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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

High-Yield Room-Temperature Aryl 211 At Radiolabeling via Redox-Activated Column-Shipped 211 At

Efficient late-stage formation of aryl– 211 At bonds is relevant to expanding the scope of targeted α-therapy radiopharmaceuticals. In this work, a catalyst-enabled astatodeboronation approach is evaluated using wet chemically regenerated 211 At recovered from shipped 3-octanone-impregnated columns. A series of aryl boronic esters bearing electron-donating and electron-withdrawing substituents were radiolabeled under mild conditions, with reaction parameters examined through time-dependent studies. Radiochemical conversions ranging from 68–97% were observed across the substrate set. Density functional theory calculations were employed as a qualitative framework to contextualize relative B–C and At–C bonding descriptors. Overall, this study demonstrates that wet chemically regenerated 211 At can be applied to the late-stage labeling of aryl boronic esters under mild conditions and provides guidance for future exploration of 211 At radiolabeling strategies.

211At-aryl labeling↗
DOE OSTI2017

TlSn 2 I 5 , a Robust Halide Antiperovskite Semiconductor for γ-Ray Detection at Room Temperature

The semiconductor TlSn 2 I 5 with a two-dimensional crystal structure and an antiperovskite topology is a promising novel detection material. The compound crystallizes in the I4/mcm space group, has an indirect band gap of 2.14 eV, and melts congruently at 314 °C. Electronic band structure calculations reveal that the most facile electron transport is along the ab layered plane. Compared to CH 3 NH 3 PbX 3 (X = Br, I), TlSn 2 I 5 features higher long-term stability, higher photon stopping power (average atomic number of 55), higher resistivity (~10 10 Ω·cm), and robust mechanical properties. Centimeter-size TlSn 2 I 5 single crystals grown from the melt by the Bridgman method can be used to fabricate detector devices, which detect Ag Kα X-rays (22 keV), 57 Co γ-rays (122 keV), and 241 Am α-particles (5.5 MeV). The mobility-lifetime product and mobility for electrons were estimated to be 1.1 × 10 -3 cm 2 ·V -1 and 94 ± 16 cm 2 ·V -1 ·s -1 , respectively. Unlike other halide perovskites, TlSn 2 I 5 shows no signs of ionic polarization under long-term, high-voltage bias.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Cu 2 I 2 Se 6 : A Metal–Inorganic Framework Wide-Bandgap Semiconductor for Photon Detection at Room Temperature

Cu 2 I 2 Se 6 is a new wide-bandgap semiconductor with high stability and great potential toward hard radiation and photon detection. Cu 2 I 2 Se 6 crystallizes in the rhombohedral R$\bar{3}m$ space group with a density of d = 5.287 g·cm –3 and a wide bandgap E g of 1.95 eV. First-principles electronic band structure calculations at the density functional theory level indicate an indirect bandgap and a low electron effective mass m e * of 0.32. The congruently melting compound was grown in centimeter-size Cu 2 I 2 Se 6 single crystals using a vertical Bridgman method. A high electric resistivity of ~10 12 Ω·cm is readily achieved, and detectors made of Cu 2 I 2 Se 6 single crystals demonstrate high photosensitivity to Ag Kα X-rays (22.4 keV) and show spectroscopic performance with energy resolutions under 241 Am α-particles (5.5 MeV) radiation. The electron mobility is measured by a time-of-flight technique to be ~46 cm 2 ·V –1 ·s –1 . This value is comparable to that of one of the leading γ-ray detector materials, TlBr, and is a factor of 30 higher than mobility values obtained for amorphous Se for X-ray detection.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