A Novel Hybrid Route to Chemically–Tailored, Three–Dimensional Oxide Nanostructures: The Basic (Bioclastic and Shape–Preserving Inorganic Conversion) Process

Sandhage, Ken H.; Dickerson, Matthew B.; Huseman, Philip M.; Zalar, Frank M.; Carroll, Mark; Rondon, Michelle R.; Sandhage, Eryn C.

doi:10.1002/9780470294758.ch72

Cited by 9 publications

(8 citation statements)

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“…A series of displacement reactions was used to convert the silica frustules first into magnesia-based replicas (via reaction with magnesium gas) and then into zirconia replicas (via reaction of the magnesia with zirconium tetrachloride gas). Prior work has shown that diatom frustules can be converted into magnesiabased replicas via the following net oxidation-reduction displacement reaction 39,40 :…”

Section: Resultsmentioning

confidence: 99%

“…where {Si} refers to silicon dissolved within a Mg-Si liquid (generated by the continued reaction of elemental silicon with excess magnesium vapor) that tended to migrate away from the MgO-based frustule replica. 39,40 Magnesia replicas generated by reaction (1) may then be exposed to zirconium tetrachloride gas to form zirconia by the following metathetic displacement reaction:…”

Section: Resultsmentioning

confidence: 99%

“…Magnesia-based replicas of Aulacoseira frustules were generated by reaction with Mg(g) at 9001C for 1.5 h in a manner similar to that described elsewhere. 39,40 The MgO-based replicas were then exposed to a 0.49M NaOH solution at 601C for 3 h to selectively dissolve residual silicon from the magnesia. MgO diatom replicas and anhydrous ZrCl 4 powder (99.9% pure, Advanced Research Chemicals Inc.) were loaded into two separate nickel crucibles.…”

Section: Methodsmentioning

confidence: 99%

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Three‐Dimensional Assemblies of Zirconia Nanocrystals Via Shape‐Preserving Reactive Conversion of Diatom Microshells

Shian

Cai

Weatherspoon

et al. 2005

Journal of the American Ceramic Society

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The synthesis of three-dimensional (3-D) assemblies of zirconia nanocrystals via the shape-preserving reactive conversion of biologically reproducible, silica-based microtemplates (diatom microshells) is demonstrated for the first time. Silica diatom microshells were first converted into magnesia replicas via an oxidation-reduction displacement reaction with magnesium gas. The magnesia replicas were then converted into zirconia replicas via a metathetic displacement reaction with zirconium tetrachloride gas. By utilizing both types of shape-preserving displacement reactions, bioclastic silica microtemplates may be converted into functional nanocrystalline assemblies with a variety of complex, but well-controlled 3-D shapes and chemistries for catalytic/chemical, biological, electrical, thermal, mechanical, and other applications. J ournal

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Three‐Dimensional Assemblies of Zirconia Nanocrystals Via Shape‐Preserving Reactive Conversion of Diatom Microshells

Shian

Cai

Weatherspoon

et al. 2005

Journal of the American Ceramic Society

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“…These processes are referred to collectively as BaSIC (Bioclastic and Shapepreserving Inorganic Conversion). [12][13][14][15][16][17][18] By merging the attractive self-assembly characteristics of nature with the chemical versatility of synthetic processing, BaSIC processes may be used to mass produce nanostructured microdevices with complex 3-D shapes and tailored chemistries, as is illustrated in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Merging Biological Self‐Assembly with Synthetic Chemical Tailoring: The Potential for 3‐D Genetically Engineered Micro/Nano‐Devices (3‐D GEMS)

Sandhage

Allan²,

Dickerson³

et al. 2009

Progress in Nanotechnology

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Appreciable global efforts are underway to develop processes for fabricating three-dimensional (3-D) nanostructured assemblies for advanced devices. Widespread commercialization of such devices will require: (i) precise 3-D fabrication of chemically tailored structures on a fine scale and (ii) mass production of such structures on a large scale. These often-conflicting demands can be addressed with a revolutionary new paradigm that couples biological self-assembly with synthetic chemistry: Bioclastic and Shape-preserving Inorganic Conversion (BaSIC). Nature provides numerous examples of microorganisms that assemble biominerals into intricate 3-D structures. Among the most spectacular of these microorganisms are diatoms (unicellular algae). Each of the tens of thousands of diatom species assembles silica nanoparticles into a microshell with a distinct 3-D shape and pattern of fine (nanoscale) features. The repeated doubling associated with biological reproduction enables enormous numbers of such 3-D microshells to be generated (e.g., only 40 reproduction cycles can yield 41 trillion 3-D replicas!). Such genetic precision and massive parallelism are highly attractive for device manufacturing. However, the natural chemistries assembled by diatoms (and other microorganisms) are rather limited. With BaSIC processes, biogenic assemblies can be converted into a wide variety of new functional chemistries, while preserving the 3-D morphologies. Ongoing advances in genetic engineering promise to yield microorganisms tailored to assemble nanoparticle structures with device-specific shapes. Large-scale culturing of such genetically tailored microorganisms, coupled with shape-preserving chemical conversion (via BaSIC processes), would then provide low-cost 3-D Genetically Engineered Micro/nano-devices (3-D GEMs).

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“…The vast majority of bioclastic structures is comprised of silica or calcium carbonate, which are not particularly attractive materials for a number of micro/nanodevice applications. Recent work has shown that the siliceous diatom chemistry can be altered without loss of the original 3D shape and features through the use of gas/solid displacement reactions, conformal coating techniques, or a combination of both (Cai and Sandhage, 2005; Gaddis and Sandhage, 2004; Sandhage et al , 2005, 2002a, 2002b; Unocic et al , 2004; Weatherspoon et al , 2005; Zhao et al , 2005). For example, the following oxidation-reduction displacement reaction has been used to convert diatom frustules into magnesia-based replicas (Cai et al , 2005; Sandhage et al , 2005, 2002a, 2002b): where {Si} refers to silicon in elemental form or dissolved within a Mg-bearing phase.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction analyses of 3D MgO-based replicas of diatom microshells synthesized by a low-temperature gas/solid displacement reaction

et al. 2005

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The nanostructural features of the gas-phase displacement reaction 2Mg(g)+SiO2→2MgO(s)+{Si}, where SiO2 is in the form of diatom shells were studied via X-ray diffraction and Fourier methods. Diatomaceous powder heated to 700 °C in a sealed graphite cell in the presence of Mg vapor formed MgO via a displacement reaction. Warren-Averbach analysis performed on samples reacted for different times showed an initial sharp MgO grain size distribution which broadened with time. New MgO crystallization was shown to occur until about 60 min, whereafter only MgO grain growth occurred. Median MgO crystallite size increased from 7.5 to 24.9 nm during this period, whereas microstrain decreased dramatically past 60 min annealing time.

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A Novel Hybrid Route to Chemically–Tailored, Three–Dimensional Oxide Nanostructures: The Basic (Bioclastic and Shape–Preserving Inorganic Conversion) Process

Cited by 9 publications

References 0 publications

Three‐Dimensional Assemblies of Zirconia Nanocrystals Via Shape‐Preserving Reactive Conversion of Diatom Microshells

Three‐Dimensional Assemblies of Zirconia Nanocrystals Via Shape‐Preserving Reactive Conversion of Diatom Microshells

Merging Biological Self‐Assembly with Synthetic Chemical Tailoring: The Potential for 3‐D Genetically Engineered Micro/Nano‐Devices (3‐D GEMS)

X-ray diffraction analyses of 3D MgO-based replicas of diatom microshells synthesized by a low-temperature gas/solid displacement reaction

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