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Showing papers on "Single crystal published in 2022"


Journal ArticleDOI
TL;DR: In this paper , the evolution of Pd species is investigated on different crystal facets of CeO2, and vastly different behaviors on the single-atomic dispersion of surface Pd atoms are surprisingly discovered.
Abstract: High‐performance, fully atomically dispersed single‐atom catalysts (SACs) are promising candidates for next‐generation industrial catalysts. However, it remains a great challenge to avoid the aggregation of isolated atoms into nanoparticles during the preparation and application of SACs. Here, the evolution of Pd species is investigated on different crystal facets of CeO2, and vastly different behaviors on the single‐atomic dispersion of surface Pd atoms are surprisingly discovered. In situ X‐ray photoelectron spectroscopy (XPS), in situ near‐ambient‐pressure‐XPS (NAP‐XPS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X‐ray absorption spectroscopy (XAS) reveal that, in a reducing atmosphere, more oxygen vacancies are generated on the (100) facet of CeO2, and Pd atoms can be trapped and thus feature atomic dispersion; by contrast, on the CeO2 (111) facet, Pd atoms will readily aggregate into clusters (Pdn). Furthermore, Pd1/CeO2(100) gives a high selectivity of 90.3% for the catalytic N‐alkylation reaction, which is 2.8 times higher than that for Pdn/CeO2(111). This direct evidence demonstrates the crucial role of crystal‐facet effects in the preparation of metal‐atom‐on‐metal‐oxide SACs. This work thus opens an avenue for the rational design and targeted synthesis of ultrastable and sinter‐resistant SACs.

46 citations



Journal ArticleDOI
18 Feb 2022-Small
TL;DR: In this article , a detailed postmortem study is presented, comparing pouch cells with single-crystal versus poly-crystalline LiNi0.60 Co 0.20 O2 (NCM622) cathodes after 1375 dis-/charge cycles against graphite anodes.
Abstract: Lithium-ion batteries based on single-crystal LiNi1- x - y Cox Mny O2 (NCM, 1-x-y ≥ 0.6) cathode materials are gaining increasing attention due to their improved structural stability resulting in superior cycle life compared to batteries based on polycrystalline NCM. However, an in-depth understanding of the less pronounced degradation mechanism of single-crystal NCM is still lacking. Here, a detailed postmortem study is presented, comparing pouch cells with single-crystal versus polycrystalline LiNi0.60 Co0.20 Mn0.20 O2 (NCM622) cathodes after 1375 dis-/charge cycles against graphite anodes. The thickness of the cation-disordered layer forming in the near-surface region of the cathode particles does not differ significantly between single-crystal and polycrystalline particles, while cracking is pronounced for polycrystalline particles, but practically absent for single-crystal particles. Transition metal dissolution as quantified by time-of-flight mass spectrometry on the surface of the cycled graphite anode is much reduced for single-crystal NCM622. Similarly, CO2 gas evolution during the first two cycles as quantified by electrochemical mass spectrometry is much reduced for single-crystal NCM622. Benefitting from these advantages, graphite/single-crystal NMC622 pouch cells are demonstrated with a cathode areal capacity of 6 mAh cm-2 with an excellent capacity retention of 83% after 3000 cycles to 4.2 V, emphasizing the potential of single-crystalline NCM622 as cathode material for next-generation lithium-ion batteries.

39 citations


Journal ArticleDOI
TL;DR: Two penta-coordinated multinuclear copper(II) complexes, [Cu 2 (L)( µ -OAc)]·MeOH ( 1 ) and [Cu 4 (L) 2 Cl 2 ]·EtOH·CH 2 Cl2 ( 2 ) have been synthesized and characterized structurally as discussed by the authors .

39 citations


Journal ArticleDOI
TL;DR: In this article , single-crystal-to-singlecrystal conversion has been a hot topic in the field of metal-organic framework materials, which could improve the stability and properties due to the structural change.
Abstract: Recently, single-crystal-to-single-crystal conversion has been a hot topic in the field of metal-organic framework (MOF) materials, which could improve the stability and properties due to the structural change. A new...

36 citations


Journal ArticleDOI
TL;DR: In this paper , the authors take LiNi0.76Mn0.14Co0.1O2 (NMC76) as a model material to study the mechanism of gas generation from single crystal and polycrystalline NMC by using both coin cells and pouch cells, which provides different conclusions on the generated gases, highlighting the importance of using relevant testing conditions for fundamental diagnostic study on battery materials.

