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K Binder - One of the best experts on this subject based on the ideXlab platform.
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from Capillary Condensation to interface localization transitions in colloid polymer mixtures confined in thin film geometry
Physical Review E, 2008Co-Authors: Andres De Virgiliis, R L C Vink, Jurgen Horbach, K BinderAbstract:Monte Carlo simulations of the Asakura-Oosawa model for colloid-polymer mixtures confined between two parallel repulsive structureless walls are presented and analyzed in the light of current theories on Capillary Condensation and interface localization transitions. Choosing a polymer-to-colloid size ratio of q=0.8 and studying ultrathin films in the range of D=3 to D=10 colloid diameters thickness, grand canonical Monte Carlo methods are used; phase transitions are analyzed via finite size scaling, as in previous work on bulk systems and under confinement between identical types of walls. Unlike the latter work, inequivalent walls are used here: While the left wall has a hard-core repulsion for both polymers and colloids, at the right-hand wall an additional square-well repulsion of variable strength acting only on the colloids is present. We study how the phase separation into colloid-rich and colloid-poor phases occurring already in the bulk is modified by such a confinement. When the asymmetry of the wall-colloid interaction increases, the character of the transition smoothly changes from Capillary Condensation type to interface localization type. For very thin films (i.e., for D=3) and a suitable choice of the wall-colloid interactions, evidence is found that the critical behavior falls in the universality class of the two-dimensional Ising model. Otherwise, we observe crossover scaling between different universality classes (namely, the crossover from the three-dimensional to the two-dimensional Ising model universality class). The colloid and polymer density profiles across the film in the various phases are discussed, as well as the correlation of interfacial fluctuations in the direction parallel to the confining walls. The broadening of the interface between the coexisting colloid-rich and polymer-rich phases (located parallel to the confining walls) is understood in terms of Capillary wave fluctuations. The experimental observability of all these phenomena is briefly discussed.
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a monte carlo test of the fisher nakanishi scaling theory for the Capillary Condensation critical point
Journal of Chemical Physics, 2001Co-Authors: O Dillmann, Marcus Muller, Wolfhard Janke, K BinderAbstract:Extending the Swendsen–Wang cluster algorithm to include both bulk (H) and surface fields (H1) in L×L×D Ising films of thickness D and two free L×L surfaces, a Monte Carlo study of the Capillary Condensation critical point of the model is presented. Applying a finite-size scaling analysis where the lateral linear dimension L is varied over a wide range, the critical temperature Tc(D) and the associated critical field Hc(D) are estimated for 4⩽D⩽32 lattice spacings, for a choice of the surface field H1 small enough that the dependence of Hc(D) on H1 is still linear. It is shown that the results are consistent with the power laws predicted by Fisher and Nakanishi [M. E. Fisher and H. Nakanishi, J. Chem. Phys. 75, 5857 (1981)], namely Tc(∞)−Tc(D)∝D−1/ν, Hc(D)∝D−(Δ−Δ1)/ν, where ν is the bulk correlation length exponent of the three-dimensional Ising model, and Δ, Δ1 are the corresponding “gap exponents” associated with bulk and surface fields, respectively. As expected, the order parameter of the thin film ne...
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a monte carlo test of the fisher nakanishi scaling theory for the Capillary Condensation critical point
arXiv: Statistical Mechanics, 2001Co-Authors: O Dillmann, Wolfhard Janke, M Mueller, K BinderAbstract:Extending the Swendsen-Wang cluster algorithm to include both bulk (H) and surface fields (H_1) in L x L x D Ising films of thickness D and two free L x L surfaces, a Monte Carlo study of the Capillary Condensation critical point of the model is presented. Applying a finite-size scaling analysis where the lateral linear dimension L is varied over a wide range, the critical temperature T_c(D) and the associated critical field H_c(D) are estimated for 4 <= D <= 32 lattice spacings, for a choice of the surface field H_1 small enough that the dependence of H_c(D) on H_1 is still linear. It is shown that the results are consistent with the power laws predicted by Fisher and Nakanishi [M.E. Fisher and H. Nakanishi, J. Chem. Phys. 75, 5857 (1981)], namely T_c(\infty)-T_c(D) \propto D^{-1/\nu}, H_c(D) \propto D^{-(\Delta -\Delta_1)/\nu}, where \nu is the bulk correlation length exponent of the three-dimensional Ising model, and \Delta, \Delta_1 are the corresponding ``gap exponents'' associated with bulk and surface fields, respectively. As expected, the order parameter of the thin film near its critical point exhibits critical behavior compatible with the universality class of the two-dimensional Ising model.
