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 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.

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.

Characterization of Porous Silicate Low-k Films by Ellipsometric Porosimetry and Variable-energy Positron Annihilation Spectroscopy

2003 ◽  
Vol 788 ◽  
Author(s):  
Kenji Ito ◽  
Yoshinori Kobayashi ◽  
Ryoichi Suzuki ◽  
Toshiyuki Ohdaira ◽  
Runsheng Yu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Positron Annihilation ◽  
Open Porosity ◽  
Average Pore Size ◽  
Relative Dielectric Constant ◽  
Positron Annihilation Spectroscopy ◽  
Dielectric Constants ◽  
Ellipsometric Porosimetry ◽  
Variable Energy

ABSTRACTWe a pplied ellipsometric porosimetry and variable-energy positron annihilation spectroscopy to the pore characterization of spin-on-glass silicon-oxide-backboned porous thin films with different relative dielectric constants between 2.3 and 3.2. It was found that the relative dielectric constant decreases linearly with increasing open porosity deduced by ellipsometric porosimetry. Comparison of the open porosity with the average pore size deduced by positron annihilation lifetime spectroscopy suggested that mesopores less contribute to open porosity and are not so effective in decreasing film relative dielectric constant in comparison with micropores.

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

Argon Plasma Decomposition of Porogen in Mesoporous Silica Films Studied by Positron Annihilation

2012 ◽  
Vol 733 ◽  
pp. 193-196
Author(s):  
Chun Qing He ◽  
K. Ito ◽  
Toshitaka Oka ◽  
Yoshinori Kobayashi ◽  
Toshiyuki Ohdaira ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Positron Annihilation ◽  
Sol Gel ◽  
Argon Plasma ◽  
Silica Film ◽  
Silica Films ◽  
Positron Annihilation Lifetime ◽  
Plasma Treatments ◽  
Plasma Decomposition ◽  
Ar Plasma

Mesoporous silica films on Si wafers were prepared via a sol-gel process using a triblock copolymer as the structural template. Spin-coated films were dried and subsequently subjected to Ar plasma treatments for decomposing the polymeric porogen. Mesopore formation in the silica film upon Ar plasma treatments was investigated by positron annihilation lifetime spectroscopy. In comparison with calcined silica film, much larger pores, more heterogeneous in size were found in silica film prepared with Ar plasma decomposition of the porogen.

Probing the microporous nature of hierarchically templated mesoporous silica via positron annihilation spectroscopy

2006 ◽  
Vol 34 (2-4) ◽  
pp. 67-75 ◽  
Author(s):  
S. Boskovic ◽  
A.J. Hill ◽  
T.W. Turney ◽  
M.L. Gee ◽  
G.W. Stevens ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Positron Annihilation ◽  
Positron Annihilation Spectroscopy
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