A study of inter-crystallite spaces in some polycrystalline inorganic systems using positron annihilation lifetime spectroscopy

Shantarovich, V. P.; Suzuki, Takenori; Ito, Yutaka; Kondo, Kenjiro; Gustov, V. V.; Мелихов, И. В.; Berdonosov, S. S.; Ivanov, L. N.; Yu, Ruan

doi:10.1016/j.radphyschem.2006.03.047

Cited by 6 publications

(8 citation statements)

References 8 publications

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“…Such a comparison enables to check some ideas on the mechanisms of o-Ps trapping and the accuracy of the lifetime spectrums processing. [33][34][35][36][37] For the super-crosslinked polystyrene 36 (Table2), there was found a good correlation between PAL and sorption data, when longlived o-Ps components s 4 , I 4 and s 5 , I 5 were used. A good correlation was seen in the fact that, from the pores detected by sorption method, o-Ps was always trapped by those having smaller size but higher concentration.…”

Section: Pal Results For Ptmsp Pim-1 and Af2400mentioning

confidence: 89%

“…Fortunately, lifetimes are so long that corresponding pore sizes can be compared with the results of low temperature gas sorption experiments. Such a comparison enables to check some ideas on the mechanisms of o ‐Ps trapping and the accuracy of the lifetime spectrums processing 33–37. For the super‐crosslinked polystyrene36 (Table 2), there was found a good correlation between PAL and sorption data, when long‐lived o ‐Ps components τ 4 , I 4 and τ 5 , I 5 were used.…”

Section: Pal Results For Ptmsp Pim‐1 and Af2400mentioning

confidence: 95%

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Positron annihilation and free volume studies in polymer glasses

Shantarovich

2008

J Polym Sci B Polym Phys

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Section: Pal Results For Ptmsp Pim-1 and Af2400mentioning

confidence: 89%

Section: Pal Results For Ptmsp Pim‐1 and Af2400mentioning

confidence: 95%

Positron annihilation and free volume studies in polymer glasses

Shantarovich

2008

J Polym Sci B Polym Phys

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“…These values are at least order of magnitude higher than for normal polymers. Systems with large pores give a chance to compare positron annihilation and sorption data on the pore size and concentration and check in this way some assumptions on the mechanism of positronium trapping and correctness of the lifetime analyses [7][8][9]. Previously, reasonable agreement was found: from the range of pores detected by sorption experiments, positronium was always trapped by pores of relatively smaller sizes but higher concentrations.…”

mentioning

confidence: 85%

Structural heterogeneity in glassy polymeric materials revealed by positron annihilation and other supplementary techniques

Shantarovich

Suzuki

Ito

et al. 2007

Phys. Status Solidi (c)

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A disagreement between effective sizes of elementary free volumes found from the four component PAT-FIT analyses of positronium annihilation lifetime spectra and experiments on low temperature sorption for two membrane materials of internal microporosity poly(tri-methyl-silyl-propyne) PTMSP and spirolinked benzodioxane polymer PIM-1 is described and discussed. This disagreement can be minimized essentially using the fifth lifetime component but not the Gaussian distribution of the fourth component. 1 Introduction Elastic and glassy polymers are normally considered as homogeneous disordered materials with a unimodal (statistical) distribution of elementary free volumes. More complex (bicentral) distributions, obtained from mathematical analyses of experimental positron annihilation lifetime spectra (PALS), were explained recently as "artefacts", i.e. results of incorrect mathematical treatment (de-convolution) of the spectra. Accepting this conclusion as a reasonable formal explanation in some cases, we discussed [1] results of our PAL measurements for a number of elastic and glassy polymers, such as polystyrene (normal and cross-linked) poly-isobutylene poly-butadiene, synthetic rubbers, etc., where observations of the two long-lived ortho-positronium components in PALS, comparison with the results of sorption experiments and irregular (nonlinear) variations of annihilation characteristics in the vicinity of the glass-transition temperature actually revealed structural heterogeneity, confirmed by supplementary techniques: measurements of thermo-stimulated luminescence (TSL), thermo-mechanics, and mobility of penetrants in the systems. The heterogeneity was explained by slow relaxation of the polymer structures. Continuing this line of investigations, we present in this paper annihilation characteristics and sorption data for two membrane materials of internal microporosity: well known poly(tri-methylsilyl-propine) PTMSP [2-4] and a novel material spiro-linked benzodioxane polymer PIM-1 [5,6].A combination of PAL experiments and sorption data for membrane materials is very important for understanding of the mechanisms of Ps annihilation and potential applications of the positron annihilation research. This combination enables testing of the PAL data on the large (1-2nm) pores. Along with

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“…According to a theoretical estimate the distance and binding energy of e + and e -in Psqf are 0.3 ~ 0.4 nm and 0.5 ~ 1 eV 13) , respectively, which are to be compared to 0.105 nm and 6.8 eV for Ps in vacuum. Psqf is quite mobile in crystals; its diffusion constant is D qf Ps~ 0.4 10 -1 cm 2 /s in inorganic crystals due to its Bloch-wave nature, but in amorphous polymers D qf Ps is estimated to be 0.5~ 1.5 10 -4 cm 2 /s 14) . Like ordinary atoms, Ps experiences repulsive molecular force and is expelled to free space.…”

Section: Ps Formation and O-ps Intensitymentioning

confidence: 98%

“…Thus Ps can be preferentially transported to larger vacancies available, and therefore Ps is often called "seeker" of holes. Once Ps is trapped in a vacancy its mobility is retarded; estimated diffusion constant is 10 -5~ 10 -4 cm 2 /s 14) , or even smaller: 1~ 2 10 -6 cm 2 /s 15) . Since reaction (3) must compete with other spur processes such as recombination of e -with parent ions, localization, capture, reactions of e -and/or e + , etc., Ps formation probability is affected in numerous ways.…”

Section: Ps Formation and O-ps Intensitymentioning

confidence: 99%

Vacancy Spectroscopy Using Positronium

Ito¹,

Mohamed

Shantarovich

et al. 2009

membrane

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Positron annihilation technique as a probe of subatomic vacancies is described for non-positron polymer scientists.Although positronium (Ps) is an unparalleled unique probe of inter-molecular vacancies in insulating materials, with both its intensity and mean lifetime carrying information about the free volume, the processes that lead to these physical quantities are not simple. The state-of-the-art understandings of how Ps is created and how its mean lifetime is determined in vacancies are described, and examples of the unique feature as well as the problems and precautions are illustrated.

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A study of inter-crystallite spaces in some polycrystalline inorganic systems using positron annihilation lifetime spectroscopy

Cited by 6 publications

References 8 publications

Positron annihilation and free volume studies in polymer glasses

Positron annihilation and free volume studies in polymer glasses

Structural heterogeneity in glassy polymeric materials revealed by positron annihilation and other supplementary techniques

Vacancy Spectroscopy Using Positronium

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