Rare-Earth Oxides as Alternative High-Energy Photon Protective Fillers in HDPE Composites: Theoretical Aspects

This work theoretically determined the high-energy photon shielding properties of high-density polyethylene (HDPE) composites containing rare-earth oxides, namely samarium oxide (Sm2O3), europium oxide (Eu2O3), and gadolinium oxide (Gd2O3), for potential use as lead-free X-ray-shielding and gamma-shielding materials using the XCOM software package. The considered properties were the mass attenuation coefficient (µm), linear attenuation coefficient (µ), half value layer (HVL), and lead equivalence (Pbeq) that were investigated at varying photon energies (0.001–5 MeV) and filler contents (0–60 wt.%). The results were in good agreement (less than 2% differences) with other available programs (Phy-X/PSD) and Monte Carlo particle transport simulation code, namely PHITS, which showed that the overall high-energy photon shielding abilities of the composites considerably increased with increasing rare-earth oxide contents but reduced with increasing photon energies. In particular, the Gd2O3/HDPE composites had the highest µm values at photon energies of 0.1, 0.5, and 5 MeV, due to having the highest atomic number (Z). Furthermore, the Pbeq determination of the composites within the X-ray energy ranges indicated that the 10 mm thick samples with filler contents of 40 wt.% and 50 wt.% had Pbeq values greater than the minimum requirements for shielding materials used in general diagnostic X-ray rooms and computerized tomography rooms, which required Pbeq values of at least 1.0 and 1.5 mmPb, respectively. In addition, the comparisons of µm, µ, and HVL among the rare-earth oxide/HDPE composites investigated in this work and other lead-free X-ray shielding composites revealed that the materials developed in this work exhibited comparable X-ray shielding properties in comparison with that of the latter, implying great potential to be used as effective X-ray shielding materials in actual applications.

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Theoretical Determination of High-Energy Photon Attenuation and Recommended Protective Filler Contents for Flexible and Enhanced Dimensionally Stable Wood/NR and NR Composites

Polymers ◽

10.3390/polym13060869 ◽

2021 ◽

Vol 13 (6) ◽

pp. 869

Author(s):

Worawat Poltabtim ◽

Donruedee Toyen ◽

Kiadtisak Saenboonruang

Keyword(s):

Attenuation Coefficient ◽

Photon Energy ◽

Mass Attenuation Coefficient ◽

High Energy ◽

Linear Attenuation Coefficient ◽

Slight Reduction ◽

High Energy Photon ◽

Energy Photon ◽

Shielding Properties ◽

Experimental Values

This work aimed to theoretically determine the high-energy-photon-shielding properties of flexible wood/natural rubber (NR) and NR composites containing photon protective fillers, namely Pb, Bi2O3, or Bi2S3, using XCOM. The properties investigated were the mass attenuation coefficient (µm), linear attenuation coefficient (µ), and half value layer (HVL) of the composites, determined at varying photon energies of 0.001–5 MeV and varying filler contents of 0–1000 parts per hundred parts of rubber by weight (phr). The simulated results, which were in good agreement with previously reported experimental values (average difference was 5.3%), indicated that overall shielding properties increased with increasing filler contents but decreased with increasing incident photon energies. The results implied the potential of bismuth compounds, especially Bi2O3, to replace effective but highly toxic Pb as a safer high-energy-photon protective filler, evidenced by just a slight reduction in µm values compared with Pb fillers at the same filler content and photon energy. Furthermore, the results suggested that the addition of 20 phr wood particles, primarily aimed to enhance the rigidity and dimensional stability of Pb/NR, Bi2O3/NR, and Bi2S3/NR composites, did not greatly reduce shielding abilities; hence, they could be used as dimensional reinforcers for NR composites. Lastly, this work also reported the optimum Pb, Bi2O3, or Bi2S3 contents in NR and wood/NR composites at photon energies of 0.1, 0.5, 1, and 5 MeV, with 316–624 phr of filler being the recommended contents, of which the values depended on filler type and photon energy of interest.

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The HEPS project

Journal of Synchrotron Radiation ◽

10.1107/s1600577518012110 ◽

2018 ◽

Vol 25 (6) ◽

pp. 1611-1618 ◽

Cited By ~ 30

Author(s):

Yi Jiao ◽

Gang Xu ◽

Xiao-Hao Cui ◽

Zhe Duan ◽

Yuan-Yuan Guo ◽

...

