activity of the prepared films were investigated. The results show that the films have a polycrystalline NiO cubic structure with dense NiO grains and average optical transmittance in the visible region. The photocatalytic properties of the films were studied through the degradation of methylene blue and 89% of degradation was achieved for 4.5h of solar light irradiation exposure which indicates the capability of NiO photocatalytic activity.

The effect of the withdrawal speed on properties of nickel oxide thin films

2019 ◽  
Vol 234 (10) ◽  
pp. 647-655
Author(s):  
Zohra Nazir Kayani ◽  
Atiqa Aslam ◽  
Rabia Ishaque ◽  
Syeda Nosheen Zahra ◽  
Hifza Hanif ◽  
...  
Keyword(s):  
Thin Films ◽  
Nickel Oxide ◽  
Band Gap ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Dip Coating ◽  
Oxide Thin Films ◽  
Withdrawal Speed ◽  
Sem Micrograph ◽  
Nickel Oxide Thin Films

Abstract Nickel oxide thin films have been prepared by sol-gel dip-coating technique on glass substrate. It is shown that nickel oxide thin films have poly crystalline nature. Nickel oxide thin films exhibit high transmission (39–85%) in the wavelength range of 400–900 nm, strong absorption between 300 and 400 nm wavelengths and decrease of band gap values are in the range 3.69–3.27 eV with increase of withdrawal speed. High band gap at low withdrawal speed is because of the small average crystallite size, which decreases with increase in withdrawal speed. The SEM micrograph shows cubic crystallites and surface of thin films become dense, smooth and homogeneous with an increase in withdrawal speed. Assessment of nickel oxide deposition conditions provides gateway for effective and cheap solar cells.

Silica Sol-Gel Supported Nickel Nano-Catalyst for Hydrogen Production Using Microreactors

2005 ◽  
Vol 885 ◽  
Author(s):  
Krithi Shetty ◽  
Shihuai Zhao ◽  
Wei Cao ◽  
Naidu V. Seetala ◽  
Debasish Kuila
Keyword(s):  
Steam Reforming ◽  
Average Pore Size ◽  
Sol Gel ◽  
Supported Catalyst ◽  
Silica Sol ◽  
Average Pore ◽  
Steam Reforming Of Methanol ◽  
Nano Catalyst ◽  
Before And After ◽  
Reforming Reactions

ABSTRACTThe goal of this research is to investigate the activities of a non-noble nano-catalyst (Ni/SiO2) using Si-microreactors for steam reforming of methanol to produce hydrogen for fuel cells. The supported catalyst was synthesized by sol-gel method using Ni (II) salts and Si(C2H5O)4 as starting materials. EDX results indicate that the actual loading of Ni (5-6%) is lower than the intended loading of 12 %. The specific surface area of the silica sol-gel encapsulated Ni nano-catalyst is 452 m2/g with an average pore size of ∼ 3 nm. Steam reforming reactions have been carried out in a microreactor with 50 µm channels in the temperature range of 180-240 °C and atmospheric pressure. Results show 53% conversion of methanol with a selectivity of 74 % to hydrogen at 5 l/min and 200 °C. The magnetic properties of the catalysts were performed using a Vibrating Sample Magnetometer (VSM) to study the activity of the catalysts before and after the steam reforming reactions. The VSM results indicate much higher activity in the microreactor compared to macro-reactor and Ni forms non-ferromagnetic species faster in the microreactor.

Sol-Gel Derived Silica Layers for Low-k Dielectrics Applications

2000 ◽  
Vol 612 ◽  
Author(s):  
Sylvie Acosta ◽  
André Ayral ◽  
Christian Guizard ◽  
Charles Lecornec ◽  
Gérard Passemard ◽  
...  
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Thin Layers ◽  
Gaseous Ammonia ◽  
Potential Candidate ◽  
Average Pore ◽  
Synthesis Strategy ◽  
Silica Layers ◽  
Highly Porous

AbstractPorous silica exhibits attractive dielectric properties, which make it a potential candidate for use as insulator into interconnect structures. A new way of preparation of highly porous silica layers by the sol-gel route was investigated and is presented. The synthesis strategy was based on the use of common and low toxicity reagents and on the development of a simple process without gaseous ammonia post-treatment or supercritical drying step. Defect free layers were deposited by spin coating on 200 mm silicon wafers and characterized. Thin layers with a total porosity larger than 70% and an average pore size of 5 nm were produced. The dielectric constant measured under nitrogen flow on these highly porous layers is equal to ∼ 2.5, which can be compared to the value calculated from the measured porosity, ∼ 1.9. This difference is explained by the presence of water adsorbed on the hydrophilic surface of the unmodified silica.

