Positron Annihilation in Carbon Fibers

Dryzek, Jerzy; Pamuła, Elżbieta; Błażewicz, S.

doi:10.1002/pssa.2211510106

Cited by 11 publications

(7 citation statements)

References 11 publications

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“…It is commonly accepted that such a value results from positrons annihilating in the open volume defect clusters like pores. Annihilation in such case occurs at the internal surface of the pores and the values obtained in our case are closely in agreement with those reported by others as well in graphite [11,12]. Many authors in general have attributed lifetimes ranging from 140 to 225 ps to free positron annihilation with π-electrons in the whole volume of the graphite.…”

Section: Resultssupporting

confidence: 93%

“…The results show that the raw, non purified CNC_05 sample is a very poor material as a potential hydrogen storage material. However, the results for the CNC_20 are comparable to previous experimental works on different carbon nanostructures such as single and multiwalled nanotubes, nanofibers and activated carbon [12][13][14][15][16], but are still far from required by US Department of Energy value of 6.5 wt% percent in storage material at ambient temperature and pressure.…”

Section: Discussionsupporting

confidence: 79%

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Calorimetric and Positron Lifetime Measurements οf Hydrogenated Carbon Nanocones

et al. 2010

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Two carbon nanostructured samples containing 5 and 20% of carbon nanocones in their volume were investigated. Using the Sieverts apparatus the hydrogen was loaded into the samples. The measurements of heat capacity in the temperature range from 100 K to 320 K and the positron lifetime measurements at the room temperature were performed for hydrogenated and non-hydrogenated carbon nanocones. The desorption of hydrogen at the temperature of 230 K is deduced from the heat capacity measurements. The detection of the positronium, the bound state of positron and electron, in the measured samples reveals the presence of open volume defects of ca. 0.198 ± 0.002 nm.

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Section: Resultssupporting

confidence: 93%

Section: Discussionsupporting

confidence: 79%

Calorimetric and Positron Lifetime Measurements οf Hydrogenated Carbon Nanocones

et al. 2010

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“…The positron lifetime components (t 1 = 137.4 ps and t 2 = 338.3 ps) in MWCNTs are typical of those reported in graphite. 43 The shorter component (137.4 ps) is ascribed to the positron annihilation from the delocalized Bloch states in graphene sheets and the longer component (338.3 ps) is ascribed to the trapped state within the interstitials or inside the tubes. 41 The positron lifetime observed in CNTs ranging from 140 to 225 ps has been attributed to free positron annihilation with p electrons in the whole volume.…”

Section: Resultsmentioning

confidence: 99%

Effect of interfacial interaction on free volumes in phenol-formaldehyde resin–carbon nanotube composites: positron annihilation lifetime and age momentum correlation studies

Sharma

Prakash

Sudarshan

et al. 2012

Phys. Chem. Chem. Phys.

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The phenol-formaldehyde-carbon nanotube composites were characterized for their free volume properties and interfacial interactions between nanotubes and the polymer matrix. The base polymeric material was a novolac type phenol-formaldehyde (PF) condensation resin cross-linked with para-toluene sulfonic acid. Multi-wall carbon nanotubes (MWCNTs) were synthesized using a catalytical chemical vapor deposition method and characterized using high-resolution transmission electron microscopy. The PF resin-carbon nanotubes composites having 2, 5, 10 and 20% (w/w%) MWCNTs were prepared. The crystallinity and morphology of the samples were characterized using X-ray diffraction and scanning electron microscopy. The free volume size in the polymer nanocomposites was observed to increase with the increase in nanotube content. Positron age momentum correlation (AMOC) studies revealed the electronic environment around different positron annihilation sites. The studies showed that ortho-positronium principally annihilates from interfacial regions of polymer and nanotubes in the nanocomposite. The positron lifetime studies together with AMOC measurements indicate an increase in the free volumes at the interface of polymer and MWCNTs in the composite. The free positron intensities showed that the polymer and nanotubes are weakly interacting in this system.

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“…The short component (t 1 ) is usually attributed to the annihilation of the positron in bulk; the second (t 2 ), longer component, is attributed to the annihilation in a place with low electron density, for example, in different types of defects and small cavities or the annihilation of surface-trapped positrons [78]. It is known that Ps is not formed in pure carbon in different forms [79][80][81] or it creates in exceptional cases only [82], so it is impossible to analyze any mesopores in the material using standard PALS porosimetry based on the measured ortho-Ps lifetime and an appropriate models [83,84]. However, a short component associated with defect states is useful for characterizing micro-pores and defects that are not detectable by standard methods, such as BET (Brunauer, Emmett and Teller).…”

Section: Discussionmentioning

confidence: 99%

Simple and Eco-Friendly Route from Agro-Food Waste to Water Pollutants Removal

et al. 2020

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The current study reflects the demand to mitigate the environmental issues caused by the waste from the agriculture and food industry. The crops that do not meet the supply chain requirements and waste from their processing are overfilling landfills. The mentioned wastes contain cellulose, which is the most abundant carbon precursor. Therefore, one of the possibilities of returning such waste into the life cycle could be preparing the activated carbon through an eco-friendly and simple route. Herein, the carrot pulp from the waste was used. Techniques such as thermogravimetric analysis (TGA), elemental analysis (EA), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray diffraction (XRD) were used to investigate the thermal treatment effect during the carbon material preparation. The development of microstructure, phase formation, and chemical composition of prepared material was evaluated. The obtained carbon material was finally tested for water cleaning from a synthetic pollutant such as rhodamine B and phloxine B. An adsorption mechanism was proposed on the base of positron annihilation lifetime spectroscopy (PALS) results and attributed to the responsible interactions. It was shown that a significant carbon sorbent from the organic waste for water purification was obtained.

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Positron Annihilation in Carbon Fibers

Cited by 11 publications

References 11 publications

Calorimetric and Positron Lifetime Measurements οf Hydrogenated Carbon Nanocones

Calorimetric and Positron Lifetime Measurements οf Hydrogenated Carbon Nanocones

Effect of interfacial interaction on free volumes in phenol-formaldehyde resin–carbon nanotube composites: positron annihilation lifetime and age momentum correlation studies

Simple and Eco-Friendly Route from Agro-Food Waste to Water Pollutants Removal

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