Keyword(s):

Storage Ring ◽

High Energy ◽

High Energy Photon ◽

Energy Photon ◽

High Brightness ◽

X Ray ◽

Longitudinal Gradients ◽

Beijing China ◽

Photon Source ◽

Central Slice

The High Energy Photon Source (HEPS), a 6 GeV green-field diffraction-limited storage ring light source, will be built in Beijing, China. The HEPS design has been evolving for about ten years, and is now mostly finished and ready for construction. The storage ring is based on a modified hybrid seven-bend achromat (7BA) design, where bending magnets with reverse bending angles and longitudinal gradients are adopted to reach an ultralow natural emittance of 34.2 pm with a circumference of 1360.4 m. The central slice of the dipole in the middle of the modified hybrid 7BA, with flexible magnetic field, is used as the source of the bending-magnet beamline. Moreover, alternating high- and low-beta sections are specially designed to generate and deliver X-ray synchrotron radiation with high brightness of 5 × 1022 photons s−1 mm−2 mrad−2 (0.1% bandwidth)−1. Here, the HEPS storage ring design and solutions to the challenges inherent in this ultralow-emittance design are presented.

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Synthesis by Hydrothermal Treatment of ZnO-Based Varistors Doped with Rare Earth Oxides and Their Characterization by Impedance Spectroscopy

Crystals ◽

10.3390/cryst10121134 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1134

Author(s):

J. Porcayo-Calderon ◽

J.J. Ramos-Hernandez ◽

C.D. Arrieta-Gonzalez ◽

J.G. Chacon-Nava ◽

J.G. Gonzalez-Rodriguez ◽

...

Keyword(s):

Rare Earth ◽

Impedance Spectroscopy ◽

Hydrothermal Treatment ◽

Rare Earth Oxide ◽

Rare Earth Oxides ◽

Chemical Compositions ◽

X Ray Diffraction ◽

X Ray ◽

Electrical And Dielectric Properties ◽

Ceramic Varistor

ZnO-based ceramic varistors have shown excellent electrical and dielectric properties due to their characteristics microstructures represented by the arrangement of their grains and grain boundaries that allow the absorption and flow of energy when subjected to an electrical surge. Their properties and characteristics depend on their chemical compositions and processing routes. Typical processing routes involve several stages of grinding and precalcination—which are time consuming processes. Because of this, this study proposes a simpler and cheaper alternative route for processing ceramic varistors. The alternative process proposed is the mixing of the precursor oxides by means of a hydrothermal treatment. The characteristics and properties of the synthesized ceramic varistors were evaluated by means of scanning electron microscopy, X-ray diffraction and impedance spectroscopy, considering the effect of the addition of rare earth oxides (La2O3, CeO2 and Nd2O3). The results showed that the mixing of the oxides through hydrothermal treatment produces ceramic varistors with characteristics and properties similar to those obtained by other processing routes. Furthermore, it was observed that the addition of rare earth oxides affects the characteristics and properties of the ceramic varistor depending on the type of rare earth oxide added, its concentration and ionic radius.

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Proposal for a photoelectron spectroscopy and microscopy beamline (0.5–11 keV) at the High Energy Photon Source

Journal of Synchrotron Radiation ◽

10.1107/s1600577519000523 ◽

2019 ◽

Vol 26 (2) ◽

pp. 559-564

Author(s):

Kun Tang ◽

Lei Zheng ◽

Jia-Ou Wang ◽

Yi-Dong Zhao

Keyword(s):

Energy Range ◽

Photoelectron Spectroscopy ◽

Optical Design ◽

High Energy ◽

High Energy Photon ◽

Energy Photon ◽

Optical Efficiency ◽

X Ray ◽

Entire Energy Range ◽

Photon Source

An optical design study of a beamline proposed for the new 6 GeV synchrotron, the High Energy Photon Source (HEPS), to be built in Beijing, China, is described. The beamline is designed to cover an energy range from 0.5 to 11 keV with two experimental stations, one for X-ray photoelectron spectroscopy (PES) experiments and the other for photoelectron emission microscopy (XPEEM) experiments. A 5 m APPLE II-type undulator with a relatively long magnetic period (55 mm) is used as the only radiation source. To optimize the optical efficiency for the full energy range, the beamline is split into a soft X-ray branch that is based on a variable-line-spacing plane-grating monochromator and a tender X-ray branch that uses a four-bounce monochromator with three Si channel-cut pairs. To allow both PES and XPEEM to be performed over the entire energy range, two toroidal mirrors and a bendable KB mirror pair are employed to deliver the soft and tender beams, respectively, to either of two experimental stations.

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