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

Ortho-Positronium Reemission Yield and Energy in Surfactant-Templated Mesoporous Silica Films

2008 ◽  
Vol 607 ◽  
pp. 30-33 ◽  
Author(s):  
Laszlo Lizkay ◽  
C. Corbel ◽  
P. Perez ◽  
P. Desgardin ◽  
Marie France Barthe ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Positron Annihilation ◽  
Time Of Flight ◽  
Positron Beam ◽  
High Porosity ◽  
Silica Layer ◽  
Silica Films ◽  
Gamma Energy ◽  
Positron Energy

Positron annihilation gamma energy distribution, lifetime spectroscopy and time-of-flight method were used to study surfactant-templated mesoporous silica films deposited on glass. The lifetime depth profiling was correlated to Doppler broadening and 3γ annihilation fraction measurements to determine the annihilation characteristics inside the films. A set of consistent fingerprints for positronium annihilation, o-Ps reemission into vacuum, and pore size was directly determined. The lifetime measurements were performed in reflection mode with a specially designed lifetime spectrometer mounted on a slow positron beam system. The intensity of the 142 ns vacuum lifetime component was recorded as a function of the energy of the positron beam. In a film with high porosity a reemission efficiency of as high as 40 % was found at low positron energy. Positron lifetime in samples capped by a thin silica layer was used to determine the pore size. The energy of the reemitted o-Ps fraction was measured by a time-of-flight detector, mounted on the same system, allowing determination of both o-Ps re-emission efficiency and energy in the same sample. We demonstrate the potential of the simultaneous use of different positron annihilation techniques in the study of thin porous films.

Positron annihilation studies of mesoporous silica films using a slow positron beam

2006 ◽  
Vol 252 (9) ◽  
pp. 3221-3227 ◽  
Author(s):  
Chunqing He ◽  
Makoto Muramatsu ◽  
Toshiyuki Ohdaira ◽  
Atsushi Kinomura ◽  
Ryoichi Suzuki ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Positron Annihilation ◽  
Positron Beam ◽  
Silica Films ◽  
Slow Positron

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.

Tunable pores in mesoporous silica films studied using a pulsed slow positron beam

2007 ◽  
Vol 76 (2) ◽  
pp. 204-208 ◽  
Author(s):  
Chunqing He ◽  
Makoto Muramatsu ◽  
Toshiyuki Ohdaira ◽  
Nagayasu Oshima ◽  
Atsushi Kinomura ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Positron Beam ◽  
Silica Films ◽  
Slow Positron ◽  
Tunable Pores

Ageing-induced enhancement of open porosity of mesoporous silica films studied by positron annihilation spectroscopy

2006 ◽  
Vol 355 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Chunqing He ◽  
Makoto Muramatsu ◽  
Nagayasu Oshima ◽  
Toshiyuki Ohdaira ◽  
Atsushi Kinomura ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Positron Annihilation ◽  
Open Porosity ◽  
Positron Annihilation Spectroscopy ◽  
Silica Films

scholarly journals Effects of morphology and pore size of mesoporous silicas on the efficiency of an immobilized enzyme

RSC Advances ◽  
2021 ◽  
Vol 11 (17) ◽  
pp. 10010-10017
Author(s):  
Ping-Chung Kuo ◽  
Zhi-Xun Lin ◽  
Tzi-Yi Wu ◽  
Chun-Han Hsu ◽  
Hong-Ping Lin ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Mesoporous Silica ◽  
Pore Size ◽  
Immobilized Enzyme ◽  
Mesoporous Silicas ◽  
High Loading ◽  
Loading Capacity ◽  
Silica Films

Mesoporous silica films were used as supports with high loading capacity and enzyme activity.

scholarly journals Pore Size-Dependent Structure of Confined Water in Mesoporous Silica Films from Water Adsorption/Desorption Using ATR–FTIR Spectroscopy

Langmuir ◽  
2019 ◽  
Vol 35 (37) ◽  
pp. 11986-11994 ◽  
Author(s):  
Bettina Baumgartner ◽  
Jakob Hayden ◽  
Jérôme Loizillon ◽  
Sophia Steinbacher ◽  
David Grosso ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Ftir Spectroscopy ◽  
Pore Size ◽  
Water Adsorption ◽  
Confined Water ◽  
Silica Films ◽  
Size Dependent ◽  
Adsorption Desorption

Controlling Thermal Conductivity in Mesoporous Silica Films Using Pore Size and Nanoscale Architecture

2020 ◽  
Vol 11 (9) ◽  
pp. 3731-3737 ◽  
Author(s):  
Yan Yan ◽  
Man Li ◽  
Sophia King ◽  
Tiphaine Galy ◽  
Michal Marszewski ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mesoporous Silica ◽  
Pore Size ◽  
Silica Films
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