scholarly journals Open Porosity and Pore Size Distribution of Mesoporous Silica Films Investigated by Positron Annihilation Lifetime Spectroscopy and Ellipsometric Porosimetry

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3371
Author(s):  
Bangyun Xiong ◽  
Jingjing Li ◽  
Chunqing He ◽  
Jiale Lai ◽  
Xiangjia Liu ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Positron Annihilation ◽  
Open Porosity ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Silica Films ◽  
Ellipsometric Porosimetry ◽  
Positron Annihilation Lifetime

Tunable mesoporous silica films were prepared though a sol-gel process directed by the self-assembly of various triblock copolymers. Positron annihilation γ-ray energy spectroscopy and positron annihilation lifetime spectroscopy (PALS) based on intense pulsed slow positron beams as well as ellipsometric porosimetry (EP) combined with heptane adsorption were utilized to characterize the open porosity/interconnectivity and pore size distribution for the prepared films. The consistency between the open porosities was examined by the variations of orthopositronium (o-Ps) 3γ annihilation fractions and the total adsorbed volumes of heptane. The average pore sizes deduced by PALS from the longest-lived o-Ps lifetimes are in good agreement with those by EP on the basis of the Barrett–Joyner–Halenda model, as indicated by a well fitted line of slope k = 1. The results indicate that the EP combined with heptane adsorption is a useful method with high sensitivity for calibrating the mesopore size in highly interconnected mesoporous films, whereas PALS is a novel, complementary tool for characterizing both closed and open pores in them.

Calculation of Pore Size Distribution in the Ellipsometric Porosimetry: Method and Reliability

1999 ◽  
Vol 565 ◽  
Author(s):  
K. P Mogilnikov ◽  
V. G Polovinkin ◽  
F. N Dultsev ◽  
M. R Baklanov
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Porous Silica ◽  
Solid Substrate ◽  
Silica Films ◽  
Ellipsometric Porosimetry ◽  
Method Of Calculation ◽  
Organic Adsorbates

AbstractEllipsometric porosimetry allows measurement of the pore size distribution in a thin porous film deposited on top of any solid substrate. The most important concept of this technique is the use of in-situ ellipsometry to determine the amount of adsorbate adsorbed/condensed in the film. Changes in refractive index and film thickness are used for calculation of the amount of adsorbate. A room temperature porosimetry based on adsorption of vapours of some organic solvents has been developed. In this paper, a method of calculation of the pore size distribution and reliability of the ELP results is discussed and the validity of the Gurvitsch rule for organic adsorbates (toluene, heptane, CCl4) is examined. Porous silica films on top of Si wafers were used for this analysis.

Study of mesoporous silica films by positron annihilation based on a slow positron beam: Effects of preparation conditions on pore size and open porosity

2007 ◽  
Vol 331 (2-3) ◽  
pp. 213-218 ◽  
Author(s):  
Chunqing He ◽  
Ryoichi Suzuki ◽  
Toshiyuki Ohdaira ◽  
Nagayasu Oshima ◽  
Atsushi Kinomura ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Positron Annihilation ◽  
Open Porosity ◽  
Positron Beam ◽  
Silica Films ◽  
Slow Positron ◽  
Preparation Conditions

Positronium Thermalization Process in Nanoporous Materials and its Influence on the Shape of PALS Spectrum

2008 ◽  
Vol 607 ◽  
pp. 39-41
Author(s):  
Jerzy Kansy ◽  
Radosław Zaleski
Keyword(s):  
Mesoporous Silica ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Size Distribution ◽  
Nanoporous Materials ◽  
New Method ◽  
New Model ◽  
Conventional Models ◽  
Mcm 41

A new method of analysis of PALS spectra of porous materials is proposed. The model considers both the thermalization process of positronium inside the pores and the pore size distribution. The new model is fitted to spectra of mesoporous silica MCM-41 and MSF. The resulting parameters are compared with parameters obtained from fitting the “conventional” models, i.e. a sum of exponential components with discrete or/and distributed lifetimes.

Characterisation of Low-K Dielectric Films by Ellipsometric Porosimetry

2000 ◽  
Vol 612 ◽  
Author(s):  
M.R. Baklanov ◽  
K.P. Mogilnikov
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Average Pore Size ◽  
Dielectric Films ◽  
Swelling Properties ◽  
Small Surface ◽  
Ellipsometric Porosimetry ◽  
Low K

AbstractEllipsometric porosimetry (EP) is a simple and effective method for the characterization of the porosity (volume of both open and close pores), average pore size, specific surface area and pore size distribution (PSD) in thin porous films deposited on top of any smooth solid substrat e. Because a laser probe is used, small surface area can be analyzed. Therefore, EP can be used on patterned wafers and it is compatible with microelectronic technology. This method is a new version of adsorption (BET) porosimetry. In situ ellipsometry is used to determine the amount of adsorptive which adsorbed/condensed in the film. Change in refractive index is used to calculate of the quantity of adsorptive present in the film. EP also allows the study of thermal stability, adsorption and swelling properties of low-K dielectric films. Room temperature EP based on the adsorption of vapor of some suitable organic solvents and method of calculation of porosity and PSD is discussed. Examination of the validity of Gurvitsch rule for various organic adsorptives (toluene, heptane, carbon tetrachloride and isopropyl alcohol) has been carried out to assess the reliability of measurements of pore size distribution by the ellipsometric porosimetry.

On the Limits of Sensitivity of PALS to Incorporated Free Volume Holes in Polymeric Membranes and Sorbents: Effect of sc-CO2 in Polyhexafluoropropylene

2017 ◽  
Vol 373 ◽  
pp. 261-264 ◽  
Author(s):  
Victor Shantarovich ◽  
Valentin Bekeshev ◽  
Nikolai Belov ◽  
Irina Kevdina ◽  
Mikhail Filimonov ◽  
...  
Keyword(s):  
Low Temperature ◽  
Size Distribution ◽  
Positron Annihilation ◽  
Free Volume ◽  
Polymeric Membranes ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Membrane Materials ◽  
Positron Annihilation Lifetime

Positron annihilation lifetime spectroscopy (PALS) is a recognized instrument for the studies of size-distribution of nanopores (intrinsic free volume holes FVH) in polymers, particularly membrane materials. The limits of this application in the case of “alien” pores, produced by swelling of poly (hexafluoro propylene) PHFP in the gas (CO2) in super-critical (sc-) state are discussed. The obtained conclusions are controlled by measurements of low temperature gas (N2) sorption (LTGS) and by comparison of the data with the results on permeation of various gases through the PHFP membrane. Attention is payed to relaxation with time of the newly created FVH in the PHFP membrane.

Influence of Hipping Pressure on the Strength and the Porosity of Porous Copper

1991 ◽  
Vol 251 ◽  
Author(s):  
Atsushi Takata ◽  
K. Ishizaki ◽  
Y. Kondo ◽  
T. Shioura
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Young’S Modulus ◽  
Open Porosity ◽  
Structural Parameters ◽  
High Strength ◽  
Porous Copper ◽  
Different Temperatures ◽  
Hip Process

ABSTRACTOpen porous copper metals, which have high strength, high open porosity and well controlled pore size distribution, were produced by a hot isostatic press (HIP) process. They were sintered at different temperatures from 973 to 1273K under various HIPping pressures up to 200MPa. Pore size distribution and Young's modulus of the sintered samples were analyzed. The HIPped products have greater strength and higher open porosity than those of the normally sintered ones. The internal structural parameters such as pore size distribution were controlled by changing the HIPping pressure.

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