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1.
Angew Chem Int Ed Engl ; : e202408551, 2024 Jun 10.
Article in English | MEDLINE | ID: mdl-38858167

ABSTRACT

Heat-activated second harmonic generation (SHG) switching materials are gaining interest for their ability to switch between SHG on and off states, offering potential in optoelectronic applications. The novel nonlinear optical (NLO) switch, (C5H6NO)+(CH3SO3)- (4-hydroxypyridinium methylsulfonate, 4HPMS), is a near-room-temperature thermal driven material with a strong SHG response (3.3 × KDP), making it one of the most potent heat-stimulated NLO switches. It offers excellent contrast of 13 and a high laser-induced damage threshold (2.5 × KDP), with reversibility > 5 cycles. At 73 °C, 4HPMS transitions from the noncentrosymmetric Pna21 room temperature phase (RTP) to the centrosymmetric P21/c phase, caused by the rotation of the (C5H6NO)+ and (CH3SO3)- due to partially thermal breaking of intermolecular hydrogen bonds. The reverse phase change exhibits a large 50 °C thermal hysteresis. Density functional theory (DFT) calculations show that (C5H6NO)+ primarily dictates both the SHG coefficient (dij) and birefringence (∆n(Zeiss) = 0.216 vs ∆n(cal.) = 0.202 at 546 nm; Δn(Immersion) = 0.210 vs ∆n(cal.) = 0.198 at 589.3 nm), while the band gap (Eg) is influenced synergistically by (C5H6NO)+ and (CH3SO3)-. Additionally, 4HPMS-RTP also exhibits mechanochromism upon grinding as well as an aggregation-enhanced emission in a mixture of acetone and water.

2.
Small ; : e2404155, 2024 Jun 10.
Article in English | MEDLINE | ID: mdl-38855996

ABSTRACT

Most 2D nonlinear optical (NLO) materials do not have an ultrawide bandgap, therefore, they are unsuitable for working in the deep-ultraviolet spectral range (< 200 nm). Herein, the theoretical prediction of an excellent monolayer BeP2O4H4 (ML-BPOH) is reported. DFT analyses suggest a low cleavage energy (≈45 meV per atom) from a naturally existed bulk-BPOH material, indicating feasible exfoliation. This novel 2D material exhibits excellent properties including an ultrawide bandgap (Eg) of 7.84 eV, and a strong second-order nonlinear susceptibility ( d b u l k e f f $d_{bulk}^{eff}$ = 0.43 pm V-1), which is comparable to that of benchmark bulk-KBBF crystal (d16 = 0.45 pm V-1). The wide bandgap and large SHG effect of ML-BPOH are mainly derived from the (PO2H2)- tetrahedron. Notably, ML-BPOH exhibits an outstanding 50% variation in dsheet under minor stress stimuli (±3%) due to rotation of structurally rigid (PO2H2)- tetrahedron. This indicates significant potential for application in material deformation monitoring.

3.
Clin Cosmet Investig Dermatol ; 17: 1111-1116, 2024.
Article in English | MEDLINE | ID: mdl-38770089

ABSTRACT

Pachyonychia congenita (PC) is a group of rare hereditary disorders, characterised by hypertrophic nails and palmoplantar keratoderma (PPK), particularly localised to the pressure areas of the feet. At a molecular level, it is caused by mutations in genes encoding KRT6A, KRT6B, KRT6C, KRT16, or KRT17. To identify the underlying gene mutation in a Chinese family with PC presenting with disabling palmoplantar keratoderma and subsequent associated acral melanoma. Genomic DNA was extracted from peripheral blood samples of three available individuals in the Chinese family, which included the patient and his two unaffected sisters. The index patient presented with severe palmoplantar keratoderma as well as a newly diagnosed acral malignant melanoma (MM). Whole-exome sequencing (WES) was carried out with amplification of exon 1 of KRT16 by polymerase chain reaction (PCR). PCR products were then sequenced to identify potential mutations. We identified the proline substitution mutation p.Arg127Pro (c.380G>C) in our patient's 1A domain of KRT16. The same mutation was not found in his sisters or unrelated healthy controls. The mutation (p.Arg127Pro (c.380G>C)) in KRT16 has been reported in Dutch patients with PC. However, it is the first such report of a patient with a PC of Chinese origin. In addition, the acral MM occurred under the background of genetic PPK caused by KRT16 mutation in this patient.

