Hafnium carbides are studied by a systematic search for possible stable stoichiometric compounds in the Hf-C system at ambient pressure using variable-composition ab initio evolutionary algorithm implemented USPEX code. In addition to well-known HfC, we predicted two additional Hf3C2 and Hf6C5. The structure of Hf6C5 with space group C2/m contains 11 atoms primitive cell this prediction revives earlier proposal A. I. Gusev. also has C2/m, is more energetically favorable than Immm, P-3m1, P2...

High-temperature metal phase of monolayer 1T-VSe2 may transform into a charge density wave (CDW) with certain pseudo-gap at around 350 K upon cooling and then an insulating the entire bandgap 140 further decreasing temperature. Is such seeming quantum transformation two pseudo-gaps opening one by real traditional two-stage transition? In this study, our theoretical calculations functional theory revealed that actually undergoes one-step pre-transformation or pseudo-two-step transition over...

The electronic and optical properties of Eu/Si-codoped anatase TiO(2) are investigated using the density functional theory. calculated results show that synergistic effects Eu/Si codoping can effectively extend absorption edge, which lead to higher visible-light photocatalytic activities than pure TiO(2). To verify reliability our results, nanocrystalline is prepared by a sol-gel-solvothermal method, experimental also indicate sample exhibits better performance

Elastic properties of NaXH4 (X = B, Al) have been studied by first-principles calculations using a projected augmented plane-wave approach. The calculated elastic constants compare favorably with experimental values. Our show that the theoretically and bulk moduli small values compared those typical metals intermetallic compounds, which indicates are highly compressible. Comparison B different complex hydrides shows correlation between decomposition temperatures. Also, we anisotropies Debye...

The structural, elastic, phonon and electronic properties of a MnPd alloy have been investigated using the first-principles calculation. calculated lattice constants structure agree well with experimental results. microscopic mechanism diffusionless martensitic transition from paramagnetic B2 (PM-B2) phase to antiferromagnetic L10 (AFM-L10) through intermediate (PM-L10) has explored theoretically. obtained negative shear modulus C' = (C11 — C12)/2 PM-B2 is closely related instability cubic...

The long-range magnetism observed in group-V tellurides quintuple layers is the only working example of carrier-free dilute magnetic semiconductors (DMS), whereas physical mechanism unclear, except speculation on band topology enhanced van Vleck paramagnetism. Based DFT calculations, we find a stable ferromagnetic order single layer Cr-doped Bi2Te3 or Sb2Te3, with dopant separation more than 9 Å. This configuration global energy minimum among all configurations. Different from conventional...

In this work, we report a detailed theoretical investigation of the phase transition ammonia borane (NH(3) BH(3); AB), from tetragonal I4mm (C(4v)(9)) with disordered orientation hydrogen to an orthorhombic Pmn2(1) (C(2v)(7)) symmetry, as function temperature based on Density Functional Theory calculations semiempirical dispersion potential correction. We define series substructures NH(3) BH(3) moiety always in C(3v) symmetry and partially occupied high state can be described continuous...

Tuning magnetic order in semiconductors is a long sought goal. A proper concentration of acceptors can dramatically suppress local favor the one. Using Mn and an acceptor codoped LiZnAs as example, we demonstrate, by first-principles calculation, emergence long-range order. This intriguing phenomenon be understood from interplay between acceptor-free magnetism band coupling magnetism. Our observation thus lays ground for precise control future spintronic devices.

The structural properties and mechanical stabilities of α-NaBH4 β-LiBH4 have been investigated using first-principles calculations. Elastic constants are calculated from the second derivative total energy as a function strain. parameters elastic in good agreement with available experimental data. Our calculations show that P63mc space group is unstable under distortions (0, 0, δ, 0) δ) these lead to Martensitic transformation into Cc Cmc21 structures, respectively. Thermodynamically, more...

GaN-based micro-LEDs are applied to visible light communication due their high modulation bandwidth with reduced chip size. It requires a deep understanding of recombination processes and impact on the bandwidth, which is mainly determined by carrier lifetime. We employed confocal time-resolved photoluminescence (TRPL) characterize variation lifetime optical excitation power density micro-LEDs. observed an initial increase followed sudden decrease within range 96.7 kW/cm 2 546 blue micro-LED...

The roller-type residual film collector is the main machine type for collecting films.The scarifying tooth harrow bears largest resistance among all components of entire machine, and it directly affects quality efficiency collector.In this study, arithmetic optimization algorithm-variational mode decomposition -bidirectional long short-term memory (AOA-VMD-BiLSTM) model was proposed to improve working condition identification accuracy harrow.First, locations three monitoring points were...

This paper presents the principle of a new composite (C2H4)n-PIN sandwiched fusion neutron detector, which uses 2mm (C2H4)n as sensitivity enhancement medium, and add circuit to merge output signals. The main merits detector are: (1) greatly improved better statistics; (2) n/γ discrimination; (3) implementing signal summation without obviously affecting time response. Characteristics including 14MeV 1.25MeV γ ray, discrimination, response, statistics are studied theoretically experimentally.

One of the keys to realization Quantum Anomalous Hall effect (QAHE) is long range ferromagnetism, which only experimentally realized in Cr or V doped (Bi,Sb)2Te3 system. Both elements are 3d transition metals and 4d found be ineffective produce ferromagnetism Bi2Se3. Still, whether can by magnetic doping an open question. Based on density functional theory calculations, we predict that Mo Bi2Te3 Sb2Te3, semiconducting. The coupling strength comparable with Sb2Te3. Therefore, Sb2Te3 their...

The structural stability, electronic structure, elastic constants and vibrational properties of TaRu β (cubic), β' (tetragonal) β'' (orthorhombic) phases have been studied using density functional theory. It is found that the β-to-β' phase transformation closely related to properties. exhibits an unstable phonon at R point (0 1/2 1/2), which induces transition from high-symmetry low-symmetry phase. obtained for first time first-principles calculations lattice parameters agree very well with...