Dataset Information

Measurements of Defect Structures by Positron Annihilation Lifetime Spectroscopy of the Tellurite Glass 70TeO₂-5XO-10P₂O₅-10ZnO-5PbF₂ (X = Mg, Bi₂, Ti) Doped with Ions of the Rare Earth Element Er³.

ABSTRACT: The objective of the study was the structural analysis of the 70TeO₂-5XO-10P₂O₅-10ZnO-5PbF₂ (X = Mg, Bi₂, Ti) tellurite glasses doped with ions of the rare-earth elements Er³⁺, based on the PALS (positron annihilation lifetime spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, the sizes of which range from a few angstroms to a few dozen nanometers. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ ₁ andτ ₂. Their interpretation was based on two-state positron trapping model where the physical parameters are the positron annihilation rate and positron trapping rate.

SUBMITTER: Pach K

PROVIDER: S-EPMC5406323 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Publications

Measurements of Defect Structures by Positron Annihilation Lifetime Spectroscopy of the Tellurite Glass 70TeO2-5XO-10P2O5-10ZnO-5PbF2 (X = Mg, Bi2, Ti) Doped with Ions of the Rare Earth Element Er3.

Pach K K Filipecki J J Golis E E Yousef El S ES Boyko V V

Nanoscale research letters 20170426 1

The objective of the study was the structural analysis of the 70TeO2-5XO-10P2O5-10ZnO-5PbF2 (X = Mg, Bi2, Ti) tellurite glasses doped with ions of the rare-earth elements Er3+, based on the PALS (positron annihilation lifetime spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, the sizes of which range ...[more]

PMID: 28449544

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Project description:Plastic deformation of low/high density polyethylene (LDPE/HDPE) was analyzed in this work using positron annihilation lifetime spectroscopy (PALS). It was shown that in undeformed LDPE, both the mean ortho-positronium lifetime (τ3) and its dispersion (σ3), corresponding to the average size and size distribution of the free-volume pores of the amorphous component, respectively, were clearly higher than in HDPE. This effect was induced by a lower and less uniform molecular packing of the amorphous regions in LDPE. During the deformation of LDPE, an increase in the τ3 value was observed within the local strains of 0-0.25. This effect was mainly stimulated by a positive relative increase in interlamellar distances due to the deformation of lamellar crystals oriented perpendicular (increased by 31.8%) and parallel (decreased by 10.1%) to the deformation directions. At the same time, the dimension of free-volume pores became more uniform, which was manifested by a decrease in the σ3 value. No significant effect of temperature or strain rate on the τ3 and σ3 values was observed during LDPE deformation. In turn, in the case of HDPE, with an increase in the strain rate/or a decrease in temperature, an intensification of the cavitation phenomenon could be observed with a simultaneous decrease in the τ3 value. This effect was caused by the lack of annihilation of ortho-positonium (o-Ps) along the longer axis of the highly anisotropic/ellipsoidal cavities. Therefore, this dimension was not detectable by the PALS technique. At the same time, the increase in the dimension of the shorter axis of the cavities was effectively limited by the thickness of amorphous layers. As the strain rate increased or the temperature decreased, the σ3 value during HDPE deformation increased. This change was correlated with the initiation and intensification of the cavitation phenomenon. Based on the mechanical response of samples with a similar yield stress, it was also proven that the susceptibility of the amorphous regions of LDPE to the formation of cavities is lower than in the case of amorphous component of HDPE.

Dataset Information

Measurements of Defect Structures by Positron Annihilation Lifetime Spectroscopy of the Tellurite Glass 70TeO₂-5XO-10P₂O₅-10ZnO-5PbF₂ (X = Mg, Bi₂, Ti) Doped with Ions of the Rare Earth Element Er³.

Publications

Measurements of Defect Structures by Positron Annihilation Lifetime Spectroscopy of the Tellurite Glass 70TeO<sub>2</sub>-5XO-10P<sub>2</sub>O<sub>5</sub>-10ZnO-5PbF<sub>2</sub> (X = Mg, Bi<sub>2</sub>, Ti) Doped with Ions of the Rare Earth Element Er<sup>3</sup>.

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