The structures and properties of rhenium nitrides are studied with density function based first principle method. New candidate ground states or high-pressure phases at Re:N ratios 3:2, 1:3 1:4 identified via a series evolutionary structure searches. We find that the 3D polyhedral stacking strong covalent N-N Re-N bonding could stabilize Re to form nitrogen rich phases, meanwhile, remarkably improve mechanical performance than sub-nitrides, as Re3N, Re2N Re3N2. By evaluating trends crystal...

The discovery of superconductivity in twisted bilayer graphene has reignited enthusiasm the field flat-band superconductivity. However, important challenges remain, such as constructing a structure and inducing superconducting state materials. Here, we successfully achieved Bi2O2Se by pressure-tuning electronic structure. Experimental measurements combined with theoretical calculations reveal that occurrence pressure-induced at 30 GPa is associated near Fermi level. Moreover, Bi2O2Se, van...

With ever increasing interest in layered materials, molybdenum disulfide has been widely investigated due to its unique optoelectronic properties. Pressure is an effective technique tune the lattice and electronic structure of materials such that high pressure studies can disclose new structural optical phenomena. In this study, taking MoS2 as example, we investigate confinement effect on monolayer by situ Raman photoluminescence (PL) measurements. Our results reveal a deformation starting...

High-pressure structures of tantalum hydrides were investigated over a wide pressure range 0–300 GPa by utilizing evolutionary structure searches. TaH and TaH2 found to be thermodynamically stable this entire range, whereas TaH3, TaH4, TaH6 become at pressures greater than 50 GPa. The dense Pnma (TaH2), R3̅m (TaH4), Fdd2 (TaH6) compounds possess metallic character with strong ionic feature. For the highly hydrogen-rich phase (TaH6), calculation electron–phonon coupling reveals potential...

Abstract The bandgap and type of optical transition are key factors in determining the functionalities applications photoelectric materials. However, it is extremely difficult to modulate indirect‐direct for most This study reports significant enhancements photocurrents an extended detection bandwidth resulting from pressure‐regulated indirect–direct hypervalent CsI 3 . Furthermore, this achieves increase photocurrent by almost five orders magnitude under visible‐light illumination....

Abstract Constantly exploring and improving the photoelectric properties of functional materials is paramount importance for development optoelectronics industry. Herein, a new strategy to extend spectral response range enhance using high pressure presented. In addition, successful application this regulation 2D layered semiconductor iodine reported. The maximum photocurrent four orders magnitude higher than that measured under initial pressure, with visible‐light illumination. Impressively,...

Abstract Crystal structures of silane have been extensively investigated using ab initio evolutionary simulation methods at high pressures. Two metallic with P 2 1 / c and C 2/ m symmetries are found stable above 383 GPa. The superconductivities phases fully explored under BCS theory, including the reported one. Perturbative linear-response calculations for 610 GPa reveal a superconducting critical temperature that beyond order 10 K.

In this study, a combination of theoretical calculations and experiments were carried out to analyze boron phosphide materials. Amorphous powder amorphous red phosphorus used as raw materials directly synthesize the target samples in one step under high-pressure high-temperature (HPHT) conditions. Theoretical then based on XRD spectra at 4 GPa 1200 °C. The experimental results show that can be successfully prepared HPHT. electrical properties characterized, it was found their conductivity...

Abstract The burgeoning demand for efficient photoelectric devices has ignited a fervent exploration of strategies regulating their performance. Herein, the enhancement and polarity switching in photoresponse MoS 2 photovoltaic with asymmetric electrodes are showcased by employing pressure band engineering strategy. Specifically, Pt/MoS /Ag setup escalates from A W⁻¹ at 0.5 GPa to 4 2.3 GPa, showcasing twofold enhancement, while displaying successive decrease under higher pressure....

At room environment, all materials can be classified as insulators or metals in-between semiconductors, by judging whether they are capable of conducting the flow electrons. One expect an insulator to convert into a metal and remain in this state upon further compression, i.e., pressure-induced metallization. Some exceptions were reported recently elementary such alkali heavy alkaline earth (Ca, Sr, Ba). Here we show that compound CLi4 becomes progressively less conductive eventually...

As the previously proposed structures of C2/m and C2/c possess similar enthalpies x-ray diffraction patterns, space group fluorine at ambient pressure is in controversy. We successfully obtain its thermodynamically stable low-pressure phase, which shares same structure as earlier known C2/c. Further investigations on phonon spectra reveal instability with imaginary frequency Brillouin zone confirm dynamically property time. Compressing up to 8 GPa, phase found undergo a transition new Cmca....