32 citations


Journal ArticleDOI
TL;DR: In this article , a single-armed salamo-type ligand (H3L), tetradentate N2O2 donor part of pocket I and NO2 donor portion of pocket II were designed to bond Zn(II) atoms, then unusually structural complexes were obtained by counteranion-driven self-assembled.

30 citations


Journal ArticleDOI
TL;DR: In this paper , the dielectric loss behavior and electromagnetic wave absorption (EMA) properties of MoO2 ceramic from single crystal to polycrystal have been in-depth investigated, and it is found that poly-crystal MoO 2 shows better dielectrics loss ability than single crystal MoOII, leading to greatly enhanced EMA performance.

29 citations


Journal ArticleDOI
TL;DR: In this paper , high-quality inch-size two-dimensional (2D) Cs3Bi2Br9 (CBB) single crystals are grown from a melt via the Bridgman method.
Abstract: Halide perovskites are promising candidates for soft X-ray detection (<80 keV) owing to their high X-ray absorption coefficient, resistivity, and mobility lifetime product. However, the lack of large high-quality single crystals (SCs) renders it challenging to manufacture robust hard X-ray imaging systems (>100 keV) with a low detection limit and stable dark current. Herein, high-quality inch-size two-dimensional (2D) Cs3Bi2Br9 (CBB) single crystals are grown from a melt via the Bridgman method. The crystal quality is enhanced by eliminating inclusions of CsBr-rich phases and restraining the trap-state density, leading to an enhanced resistivity of 1.41 × 1012 Ω cm and a mobility lifetime product of 8.32 × 10-4 cm2 V-1. The Au/CBB/Au single-crystal device exhibits a high sensitivity of 1705 μC Gyair-1 cm-2 in all-inorganic bismuth-based perovskites and an ultralow detection limit of 0.58 nGyair s-1 in all of the bismuth-based perovskites for 120 keV hard X-ray detection. The CBB detector exhibits high work stability with an ultralow dark current drift of 2.8 × 10-10 nA cm-1 s-1 V-1 and long-term air environment reliability under a high electric field of 10 000 V cm-1 owing to the ultrahigh ionic activation energy of the 2D structure. The proposed robust imaging system based on CBB SC is a promising tool for X-ray medical imaging and diagnostics.

29 citations


Journal ArticleDOI
TL;DR: In this paper, LiNi0.9Co0.055Mn0.045O2 (NCM90)-4LN was used as a precursor for single crystal Ni-rich cathode materials.

29 citations


Journal ArticleDOI
TL;DR: In this article , a stress field model induced by the scratch was developed by considering the anisotropy, which indicated that during the loading process, median cracks induced by tensile stress initiated and propagated at the front of the indenter.
Abstract: To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF2 single crystals, nanoscratch tests of MgF2 single crystals with different crystal planes and directions were systematically performed, and surface morphologies of the scratched grooves under different conditions were analyzed. The experimental results indicated that anisotropy considerably affected the damage evolution in the machining process of MgF2 single crystals. A stress field model induced by the scratch was developed by considering the anisotropy, which indicated that during the loading process, median cracks induced by the tensile stress initiated and propagated at the front of the indenter. Lateral cracks induced by tensile stress initiated and propagated on the subsurface during the unloading process. In addition, surface radial cracks induced by the tensile stress were easily generated during the unloading process. The stress change led to the deflection of the propagation direction of lateral cracks. Therefore, the lateral cracks propagated to the workpiece surface, resulting in brittle removal in the form of chunk chips. The plastic deformation parameter indicated that the more the slip systems were activated, the more easily the plastic deformation occurred. The cleavage fracture parameter indicated that the cracks propagated along the activated cleavage planes, and the brittle chunk removal was owing to the subsurface cleavage cracks propagating to the crystal surface. Under the same processing parameters, the scratch of the (001) crystal plane along the [100] crystal-orientation was found to be the most conducive to achieving plastic machining of MgF2 single crystals. The theoretical results agreed well with the experimental results, which will not only enhance the understanding of the anisotropy dependence of the damage evolution and removal process during the machining of MgF2 crystals, but also provide a theoretical foundation for achieving the high-efficiency and low-damage processing of anisotropic single crystals.

Journal ArticleDOI
TL;DR: In this article, the authors incorporated Te4+ into Cs2ZrCl6 single crystal, simultaneously preserving the vacancy-ordered structure, to obtain an efficient yellow-emitting perovskite with a near-unity photoluminescence quantum yield (PLQY ≈ 97.6%).

