scholarly journals Thermal Conductivity of Ordered Mesoporous Titania Films Made from Nanocrystalline Building Blocks and Sol−Gel Reagents

2010 ◽  
Vol 114 (29) ◽  
pp. 12451-12458 ◽  
Author(s):  
Thomas Coquil ◽  
Christian Reitz ◽  
Torsten Brezesinski ◽  
E. Joseph Nemanick ◽  
Sarah H. Tolbert ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Sol Gel ◽  
Building Blocks ◽  
Mesoporous Titania ◽  
Ordered Mesoporous ◽  
Titania Films

Thermal Conductivity of Highly Ordered Amorphous and Crystalline Mesoporous Titania Thin Films

2010 ◽  
Author(s):  
Thomas Coquil ◽  
Laurent Pilon ◽  
Christian Reitz ◽  
Torsten Brezesinski ◽  
Joseph E. Nemanick ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Film Thickness ◽  
Pore Size ◽  
Wall Thickness ◽  
Sol Gel ◽  
Atomic Scale ◽  
Mesoporous Titania ◽  
Titania Films ◽  
The Cross

This paper reports the cross-plane thermal conductivity of amorphous and crystalline templated mesoporous titania thin films synthesized by evaporation-induced self-assembly. Both sol-gel and nanocrystal-based films were considered, with respective average porosities of 30% and 35%. The pore diameter ranged from 7 to 25 nm and film thickness from 60 to 370 nm while the average wall thickness varied from 3 to 25 nm. Nanocrystals in crystalline mesoporous films featured diameters between 9 and 13 nm. The thermal conductivity was measured at room temperature using the 3ω method. The experimental setup and the associated analysis were validated by comparing the thermal conductivity measurements with data reported in the literature for dense titania films with thickness ranging from 95 to 1000 nm. The cross-plane thermal conductivity of the amorphous mesoporous titania thin films did not show strong dependence on pore size, wall thickness, or film thickness. This can be attributed to the high atomic scale disorder of amorphous materials. Heat is thus mainly carried by localized non-propagating vibrational modes. The average thermal conductivity of the amorphous mesoporous titania films was identical to that of the nanocrystal-based films and equal to 0.37 W/m.K. Thermal conductivity of sol-gel crystalline mesoporous titania thin films was significantly larger than that of their amorphous counterparts. It also depended on the organic template used to make the films. The results indicated that the pore size was not an important factor. Instead thermal conductivity depended only on porosity, crystallinity, nanocrystal size and connectivity.

scholarly journals Nano-sized blue spectral shift in sol–gel derived mesoporous titania films

2011 ◽  
Vol 61 (2) ◽  
pp. 355-361 ◽  
Author(s):  
P. Karasiński ◽  
E. Gondek ◽  
S. Drewniak ◽  
I. V. Kityk
Keyword(s):  
Sol Gel ◽  
Spectral Shift ◽  
Mesoporous Titania ◽  
Titania Films

scholarly journals SYNTHESIS OF MESOPOROUS TITANIA BY POTATO STARCH TEMPLATED SOL-GEL REACTIONS AND ITS CHARACTERIZATION

2010 ◽  
Vol 10 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Canggih Setya Budi ◽  
Indriana Kartini ◽  
Bambang Rusdiarso
Keyword(s):  
Water Solution ◽  
Potato Starch ◽  
Sol Gel ◽  
Building Blocks ◽  
Mesoporous Tio2 ◽  
Mesoporous Titania ◽  
Tio2 Powder ◽  
Nanocrystalline Tio2 ◽  
Template Removal ◽  
Starch Gel