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non monotonous crossover between Capillary Condensation and interface localisation delocalisation transition in binary polymer blends
EPL, 2000Co-Authors: Marcus Muller, K Binder, Ezequiel V AlbanoAbstract:Within self-consistent field theory we study the phase behaviour of a symmetric binary AB polymer blend confined into a thin film. The film surfaces interact with the monomers via short-range potentials. One surface attracts the A component and the corresponding semi-infinite system exhibits a first-order wetting transition. The surface interaction of the opposite surface is varied as to study the crossover from Capillary Condensation for symmetric surface fields to the interface localisation/delocalisation transition for antisymmetric surface fields. In the former case the phase diagram has a single critical point close to the bulk critical point. In the latter case the phase diagram exhibits two critical points which correspond to the prewetting critical points of the semi-infinite system. The cross over between these qualitatively different limiting behaviours occurs gradually; however, the critical temperature and the critical composition exhibit a non-monotonic dependence on the surface field.
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wetting in fluid systems wetting and Capillary Condensation of lattice gases in thin film geometry
Berichte der Bunsengesellschaft für physikalische Chemie, 1994Co-Authors: K Binder, Alan M Ferrenberg, D P LandauAbstract:Monte Carlo studies of lattice gas models with attractive interactions between nearest neighbors on a simple cubic lattice are carried out for a L×L×D geometry with two hard walls of size L×L and periodic boundary conditions parallel to the wall. Two types of short-range forces at the walls are considered: (i) Both walls are of the same type and exert an attractive force of the same strength (in Ising model terminology, surface fields HD = H1 occur). (ii) The walls differ, one attracts and the other repels particles, again with the same strength (HD = −H1). In the first case, Capillary Condensation occurs at a chemical potential differing from its value for phase coexistence in the bulk, and the (second-order) wetting transition that occurs for D∞ is rounded off. In the second case, an interface parallel to the walls is stabilized and we observe the interface delocalization transition predicted by Parry and Evans. A first attempt to study the nature of this “quasi wetting transition” by finite size scaling methods is reported, and discussed in the context of recent theories.
Katsumi Kaneko - One of the best experts on this subject based on the ideXlab platform.
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improvement of the derjaguin broekhoff de boer theory for the Capillary Condensation evaporation of nitrogen in spherical cavities and its application for the pore size analysis of silicas with ordered cagelike mesopores
Langmuir, 2005Co-Authors: Piotr Kowalczyk, Katsumi Kaneko, Mietek Jaroniec, Artur P Terzyk, Piotr A GaudenAbstract:In a previous work, we proposed an improvement of the Derjaguin-Broekhoff-de Boer (DBdB) theory for Capillary Condensation/evaporation in open-ended cylindrical mesopores. In this paper, we report a further extension of this approach to the Capillary Condensation/evaporation of nitrogen in siliceous spherical cavities. The main idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the variation of the surface tension in spherical mesopores. In addition, the statistical film thickness (the so-called t-curve), which is evaluated accurately on the basis of adsorption isotherms measured for MCM-41 materials, is used instead of the originally proposed t-curve to take into account the excess chemical potential due to the surface forces. It is shown that the aforementioned modifications of the original DBdB theory that was refined by Ravikovitch and Neimark have significant implications for the pore size analysis of cagelike mesoporous silicas. To verify the proposed improvement of the DBdB pore size analysis (IDBdB), two series of FDU-1 samples, which are well-defined cagelike mesoporous materials (composed of siliceous spherical cavities interconnected by short necks), were used for the evaluation of the pore size distributions (PSDs). The correlation between the spinodal Condensation point in the spherical pores predicted by the nonlocal density functional theory (NDFT) developed by Ravikovitch and Neimark and that predicted by the IDBdB theory is very good in the whole range of mesopores. This feature is mirrored to the realistic PSD characterized by the bimodal structure of pores computed from the IDBdB theory. As in the case of open-ended cylindrical pores, the improvement of the classical DBdB theory preserves its simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the average pore size by the NDFT and the powder X-ray diffraction method.