Journal ArticleDOI
TL;DR: In this article , two lead-free zero-dimensional (0D) hybrid halides, (Bmpip)2Cu2Br4 and PPh4CuBr2 single crystals, were grown by the low-cost solution-processing method.
Abstract: Low-dimensional organic-metal halides are regarded as an emerging class of X-ray scintillation materials, but most of the discovered compounds are confronted with challenges of toxicity and instability. To address these challenges, we herein report two lead-free zero-dimensional (0D) hybrid halides, (Bmpip)2Cu2Br4 and PPh4CuBr2 single crystals, grown by the low-cost solution-processing method. By single-crystal X-ray diffraction refinement, the crystal structures of (Bmpip)2Cu2Br4 and PPh4CuBr2 were determined to be orthorhombic and monoclinic crystal systems, respectively. (Bmpip)2Cu2Br4 and PPh4CuBr2 show broadband orange and yellow emissions peaking at 620 and 538 nm, respectively. Different from the emission nature of the recent reported Cu-based halide hybrids, both (Bmpip)2Cu2Br4 and PPh4CuBr2 emit from excitons bound to defects featuring spin-allowed transition, enabling them to possess fast scintillation decay time of tens of nanoseconds, respectively. In particular, the (Bmpip)2Cu2Br4 single crystal has a high photoluminescence quantum yield of 48.2%, a high scintillation yield of 16,000 photons/MeV, and a low detection limit of 710 nGyair/s. Due to the combination of nontoxicity, long-term stability, and decent detection performance, (Bmpip)2Cu2Br4 could be regarded as a promising X-ray scintillator.

Journal ArticleDOI
TL;DR: In this paper , the authors theoretically report an instability toward a skyrmion crystal in centrosymmetric magnets under hexagonal and trigonal single-ion anisotropy.

Journal ArticleDOI
TL;DR: In this paper , the authors provide an overview of the development in this area, since it has garnered much attention among solid state chemists, and present selected examples of important strategies, which will help in a rational approach for the fabrication of advanced solid state materials.
Abstract: ConspectusConducting a reaction in the solid state eliminates the usage of solvents. If such reactions are conducted in a single-crystal to single-crystal (SCSC) fashion, then structural characterization by single-crystal X-ray crystallography (SCXRD) techniques provides unequivocal structural details. Although topochemical principles govern, getting single crystals at the end of a SCSC reaction purely depends on the experimental skills of the researchers. SCSC reactions are common among solid-state [2 + 2] cycloaddition reactions (hereafter "photoreaction") after the classical work of Schmidt and co-workers in 1960s. Synthons and tectons in the crystal engineering box can be exploited to bring the functional groups into the required alignment and packing to achieve the desired chemical reactivities and physical properties, respectively. Bringing a pair of alkenes closer together in the organic molecules provides an effective starting point to achieve the goal of crystal engineering.Further, understanding and controlling photoreactivity in the solid state provide a gateway to designing new advanced materials, for example, making cycloreversible optical storage materials, photosalient and photomechanical materials, highly crystalline or even single-crystalline organic polymers, covalent organic framework structures, and organic polymers incorporated inside metal-organic frameworks (MOFs). Photoreactions often proceed in a SCSC manner due to the limited movements of the closely disposed reactive functional groups in the crystals. Thus, these photoreactions yield not only quantitative photoproducts but also regio- and stereospecificity, which are otherwise inaccessible by solution syntheses.The traditional definition of crystals being hard, rigid, and brittle is no longer valid ever since the mechanically responsive crystals were discovered. These dynamic crystals undergo various movements like curling, jumping, hopping, popping, splitting, and wiggling, when exposed to light (called "photosalient effect") or heat (called "thermosalient" effect). These crystals generate new methods of transforming light and heat energy into mechanical work. Recently, photosalient behavior during the [2 + 2] cycloaddition reaction under UV light has been frequently observed. With the emergence of the field of "crystal adaptronics", dynamic photoreactive crystals have emerged as smart actuating materials.This Account aims to provide an overview of the development in this area, since it has garnered much attention among solid state chemists. While presenting selected examples of important strategies, we try to illustrate the intentions and concepts behind the methods developed, which will help in a rational approach for the fabrication of advanced solid state materials. Apart from topochemical transformations, the important roles played by weak interactions, guest solvents, and mechanical grinding have been highlighted in several classes of compounds to show structural transformations that defy the expected outcomes. Overall, the progress of [2 + 2] cycloaddition reaction in solid state materials has been discussed from UV induced structural transformations to the development of smart actuating materials.