Mesoporous titania powders with high-order crystalline building blocks had been synthesized through the sol-gel process using potato starch gel template. Internal spongelike pore structure of starch gel template was generated by heating the starch granules at 95 °C in water solution and freezing the starch gel at -15 °C. The synthesis routes were performed by immersing the starch gel template for 4 days into the white colloidal solution of TiO2 nanoparticles, which were prepared by hydrolyzing titanium (IV) tetraisopropoxide (TTIP) in ethanol at pH 1. Mesoporous TiO2 powders were obtained by two different ways of template removal, performed by calcination of the TiO2-starch composites at 600 °C for 4 h or combination of extraction with ethanol-HCl (2:1) at 80 °C and calcination at 500 °C for 4 h. Fourier Transform Infra Red (FT-IR) spectra shows both of template removal methods result in decreasing of characteristic vibrational band of the starch hydrocarbon on the resulted TiO2 powders. The X-Ray Diffraction (XRD) pattern imply that the concentrations of starch gel template influence the anatase crystallite peaks intensity of the synthesized TiO2 powders. TiO2 templated by 20% of starch sponges gel has highest intensity of anatase crystallite. Scherrer calculation inidicated that anatase particle size has nanoscale dimmension up to 12.96 nm. The nano-architecture feature of mesoporous TiO2 scaffolds was also evaluated by the Scanning Electron Microscope (SEM). It is shown that mesoporous TiO2 framework consist of nanocrystalline TiO2 particles as buiding blocks. The N2 adsorption-desorption isotherm curves assign that TiO2 powder resulted from extraction-calcination route has higher mesoporosity than that of only calcinated. The synthesized mesoporous TiO2 powder exhibits high Brunauer-Emmet-Teller (BET) specific surface area up to 65.65 m2/g.   Keywords: mesoporous TiO2, potato starch, template

Exfoliated Graphene into Highly Ordered Mesoporous Titania Films: Highly Performing Nanocomposites from Integrated Processing

2013 ◽  
Vol 6 (2) ◽  
pp. 795-802 ◽  
Author(s):  
Luca Malfatti ◽  
Paolo Falcaro ◽  
Alessandra Pinna ◽  
Barbara Lasio ◽  
Maria F. Casula ◽  
...  
Keyword(s):  
Mesoporous Titania ◽  
Exfoliated Graphene ◽  
Ordered Mesoporous ◽  
Integrated Processing ◽  
Titania Films

Low-Temperature Fabrication of Mesoporous Titania Thin Films

MRS Advances ◽  
2017 ◽  
Vol 2 (43) ◽  
pp. 2315-2325 ◽  
Author(s):  
Lin Song ◽  
Volker Körstgens ◽  
David Magerl ◽  
Bo Su ◽  
Thomas Fröschl ◽  
...  
Keyword(s):  
Low Temperature ◽  
Uv Irradiation ◽  
Sol Gel ◽  
Composite Films ◽  
Grazing Incidence ◽  
Mesoporous Titania ◽  
Vis Spectroscopy ◽  
Titania Films ◽  
Polymer Template ◽  
Sol Gel Synthesis

ABSTRACTMesoporous titania films are prepared via the polymer-template assisted sol-gel synthesis at low temperatures, using the titania precursor ethylene glycol-modified titanate (EGMT) and the diblock copolymer polystyrene-block-polyethyleneoxide (PS-b-PEO). UV-irradiation is chosen as a low temperature technique to remove the polymer template and thereby to obtain titania sponge-like nanostructures at processing temperatures below 100 °C. After different UV irradiation times, ranging for 0 h to 24 h, the surface and inner morphologies of the titania films are studied with scanning electron microscopy (SEM) and grazing incidence small-angle x-ray scattering (GISAXS), respectively. The evolution of the band gap energies is investigated using ultraviolet/visible (UV/Vis) spectroscopy. The findings reveal that 12 h UV-treatment is sufficient to remove the polymer template from the titania/PS-b-PEO composite films with a thickness of 80 nm, and the determined bad gap energies indicate an incomplete crystallization of the titania nanostructures.

Mesoporous Thin Films: Thermoelectric Application

2012 ◽  
Vol 260-261 ◽  
pp. 34-39
Author(s):  
Min Hee Hong ◽  
Chang Sun Park ◽  
Yong June Choi ◽  
Hong Sup Lee ◽  
Hyung Ho Park
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Thermoelectric Device ◽  
Mesoporous Titania ◽  
Titanium Tetraisopropoxide ◽  
Mesoporous Thin Films ◽  
High Seebeck Coefficient ◽  
Titania Films

The efficiency of a thermoelectric device depends on material properties through the figure of merit, Z = σS2/κ, where σ, S, and κ are electrical conductivity, Seebeck coefficient, and thermal conductivity, respectively. To maximize the thermoelectric figure of merit of a material, high electrical conductivity, high Seebeck coefficient, and low thermal conductivity are required. This work has focused on the synthesis of a mesoporous titania films for its application in thermoelectric generation. The mesoporous titania film was synthesized with titanium tetraisopropoxide. The triblock copolymer, Pluronic P-123 (EO20PO70EO20) was used as surfactant in 1-propanol. As a result, an improvement of electrical conductivity and reduced annealing with a lowering of thermal conductivity by distributions of pores were found to be effective to enhance the thermoelectric property.