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improvement of the derjaguin broekhoff de boer theory for Capillary Condensation evaporation of nitrogen in mesoporous systems and its implications for pore size analysis of mcm 41 silicas and related materials
Langmuir, 2005Co-Authors: Piotr Kowalczyk, Mietek Jaroniec, Artur P Terzyk, Katsumi KanekoAbstract:In this work, we propose an improvement of the classical Derjaguin-Broekhoff-de Boer (DBdB) theory for Capillary Condensation/evaporation in mesoporous systems. The primary idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the surface tension changes in mesopores. In addition, the statistical film thickness (so-called t-curve) evaluated accurately on the basis of the adsorption isotherms measured for the MCM-41 materials is used instead of the originally proposed t-curve (to take into account the excess of the chemical potential due to the surface forces). It is shown that the aforementioned modifications of the original DBdB theory have significant implications for the pore size analysis of mesoporous solids. To verify our improvement of the DBdB pore size analysis method (IDBdB), a series of the calcined MCM-41 samples, which are well-defined materials with hexagonally ordered cylindrical mesopores, were used for the evaluation of the pore size distributions. The correlation of the IDBdB method with the empirically calibrated Kruk-Jaroniec-Sayari (KJS) relationship is very good in the range of small mesopores. So, a major advantage of the IDBdB method is its applicability for small mesopores as well as for the mesopore range beyond that established by the KJS calibration, i.e., for mesopore radii greater than approximately 4.5 nm. The comparison of the IDBdB results with experimental data reported by Kruk and Jaroniec for Capillary Condensation/evaporation as well as with the results from nonlocal density functional theory developed by Neimark et al. clearly justifies our approach. Note that the proposed improvement of the classical DBdB method preserves its original simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the mean pore size by the powder X-ray diffraction method.
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molecular mechanism of Capillary Condensation of acetonitrile vapor on mcm 41 with the aid of a time correlation function analysis of ir spectroscopy
Chemical Physics Letters, 1998Co-Authors: Hideki Tanaka, Taku Iiyama, Takaomi Suzuki, Akihiko Matsumoto, Michael Grun, Klaus K. Unger, Naofumi Uekawa, Katsumi KanekoAbstract:Abstract The adsorption isotherm and IR spectra of acetonitrile adsorbed on MCM-41 (pore-width=3.2 nm) were measured at 303 K. The adsorption isotherm had a sharp jump at P / P 0 =0.3 without adsorption hysteresis. The CN stretching ν 2 -band of adsorbed acetonitrile had two-component α- and β-bands at 2263 and 2254 cm −1 , respectively, assigned to hydrogen-bonded molecules on surface hydroxyls of MCM-41 and physisorbed molecules in mesopores whose walls are coated with hydrogen-bonded molecules, respectively. The β-band was analyzed with a time correlation function, giving a reorientation time τ . The τ value of the adsorbed molecule before Capillary Condensation was smaller than that of the bulk liquid, indicating a gas-like state. After Capillary Condensation, τ was the same as for the bulk liquid.
Mietek Jaroniec - One of the best experts on this subject based on the ideXlab platform.
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Improvement of the Kruk-Jaroniec-Sayari method for pore size analysis of ordered silicas with cylindrical mesopores.
Langmuir : the ACS journal of surfaces and colloids, 2006Co-Authors: Mietek Jaroniec, Leonid A. SolovyovAbstract:In this work, the X-ray diffraction structure modeling was employed for analysis of hexagonally ordered large-pore silicas, SBA-15, to determine their pore width independently of adsorption measurements. Nitrogen adsorption isotherms were used to evaluate the relative pressure of Capillary Condensation in cylindrical mesopores of these materials. This approach allowed us to extend the original Kruk−Jaroniec−Sayari (KJS) relation (Langmuir 1997, 13, 6267) between the pore width and Capillary Condensation pressure up to 10 nm instead of previously established range from 2 to 6.5 nm for a series of MCM-41 and to improve the KJS pore size analysis of large pore silicas.