4.
Inorg Chem ; 63(4): 2217-2223, 2024 Jan 29.
Article in English | MEDLINE | ID: mdl-38207277

ABSTRACT

Birefringent crystals are the key components of functional optics, contributing significantly to scientific and technological advancements. To enhance birefringence, the presence of stereochemically active lone pairs offers a unique opportunity. In fact, strengthening the stereochemical activity and aligning uniformly lone pairs face tough challenges. Herein, an anisotropic layered crystal, Sb4O5I2, is discovered to exhibit enhanced birefringence. The influence of crystal symmetry on the birefringence of Sb4O5X2 (X = Cl, Br, or I) is found to be minor. Instead, the asymmetric nature of ABUCBs (i.e., cis-X3[SbO3]6- and cis-X3[SbO4]8-) plays a crucial role in enhancing the optical anisotropy. And the orientation of these ABUCBs is equally important. We demonstrate that by adjusting the Sb/I ratio from 5:1 to 2:1, all of the intralayer Sb atoms in Sb5O7I-P63 are forced onto the surface position. This structural adjustment leads to strengthened ionic bonding interactions, enhanced activity of the lone pairs, and uniform alignments of the ABUCBs in Sb4O5I2. Consequently, this results in a 6-fold increase in birefringence.

5.
Chem Soc Rev ; 52(24): 8699-8720, 2023 Dec 11.
Article in English | MEDLINE | ID: mdl-38014465

ABSTRACT

We define the anisotropic structure building unit that encompasses diverse chemical bonds (ABUCB). The ABUCB is highly likely to cause anisotropy in both crystallographic structure and spatial electron distribution, ultimately resulting in enhanced macroscopic optical anisotropy. Accordingly, the (PO3F)2- or (SO3F)- tetrahedron involving the unique P-F or S-F bond serves as such an ABUCB. The distinct chemical bond effectively alters the microscopic nature of the structure building unit, such as polarizability anisotropy, hyperpolarizability, and geometry distortion; this consequently changes the macroscopic second-order nonlinear optical (2nd-NLO) properties of the materials. In this review, we summarize both typical and newly emerged compounds containing ABUCBs. These compounds encompass approximately 90 examples representing six distinct categories, including phosphates, borates, sulfates, silicates, chalcogenides and oxyhalides. Furthermore, we demonstrate that the presence of ABUCBs in DUV/UV NLO compounds contributes to an increase in birefringence and retention of a large band gap, facilitating phase matching in high-energy short-wavelength spectral ranges. On the other hand, the inclusion of ABUCBs in IR NLO compounds offers a feasible method for increasing the band gap and consequently enhancing the larger laser-induced damage threshold. This review consolidates various trial-and-error explorations and presents a novel strategy for designing 2nd-NLO compounds, potentially offering an opportunity for the development of high-performance 2nd-NLO materials.

6.
Angew Chem Int Ed Engl ; 62(51): e202315642, 2023 Dec 18.
Article in English | MEDLINE | ID: mdl-37932863

ABSTRACT

The discovery of compounds with low thermal conductivity and the understanding of their microscopic mechanisms are of great challenges and scientific significance. Herein, we report a unique ternary sulfide compound, Cu3 BiS3 , in which all Cu atoms are coordinated within a two-dimensional [CuS3 ] triangle plane. This local coordination leads to efficient out-of-plane phonon scattering and an ultralow thermal conductivity. Through DFT phonon spectrum calculations and analyses, we reveal that the lowest vibration frequency decreases from 2 THz for high-dimensional [CuS4 ] tetrahedral coordinated Cu atoms in CuBiS2 (CN=4, with an average Cu-S bond length of 2.328 Å) to 1.5 THz for low-dimensional [CuS3 ] triangular coordinated Cu atoms in Cu3 BiS3 (CN=3, with a shorter Cu-S bond length of 2.285 Å). This is due to the out-of-plane thermal vibration of the Cu atoms in the latter. Consequently,Cu3 BiS3 exhibits one of the lowest values of κlat (0.32 W/m K) among its peer, with a 36 % reduction compared to CuBiS2 (0.50 W/m K). This groundbreaking discovery highlights the significant role of 2D local coordination in reducing thermal conductivity through characteristic out-of-plane phonon scattering, while also contributing to a large Grüneisen parameter (2.06) in Cu3 BiS3 .

