A large-size silica glass produced by a new sol-gel process

Toki, Motoyuki; Miyashita, Satoru; Takeuchi, Toshio; Kanbe, S.; Kochi, Akinori

doi:10.1016/0022-3093(88)90067-1

Cited by 127 publications

(66 citation statements)

References 6 publications

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“…[2] The molding of sol-gel precursor solutions has produced monolithic silica pieces [3] as well as Fresnel lenses or gratings with sub-micrometer periods.…”

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confidence: 99%

Fabrication of Glass Microstructures by Micro-Molding of Sol-Gel Precursors

Marzolin¹,

et al. 1998

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This paper demonstrates that the molding of a sol-gel precursor against an elastomeric replica of the desired features (a form of soft lithography) [1] is a convenient method to generate submicrometer patterns of glasses on a substrate. We were able to fabricate glass (silicon dioxide doped with boron oxide, titanium oxide, or aluminum oxide) structures with micrometer-scale features supported on a flat Si/SiO 2 substrate, as well as free-standing membranes.In molding, an initially fluid material is allowed to acquire its final geometry by solidifying in a mold. This technique allows the reproduction of the fine details of the mold: replica molding of structures in polymers has generated structures with 10 nm sized features.[2] The molding of sol-gel precursor solutions has produced monolithic silica pieces [3] as well as Fresnel lenses or gratings with sub-micrometer periods.[4] Replica molding is a method that has several potentially useful features. It does not require photolithography and can be used without access to a clean room. Once the mold is fabricated, many replicas can be produced.[2] It has a theoretical limit to resolution that is much below that that can be achieved by photolithography. It can be used to make patterns on curved substrates. The throughput of a process based on molding can be high and its cost low. Unlike electron-beam or scanning tunneling microscopy (STM) writing, molding allows parallel fabrication. We believe that micro-molding is a type of process that will be widely useful in microfabrication. The sol-gel process is a versatile method for synthesizing many inorganic oxides.[5] This method generates materials with controlled chemical composition and low levels of impurities. Most common glasses, with the exception of some halide glasses, have been successfully synthesized; these compositions range from high purity silica to an eight-component glass ceramic. [6] Other materials that have been prepared by sol-gel process include PZT ceramics (i.e., Pb(Zr,Ti)O 3 ), [7,8] electro-optic films, [9] high efficiency phosphors, [10] and electrochromic glasses.[11]The use of sol-gel chemistry to prepare materials has one unattractive characteristic: the shrinkage induced in the drying stage gives rise to high stresses in the structures. These stresses can cause the deformation and breaking of the structures. In order to reduce these stresses, drying additives can be used.[12] The incorporation of non-hydrolyzing organic groups in the material (methyl or phenyl) gives structures with higher compliance and allows structural relaxation during the drying stage.[13] Controlled slow drying can also decrease the risk of cracking of the glass; it will, however, result in long process times. Good adhesion of the glass to the substrate is necessary to prevent the delamination of the structure. We wished to fabricate glass structures with dimensions in the range of 0.1 mm to several micrometers by non-lithographic methods, and have examined the molding of solgels in an elastomeric mold. This pape...

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“…[2] The molding of sol-gel precursor solutions has produced monolithic silica pieces [3] as well as Fresnel lenses or gratings with sub-micrometer periods.…”

mentioning

confidence: 99%

Fabrication of Glass Microstructures by Micro-Molding of Sol-Gel Precursors

Marzolin¹,

et al. 1998

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“…In the particulate sol-gel process, the porous silica precursor of porous silica monolith was prepared via gelation of a silica suspension and gel drying. It has been reported to fabricate over centimeter size of the porous silica precursor, as well as a silica glass monolith by sintering, with a shape of rods [9] [10] [11] [12] [13], tubes [14] [15] [16] [17] [18], rings [19], and plates [20].…”

Section: Introductionmentioning

confidence: 99%

“…In order to overcome the crack generation, important developments for the particulate sol-gel process have been widely studied. For instance, to suppress the crack generation during gel drying, many research groups have used dozens nanometer size of silica particles with adding some chemical additive [9]- [20].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Porous Silica Monolith by Sintering Silica Nanoparticles

Ikeda¹,

Fujino²

2017

JMMCE

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This paper aims to fabricate over centimeter size of porous silica monolith having meso-pores with large surface area. A precursor of porous silica monolith was obtained by sintering a monolithic SiO 2 -poly (vinyl alcohol) (PVA) nanocomposite at 600˚C -1100˚C. The sintering behavior was examined by means of Raman spectroscopy and a porosimetry. The PVA of the SiO 2 -PVA nanocomposite was combusted below 600˚C, subsequently the silica nanoparticles of the nanocomposite were sintered above 900˚C. The Raman spectroscopy suggested that amorphous structure of the porous silica monolith obtained above 1000˚C was similar to that of a silica glass. The BET surface area and pore radius of the porous silica monolith decreased with increasing sintering temperature. These values were tailored in the range of ca. 0 -291 m 2 ·g −1 and 5 -25 nm, respectively, by controlling the sintering temperature and time. The fabricated porous-silica monolith was translucent or opaque porous-silica depending on the pore size.

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“…The major technological problems in the direct preparation of a silica gel monolith are the possible occurrence of cracks and fractures dur- 31 ) Wallace and Hench32), Adachi and Sakka 33) Kozuka and Sakka 34) ing the process of a wet gel monolith to a dry gel monolith. The six methods shown in Table 3 have been proposed 4 ) to avoid cracks during drying, and they were actually used for producing silica gel monoliths without cracks.…”

Section: Particles For Monolith Formationmentioning

confidence: 99%