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improvement of the derjaguin broekhoff de boer theory for the Capillary Condensation evaporation of nitrogen in spherical cavities and its application for the pore size analysis of silicas with ordered cagelike mesopores
Langmuir, 2005Co-Authors: Piotr Kowalczyk, Katsumi Kaneko, Mietek Jaroniec, Artur P Terzyk, Piotr A GaudenAbstract:In a previous work, we proposed an improvement of the Derjaguin-Broekhoff-de Boer (DBdB) theory for Capillary Condensation/evaporation in open-ended cylindrical mesopores. In this paper, we report a further extension of this approach to the Capillary Condensation/evaporation of nitrogen in siliceous spherical cavities. The main idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the variation of the surface tension in spherical mesopores. In addition, the statistical film thickness (the so-called t-curve), which is evaluated accurately on the basis of adsorption isotherms measured for MCM-41 materials, is used instead of the originally proposed t-curve to take into account the excess chemical potential due to the surface forces. It is shown that the aforementioned modifications of the original DBdB theory that was refined by Ravikovitch and Neimark have significant implications for the pore size analysis of cagelike mesoporous silicas. To verify the proposed improvement of the DBdB pore size analysis (IDBdB), two series of FDU-1 samples, which are well-defined cagelike mesoporous materials (composed of siliceous spherical cavities interconnected by short necks), were used for the evaluation of the pore size distributions (PSDs). The correlation between the spinodal Condensation point in the spherical pores predicted by the nonlocal density functional theory (NDFT) developed by Ravikovitch and Neimark and that predicted by the IDBdB theory is very good in the whole range of mesopores. This feature is mirrored to the realistic PSD characterized by the bimodal structure of pores computed from the IDBdB theory. As in the case of open-ended cylindrical pores, the improvement of the classical DBdB theory preserves its simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the average pore size by the NDFT and the powder X-ray diffraction method.
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improvement of the derjaguin broekhoff de boer theory for Capillary Condensation evaporation of nitrogen in mesoporous systems and its implications for pore size analysis of mcm 41 silicas and related materials
Langmuir, 2005Co-Authors: Piotr Kowalczyk, Mietek Jaroniec, Artur P Terzyk, Katsumi KanekoAbstract:In this work, we propose an improvement of the classical Derjaguin-Broekhoff-de Boer (DBdB) theory for Capillary Condensation/evaporation in mesoporous systems. The primary idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the surface tension changes in mesopores. In addition, the statistical film thickness (so-called t-curve) evaluated accurately on the basis of the adsorption isotherms measured for the MCM-41 materials is used instead of the originally proposed t-curve (to take into account the excess of the chemical potential due to the surface forces). It is shown that the aforementioned modifications of the original DBdB theory have significant implications for the pore size analysis of mesoporous solids. To verify our improvement of the DBdB pore size analysis method (IDBdB), a series of the calcined MCM-41 samples, which are well-defined materials with hexagonally ordered cylindrical mesopores, were used for the evaluation of the pore size distributions. The correlation of the IDBdB method with the empirically calibrated Kruk-Jaroniec-Sayari (KJS) relationship is very good in the range of small mesopores. So, a major advantage of the IDBdB method is its applicability for small mesopores as well as for the mesopore range beyond that established by the KJS calibration, i.e., for mesopore radii greater than approximately 4.5 nm. The comparison of the IDBdB results with experimental data reported by Kruk and Jaroniec for Capillary Condensation/evaporation as well as with the results from nonlocal density functional theory developed by Neimark et al. clearly justifies our approach. Note that the proposed improvement of the classical DBdB method preserves its original simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the mean pore size by the powder X-ray diffraction method.