8.
J Am Chem Soc ; 145(27): 14981-14993, 2023 Jul 12.
Article in English | MEDLINE | ID: mdl-37382475

ABSTRACT

Thermoelectric copper selenides are highly attractive owing to not only their constituent nontoxic, abundant elements but also their ultralow liquid-like lattice thermal conductivity (κlat). For the first time, the promising thermoelectric properties of the new KCu5Se3 are reported herein, showing a high power factor (PF = 9.0 µWcm-1 K-2) and an intrinsically ultralow κlat = 0.48 Wm-1 K-1. The doped K1-xBaxCu5Se3 (x = 0.03) realizes a figure-of-merit ZT = 1.3 at 950 K. The crystallographic structure of KCu5Se3 allows complex lattice dynamics that obey a rare dual-phonon transport model well describing a high scattering rate and an extremely short phonon lifetime that are attributed to interband phonon tunneling, confinement of the transverse acoustic branches, and temperature-dependent anharmonic renormalization, all of which generate an unprecedently high contribution of the diffusive phonons (70% at 300 K). The overall weak chemical bonding feature of KCu5Se3 gives K+ cations a quiescence behavior that further blocks the heat flux transfer. In addition, the valence band edge energy dispersion of KCu5Se3 is quasilinear that allows a large Seebeck coefficient even at high hole concentrations. These in-depth understandings of the ultralow lattice thermal conductivity provide new insights into the property-oriented design and synthesis of advanced complex chalcogenide materials.

9.
Front Med (Lausanne) ; 10: 1187186, 2023.
Article in English | MEDLINE | ID: mdl-37250640

ABSTRACT

Acne vulgaris is a common skin condition that affects a large proportion of teenagers and young adults. Despite the availability of various treatment options, many patients experience inadequate relief or intolerable side effects. Photodynamic therapy (PDT) is a growing interest in the treatment of acne vulgaris, with 5-Aminolaevulinic acid (ALA) being one of the most commonly used photosensitizers. Adalimumab is a biologic medication used to treat inflammatory skin conditions such as Psoriasis and Hidradenitis suppurativa (HS), which targets TNF-α. Combining different therapies, such as ALA-PDT and adalimumab, can often provide more effective and longer-lasting results. This report presents the case of a patient with severe and refractory acne vulgaris who was treated with a combination of ALA-PDT and adalimumab, resulting in significant improvement in the condition. The literature review highlights the significant comorbidity associated with acne, emphasizing the need for potential of TNF-α inhibitors for its effective treatments that address physical symptoms and ALA-PDT is known to treat scar hyperplasia, and to prevent or minimize the formation of post-acne hypertrophic scars. The combination of TNF inhibitors and ALA-PDT or adalimumab has shown promising results in treating inflammatory skin conditions, including severe and refractory acne vulgaris, as per recent studies.

10.
BMC Musculoskelet Disord ; 24(1): 325, 2023 Apr 25.
Article in English | MEDLINE | ID: mdl-37098516

ABSTRACT

AIM: To explore the mechanism of the healing of tendon tissue and anti-adhesion, and to discuss the role of the transforming growth factor-ß3 (TGF-ß3)/cAMP response element binding protein-1 (CREB-1) signaling pathway in the healing process of tendons. METHOD: All mice were divided into four groups of 1, 2, 4, and 8 weeks respectively. Each time group was divided into four treatment groups: the amplification group, the inhibition group, the negative group, and the control group. When the tendon injury model was established, the CREB-1 virus was injected into the tendon injury parts. A series of methods such as gait behaviourism, anatomy, histological examination, immunohistochemical examination and collagen staining were employed to assess the tendon healing and the protein expression of TGF-ß3, CREB-1, Smad3/7 and type I/III collagen (COL-I/III). CREB-1 virus was sent to tendon stem cells to assess the protein expression of TGF-ß1, TGF-ß3, CREB-1, COL-I/III by methods such as immunohistochemistry and Western blot. RESULTS: The amplification group showed better gait behaviourism than the inhibition group in the healing process. The amplification group also had less adhesion than the negative group. Hematoxylin-eosin (HE) staining of tendon tissue sections showed that the number of fibroblasts in the amplification group was less than the inhibition group, and the immunohistochemical results indicated that the expression of TGF-ß3, CREB-1, and Smad7 at each time point was higher than the inhibition group. The expression of COL-I/III and Smad3 in the amplification group was lower than the inhibition group at all time points. The collagen staining indicated that the ratio of type I/III collagen in the amplification group was higher than the negative group at 2,4,8 week. The CREB-1 amplification virus could promote the protein expression of TGF-ß3, CREB-1 and inhibit the protein expression of TGF-ß1 and COL-I/III in the tendon stem cells. CONCLUSION: In the process of tendon injury healing, CREB-1 could promote the secretion of TGF-ß3, so as to promote the tendon healing and have the effect of anti-adhesion in tendons. It might provide new intervention targets for anti-adhesion treatment of tendon injuries.


