Browse
Submit Data
Databases
API
Help

Dataset Information

24 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Anisotropic and hierarchical SiC@SiO2 nanowire aerogel with exceptional stiffness and stability for thermal superinsulation.

ABSTRACT: Ceramic aerogels are promising lightweight and high-efficient thermal insulators for applications in buildings, industry, and aerospace vehicles but are usually limited by their brittleness and structural collapse at high temperatures. In recent years, fabricating nanostructure-based ultralight materials has been proved to be an effective way to realize the resilience of ceramic aerogels. However, the randomly distributed macroscale pores in these architectures usually lead to low stiffness and reduced thermal insulation performance. Here, to overcome these obstacles, a SiC@SiO2 nanowire aerogel with a nanowire-assembled anisotropic and hierarchical microstructure was prepared by using directional freeze casting and subsequent heat treatment. The aerogel exhibits an ultralow thermal conductivity of ~14 mW/m·K, an exceptional high stiffness (a specific modulus of ~24.7 kN·m/kg), and excellent thermal and chemical stabilities even under heating at 1200°C by a butane blow torch, which makes it an ideal thermally superinsulating material for applications under extreme conditions.

SUBMITTER: Su L

PROVIDER: S-EPMC7314525 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Robust SiO2-Al2O3/Agarose Composite Aerogel Beads with Outstanding Thermal Insulation Based on Coal Gangue.

Project description:Advanced SiO2-Al2O3 aerogel materials have outstanding potential in the field of thermal insulation. Nevertheless, the creation of a mechanically robust and low-cost SiO2-Al2O3 aerogel material remains a considerable challenge. In this study, SiO2-Al2O3 aerogel based on coal gangue, which is a type of zero-cost inorganic waste, was constructed in porous agarose aerogel beads, followed by simple chemical vapor deposition of trimethylchlorosilane to fabricate SiO2-Al2O3/agarose composite aerogel beads (SCABs). The resulting SCABs exhibited a unique nanoscale interpenetrating network structure, which is lightweight and has high specific surface area (538.3 m2/g), hydrophobicity (approximately 128°), and excellent thermal stability and thermal insulation performance. Moreover, the compressive strength of the SCABs was dramatically increased by approximately a factor of ten compared to that of native SiO2-Al2O3 aerogel beads. The prepared SCABs not only pave the way for the design of a novel aerogel material for use in thermal insulation without requiring expensive raw materials, but also provide an effective way to comprehensively use coal gangue.

| S-EPMC8952686 | biostudies-literature

Ultra-low Thermal Conductivity in Si/Ge Hierarchical Superlattice Nanowire.

Project description:Due to interfacial phonon scattering and nanoscale size effect, silicon/germanium (Si/Ge) superlattice nanowire (SNW) can have very low thermal conductivity, which is very attractive for thermoelectrics. In this paper, we demonstrate using molecular dynamics simulations that the already low thermal conductivity of Si/Ge SNW can be further reduced by introducing hierarchical structure to form Si/Ge hierarchical superlattice nanowire (H-SNW). The structural hierarchy introduces defects to disrupt the periodicity of regular SNW and scatters coherent phonons, which are the key contributors to thermal transport in regular SNW. Our simulation results show that periodically arranged defects in Si/Ge H-SNW lead to a ~38% reduction of the already low thermal conductivity of regular Si/Ge SNW. By randomizing the arrangement of defects and imposing additional surface complexities to enhance phonon scattering, further reduction in thermal conductivity can be achieved. Compared to pure Si nanowire, the thermal conductivity reduction of Si/Ge H-SNW can be as large as ~95%. It is concluded that the hierarchical structuring is an effective way of reducing thermal conductivity significantly in SNW, which can be a promising path for improving the efficiency of Si/Ge-based SNW thermoelectrics.

| S-EPMC4644949 | biostudies-literature

Exceptional chemical and thermal stability of zeolitic imidazolate frameworks.

Project description:Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m(2)/g), high thermal stability (up to 550 degrees C), and remarkable chemical resistance to boiling alkaline water and organic solvents.

| S-EPMC1502432 | biostudies-literature

Thermal stability data of silver nanowire transparent conducting electrode.

Project description:The authors have recently reported the enhanced thermal stability of silver nanowire (AgNW) network transparent electrodes by electrodeposition method [1]. AgNW networks are known to break into droplets at elevated temperatures (spherodization temperature) that are still much lower than the bulk Ag melting temperature. This phenomenon is known as Rayleigh instability. As the diameter of individual AgNW in the network increases by electrodeposited Ag on the AgNW surface, the thermal stability of AgNW network can be enhanced. Here, we provide the data on the spherodization temperature depending on AgNW diameter. We also report the calculated activation energy required to induce the spherodization of AgNW network.

| S-EPMC7109625 | biostudies-literature

Ultrastrong nanocrystalline steel with exceptional thermal stability and radiation tolerance.