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accurate method for calculating mesopore size distributions from argon adsorption data at 87 k developed using model mcm 41 materials
Chemistry of Materials, 2000Co-Authors: Michal Kruk And, Mietek JaroniecAbstract:Argon adsorption isotherms were measured at 87 K for two macroporous silicas and a series of high-quality MCM-41 silicas with approximately cylindrical pores of average diameters from 2 to 6.5 nm. The pore sizes of the MCM-41 samples were accurately determined in earlier studies on the basis of powder X-ray diffraction and nitrogen adsorption using a geometrical relation between the pore volume, pore−center distance, and pore size in the honeycomb structure. Thus acquired model argon adsorption data for cylindrical mesopores were used to determine the statistical film thickness in the pores and the relation between the pore core radius and the Capillary Condensation/evaporation pressure. The statistical film thickness curve (t-curve) was extrapolated over the entire pressure range by using data for suitable macroporous silicas. The t-curve is reported in forms of a simple empirical equation and tabulated data. The relation between the pore core radius and the Capillary Condensation pressure was interpolat...
Alexander V Neimark - One of the best experts on this subject based on the ideXlab platform.
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adsorption induced deformation of mesoporous solids
Langmuir, 2010Co-Authors: Alexander V NeimarkAbstract:The Derjaguin−Broekhoff−de Boer theory of Capillary Condensation is employed to describe deformation of mesoporous solids in the course of adsorption−desorption hysteretic cycles. We suggest a thermodynamic model, which relates the mechanical stress induced by the adsorbed phase to the adsorption isotherm. Analytical expressions are derived for the dependence of the solvation pressure on the vapor pressure. The proposed method provides a description of nonmonotonic hysteretic deformation during Capillary Condensation without invoking any adjustable parameters. The method is showcased drawing on the examples of literature experimental data on adsorption deformation of porous glass and SBA-15 silica.
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surface area and porosity
Handbook of Heterogeneous Catalysis, 2008Co-Authors: Alexander V Neimark, Kenneth S. W. SingAbstract:The sections in this article are Introduction Physisorption of Gases Determination of Surface Area The BET Method The Standard Isotherm Concept Assessment of Porosity Capillary Condensation and the Kelvin Equation Adsorption Hysteresis Microporosity Micropore Analysis: Dubinin's Theory of Micropore Filling Micropore Analysis: Empirical Methods Other Methods for Micropore Pore Size Analysis Application of Density Functional Theory Adsorption at the Liquid–Solid Interface Adsorption from Solution Heat of Immersion Mercury Porosimetry General Conclusions Keywords: physisorption; pore size; mercury porosimetry; heat of immersion
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bridging scales from molecular simulations to classical thermodynamics density functional theory of Capillary Condensation in nanopores
Journal of Physics: Condensed Matter, 2003Co-Authors: Alexander V Neimark, Peter I Ravikovitch, Aleksey VishnyakovAbstract:With the example of the Capillary Condensation of Lennard-Jones fluid in nanopores ranging from 1 to 10 nm, we show that the non-local density functional theory (NLDFT) with properly chosen parameters of intermolecular interactions bridges the scale gap from molecular simulations to macroscopic thermodynamics. On the one hand, NLDFT correctly approximates the results of Monte Carlo simulations (shift of vapour–liquid equilibrium, spinodals, density profiles, adsorption isotherms) for pores wider than about 2 nm. On the other hand, NLDFT smoothly merges (above 7–10 nm) with the Derjaguin–Broekhoff–de Boer equations which represent augmented Laplace–Kelvin equations of Capillary Condensation and desorption.
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density functional theory of adsorption in spherical cavities and pore size characterization of templated nanoporous silicas with cubic and three dimensional hexagonal structures
Langmuir, 2002Co-Authors: Alexander V NeimarkAbstract:Adsorption in spherical cavities is studied by the nonlocal density functional theory (NLDFT). Theoretical results are compared with experimental data on ordered nanoporous materials with cubic Pm3n (SBA-1, HMM-3), cubic Im3m (SBA-16), and 3D hexagonal P63/mmc (SBA-2, SBA-12) cagelike structures. Quantitative comparison shows that Capillary Condensation of N2 at 77 K in sufficiently small cavities (pore diameters 3 ca. 6 nm, the Capillary Condensation step corresponds to the theoretical limit of stability of the metastable adsorption film. For pores wider than ca. 10 nm, this limit is approximated by the macroscopic Derjaguin−Broekhoff−de Boer equations. Desorption from cavities of >6 nm is controlled by the size of the windows that connect the cavity with the bulk fluid. If the diameter of the window is below ca. 4 nm, desorp...