Subject(s)
Cyclic AMP Response Element-Binding Protein , Tendon Injuries , Transforming Growth Factor beta3 , Wound Healing , Animals , Mice , Tendons , Tendon Injuries/metabolism , Cyclic AMP Response Element-Binding Protein/metabolism , Signal Transduction , Transforming Growth Factor beta3/metabolism , Mice, Inbred C57BL , Male , Stem Cells , Gait Analysis , Tissue Adhesions/prevention & control
11.
Angew Chem Int Ed Engl ; 62(15): e202301404, 2023 Apr 03.
Article in English | MEDLINE | ID: mdl-36792538

ABSTRACT

Nonlinear optical (NLO) switch materials that turn on/off second-harmonic generation (SHG) at a phase transition temperature (Tc ) are promising for applications in the fields of photoswitching and optical computing. However, precise control of Tc remains challenging, mainly because a linearly tunable Tc has not been reported to date. Herein, we report a unique selenate, tetragonal P 4 ‾ ${\bar{4}}$ 21 c [Ag(NH3 )2 ]2 SeO4 with a=b=8.5569(2) Šand c=6.5208(2) Šthat exhibits a strong SHG intensity (1.3×KDP) and a large birefringence (Δnobv. =0.08). This compound forms a series of isostructural solid-solution crystals [Ag(NH3 )2 ]2 Sx Se1-x O4 (x=0-1.00) that exhibit excellent NLO switching performance and an unprecedented linearly tunable T c , x , e x p . = T 0 - k x ${{T}_{\left(c,{\rm \ }x\right),{\rm \ }\left({\rm e}{\rm x}{\rm p}.\right)}{\rm \ }={T}_{0}-kx}$ spanning 430 to 356 K. The breaking of localized hydrogen bonds between SeO4 2- and the cation triggers a phase transition accompanied by hydrogen bond length changes with increasing x and a linear change in the enthalpy Δ H x = Δ U 1 - Δ U 2 x + Δ U 2 ${{{\rm { \Delta{}}}H}_{x}=\left({\rm { \Delta{}}}{U}_{1}-{\rm { \Delta{}}}{U}_{2}\right)x+{\rm { \Delta{}}}{U}_{2}}$ .

12.
Int J Numer Method Biomed Eng ; 39(10): e3691, 2023 10.
Article in English | MEDLINE | ID: mdl-36799066

ABSTRACT

Orthokeratology (OK) is becoming a mainstream modality for myopia correction and control, but its underlying mechanism is not yet fully understood. In this study, the biomechanical response of cornea under the OK lens was investigated to further understand the mechanism of OK therapy. Numerical models of the cornea and OK lens with different corneal refractive powers and myopia degrees were established to analyze features and differences of the spatial displacement and stress distribution in different areas of the anterior corneal surface by finite element method. Displacement distributions on the anterior cornea surface with refractive powers of 39.5, 43, 46 D, and myopia degrees of -1.0, -3.0, -6.0 D demonstrate similar deformation trends and nearly rotationally symmetrical attributes of different corneal parameters. Displacement of mid-peripheral cornea was significantly high compared with that of the central and peripheral cornea, peaking at ~2.4 mm off the corneal apex. The stress increased with the increase in myopia degrees and was significantly large for the myopia degrees of -6.0 D at S1; the stress at S2 and S6 was low and stable and did not differ much at S3; the stress at S4 and S5, however, was extremely high. In summary, simulation result of orthokeratology can effectively evaluate the performance of OK lens and it properly associates with the differential map of the corneal topography. The base curve of the OK lens may also play a role in mid-peripheral corneal steepening. The design around the OK lens' alignment curve needs to be optimized.


