Preparation of Microporous Films with Sub Nanometer Pores and their Characterization Using Stress and FTIR Measurements

AbstractWe have used a novel technique, measurement of stress isotherms in microporous thin films, as a means of characterizing porosity. The stress measurement was carried out by applying sol-gel thin films on a thin silicon substrate and monitoring the curvature of the substrate under a controlled atmosphere of various vapors. The magnitude of macroscopic bending stress developed in microporous films depends on the relative pressure and molar volume of the adsorbate and reaches a value of 180 MPa for a relative vapor pressure, P/Po = 0.001, of methanol. By using a series of molecules, and observing both the magnitude and the kinetics of stress development while changing the relative pressure, we have determined the pore size of microporous thin films. FTIR measurements were used to acquire adsorption isotherms and to compare pore emptying to stress development, about 80% of the change in stress takes place with no measurable change in the amount adsorbed. We show that for sol-gel films, pore diameters can be controlled in the range of 5 – 8 Å by “solvent templating”.

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Synthesis and Oxidation Kinetics of Sol-Gel and Sputtered Tantalum Nitride Thin Films

MRS Proceedings ◽

10.1557/proc-410-295 ◽

1995 ◽

Vol 410 ◽

Author(s):

Gerald T. Kraus ◽

Cory S. Oldweiler ◽

Emmanuel P. Giannelis

Keyword(s):

Thin Films ◽

Activation Energy ◽

Oxidation Kinetics ◽

Sol Gel ◽

Tantalum Nitride ◽

Sputtered Films ◽

Parabolic Oxidation ◽

Sol Gel Films ◽

Kinetics Of

ABSTRACTTantalum nitride thin films were produced by nitridation of sol-gel tantala thin films. The oxidation kinetics and the activation energy for oxidation were investigated and compared to those of sputtered tantalum nitride thin films. Data was gathered from in situ sheet resistance measurements taken between 550 and 720 K. Sol-gel films exhibited parabolic oxidation kinetics and had an activation energy of 1.9 eV. Sputtered films displayed quartic oxidation kinetics at lower temperatures tending toward cubic kinetics at higher temperatures and had an activation energy of 1.6 eV.

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Capillary Stress in Microporous Thin Films

MRS Proceedings ◽

10.1557/proc-436-373 ◽

1996 ◽

Vol 436 ◽

Author(s):

J. Samuel ◽

A. J. Hurd ◽

C. J. Brinker ◽

L. J. Douglas Frink ◽

F. Van Swol

Keyword(s):

Thin Films ◽

Density Functional ◽

Sol Gel ◽

Vacuum System ◽

Relative Pressure ◽

A Value ◽

Capillary Stress ◽

Mesoporous Thin Films ◽

Order Of Magnitude ◽

Beam Bending

AbstractDevelopment of capillary stress in porous xerogels, although ubiquitous, has not been systematically studied. We have used the beam bending technique to measure stress isotherms of microporous thin films prepared by a sol-gel route. The thin films were prepared on deformablesilicon substrates which were then placed in a vacuum system. The automated measurement was carried out by monitoring the deflection of a laser reflected off the substrate while changing the overlying relative pressure of various solvents. The magnitude of the macroscopic bending stress was found to reach a value of 180 MPa at a relative pressure of methanol, P/Po = 0.001. The observed stress is determined by the pore size distribution and is an order of magnitude smaller in mesoporous thin films. Density Functional Theory (DFT) indicates that for the microporous materials, the stress at saturation is compressive and drops as the relative pressure is reduced.

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Sintering kinetics of silica-titania sol-gel films on silicon wafers

Journal of Materials Research ◽

10.1557/jmr.1996.0042 ◽

1996 ◽

Vol 11 (2) ◽

pp. 353-357 ◽

Cited By ~ 27

Author(s):

Xin Min Du ◽

Rui M. Almeida

Keyword(s):

Thin Films ◽

Refractive Index ◽

Spin Coating ◽

Sol Gel ◽

Full Density ◽

Sintering Behavior ◽

Sintering Kinetics ◽

Titania Sol ◽

Sol Gel Films ◽

Kinetics Of

The sintering behavior of 80SiO2–20TiO2 sol-gel thin films on Si wafers, prepared by spin coating, was studied by the calculation of density as a function of temperature, from refractive index measurements and the Lorenz–Lorentz relationship. The sintering kinetics of the films were fit to the Mackenzie and Shuttleworth model, over the temperature range of 700 °C–850 °C. Using this model, the viscosity was determined as a function of temperature. These gel films sintered to full density at 850 °C.

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Sol-gel synthesis of textured lanthanum titanate thin films

Journal of Materials Research ◽

10.1557/jmr.2003.0046 ◽

2003 ◽

Vol 18 (2) ◽

pp. 357-362 ◽

Cited By ~ 12

Author(s):

Mary M. Sandstrom ◽

Paul Fuierer

Keyword(s):

Thin Films ◽

Sol Gel ◽

Precursor Solution ◽

Solution Concentration ◽

Optical Measurements ◽

Layered Perovskite ◽

Orientation Factor ◽

Anisotropic Structures ◽

Sol Gel Films ◽

Sol Gel Synthesis

Control over crystallographic orientation in thin films is important, particularly with highly anisotropic structures. Because of its ferroelectric nature, the layered perovskite La2Ti2O7 has interesting piezoelectric and electrooptic properties that may be exploited when films are highly textured. Sol-gel films with an orientation factor of greater than 95% were fabricated without relying on epitaxial (lattice-matching) growth from the substrate. Film orientation and crystallization were confirmed by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and optical measurements. The particle sizes in all precursor solutions were measured by dynamic light scattering experiments. Experimental results indicate that film orientation is a function of precursor solution concentration, size of the molecular clusters in the solution, and film thickness.