Optical, magnetic and structural properties of Cr-doped ZnO thin films by sol–gel dip-coating method

2017 ◽  
Vol 4 (9) ◽  
pp. 096403 ◽  
Author(s):  
Zohra N Kayani ◽  
Marya Siddiq ◽  
Saira Riaz ◽  
Shahzad Naseem
Keyword(s):  
Thin Films ◽  
Structural Properties ◽  
Sol Gel ◽  
Dip Coating ◽  
Zno Thin Films ◽  
Coating Method ◽  
Doped Zno ◽  
Dip Coating Method

Preparation and characterization of V2O5 doped SiO2-TiO2 thin films

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Marek Nocuń ◽  
Sławomir Kwaśny
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Dip Coating ◽  
Band Gap Energy ◽  
Tio2 Thin Films ◽  
Glass Substrates ◽  
Gel Technique

AbstractIn our investigation, V doped SiO2/TiO2 thin films were prepared on glass substrates by dip coating sol-gel technique. Chemical composition of the samples was studied by X-ray photoelectron spectroscopy (XPS). Transmittance of the samples was characterized using UV-VIS spectrophotometry. Subsequently band-gap energy (Eg) was estimated for these films. Powders obtained from sols were characterized by FTIR spectroscopy. It was found that vanadium decreases optical band gap of SSiO2/TiO2 films.

Conductivity of Graphene-Like Thin Films Prepared from Chemically Exfoliated Carbon Nanotubes (CNTs), Highly Oriented Pyrolytic Graphite (HOPG), Natural Flake Graphite, and Carbon Powder

2012 ◽  
Vol 1451 ◽  
pp. 125-130
Author(s):  
Matthew M. Marchese ◽  
Rosario A. Gerhardt
Keyword(s):  
Thin Films ◽  
Spin Coating ◽  
Average Pore Size ◽  
Pyrolytic Graphite ◽  
Chlorosulfonic Acid ◽  
Surfactant Solution ◽  
Carbon Powder ◽  
Free Standing ◽  
Average Pore ◽  
High Concentrations

ABSTRACTThe use of super acids such as chlorosulfonic acid (CSA) has proven to be extremely effective at exfoliating different forms of graphite in high concentrations without covalently functionalizing the surface of the graphene. Once quenched, the acid solutions can then be vacuum filtered through acid resistant polypropylene filter paper with an average pore size of 0.2 μm to collect the exfoliated carbon into a free standing retentate film. These films can then be easily washed, removed, and redispersed into solution by sonicating the films in a surfactant solution. Films were deposited onto various substrates using a range of spin coating parameters. This study has found that exfoliated CNTs provide the best conductivity out of the four types of chemically exfoliated carbon structures studied. CNTs have also proven to be the easiest type of exfoliated carbon to disperse and are able to stay in solution with less than 1%wt surfactant. The findings have shown that the electrical conductivity of the spin coated films actually increases with RPM and is inversely proportional to the film thickness. It is possible to achieve electrical conductivities as high as 10,507 ± 3728.64 [S/m] while still maintaining the transparency of the thin films. The initial spin coating step is more efficient at low ramp rates around 100 rpm/s and results in very smooth films. High spin speeds of 1800 rpm during the casting stage are found to play a large role in improving the conductivity of the films. Lastly, drying the samples on a hot plate for 5 min. on high has significantly improved the films electrical properties and virtually eliminated the need for tedious and expensive plasma cleaning treatments.

Sign in / Sign up

Export Citation Format

Share Document