Subject(s)
Myopia , Orthokeratologic Procedures , Humans , Finite Element Analysis , Refraction, Ocular , Orthokeratologic Procedures/methods , Cornea , Myopia/therapy
13.
Angew Chem Int Ed Engl ; 62(15): e202218019, 2023 Apr 03.
Article in English | MEDLINE | ID: mdl-36750448

ABSTRACT

Room-temperature thermoelectric materials are the key to miniaturizing refrigeration equipment and have great scientific and social implications, yet their application is hindered by their extreme scarcity. BiTe exhibiting strong spin-orbit coupling peaks ZT at 600 K. Herein, we discover the synergy effect of Sb doping in BiTe that eliminates the detrimental band inversion and leads to an overlap of conduction band (CB) and valence band that significantly increases the S from 33 to 124 µV K-1 . In addition, this effect enhances the µ from 58 to 92 cm2  V-1 s-1 owing to the sharp increase in the CB slope along the Γ-A in the first Brillouin zone. Furthermore, Sb doping increases the anharmonicity, shortens the phonon lifetime and lowers κlat . Finally, Se/Sb codoping further optimizes the ZT to 0.6 at 300 K, suggesting that Bi0.6 Sb0.4 Te1-y Sey is a potential room-temperature TE material.

14.
Angew Chem Int Ed Engl ; 62(13): e202218666, 2023 Mar 20.
Article in English | MEDLINE | ID: mdl-36723272

ABSTRACT

The fictive temperature (Tf ) is widely applied to understand the relaxation thermodynamics of a glass; however, its atomic structural origin is still unclear. Here, we report two novel AZnP3 O9 glasses obtained by melting the composition identical single crystals. These glasses exhibit structural inheritance within 5 Šfrom the single crystal counterparts that is quantified by δ=nglass /ncry (0≤δ≤1, n is the number of pair correlation functions). Among the available glass-formers, glass KZnP3 O9 exhibits the highest structural inheritance (δ=1, nglass =8). More insightfully, a reverse correlation between δ and the relaxation thermodynamic parameters is observed in glass AZnP3 O9 , revealing for the first time the atomic structural origin of fictive temperature.

15.
Angew Chem Int Ed Engl ; 62(7): e202218048, 2023 Feb 06.
Article in English | MEDLINE | ID: mdl-36541587

ABSTRACT

The strong mutual coupling of and even the opposite change in the key parameters, such as the band gap (Eg ) and second-order harmonic generation (SHG), leads to the extreme scarcity in high-performance IR nonlinear optical (NLO) chalcogenides. Herein, we report 8 new sulfides, Na2 Ba[(Agx Na1-x )2 Sn2 S7 ] (1, x=0; 1 series, x=0.1-0.6; Na2 Ba[(Li0.58 Na0.42 )2 Sn2 S7 ], 1-0.6Li); Na2 Sr[Cu2 Sn2 S7 ] (2); and Na2 Ba[Cu2 Sn2 S7 ] (3). We use the structural tolerance factor ( t I e x p ${{t}_{I}^{exp}}$ ) to connect the chemical composition, crystal structure, and NLO properties. Guided by these correlations, a better balance between Eg and SHG is realized in 1, which exhibits a large Eg of 3.42 eV and excellent NLO properties (SHG: 1.5×AGS; laser-induced damage threshold: 12×AGS), representing the best performance among the known Hg- or As-free sulfides to date.

16.
JACS Au ; 2(9): 2059-2067, 2022 Sep 26.
Article in English | MEDLINE | ID: mdl-36186558

ABSTRACT

Herein, we report a near-room-temperature nonlinear optical (NLO) switch material, [Ag(NH3)2]2SO4, exhibiting switching performance with strong room-temperature second harmonic generation (SHG) intensity that outperforms the UV-vis spectral region industry standard KH2PO4 (1.4 times stronger). [Ag(NH3)2]2SO4 undergoes a reversible phase transition (T c = 356 K) from the noncentrosymmetric room-temperature phase (P4̅21 c, RTP) to a centrosymmetric high-temperature phase (I4/mmm, HTP) where both the SO4 2- anions and [Ag(NH3)2]+ cations are highly disordered. The weakening of hydrogen bond interactions in the HTP is also evidenced by the lower energy shift of the stretching vibration of the N-H···O bonds revealed by the in situ FT-IR spectra. Such weakening leads to an unusual negative thermal expansion along the c axis (-3%). In addition, both the atomic displacement parameters of the single-crystal diffraction data and the molecular dynamics-simulated mean squared displacements suggest the motions of the O and N atoms. Such a structural disorder not only hinders the phonon propagation and dramatically drops the thermal conductivity to 0.22 W m-1 K-1 at 361 K but also significantly weakens the optical anisotropy and SHG as verified by the DFT theoretical studies.

