Positron annihilation in sodium borate and calcium phosphate glasses

Singh, K.P.; West, R N

doi:10.1088/0022-3719/9/2/016

Cited by 12 publications

(3 citation statements)

References 9 publications

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“…Thus, the progressive decrease in I 3 , on addition of NaI can now reasonably be attributed to an inhibition of Ps formation.The o-Ps intensity I 3 of the sodium iodide on PVA polymer data is consistent with current beliefs concerning the importance of such mechanisms in Ps formation, but we should not overlook the slight possibility that the effects observed are the direct results of the addition of sodium ions. However, Na + ions are known to be fairly inactive in positronium chemistry 57,58. The impact of different additives on Ps formation (especially o-Ps intensity I 3 ) has been widely studied for molecular liquids 59.…”

mentioning

confidence: 99%

Study of the nanostructure of free volume and ionic conductivity of polyvinyl alcohol doped with NaI

Hmamm

Zedan

Hamed

et al. 2020

Polymers for Advanced Techs

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Positron annihilation lifetime (PAL), AC conductivity, and impedance spectroscopy have been applied for the investigation of polyvinyl alcohol (PVA) doped with different concentrations of NaI in the range from zero to 25 wt%. Wide‐angle x‐ray diffraction measurements reveal that the addition of NaI to the PVA structure leads to a decrease in the crystallinity of the sample. The free volume size obtained from PAL measurements increases with the increase of the NaI concentration on PVA. NaI acts as an inhibitor of positronium formation on the doped polymer with inhibition constant of 0.028 (Mol%)−1. The ionic conductivity of the investigated sample was found to be correlated with the free volume size, which indicates the major role of free volume in the conduction mechanism. The AC conductivity of the prepared samples is measured at room temperature in the frequency range from 50 Hz to 5 MHz. The calculated values of frequency exponent s indicate the hopping mechanism in ionic conductivity. Impedance spectroscopy of PVA doped with different concentrations of NaI was studied. The appeared semi‐circle, in the Nyquist plot, denotes the bulk influence of PVA with different concentrations of NaI. This has been attributed to the parallel connection of bulk resistance and bulk capacitance. Also, the semi‐circle radius of Cole‐Cole plots was found to decrease with the increase of the concentration ratio (wt%) of NaI. So, the increase of the conductivity of PVA with the increase of NaI contents has been investigated.

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mentioning

confidence: 99%

Study of the nanostructure of free volume and ionic conductivity of polyvinyl alcohol doped with NaI

Hmamm

Zedan

Hamed

et al. 2020

Polymers for Advanced Techs

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show abstract

“…(ii) Presence of paramagnetic transition metal ions in IPG (Fe) that could quench the o-Ps component on account of the spin conversion (conversion of the o-Ps to p-Ps) [23,24].…”

Section: Positron Annihilation In Ipg Across Glass Transition and Crymentioning

confidence: 99%

“…It is well known that positrons are unique probes that serve to understand the nature and evolution of defects at the atomistic scale [18]. Barring a few earlier reports on the study of borosilicate glass matrices [19][20][21][22] and phosphate glasses [23,24] using positrons, there seems to be no work involving the study of iron phosphate glasses using positrons in the context of nuclear waste immobilization. It is well known that crystallization kinetics of nuclear waste glasses play a vital role in determining the suitability of these glasses as nuclear waste matrices [13,16] and hence it becomes interesting to understand the microstructural evolution of defects/voids accompanying the crystalline transition.…”

Section: Introductionmentioning

confidence: 99%