Project description:Nanocrystalline (NC) metals are stronger and more radiation-tolerant than their coarse-grained (CG) counterparts, but they often suffer from poor thermal stability as nanograins coarsen significantly when heated to 0.3 to 0.5 of their melting temperature (Tm). Here, we report an NC austenitic stainless steel (NC-SS) containing 1 at% lanthanum with an average grain size of 45 nm and an ultrahigh yield strength of ~2.5 GPa that exhibits exceptional thermal stability up to 1000 °C (0.75 Tm). In-situ irradiation to 40 dpa at 450 °C and ex-situ irradiation to 108 dpa at 600 °C produce neither significant grain growth nor void swelling, in contrast to significant void swelling of CG-SS at similar doses. This thermal stability is due to segregation of elemental lanthanum and (La, O, Si)-rich nanoprecipitates at grain boundaries. Microstructure dependent cluster dynamics show grain boundary sinks effectively reduce steady-state vacancy concentrations to suppress void swelling upon irradiation.

| S-EPMC6300597 | biostudies-literature

Imaging how thermal capillary waves and anisotropic interfacial stiffness shape nanoparticle supracrystals.

Project description:Development of the surface morphology and shape of crystalline nanostructures governs the functionality of various materials, ranging from phonon transport to biocompatibility. However, the kinetic pathways, following which such development occurs, have been largely unexplored due to the lack of real-space imaging at single particle resolution. Here, we use colloidal nanoparticles assembling into supracrystals as a model system, and pinpoint the key role of surface fluctuation in shaping supracrystals. Utilizing liquid-phase transmission electron microscopy, we map the spatiotemporal surface profiles of supracrystals, which follow a capillary wave theory. Based on this theory, we measure otherwise elusive interfacial properties such as interfacial stiffness and mobility, the former of which demonstrates a remarkable dependence on the exposed facet of the supracrystal. The facet of lower surface energy is favored, consistent with the Wulff construction rule. Our imaging-analysis framework can be applicable to other phenomena, such as electrodeposition, nucleation, and membrane deformation.

| S-EPMC7486387 | biostudies-literature

Thermal Stability and Anisotropic Sublimation of Two-Dimensional Colloidal Bi2Te3 and Bi2Se3 Nanocrystals.

Project description:The structural and compositional stabilities of two-dimensional (2D) Bi2Te3 and Bi2Se3 nanocrystals, produced by both colloidal synthesis and by liquid phase exfoliation, were studied by in situ transmission electron microscopy (TEM) during annealing at temperatures between 350 and 500 °C. The sublimation process induced by annealing is structurally and chemically anisotropic and takes place through the preferential dismantling of the prismatic {011?0} type planes, and through the preferential sublimation of Te (or Se). The observed anisotropic sublimation is independent of the method of nanocrystal's synthesis, their morphology, or the presence of surfactant molecules on the nanocrystals surface. A thickness-dependent depression in the sublimation point has been observed with nanocrystals thinner than about 15 nm. The Bi2Se3 nanocrystals were found to sublimate below 280 °C, while the Bi2Te3 ones sublimated at temperatures between 350 and 450 °C, depending on their thickness, under the vacuum conditions in the TEM column. Density functional theory calculations confirm that the sublimation of the prismatic {011?0} facets is more energetically favorable. Within the level of modeling employed, the sublimation occurs at a rate about 700 times faster than the sublimation of the {0001} planes at the annealing temperatures used in this work. This supports the distinctly anisotropic mechanisms of both sublimation and growth of Bi2Te3 and Bi2Se3 nanocrystals, known to preferentially adopt a 2D morphology. The anisotropic sublimation behavior is in agreement with the intrinsic anisotropy in the surface free energy brought about by the crystal structure of Bi2Te3 or Bi2Se3.

| S-EPMC5633265 | biostudies-literature

Ultralight, Ultraflexible, Anisotropic, Highly Thermally Conductive Graphene Aerogel Films.

Project description:Graphene aerogels have attracted much attention as a promising material for various applications. The unusually high intrinsic thermal conductivity of individual graphene sheets makes an obvious contrast with the thermal insulating performance of assembled 3D graphene materials. We report the preparation of anisotropy 3D graphene aerogel films (GAFs) made from tightly packed graphene films using a thermal expansion method. GAFs with different thicknesses and an ultimate low density of 4.19 mg cm-3 were obtained. GAFs show high anisotropy on average cross-plane thermal conductivity (K⊥) and average in-plane thermal conductivity (K||). Additionally, uniaxially compressed GAFs performed a large elongation of 11.76% due to the Z-shape folding of graphene layers. Our results reveal the ultralight, ultraflexible, highly thermally conductive, anisotropy GAFs, as well as the fundamental evolution of macroscopic assembled graphene materials at elevated temperature.

| S-EPMC8623857 | biostudies-literature

Growing CeO2 Nanoparticles Within the Nano-Porous Architecture of the SiO2 Aerogel.

Project description:In this study, new CeO2-SiO2 aerogel nanocomposites obtained by controlled growth of CeO2 nanoparticles within the highly porous matrix of a SiO2 aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO2 precursor and selected surfactants to control the growth of the CeO2 nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO2 dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO2 aerogels such as open mesoporosity with surface area values up to 430 m2·g-1. TEM and XRD characterizations show that nanocrystals of the dispersed CeO2 nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO2 nanoparticles are well-distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO2 nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment.

| S-EPMC7018665 | biostudies-literature

TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating.

Project description:Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.

| S-EPMC5750032 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data