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Crystallisation kinetics of hydroxyapatite thin films prepared by sol-gel process

Advances in Applied Ceramics ◽

10.1179/174367609x422144 ◽

2010 ◽

Vol 109 (6) ◽

pp. 313-317 ◽

Cited By ~ 6

Author(s):

H Najafi ◽

A Nemati ◽

Z Sadeghian

Keyword(s):

Thin Films ◽

Sol Gel ◽

Crystallisation Kinetics ◽

Sol Gel Process ◽

Kinetics Of

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Ten Analyses Of Sol-Gel Derived And Sputtered PZT Thin Films

MRS Proceedings ◽

10.1557/proc-200-219 ◽

1990 ◽

Vol 200 ◽

Cited By ~ 16

Author(s):

Cheng-Chen Hsueh ◽

Martha L. MeCartney

Keyword(s):

Thin Films ◽

Ferroelectric Properties ◽

Sol Gel ◽

Rf Magnetron Sputtering ◽

Pzt Thin Films ◽

Ferroelectric Domains ◽

Metal Organic ◽

Organic Precursors ◽

Acid Catalyzed ◽

Sol Gel Films

ABSTRACTFerroelectric PZT thin films were prepared by sol-gel methods and RF magnetron sputtering. Sputtered PZT fast fired at 650° for 30 minutes showed microporosity. For the sol-gel route, solution precursors had a significant effect on the microstructure of the crystalline PZT films. PZT thin films derived from metal-organic precursors dissolved in n-propanol were observed to have large and microporous spherulitic grains on the order of 2 μm and phase separation in acetic acid-catalyzed films. In contrast, PZT precursors originated from alcohol exchanges with 2-methoxyethanols resulted in dense films with fine grains of ∼0.2 μm and clear evidence of ferroelectric domains. The dense sol-gel films possessed superior dielectric and ferroelectric properties.

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Microstructural Evolution of TiO2 Sol-Gel Thin Films

MRS Proceedings ◽

10.1557/proc-180-425 ◽

1990 ◽

Vol 180 ◽

Cited By ~ 5

Author(s):

J.L. Keddie ◽

E.P. Giannelis

Keyword(s):

Thin Films ◽

Relative Density ◽

Microstructural Evolution ◽

Sol Gel ◽

Dynamic Vacuum ◽

Tio2 Sol ◽

Sol Gel Films ◽

Deposited Films ◽

Deposition Conditions

ABSTRACTBackscattering spectrometry has been used to determine the density of TiO2 sol-gel films. The density of the as-deposited films relative to that of anatase varies slightly with respect to deposition conditions and is approximately 0.5. Annealing at temperatures as high as 750°C increases the relative density to 0.7 with concomitant decreases in the O:Ti ratio and H content but it does not result in complete densification. Film densities are consistently higher for films annealed under dynamic vacuum compared to those in air.

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Modification of Sol-Gel Thin Films By Ion Implantation

MRS Proceedings ◽

10.1557/proc-346-183 ◽

1994 ◽

Vol 346 ◽

Cited By ~ 6

Author(s):

Hiroshi Hirashima ◽

Kenji Adachi ◽

Hiroaki Imai

Keyword(s):

Thin Films ◽

Refractive Index ◽

Ion Implantation ◽

Sol Gel ◽

The Other ◽

Ir Absorption ◽

Absorption Bands ◽

Chemically Modified ◽

Sol Gel Films ◽

Ion Species

ABSTRACTIn order to densify and to improve the physical properties, TiO2 sol-gel films, about 100 nm in thickness, on silica glass or silicon wafer were implanted with Ar+ or B+ ions. The refractive index of the as-dried films increased and the IR absorption band of OH disappeared after Ar+ implantation. Drying and densification of sol-gel films were enhanced by Ar+ implantation. On the other hand, the refractive index and the thickness of the films hardly changed with B+ implantation. However, IR absorption bands of B-O bond were observed after B+ implantation. This suggests that sol-gel films could be chemically modified by ion implantation with reactive ion species.

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Improving of Tribological Properties of Nanocomposites Sol-Gel Thin Films by Fluorocyclophosphazene Derivatives

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-64261 ◽

2005 ◽

Author(s):

G. Celichowski ◽

K. Chrobak

Keyword(s):

Thin Films ◽

Tribological Properties ◽

Sol Gel ◽

Dip Coating ◽

Rf Plasma ◽

Good Thermal Stability ◽

Force Microscopy ◽

Coating Method ◽

Dip Coating Method ◽

Sol Gel Films

Fluorocyclophospazenes’ derivatives were used as modifiers for improving tribological properties of thin films prepared by sol-gel technique. Thin films were made on the base of aminopropyltriethoxysilane (APTS). All films were deposited by dip-coating method and post-treated by heat, UV radiation and low pressure of RF plasma. Chemical changes in sol-gel films during all steps of post-treatments and modifications were monitored by FT-IR spectroscopy and SIMS spectrometry. Topographies of modified surfaces were imaged by Atomic Force Microscopy (AFM). After final modification significant improvements of frictional properties were observed as well as their very good thermal stability.

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