67 research outputs found
Does the Dirac Cone Exist in Silicene on Metal Substrates?
Absence of the Dirac cone due to a strong band hybridization is revealed to
be a common feature for epitaxial silicene on metal substrates according to our
first-principles calculations for silicene on Ir, Cu, Mg, Au, Pt, Al, and Ag
substrates. The destroyed Dirac cone of silicene, however, can be effectively
restored with linear or parabolic dispersion by intercalating alkali metal
atoms between silicene and the metal substrates, offering an opportunity to
study the intriguing properties of silicene without further transfer of
silicene from the metal substrates
Generating Electrically Conducting Single Crystals of Rutile Titania Through Repetitive Flash Experiments
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Designing Optimal Perovskite Structure for High Ionic Conduction.
Solid-oxide fuel/electrolyzer cells are limited by a dearth of electrolyte materials with low ohmic loss and an incomplete understanding of the structure-property relationships that would enable the rational design of better materials. Here, using epitaxial thin-film growth, synchrotron radiation, impedance spectroscopy, and density-functional theory, the impact of structural parameters (i.e., unit-cell volume and octahedral rotations) on ionic conductivity is delineated in La0.9 Sr0.1 Ga0.95 Mg0.05 O3- δ . As compared to the zero-strain state, compressive strain reduces the unit-cell volume while maintaining large octahedral rotations, resulting in a strong reduction of ionic conductivity, while tensile strain increases the unit-cell volume while quenching octahedral rotations, resulting in a negligible effect on the ionic conductivity. Calculations reveal that larger unit-cell volumes and octahedral rotations decrease migration barriers and create low-energy migration pathways, respectively. The desired combination of large unit-cell volume and octahedral rotations is normally contraindicated, but through the creation of superlattice structures both expanded unit-cell volume and large octahedral rotations are experimentally realized, which result in an enhancement of the ionic conductivity. All told, the potential to tune ionic conductivity with structure alone by a factor of ≈2.5 at around 600 °C is observed, which sheds new light on the rational design of ion-conducting perovskite electrolytes
Direct observation of 3D atomic packing in monatomic amorphous materials
Liquids and solids are two fundamental states of matter. However, due to the
lack of direct experimental determination, our understanding of the 3D atomic
structure of liquids and amorphous solids remained speculative. Here we advance
atomic electron tomography to determine for the first time the 3D atomic
positions in monatomic amorphous materials, including a Ta thin film and two Pd
nanoparticles. We observe that pentagonal bipyramids are the most abundant
atomic motifs in these amorphous materials. Instead of forming icosahedra, the
majority of pentagonal bipyramids arrange into networks that extend to
medium-range scale. Molecular dynamic simulations further reveal that
pentagonal bipyramid networks are prevalent in monatomic amorphous liquids,
which rapidly grow in size and form icosahedra during the quench from the
liquid state to glass state. The experimental method and results are expected
to advance the study of the amorphous-crystalline phase transition and glass
transition at the single-atom level
Behaviour of continuous reinforced concrete floor slabs subjected to different compartment fires
Fundamental Research Funds for the Central Universities, China University of Mining and Technolog
Subtyping of type A influenza by sequencing the variable regions of HA gene specifically amplified with RT-PCR
Excessive proliferation and impaired function of primitive hematopoietic cells in bone marrow due to senescence post chemotherapy in a T cell acute lymphoblastic leukemia model
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