Abstract Traditional strengthening ways, such as strain, precipitation and solid-solution, come into effect by pinning the motion of dislocation. Here, through first-principles calculations we report on an extra-electron induced covalent mechanism, which alters chemical bonding upon introduction extra-valence electrons in matrix parent materials. It is responsible for brittle high-strength properties Al 12 W-type compounds featured typical fivefold icosahedral cages, are common quasicrystals...

Beryllium is a simple alkali earth metal, but has been the target of intensive studies for decades because its unusual electron behaviors at surfaces. Puzzling aspects include (i) severe deviations from description nearly free picture, (ii) anomalously large electron-phonon coupling effect, and (iii) giant Friedal oscillations. The underlying origins such anomalous surface have under active debate, with no consensus. Here, by means first-principle calculations, we discover that this pure...

Abstract A big challenge for nonlinear optical (NLO) materials is the application in high power lasers, which needs simultaneous occurrence of large second harmonic generation (SHG) and laser induced damage threshold (LIDT). Herein we report preparation a new Ga 2 Se 3 phase, shows SHG intensities around 2.3 times LIDT 16.7 those AgGaS (AGS), respectively. In addition, its IR transparent window ca. 0.59–25 μm also significantly wider than that AGS (ca. 0.48–≈11.4 μm). The strong responses...

By means of variable-compositional evolutionary algorithms, in combination with first-principles calculations, the compositions, structures and mechanical properties W-B system have been theoretically investigated. As well as confirming experimental observations (including their crystal structures) for four known compounds W2B, WB, WB2 WB3, new stable compound W8B7 two nearly compounds, W2B3 WB4, also predicted ground state. The elastic estimated Vickers hardnesses all these borides...

We evaluated the individual atom contributions to second harmonic generation (SHG) coefficients of LiCs2PO4 (LCPO) by introducing partial response functionals on basis first principles calculations. The SHG LCPO is dominated metal-cation-centered groups CsO6 and LiO4, not nonmetal-cation-centered PO4 one expects from existing models theories. are determined mainly occupied orbitals O-2p Cs-5p as well unoccupied Cs-5d Li-2p. For a material, polarizable atomic states both important.

This work reports the dehydrated Zr-based MOF UiO-66(SH)2 as a visible-light-driven photocatalyst to mimic biological N2 fixation process. The 15 and other control experiments demonstrated that new is highly efficient in converting ammonia. In-situ TGA, XPS, EXAFS well first-principles simulations were used demonstrate role of thermal treatment changes local structures around Zr due dehydration. It was shown dehydration opened gate for entry molecules into [Zr6 O6 ] cluster where strong N≡N...

By means of variable-composition evolutionary algorithm coupled with density functional theory and in combination aberration-corrected high-resolution transmission electron microscopy experiments, we have studied characterized the composition, structure hardness properties WB$_{3+x}$ ($x$ $<$ 0.5). We provide robust evidence for occurrence stoichiometric WB$_3$ non-stoichiometric both crystallizing metastable $hP$16 ($P6_3/mmc$) structure. No signs formation highly debated WB$_4$ (both...

Abstract Herein, we report the design of novel ultraviolet luminescent CsPbCl 3 nanocrystals (NCs) with emission peak at 381 nm through doping cadmium ions. Subsequently, a surface passivation strategy CdCl 2 is adopted to improve their photoluminescence quantum yield (PLQY) maximum value 60.5 %, which 67 times higher than that pristine counterparts. The PLQY passivated NCs remains over 50 % after one week while show negligible emission. By virtue density functional theory calculations,...

By means of first-principles calculations coupled with the kinetic Monte Carlo simulations, we have systematically investigated effects dilute substitutional solutes on behaviors carbon in $\ensuremath{\alpha}$-Fe. Our results uncover following. (i) Without Fe vacancy interactions between most and are repulsive due to strain relief, whereas Mn has a weak attractive interaction its nearest-neighbor local ferromagnetic coupling effect. (ii) The presence all carbon. In particular, Mn-vacancy...

Abstract A big challenge for nonlinear optical (NLO) materials is the application in high power lasers, which needs simultaneous occurrence of large second harmonic generation (SHG) and laser induced damage threshold (LIDT). Herein we report preparation a new Ga 2 Se 3 phase, shows SHG intensities around 2.3 times LIDT 16.7 those AgGaS (AGS), respectively. In addition, its IR transparent window ca. 0.59–25 μm also significantly wider than that AGS (ca. 0.48–≈11.4 μm). The strong responses...

