Pore Size Determination of TEMPO-Oxidized Cellulose Nanofibril Films by Positron Annihilation Lifetime Spectroscopy

2011 ◽  
Vol 12 (11) ◽  
pp. 4057-4062 ◽  
Author(s):  
Hayaka Fukuzumi ◽  
Tsuguyuki Saito ◽  
Shinichiro Iwamoto ◽  
Yoshiaki Kumamoto ◽  
Toshiyuki Ohdaira ◽  
...  
Keyword(s):  
Pore Size ◽  
Positron Annihilation ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Oxidized Cellulose ◽  
Size Determination ◽  
Cellulose Nanofibril ◽  
Positron Annihilation Lifetime

Study of Fe75Al25 Alloys by the Mössbauer Spectroscopy Positron Annihilation Lifetime Spectroscopy (PALS), XRD and SEM

2013 ◽  
Vol 203-204 ◽  
pp. 137-141 ◽  
Author(s):  
Aneta Hanc-Kuczkowska ◽  
Jerzy Kansy ◽  
Grzegorz Dercz ◽  
Lucjan Pająk ◽  
Józef Lelątko ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Positron Annihilation ◽  
Mossbauer Spectroscopy ◽  
Vacancy Concentration ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
Positron Annihilation Lifetime ◽  
Mößbauer Spectroscopy

The structure, point defect and ordering parameter of Fe25Al samples is examined with the Mössbauer spectroscopy Positron Annihilation Lifetime Spectroscopy XRD and SEM. The studies are carried out for samples in as-cast state and after heat treatments: annealing for 24 hours at 900°C (or 1050°C) and either slow cooling with furnace or quenching to oil. Among the research method used, Mössbauer spectroscopy for determination of hyperfine structure parameters was adopted. These parameters, sensitive to changes in spin and charge electron densities in the nearest neighbourhood of a Mössbauer isotope nucleus, caused by specific configurations of atoms, are directly connected with the degree of ordering of a compound. Spectral analysis has been carried out using an authors’ software developed based on a theoretical model relating the shape of a Mössbauer spectrum to the sample microstructure. It has been shown that Mössbauer spectroscopy enables quantitative evaluation of the degree of ordering of phases occurring in samples characterised by large graining, in the case of which it is not possible to determine the long-range order parameter by X-ray diffraction. The PALS method only one type of defects is detected. The positron lifetime in these defects (V) suggests that they are quenched-in Fe-monovacancies (VFe). The vacancy concentration strongly depends on the rate of cooling.

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.

Positron Annihilation Lifetime Spectroscopy (Pals) Application in Metal Barrier Layer Integrity for Porous Low-K Materials

2001 ◽  
Vol 686 ◽  
Author(s):  
Simon Lin ◽  
Jia-Ning Sun ◽  
David W. Gidley ◽  
Jeffrey T. Wetzel ◽  
K.A. Monnig ◽  
...  
Keyword(s):  
Pore Size ◽  
Positron Annihilation ◽  
Barrier Layer ◽  
Large Scale ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Small Scale ◽  
Barrier Integrity ◽  
Positron Annihilation Lifetime ◽  
Low K ◽  
Metal Barrier

AbstractPositron Annihilation Lifetime Spectroscopy (PALS) (1, 2) is a useful tool to pre-screen metal barrier integrity for Si-based porous low-k dielectrics. Pore size of low-k, thickness of metal barrier Ta, positronium (Ps) leakage from PALS, trench sidewall morphology, electrical test from one level metal (1LM) pattern wafer and Cu diffusion analysis were all correlated. Macro-porous low-k (pore size >= 200A) and large scale meso-porous low-k (>50∼200A) encounter both Ps leakage and Cu diffusion into low-k dielectric in the 0.25μmL/0.3μmS structures when using SEMATECH in-house PVD Ta 250A as barrier layer. For small scale meso-porous (>20∼50A) and micro-porous (<=20A) low-k, no Ps leakage and no Cu diffusion into low-k were observed even with PVD Ta 50A, which is proved also owing to sidewall densification to seal all sidewall pores due to plasma etch and ash. For future technology, smaller pore size of porous Si-based low-k (=< 50A) will be preferential for dense low-k like trench sidewall to avoid metal barrier integrity due to coverage problems from sidewall pores.

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