Characterization of Pore Framework Structure in Monolithic Mesoporous Silica

2009 ◽  
Vol 1217 ◽  
Author(s):  
Ching-Mao Wu ◽  
Szu-Yin Lin ◽  
Chin-Cheng Weng ◽  
Kuo-Tung Huang
Keyword(s):  
Fractal Dimension ◽  
Mesoporous Silica ◽  
Power Law ◽  
Sol Gel ◽  
Spherical Model ◽  
Pore Network ◽  
Transmission Electron Microscopy Micrographs ◽  
Mass Fractal ◽  
Commercial Applications ◽  
The Individual

AbstractMesoporous silica materials have received much interest due to commercial applications in chemical separations and heterogeneous catalysis. Recent studies have reported via a sol-gel nanocasting technique, monolithic mesoporous silica with wormlike pore framework could be prepared by utilizing room-temperature ionic liquids (RTILs) as templates and solvents. Although previous reports have indicated that the wormlike pores would be formed in the silica, the detailed pore network structure still remained the crucial issues to be resolved. In the present study, we investigated the pore structure in the monolithic mesoporous silica, which was templated by RTIL (1-butyl-3-methyl-imidazolium-tetrafluoroborate). We revealed an open fractal pore network with a branched and self-similar appearance was formed by the aggregation of the individual spherical pores. Transmission electron microscopy micrographs displayed that the disordered wormlike pore framework was formed in the silica. Furthermore, the small angle X-ray scattering profile measured herein further exhibited three distinct regions of power-law scattering on the respective length scales. In the high-q region, the profile followed Power behavior and a power-law of -4 was observed for the surface fractal dimension of 2, manifesting the primary pore with a smooth surface and a spherical appearance. In the intermediate-q region, a power-law of -2.5 (mass fractal dimension of 2.5), indicating an open mass fractal network was formed by the aggregation of the individual primary pores. Moreover in the low-q region, the power-law of -4 was observed for mass-fractal agglomerates of aggregates. With the proceeding analysis of unified equation in terms of two structural levels, the radiuses of gyration of primary pore (Rg1)and its aggregates (Rg2) were fitted as ca. 0.9 nm and 5.5 nm, respectively. For a spherical-model pore, the radius of pore (R) was ca. 1.16 nm; thus, the averaged pore diameter (D) was 2.32 nm. The number of primary pores in a fractal aggregate (degree of aggregation, z) was calculated as ca. 67.

Large-Scale Morphology of Dispersed Layered Silicates

2004 ◽  
Vol 840 ◽  
Author(s):  
Dale W. Schaefer ◽  
Ryan S. Justice ◽  
Hilmar Koerner ◽  
Richard Vaia ◽  
Chungui Zhao ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Large Scale ◽  
Persistence Length ◽  
Radius Of Gyration ◽  
Gel Point ◽  
Polyamide 66 ◽  
Mass Fractal ◽  
Mass Fractal Dimension ◽  
Flat Disk ◽  
The Individual

ABSTRACTUltra small angle x-ray scattering is used to probe the morphology of highly dispersed montmorillonite (MMT) in water and polyamide-66. In water the scattered intensity, I(q) shows a q-2 dependence for q > 0.01 Å-1, where q is the magnitude of the scattering vector. This is as expected for a two dimensional sheet-like object. On larger scales (smaller q) mass-fractal character is evident up to the radius-of-gyration of the individual scattering entities. The scattering profile is interpreted using a semi-flexible sheet model in which flat, disk-like entities of radius = 80 Å (an areal persistence length) are fractally distributed on large scales with a mass fractal dimension of 2.65. These size scales correspond to a scattering entity comprised of one or a few crumpled sheets. No evidence of inter-particle correlations is found at concentrations below the gel point. In polyamide-66 loaded with organically modified MMT long-range fractal behavior is also observed but with larger fractal dimension.

scholarly journals Scattering from surface fractals in terms of composing mass fractals

2017 ◽  
Vol 50 (3) ◽  
pp. 919-931 ◽  
Author(s):  
A. Yu. Cherny ◽  
E. M. Anitas ◽  
V. A. Osipov ◽  
A. I. Kuklin
Keyword(s):  
Fractal Dimension ◽  
Power Law ◽  
Scattering Amplitude ◽  
Three Dimensional ◽  
Power Law Distribution ◽  
Scattering Intensity ◽  
Three Dimensional Objects ◽  
Additional Information ◽  
Mass Fractal ◽  
Surface Fractal