17.
Angew Chem Int Ed Engl ; 61(35): e202208216, 2022 Aug 26.
Article in English | MEDLINE | ID: mdl-35817753

ABSTRACT

We report a Zintl phase thermoelectric material, coarse grain-In0.99 Ga0.01 Te, achieving a ZT peak of 1.2 at 648 K and an average ZT=0.8 in 300-650 K, which outperforms all the known InTe-based materials to date. The synergistic optimization of electronic property and phonon transport are achieved by the purification of grain boundary scattering, together with the Ga-doping-induced weak phonon-electron coupling, which enhances the carrier mobility and carrier concentration simultaneously and consequently gives a remarkably increased power factor of 8.9 µW cm-1 K-2 . The DFT phonon calculations indicate the dopant reduces the deformation potential coefficient and induces the lattice shrink, which reduces significantly the acoustic cutoff frequency, and enhances the scattering phase space. Moreover, the bonding hierarchy leads to the dense intragranular dislocation arrays, which suppresses the lattice thermal conductivity further and induces an ultralow lattice thermal conductivity (0.21 Wm-1 K-1 ).

18.
Angew Chem Int Ed Engl ; 61(28): e202205587, 2022 Jul 11.
Article in English | MEDLINE | ID: mdl-35513754

ABSTRACT

Non-linear optical chalcogenides with a wide band gap (Eg ) and excellent NLO properties are key materials for highly desirable multiwaveband tunable optical parametric oscillators (OPOs). We exploit the "electronic structure engineer bucket effect" to develop a novel dual-waveband SrZnGeS4 with an ultrawide transparency window. It exhibits an asymmetric Fdd2 structure that consists of layers formed by corner-sharing [ZnGeS6 ] dimers. SrZnGeS4 is transparent from 0.30 to 23.6 µm, spanning the UV-, vis-, mid- and far-IR spectral regions and has the widest Eg (3.63 eV) in the AeMII MIV Q4 family to date. It exhibits phase matching, high SHG intensities (e.g., 11.0×KDP and 17.5×AGS under λinc =1450 and 950 nm, respectively), and a very high laser-induced damage threshold (35×AGS). These results not only suggest bright prospects for high-power laser applications but may also enable applications of the multiwaveband OPO system from the UV-visible to far-IR regions.

19.
Article in English | MEDLINE | ID: mdl-35538675

ABSTRACT

The achievement of balanced performance with a strong second-harmonic generation (SHG) response, proper birefringence, and wide band gap concurrently is a crucial but challenging task in infrared nonlinear optical (IR-NLO) crystals. Here, we theoretically confirmed that the heteroanionic oxysulfide tetrahedron would produce improved polarizability anisotropy and quadratic hyperpolarizability compared with the monoanionic oxide or sulfide tetrahedra. When this anion-mixing strategy was applied, melilite oxysulfide with the four representative members A2GeGa2OS6 (A = Ca, Sr) and Sr2MGe2OS6 (M = Zn, Cd) was successfully discovered as a promising IR-NLO material system. Remarkably, compared with the monoanionic melilite oxides, these compounds exhibited unbiased performances of proper birefringences (0.106-0.143), strong SHG responses (>10× melilite oxide Ba2CdGe2O7, 1.3-2.1× AgGaS2 (AGS) @1570 nm) with phase-matchable ability, wide band gaps (2.95-3.15 eV), and large laser-induced damage thresholds (LIDTs, 5.6-13.4× AGS). The high structure tolerance of melilite offers a great possibility to improve the SHG response via tuning the orbital composition and hybridization near band edges. This work provides an effective approach for the design of high-performance IR-NLO materials.

20.
Nat Commun ; 13(1): 2966, 2022 May 27.
Article in English | MEDLINE | ID: mdl-35624124

ABSTRACT

The argyrodite Ag9GaSe6 is a newly recognized high-efficiency thermoelectric material with an ultralow thermal conductivity; however, liquid-like Ag atoms are believed to cause poor stability and performance irreproducibility, which was evidenced even after the 1st measurement run. Herein, we demonstrate the abovementioned instability and irreproducibility are caused by standard thermoelectric sample hot-pressing procedure, during which high pressure promotes the 3-fold-coordinated Ag atoms migrate to 4-fold-coordinated sites with higher-chemical potentials. Such instability can be eliminated by a simple annealing treatment, driving the metastable Ag atoms back to the original sites with lower-chemical potentials as revealed by the valence band X-ray photoelectron chemical potential spectra and single crystal X-ray diffraction data. Furthermore, the hot-pressed-annealed samples exhibit great stability and TE property repeatability. Such a stability and repeatability has never been reported before. This discovery will give liquid-like materials great application potential.

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