Particulate morphology of nanostructured materials

Abstract

The aim of this study was to develop a technique to analyze the crystalline and particulate morphology of highly disperse complex metal and metalloid oxides, which include both crystalline and amorphous phases, using X-ray diffraction (XRD) data to compute crystallite size distributions (CSD) compared to the particles size distribution functions estimated from high-resolution transmission electron microscopy (TEM) images treated with specific software. Two versions of the XRD treatment methods were used: (i) full profile analysis (FPA) of whole XRD patterns with a self-consistent regularization (SCR) procedure using models for spherical and lamellar crystallites that allows us to estimate relative contributions of crystallites of different shapes; and (ii) analysis of main pure XRD lines with consideration of corrections on an instrumental line profile and background using a regularization procedure with models of spherical or lamellar crystallites. The XRD and TEM based approaches were tested to analyze the crystalline and particulate morphology of various disperse materials: complex (binary and ternary) fumed oxides with silica/alumina, silica/titania, and alumina/silica/titania including crystalline alumina and titania and amorphous silica; nanocomposites CeO 2-ZrO 2 /SiO 2 (10 : 10 : 80 wt.%) and TiO 2-ZrO 2 /SiO 2 (10 : 10 : 80 wt.%) including crystalline and amorphous phases and synthesized using a liquid-phase method and fumed silica A-300 as a substrate; and natural clays of complex composition including several crystalline phases. Obtained results show that the developed approaches to analyze the XRD patterns could be effectively used to compute the CSD in parallel with TEM image treatments, using specific software, for a deeper insight into crystalline and particulate morphology of various disperse materials.

Polymer Adsorbents vs. Functionalized Oxides and Carbons: Particulate Morphology and Textural and SurfaceCharacteristics

“…[ 28 , 54 , 55 , 56 , 85 , 86 , 87 , 88 , 89 , 90 ]. Therefore, to separate the results with large and small systematic errors, a set of various methods should be used for accurate morphological, textural, and structural characterization of composites and hybrid systems, considering all their components, as well as interactions of these components in composites [ 28 , 89 , 90 , 91 ].…”

“…This study’s main aim was to show some ways to improve information extraction for more complete and accurate characterization of complex adsorbents, polymer fillers, and composites of different kinds. This could be provided by using the models, which correctly describe each component in composites concerning material kinds and shapes of pores and particles, and by using the self-consistent regularization procedures for simultaneously solving a set of related integral equations [ 89 , 90 , 91 ]. For effective data treatments and maximal information extraction, it is of importance to use appropriate methods to treat the experimental (especially indirect) data with accurate physicomathematical models of the experimental dependences on pressure, concentration, temperature, and other parameters and related computational programs, e.g., with the SCR procedures.…”

“…Additionally, complex and hybrid systems with PVA/AC, fumed silica/PDMS, etc., are described here mainly concerning the morphological and textural characteristics. All these materials can be considered as representatives of various classes of simple and complex adsorbents and polymer fillers described in detail elsewhere [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 28 , 31 , 32 , 54 , 55 , 56 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 89 , 90 , 91 ]. Some details on the materials used here are given in the Supplementary Materials file.…”

“…Note that firm software used with various adsorption analyzers is oriented on such simple materials as silica or carbon, i.e., the treatment results with this software are rather incorrect for complex and hybrid composites. Therefore, to increase the reliability and validity of the characterization of complex systems, several experimental and theoretical methods should be used in parallel with software, including models for complex materials [ 28 , 32 , 54 , 89 , 90 , 91 ], and this aspect is analyzed here in detail.…”

“…In this work, some aspects of relatively comprehensive characterization of individual and complex, unmodified and functionalized materials with oxides, carbons, and polymers are analyzed to show the possibilities of parallel applications of several experimental methods with the treatment of the data with simple regularization/functional minimization or more complex self-consistent regularization procedures [ 87 , 89 , 90 , 91 , 92 ] and other applied mathematics and computational methods. Note that some experimental methods, which complement each other well, can give different pictures on the same materials.…”