Thermal Conductivity of Cubic Mesoporous Silica Thin Films

2007 ◽  
Author(s):  
Soojung C. Hur ◽  
Laurent Pilon ◽  
Adam Christensen ◽  
Samuel Graham
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Mesoporous Silica ◽  
Self Assembly ◽  
Room Temperature ◽  
Mean Free Path ◽  
Fused Silica ◽  
Silica Thin Films ◽  
The Cross ◽  
Cubic Mesoporous

This paper reports, for the first time, the cross-plane thermal conductivity of highly ordered cubic mesoporous silica thin films with porosity of 31% and thickness ranging between 200 and 500 nm. The mesoporous thin films are synthesized based on evaporation induced self-assembly process. The pores are spherical with average inter-pore spacing and pore diameter equal to 5.95 nm and 5 nm, respectively. The thermal conductivity is measured at room temperature using the 3ω method. The experimental setup and the associated analysis are validated by comparing the thermal conductivity measurements for the silicon substrate and for high quality thermal oxide thin films with data reported in the literature. The cross-plane thermal conductivity of the synthesized mesoporous silica thin films does not strongly depend on film thickness due to the reduction in phonon mean free path caused by the presence of nanopores. The average thermal conductivity is 0.61 ± 0.011 W/mK, which is 56% lower than that of bulk fused silica at room temperature.

scholarly journals Thermal Conductivity of Cubic and Hexagonal Mesoporous Silica Thin Films

2009 ◽  
Author(s):  
Thomas Coquil ◽  
Neal Hutchinson ◽  
Laurent Pilon ◽  
Erik Richman ◽  
Sarah Tolbert
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Mesoporous Silica ◽  
Film Thickness ◽  
Wall Thickness ◽  
Room Temperature ◽  
Strong Dependence ◽  
Fused Silica ◽  
Silica Thin Films ◽  
The Cross

This paper reports the cross-plane thermal conductivity of highly ordered cubic and hexagonal templated mesoporous amorphous silica thin films synthesized by evaporation-induced self-assembly process. Cubic and hexagonal films featured spherical and cylindrical pores and average porosity of 25% and 45%, respectively. The pore diameter ranged from 3 to 18 nm and film thickness from 80 to 540 nm while the average wall thickness varied from 3 to 12 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 the silicon substrate and for high quality thermal oxide thin films with thickness ranging from 100 to 500 nm. The cross-plane thermal conductivity of the synthesized mesoporous silica thin films does not show strong dependence on pore size, wall thickness, or film thickness. This is due to the fact that heat is mainly carried by very localized non propagating vibrational modes. The average thermal conductivity for the cubic mesoporous silica films was 0.30 ± 0.02 W/mK, while it was 0.20 ± 0.01 W/mK for the hexagonal films. This corresponds to a reduction of 79% and 86% from bulk fused silica at room temperature.

scholarly journals Thermal conductivity of cubic and hexagonal mesoporous silica thin films

2009 ◽  
Vol 106 (3) ◽  
pp. 034910 ◽  
Author(s):  
Thomas Coquil ◽  
Erik K. Richman ◽  
Neal J. Hutchinson ◽  
Sarah H. Tolbert ◽  
Laurent Pilon
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Mesoporous Silica ◽  
Hexagonal Mesoporous Silica ◽  
Silica Thin Films

Electrochemically assisted self-assembly of mesoporous silica thin films

2007 ◽  
Vol 6 (8) ◽  
pp. 602-608 ◽  
Author(s):  
A. Walcarius ◽  
E. Sibottier ◽  
M. Etienne ◽  
J. Ghanbaja
Keyword(s):  
Thin Films ◽  
Mesoporous Silica ◽  
Self Assembly ◽  
Silica Thin Films

scholarly journals Synthesis and Properties of Electrochemically Deposited Vertical Mesoporous Silica Thin Films

2015 ◽  
Vol 18 (3) ◽  
pp. 169-175
Author(s):  
Yuan Zhou ◽  
Qiming Liu ◽  
Ye Feng ◽  
Min Tan
Keyword(s):  
Thin Films ◽  
Mesoporous Silica ◽  
Self Assembly ◽  
Ammonium Bromide ◽  
Silica Thin Films ◽  
Transmission Electron ◽  
Hydroxyl Ion ◽  
Mesoporous Film ◽  
Electrochemically Deposited ◽  
Cetyltrimethyl Ammonium