It is argued that a finite iteration of any surface fractal can be composed of mass-fractal iterations of the same fractal dimension. Within this assertion, the scattering amplitude of a surface fractal is shown to be a sum of the amplitudes of the composing mass fractals. Various approximations for the scattering intensity of surface fractals are considered. It is shown that small-angle scattering (SAS) from a surface fractal can be explained in terms of a power-law distribution of sizes of objects composing the fractal (internal polydispersity), provided the distance between objects is much larger than their size for each composing mass fractal. The power-law decay of the scattering intensityI(q) ∝ q^{D_{\rm s}-6}, where 2 <Ds< 3 is the surface-fractal dimension of the system, is realized as a non-coherent sum of scattering amplitudes of three-dimensional objects composing the fractal and obeying a power-law distribution dN(r) ∝r−τdr, withDs= τ − 1. The distribution is continuous for random fractals and discrete for deterministic fractals. A model of the surface deterministic fractal is suggested, the surface Cantor-like fractal, which is a sum of three-dimensional Cantor dusts at various iterations, and its scattering properties are studied. The present analysis allows one to extract additional information from SAS intensity for dilute aggregates of single-scaled surface fractals, such as the fractal iteration number and the scaling factor.

Sol–gel derived mesoporous silica films using amphiphilic triblock copolymers

2003 ◽  
Vol 332 (1-3) ◽  
pp. 199-206 ◽  
Author(s):  
Nobuaki Kitazawa ◽  
Hideyoshi Namba ◽  
Masami Aono ◽  
Yoshihisa Watanabe
Keyword(s):  
Mesoporous Silica ◽  
Triblock Copolymers ◽  
Sol Gel ◽  
Silica Films

scholarly journals Effect of surface carbonates on the cyclability of LiNbO3-coated NCM622 in all-solid-state batteries with lithium thiophosphate electrolytes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A-Young Kim ◽  
Florian Strauss ◽  
Timo Bartsch ◽  
Jun Hao Teo ◽  
Jürgen Janek ◽  
...  
Keyword(s):  
Solid State ◽  
Solid Electrolyte ◽  
Sol Gel ◽  
Rate Capability ◽  
Cycling Performance ◽  
Side Reactions ◽  
Bulk Solid ◽  
Solid State Batteries ◽  
The Individual ◽  
Surface Carbonates

AbstractWhile still premature as an energy storage technology, bulk solid-state batteries are attracting much attention in the academic and industrial communities lately. In particular, layered lithium metal oxides and lithium thiophosphates hold promise as cathode materials and superionic solid electrolytes, respectively. However, interfacial side reactions between the individual components during battery operation usually result in accelerated performance degradation. Hence, effective surface coatings are required to mitigate or ideally prevent detrimental reactions from occurring and having an impact on the cyclability. In the present work, we examine how surface carbonates incorporated into the sol–gel-derived LiNbO3 protective coating on NCM622 [Li1+x(Ni0.6Co0.2Mn0.2)1–xO2] cathode material affect the efficiency and rate capability of pellet-stack solid-state battery cells with β-Li3PS4 or argyrodite Li6PS5Cl solid electrolyte and a Li4Ti5O12 anode. Our research data indicate that a hybrid coating may in fact be beneficial to the kinetics and the cycling performance strongly depends on the solid electrolyte used.

scholarly journals “TNOs are Cool”: A survey of the trans-Neptunian region

2018 ◽  
Vol 618 ◽  
pp. A136 ◽  
Author(s):  
E. Vilenius ◽  
J. Stansberry ◽  
T. Müller ◽  
M. Mueller ◽  
C. Kiss ◽  
...  
Keyword(s):  
Power Law ◽  
Total Mass ◽  
Size Range ◽  
Family Members ◽  
Far Infrared ◽  
Effective Diameter ◽  
Water Ice ◽  
The Family ◽  
The Individual ◽  
Geometric Albedo