Piotr Kowalczyk - One of the best experts on this subject based on the ideXlab platform.
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improvement of the derjaguin broekhoff de boer theory for the Capillary Condensation evaporation of nitrogen in spherical cavities and its application for the pore size analysis of silicas with ordered cagelike mesopores
Langmuir, 2005Co-Authors: Piotr Kowalczyk, Katsumi Kaneko, Mietek Jaroniec, Artur P Terzyk, Piotr A GaudenAbstract:In a previous work, we proposed an improvement of the Derjaguin-Broekhoff-de Boer (DBdB) theory for Capillary Condensation/evaporation in open-ended cylindrical mesopores. In this paper, we report a further extension of this approach to the Capillary Condensation/evaporation of nitrogen in siliceous spherical cavities. The main idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the variation of the surface tension in spherical mesopores. In addition, the statistical film thickness (the so-called t-curve), which is evaluated accurately on the basis of adsorption isotherms measured for MCM-41 materials, is used instead of the originally proposed t-curve to take into account the excess chemical potential due to the surface forces. It is shown that the aforementioned modifications of the original DBdB theory that was refined by Ravikovitch and Neimark have significant implications for the pore size analysis of cagelike mesoporous silicas. To verify the proposed improvement of the DBdB pore size analysis (IDBdB), two series of FDU-1 samples, which are well-defined cagelike mesoporous materials (composed of siliceous spherical cavities interconnected by short necks), were used for the evaluation of the pore size distributions (PSDs). The correlation between the spinodal Condensation point in the spherical pores predicted by the nonlocal density functional theory (NDFT) developed by Ravikovitch and Neimark and that predicted by the IDBdB theory is very good in the whole range of mesopores. This feature is mirrored to the realistic PSD characterized by the bimodal structure of pores computed from the IDBdB theory. As in the case of open-ended cylindrical pores, the improvement of the classical DBdB theory preserves its simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the average pore size by the NDFT and the powder X-ray diffraction method.
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improvement of the derjaguin broekhoff de boer theory for Capillary Condensation evaporation of nitrogen in mesoporous systems and its implications for pore size analysis of mcm 41 silicas and related materials
Langmuir, 2005Co-Authors: Piotr Kowalczyk, Mietek Jaroniec, Artur P Terzyk, Katsumi KanekoAbstract:In this work, we propose an improvement of the classical Derjaguin-Broekhoff-de Boer (DBdB) theory for Capillary Condensation/evaporation in mesoporous systems. The primary idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the surface tension changes in mesopores. In addition, the statistical film thickness (so-called t-curve) evaluated accurately on the basis of the adsorption isotherms measured for the MCM-41 materials is used instead of the originally proposed t-curve (to take into account the excess of the chemical potential due to the surface forces). It is shown that the aforementioned modifications of the original DBdB theory have significant implications for the pore size analysis of mesoporous solids. To verify our improvement of the DBdB pore size analysis method (IDBdB), a series of the calcined MCM-41 samples, which are well-defined materials with hexagonally ordered cylindrical mesopores, were used for the evaluation of the pore size distributions. The correlation of the IDBdB method with the empirically calibrated Kruk-Jaroniec-Sayari (KJS) relationship is very good in the range of small mesopores. So, a major advantage of the IDBdB method is its applicability for small mesopores as well as for the mesopore range beyond that established by the KJS calibration, i.e., for mesopore radii greater than approximately 4.5 nm. The comparison of the IDBdB results with experimental data reported by Kruk and Jaroniec for Capillary Condensation/evaporation as well as with the results from nonlocal density functional theory developed by Neimark et al. clearly justifies our approach. Note that the proposed improvement of the classical DBdB method preserves its original simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the mean pore size by the powder X-ray diffraction method.