Electrochemical deposition was successfully used to prepare mesoporous silica thin films with highly ordered and vertically oriented pores. Tetraethyl orthosilicate was used as the inorganic silicon source and cetyltrimethyl ammonium bromide was the template. A negative potential was applied to the working electrode, which was initially immersed in collosol and then in hydroxyl at the electrode/solution interface. Hydroxyl ion served as the catalyst that promoted the polycondensation and self-assembly of the silicon precursor, as well as the formation of thin films with pores which are highly ordered and vertically oriented with respect to the panel.The pore arrangement of the mesoporous film was hexagonal, and its aperture was 2 nm to 3 nm. The verticality of the thin film pore was demonstrated through permeability and transmission electron microscopy analyses. The prepared mesoporous film possessed good optical amorphous antireflective property with ordered and vertically oriented pores.

Control of pore size and condensation rate of cubic mesoporous silica thin films using a swelling agent

2005 ◽  
Vol 78 (2-3) ◽  
pp. 245-253 ◽  
Author(s):  
Young Kyu Hwang ◽  
Kashinath Rangu Patil ◽  
Sung Hwa Jhung ◽  
Jong-San Chang ◽  
Young June Ko ◽  
...  
Keyword(s):  
Thin Films ◽  
Mesoporous Silica ◽  
Pore Size ◽  
Condensation Rate ◽  
Swelling Agent ◽  
Silica Thin Films ◽  
Cubic Mesoporous

scholarly journals Cubic Mesoporous Silica Thin Films Coated on Titanium to Induce Carbonated Hydroxyapatite Deposition

2015 ◽  
Vol 30 (7) ◽  
pp. 725
Author(s):  
ZHANG Zhen-Rong ◽  
YAO Yi-Yuan ◽  
LUO Kai ◽  
WAN Long ◽  
LIU Xuan-Yong
Keyword(s):  
Thin Films ◽  
Mesoporous Silica ◽  
Carbonated Hydroxyapatite ◽  
Silica Thin Films ◽  
Cubic Mesoporous

scholarly journals Investigation on the Power Factor of Skutterudite Smy(FexNi1-x)4Sb12 Thin Films: Effects of Deposition and Annealing Temperature

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5773
Author(s):  
Giovanna Latronico ◽  
Paolo Mele ◽  
Cristina Artini ◽  
Pietro Manfrinetti ◽  
Sian Wei Pan ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Power Factor ◽  
Room Temperature ◽  
Fused Silica ◽  
Annealing Process ◽  
Seebeck Coefficients ◽  
Heating And Cooling ◽  
Scattering Centers ◽  
Filled Skutterudites

Filled skutterudites are currently studied as promising thermoelectric materials due to their high power factor and low thermal conductivity. The latter property, in particular, can be enhanced by adding scattering centers, such as the ones deriving from low dimensionality and the presence of interfaces. This work reports on the synthesis and characterization of thin films belonging to the Smy(FexNi1-x)4Sb12-filled skutterudite system. Films were deposited under vacuum conditions by the pulsed laser deposition (PLD) method on fused silica substrates, and the deposition temperature was varied. The effect of the annealing process was studied by subjecting a set of films to a thermal treatment for 1 h at 423 K. Electrical conductivity σ and Seebeck coefficient S were acquired by the four-probe method using a ZEM-3 apparatus performing cycles in the 348–523 K temperature range, recording both heating and cooling processes. Films deposited at room temperature required three cycles up to 523 K before being stabilized, thus revealing the importance of a proper annealing process in order to obtain reliable physical data. XRD analyses confirm the previous result, as only annealed films present a highly crystalline skutterudite not accompanied by extra phases. The power factor of annealed films is shown to be lower than in the corresponding bulk samples due to the lower Seebeck coefficients occurring in films. Room temperature thermal conductivity, on the contrary, shows values comparable to the ones of doubly doped bulk samples, thus highlighting the positive effect of interfaces on the introduction of scattering centers, and therefore on the reduction of thermal conductivity.

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