scholarly journals Spray Deposition Synthesis of Locally Ordered Mesoporous Polycrystalline Titania Films at Low Temperature

Molecules ◽  
2022 ◽  
Vol 27 (1) ◽  
pp. 303
Author(s):  
Gunnar Símonarson ◽  
Antiope Lotsari ◽  
Anders E. C. Palmqvist
Keyword(s):  
Low Temperature ◽  
Aging Time ◽  
Self Assembly ◽  
Spray Deposition ◽  
Spray Coating ◽  
Mesoporous Titania ◽  
Structure Directing Agent ◽  
Synthesis Time ◽  
Ordered Mesoporous ◽  
Titania Films

A low-temperature spray deposition synthesis was developed to prepare locally hexagonally ordered mesoporous titania films with polycrystalline anatase pore walls in an evaporation-induced self-assembly process. The titania film preparation procedure is conducted completely at temperatures below 50 °C. The effects of spray time, film thickness, synthesis time prior to spray deposition, and aging time at high relative humidity after deposition on the atomic arrangement and the mesoorder of the mesoporous titania were studied. We find the crystallite size to depend on both the synthesis time and aging time of the films, where longer times result in larger crystallites. Using the photocatalytic activity of titania, the structure-directing agent is removed with UV radiation at 43–46 °C. The capability of the prepared films to remove the polymer template increased with longer synthesis and aging times due to the increased crystallinity, which increases the photocatalytic efficiency of the titania films. However, with increasingly longer times, the crystallites grow too large for the mesoorder of the pores to be maintained. This work shows that a scalable spray coating method can be used to prepare locally ordered mesoporous polycrystalline titania films by judiciously tuning the synthesis parameters.

scholarly journals Thermal Conductivity of Highly-Ordered Mesoporous Titania Thin Films from 30 to 320 K

2011 ◽  
Vol 115 (30) ◽  
pp. 14606-14614 ◽  
Author(s):  
Jin Fang ◽  
Christian Reitz ◽  
Torsten Brezesinski ◽  
E. Joseph Nemanick ◽  
Chris B. Kang ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Mesoporous Titania ◽  
Ordered Mesoporous

Thermal Conductivity of Amorphous and Crystalline Mesoporous Titania Thin Films From 30 to 320 K

2011 ◽  
Author(s):  
Jin Fang ◽  
Laurent Pilon ◽  
Christian Reitz ◽  
Torsten Brezesinski ◽  
E. Joseph Nemanick ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Sol Gel ◽  
Mesoporous Tio2 ◽  
Mesoporous Titania ◽  
Tio2 Films ◽  
Mesoporous Films ◽  
Mesoporous Tio2 Films ◽  
Increasing Temperature

This paper reports, for the first time, the cross-plane thermal conductivity of amorphous and crystalline templated cubic mesoporous titania thin films from 30 to 320 K. Both sol-gel and nanocrystal-based films were synthesized by evaporation-induced self-assembly with porosity of 30% to 35%, respectively. The pore diameter in sol-gel mesoporous films ranged from 14 to 25 nm and film thickness from 120 to 370 nm. Crystalline domains in crystalline mesoporous films were 9 to 13 nm in diameter. The thermal conductivity was measured between 30 and 320 K using the 3ω method. The experimental setup and the associated analysis were first validated by comparing experimental measurements with data reported in the literature for high purity silicon substrate and thermal oxide films over the temperature range considered. The thermal conductivity of sol-gel dense and mesoporous TiO2 films was found to increase with increasing temperature. The thermal conductivity of polycrystalline dense film was strongly dependent on temperature while that of dense amorphous and mesoporous films increased slowly with increasing temperature. The amorphous mesoporous TiO2 films featured very small thermal conductivity due to the fact that heat was mainly transferred by very localized non-propagating vibrational modes. Despite the particles crystallinity, the nanocrystal-based film showed significantly lower thermal conductivity than that of the sol-gel polycrystalline mesoporous thin films due to the strong phonon scattering at the nanocrystal boundaries.

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