Heat-induced blueshift (HIB) observed in many luminescent materials is a puzzling phenomenon that has remained unexplained for decades. By using the high-throughput first-principles calculations and energy-screening techniques, we generated number of model structures five phosphors, RbLi[Li3 SiO4 ]2 :Eu2+ , Na[Li3 ]:Eu2+ K[Li3 Sr[LiAl3 N4 Ca[LiAl3 . Our analyses suggest, to first approximation, logarithmic energy dependence on nearest distance between dopant metal-cation vacancy. identifying...

Compounds of diamond-like (DL) structures are one the important systems in searching for new high-performance infrared nonlinear optical (IR NLO) materials. However, phase competition diverse DL allotropes and origin SHG response at atom orbital level these NLO materials remain an unsolved hot topic. In this work, theory (ART) combined with hybrid density functional calculations was applied to explore properties Li2MIIMIVSe4 (MII = Zn, Cd, Hg; MIV Si, Ge, Sn) family. Twenty-three promising...

By means of the first-principles calculations, we found that early characterized 3D topological Dirac semimetal $P$6${}_{3}$/$mmc$-${\mathrm{Na}}_{3}\mathrm{Bi}$ is dynamically unstable at ground state due to presence large imaginary phonon frequencies around $K$ point. Alternatively, our calculations suggested a new ground-state phase crystalizing in $P$$\overline{3}$$c$1 structure with buckled graphite-like Na/Bi sheets, which both energetically and stable. Moreover, also uncovered...

The second harmonic generation (SHG) responses of nonisostructural nonlinear optical (NLO) compounds, β-BaB2O4, LiB3O5, CsB3O5, CsLiB6O10, KBe2BO3F2, and LiCs2PO4, were examined by density functional theory (DFT) calculations, the contributions their individual cations anions determined performing atomic response analyses. In all these contribution metal lies in range ∼9.3 to ∼29.7% total SHG responses, that between ∼57.4 ∼72.3%. However, terms atom contribution, a large cation can...

The second harmonic generation (SHG) responses of the paraelectric and ferroelectric phases KH2PO4 (KDP) were calculated by first-principles density functional theory (DFT) calculations, individual atom contributions to SHG analyzed response (ART). We show that occurrence static polarization does not enhance KDP, Kleinman symmetry is reasonably well obeyed for phase, but phase despite latter has a larger bandgap. This caused most likely fact lower-symmetry local structures than phase....

Metal halide borates are promising candidates for high-performance nonlinear optical (NLO) applications, yet the origins of their second harmonic generation (SHG) properties remain unclear. Using atom response theory combined with density functional calculations, this study investigates why halogen substitution leads to distinctly different SHG responses in monoborates (Pb

Long wave infrared (LWIR) birefringent crystals are essential for optical applications but such materials rarely reported due to the requirements of large birefringence and wide transmission range. This study proposes a facile route create new LWIR crystal by oxygenation strategy in halides with cations containing lone pair electrons. Given tendency form holodirected geometry, divalent oxygen was introduced substitute monovalent halogen decrease coordination number activate Our efforts...

Long wave infrared (LWIR) birefringent crystals are essential for optical applications but such materials rarely reported due to the requirements of large birefringence and wide transmission range. This study proposes a facile route create new LWIR crystal by oxygenation strategy in halides with cations containing lone pair electrons. Given tendency form holodirected geometry, divalent oxygen was introduced substitute monovalent halogen decrease coordination number activate Our efforts...

Carbon isotopes, particularly 13C, are critical for applications in food authentication, biomedical diagnostics, and metabolic research; however, their efficient separation remains challenging due to low natural abundance. This study investigates the adsorption behavior of 12CO 13CO on various low-index α-Al2O3 surfaces as a strategy isotope separation. Density functional theory (DFT) calculations with D3 (BJ) dispersion corrections were employed optimize surface models five representative...

By means of first-principles calculations, we have systematically investigated the structural, elastic, vibrational, thermal and electronic properties ground-state phase for intermetallic compound U2Mo. Our results reveal that previously synthesized I4/mmm structure U2Mo is a metastable unstable, neither thermodynamically nor vibrationally at ground state. In combination with evolutionary structural searches, our calculations suggest new Pmmn phase, which has been confirmed theoretically to...

High performance infrared nonlinear optical Na₂MSn₂Se₆ (M = Zn/Cd) was synthesized based on a new atom response theory aided searching approach.

Predicted phase diversity and interesting properties of the Na–Bi system in range 0–320 GPa from first-principles calculations.

Abstract We evaluated the individual atom contributions to second harmonic generation (SHG) coefficients of LiCs 2 PO 4 (LCPO) by introducing partial response functionals on basis first principles calculations. The SHG LCPO is dominated metal‐cation‐centered groups CsO 6 and LiO , not nonmetal‐cation‐centered expected from existing models theories. are determined mainly occupied orbitals O 2p Cs 5p as well unoccupied 5d Li 2p. For a material, polarizable atomic states both important.