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Title: Properties of the exotic metastable ST12 germanium allotrope

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Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Energy Frontier Research in Extreme Environments (EFree)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Communications; Journal Volume: 8; Related Information: EFree partners with Carnegie Institution of Washington (lead); California Institute of Technology; Colorado School of Mines; Cornell University; Lehigh University; Pennsylvania State University
Country of Publication:
United States
catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, charge transport, mesostructured materials, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Zhao, Zhisheng, Zhang, Haidong, Kim, Duck Young, Hu, Wentao, Bullock, Emma S., and Strobel, Timothy A. Properties of the exotic metastable ST12 germanium allotrope. United States: N. p., 2017. Web. doi:10.1038/ncomms13909.
Zhao, Zhisheng, Zhang, Haidong, Kim, Duck Young, Hu, Wentao, Bullock, Emma S., & Strobel, Timothy A. Properties of the exotic metastable ST12 germanium allotrope. United States. doi:10.1038/ncomms13909.
Zhao, Zhisheng, Zhang, Haidong, Kim, Duck Young, Hu, Wentao, Bullock, Emma S., and Strobel, Timothy A. Tue . "Properties of the exotic metastable ST12 germanium allotrope". United States. doi:10.1038/ncomms13909.
title = {Properties of the exotic metastable ST12 germanium allotrope},
author = {Zhao, Zhisheng and Zhang, Haidong and Kim, Duck Young and Hu, Wentao and Bullock, Emma S. and Strobel, Timothy A.},
abstractNote = {},
doi = {10.1038/ncomms13909},
journal = {Nature Communications},
number = ,
volume = 8,
place = {United States},
year = {Tue Jan 03 00:00:00 EST 2017},
month = {Tue Jan 03 00:00:00 EST 2017}
  • The optical and electronic properties of semiconducting materials are of great importance to a vast range of contemporary technologies. Diamond-cubic germanium is a well-known semiconductor, although other ‘exotic’ forms may possess distinct properties. In particular, there is currently no consensus for the band gap and electronic structure of ST12-Ge (tP12, P4 32 12) due to experimental limitations in sample preparation and varying theoretical predictions. Here we report clear experimental and theoretical evidence for the intrinsic properties of ST12-Ge, including the first optical measurements on bulk samples. Phase-pure bulk samples of ST12-Ge were synthesized, and the structure and purity were verifiedmore » using powder X-ray diffraction, transmission electron microscopy, Raman and wavelength/energy dispersive X-ray spectroscopy. Lastly, optical measurements indicate that ST12-Ge is a semiconductor with an indirect band gap of 0.59 eV and a direct optical transition at 0.74 eV, which is in good agreement with electrical transport measurements and our first-principles calculations.« less
  • Relativistic heavy ion collisions constitute a prolific source of hyperons: tens of hyperons per event are predicted at energies {ital E}{ge}10 GeV/nucleon, providing a scenario for the formation of metastable exotic multihypernuclear objects. They may exhibit exceptional properties: {ital bound} {ital neutral} (e.g., {sup 4}{ital M}{sub 2{Lambda}}{sup 2{ital n}}, {sup 10}{ital M}{sub 2{Lambda}}{sup 8{ital n}}, pure {Lambda} droplets, {sup 8}{Lambda}) and even {ital negatively} charged composites objects with {ital positive} {ital baryon} number (e.g., {sup 4}{ital M}{sub 2{Sigma}}{sup {minus}2{ital n}}, {sup 6}{ital M}{sub 2{Lambda}2{Xi}}{sup {minus}2{ital n}}) could be formed in rare events. Such {ital negative} {ital nuclei} can easily bemore » identified in a magnetic spectrometer. They could be considerably more abundant than antinuclei of the same {ital A}. We use the relativistic meson-baryon field theory---which gives an excellent description of normal nuclear and single-{Lambda} hypernuclear properties---to calculate the rich spectrum of such exotic objects, their stability, and their structure. We also find solutions for a large variety of bound short-lived nuclei (e.g., {sup 8}{ital M}{sub 2{Lambda},2{Sigma}}{sup {minus}2{ital p}2{ital n}}), which may decay strongly via formation of cascade ({Xi}) particles. Multi-{Xi} hypernuclei are also evaluated. A variety of potential candidates for such metastable exotic nuclei is presented. It turns out that the properties of such exotic multihypernuclear objects reveal quite similar features as the strangelet proposed as a unique signature for quark-gluon plasma formation in heavy ion collisions.« less
  • A diquark-antidiquark model is proposed to account for the narrow mesonic states reported in the 1.4-to-2.0-GeV mass region, and also for the higher-lying broad baryonium states. Several experimental tests are suggested.
  • We present a precise calculation of the nonrelativistic energies and Auger decay widths for the Condo-type metastable states of exotic helium atoms He{sup +}X{sup -}, where X{sup -} stands for one of the negatively charged heavy particles {mu}{sup -}, {pi}{sup -}, or K{sup -}. It has been found that some of the states in muonic and pionic atoms have an anomalously small Auger rate and decay predominantly via slow radiative transitions with the time up to a few hundreds of nanoseconds (muonic atoms) or via a pion decay 'at rest' (He{sup +}{pi}{sup -})
  • We present a new measurement of the s-wave scattering length a of spin-polarized helium atoms in the 2 {sup 3}S{sub 1} metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy E{sub v=14}=-91.35{+-}0.06 MHz of the least-bound state v=14 in the interaction potential of the two atoms. We deduce a value of a=7.512{+-}0.005 nm, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of 1more » {mu}s.« less