For exploring the superconductivity mechanisms and seeking potential high-temperature superconductors in hydrogen-rich compounds, we perform a systematical investigation of phase diagram, crystal structures, electronic properties, electron-phonon coupling (EPC) titanium hydrides under high pressures. Strikingly, low ${T}_{\mathrm{c}}$ $\mathrm{Ti}{\mathrm{H}}_{3}$ (\ensuremath{\sim}4 K) contrast sharply with (above 200 $\mathrm{S}{\mathrm{H}}_{3}$, though they both possess same stoichiometry...

Photoinduced ultrafast phase transitions can generate quasiequilibrium states with novel emergent properties modulated by the interplay of electronic and lattice degrees freedoms. Therefore, accurately probing transient atomic structures their dynamics is crucial to understand control interaction electrons but remains a central challenge science. Using MeV electron diffraction on single crystals, we quantitatively reveal photoinduced distortion monoclinic M1 VO2. Our results resolve previous...

Two new metallic polymeric structures of nitrogen, Pnnm and Cccm, are found by means the first-principles density functional theory a random structure-searching method. Firstly, it is shown that transition behavior nitrogen from insulator to metal starts at pressure approximately 460 GPa 0 K. The phase becomes energetically favorable with respect cubic gauche 363 GPa, then transforms Cccm structure 884 GPa. Electron–phonon coupling calculations suggest crystal possesses superconductivity....

High-pressure structures of MH2 (M = V, Nb) are explored through ab initio evolutionary methodology. As the same main group metal hydrides, VH2 and NbH2 adopt tetragonal structure with space Fm-3m at low pressures. However, high pressures possess Pnma P63mc phases differently. The two phase transitions both first order transition identified by volume collapses. Our calculations suggest that high-pressure have dynamical mechanical stability up to 100 GPa. metallic demonstrated band density...

The evolutionary structure-searching method discovers that the energetically preferred compounds of germane can be synthesized at a pressure 190 GPa. New structures with space groups Ama2 and C2/c proposed here contain semimolecular H2 V-type H3 units, respectively. Electronic structure analysis shows metallic character charge transfer from Ge to H. conductivity two originates electrons around hydrogen atoms. Further electron-phonon coupling calculations predict phases are superconductors...

Based on ab initio evolutionary algorithms, a high-pressure close-packed phase of boron with hexagonal P63/mcm symmetry is predicted, named as B10, which stable over α-Ga above 375 GPa to at least 500 GPa. High pressure makes the typical B12 icosahedron collapse form an incompressible linear atomic chain arrangement together isosceles triangle arrangement. The electron localization function calculations confirm that B10 has strong covalency in this special arranged structure. vibration three...

The mechanism for superconductivity is analyzed based on the trends of <italic>λ</italic>, 〈<italic>I</italic>²〉, <italic>N</italic>(<italic>ε</italic>_F), and 〈<italic>ω</italic>²〉^1/2 as a function pressure.

The behavior of pyrrole under high pressure has been investigated by in situ high-pressure synchrotron X-ray diffraction (XRD) and Raman scattering up to 34 GPa. A solid-to-solid transition at about 6.2 GPa with a large collapse volume (∼40%) from Pnma P21/c found after liquid-to-solid 0.6 GPa, which is caused the molecular rotational repacking π-stacking. This new phase plays central role following pressure-induced polymerization due formation closed dimer, very important precursor....

The study of abnormal Wilson transitions from metal to nonmetal states in simple electronic systems under high pressure plays an important role understanding the profound physical mechanisms associated with structures materials. Moreover, such studies serve as references for complex systems. Of particular interest is that Li-O have been demonstrated exhibit both normal and transition behaviors at depending on Li O ratio, compounds also superconductivity. However, pressure-induced phase...

In 2009, a super-hard MnB2 with ReB2-type structure was predicted as being in the ground state. However, it has not been synthesized successfully about two years either by high temperature and pressure (HTHP) method or arc-melting method. To obtain accurate synthesis conditions, P–T phase boundary between AlB2-type studied first-principles lattice dynamics calculations within quasi-harmonic approximation (QHA). Our results show that can be only below 1020 K at ambient pressure. Pressure...

Conductivity comes from the electrons surrounding S atom chains rather than K atoms under pressure.

Transition metal carbides (TMCs) are considered to be potential superhard materials and have attracted much attention. With respect titanium carbon atoms, we confirm the pressure-composition phase diagram of Ti-C system using structure searches first-principles calculations. We firstly discovered stable TiC4 which was expected synthesized at high pressure, as well metastable TiC2 TiC3. These layered diamond net analogues due unusual C-layers in form puckered graphene-like, diamond-like...