Context. A group of trans-Neptunian objects (TNOs) are dynamically related to the dwarf planet 136108 Haumea. Ten of them show strong indications of water ice on their surfaces, are assumed to have resulted from a collision, and are accepted as the only known TNO collisional family. Nineteen other dynamically similar objects lack water ice absorptions and are hypothesized to be dynamical interlopers. Aims. We have made observations to determine sizes and geometric albedos of six of the accepted Haumea family members and one dynamical interloper. Ten other dynamical interlopers have been measured by previous works. We compare the individual and statistical properties of the family members and interlopers, examining the size and albedo distributions of both groups. We also examine implications for the total mass of the family and their ejection velocities. Methods. We use far-infrared space-based telescopes to observe the target TNOs near their thermal peak and combine these data with optical magnitudes to derive sizes and albedos using radiometric techniques. Using measured and inferred sizes together with ejection velocities, we determine the power-law slope of ejection velocity as a function of effective diameter. Results. The detected Haumea family members have a diversity of geometric albedos ~0.3–0.8, which are higher than geometric albedos of dynamically similar objects without water ice. The median geometric albedo for accepted family members is pV = 0.48−0.18+0.28, compared to 0.08−0.05+0.07 for the dynamical interlopers. In the size range D = 175−300 km, the slope of the cumulative size distribution is q = 3.2−0.4+0.7 for accepted family members, steeper than the q = 2.0 ± 0.6 slope for the dynamical interlopers with D < 500 km. The total mass of Haumea’s moons and family members is 2.4% of Haumea’s mass. The ejection velocities required to emplace them on their current orbits show a dependence on diameter, with a power-law slope of 0.21–0.50.

ChemInform Abstract: Sol-Gel-Derived Mesoporous Silica Films with Low Dielectric Constants.

ChemInform ◽  
2001 ◽  
Vol 32 (10) ◽  
pp. no-no
Author(s):  
Seana Seraji ◽  
Yun Wu ◽  
Michael Forbess ◽  
Steven J. Limmer ◽  
Tammy Chou ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Sol Gel ◽  
Dielectric Constants ◽  
Silica Films ◽  
Low Dielectric

scholarly journals The fractal dimension of the tree of life

2014 ◽  
Author(s):  
Xiaofei Lv ◽  
Yuping Wu ◽  
Bin Ma
Keyword(s):  
Fractal Dimension ◽  
Power Law ◽  
Fractal Dimensions ◽  
Predictive Modelling ◽  
Tree Of Life ◽  
Fundamental Question ◽  
Theoretical Studies ◽  
Structure Pattern ◽  
Intermediate Size ◽  
Taxonomic Groups

The structure pattern of the tree of life clues on the key ecological issues; hence knowing the fractal dimension is the fundamental question in understanding the tree of life. Yet the fractal dimension of the tree of life remains unclear since the scale of the tree of life has hypergrown in recent years. Here we show that the tree of life display a consistent power-law rules for inter- and intra-taxonomic levels, but the fractal dimensions were different among different kingdoms. The fractal dimension of hierarchical structure (Dr) is 0.873 for the entire tree of life, which smaller than the values of Dr for Animalia and Plantae but greater than the values of Dr for Fungi, Chromista, and Protozoa. The hierarchical fractal dimensions values for prokaryotic kingdoms are lower than for other kingdoms. The Dr value for Viruses was lower than most eukaryotic kingdoms, but greater than prokaryotes. The distribution of taxa size is governed by fractal diversity but skewed by overdominating taxa with large subtaxa size. The proportion of subtaxa in taxa with small and large sizes was greater than in taxa with intermediate size. Our results suggest that the distribution of subtaxa in taxa can be predicted with fractal dimension for the accumulating taxa abundance rather than the taxa abundance. Our study determined the fractal dimensions for inter- and intra-taxonomic levels of the present tree of life. These results emphases the need for further theoretical studies, as well as predictive modelling, to interpret the different fractal dimension for different taxonomic groups and skewness of taxa with large subtaxa size.

Development of Novel Mesoporous Silica-Based Bioactive Glass Scaffolds with Drug Delivery Capabilities

2014 ◽  
Vol 96 ◽  
pp. 54-60 ◽  
Author(s):  
Anahí Philippart ◽  
Elena Boccardi ◽  
Lucia Pontiroli ◽  
Ana Maria Beltrán ◽  
Alexandra Inayat ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Simulated Body Fluid ◽  
Mesoporous Silica ◽  
Body Fluid ◽  
Glass Composition ◽  
Glass Structure ◽  
Sol Gel ◽  
Bioactive Glasses

Novel silica-based bioactive glasses were successfully prepared by the sol-gel method. The optimized glass composition for fabrication of the scaffolds was (in mol.%) 60% SiO2 – 30% CaO - 5% Na2O - 5% P2O5 (60S30C5N5P). This composition was confirmed to develop a thick hydroxycarbonate apatite (HCA) layer in Simulated Body Fluid (SBF) after 7 days, as revealed by Fourier Transform Infrared Spectroscopy (FTIR), indicating the bioactive character of the scaffolds. The mesoporous nature of the glass structure allows the load of tetracycline and a sustained release of the drug in PBS during 7 days was measured.

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