Journal ArticleDOI
TL;DR: In this paper , a synergy of gradient Nb doping on single-crystal LiNi0.8Co0.1O2 stabilizes the core by strong Nb-O bond and induces Li/Ni antisite migration forming a disordered buffer layer on the surface.

Journal ArticleDOI
TL;DR: In this article, a salamo-type fluorescence probe H2L was synthesized by a series of reactions and corroborated by single-crystal X-ray crystallography and 1H NMR spectra.

Journal ArticleDOI
TL;DR: In this article , the synthesis of two halo functionalized crystalline Schiff base (imine) compounds, namely (E)-2-methoxy-6-(((3-(trifluoromethyl)phenyl)imino)methyl)phenol (MFIP) and (E]-1-(2-fluorophenyl)-imino (methyl)naphthalen-2-ol (FPIN) by the condensation reaction of substituted benzaldehydes and substituted aniline.
Abstract: This investigation is focused on the synthesis of two halo-functionalized crystalline Schiff base (imine) compounds: (E)-2-methoxy-6-(((3-(trifluoromethyl)phenyl)imino)methyl)phenol (MFIP) and (E)-1-(((2-fluorophenyl)imino)methyl)naphthalen-2-ol (FPIN) by the condensation reaction of substituted benzaldehydes and substituted aniline. The crystal structures of MFIP and FPIN were determined unambiguously by single-crystal X-ray diffraction (SC-XRD) studies. Intermolecular interactions and the role of fluorine atoms in the stabilization of the crystal packing are explored for both compounds using Hirshfeld surface analysis. Accompanied with experimental studies, quantum chemical calculations were also performed for comprehensive structure elucidation at the M06/6-311G(d,p) level of theory. A comparison of experimental and density functional theory results for geometrical parameters exhibited excellent agreement. Interestingly, Frontier molecular orbitals and natural bond orbital (NBO) findings revealed that intramolecular charge transfer and hyper-conjugation interactions had played a significant role to stabilize the molecules. Both compounds exhibited a relatively larger value of hardness with a smaller global softness, which, as proposed by the SC-XRD and NBO study, shows a higher stability. Nonlinear optical (NLO) findings showed that FPIN manifested a larger value of linear polarizability ( = 293.06 a.u.) and second-order hyperpolarizability ( = 3.31 × 105 a.u.) than MFIP ( = 252.42 and = 2.08 × 105 a.u.) due to an extended conjugation. The above-mentioned findings of the entitled compounds may play a crucial role in NLO applications.

Journal ArticleDOI
TL;DR: In this paper , a salamo-type fluorescence probe H 2 L was synthesized by a series of reactions and corroborated by single-crystal X-ray crystallography and 1 H NMR spectra.

Journal ArticleDOI
01 Feb 2022
TL;DR: In this paper , the authors reviewed recent research on the additive manufacturing of single-crystal nickel-based superalloys and discussed the challenges faced by additive manufacturing for singlecrystal fabrication, and provided perspectives on the trends of future developments.
Abstract: The conventional fabrication process for single-crystal nickel-based superalloy materials is directional solidification, which is classified as casting. With the rapid development of additive manufacturing (AM) technologies, a novel process for fabricating single-crystal superalloys has become possible. This article reviews recent research on the AM of single-crystal nickel-based superalloys. Laser AM technologies, particularly directed energy deposition, are mainly used to repair single-crystal materials. Electron beam powder bed fusion is an innovative method for the direct fabrication of single-crystal materials. Accordingly, the mechanisms of single-crystal formation during AM are analyzed to elucidate the potential of this process route. Furthermore, this article discusses the challenges faced by AM for single-crystal fabrication, and provides perspectives on the trends of future developments.

Journal ArticleDOI
TL;DR: In this paper , a review of recent advanced literature reported on crystalline Coordination Compounds with emphasis in Coordination Polymers (CPs) involving reversibility in singlecrystal to single-crystal transformations (SCSC).

Journal ArticleDOI
TL;DR: In this paper, a review of recent advanced literature reported on crystalline Coordination Compounds with emphasis in Coordination Polymers (CPs) involving reversibility in singlecrystal to single-crystal transformations (SCSC).

Journal ArticleDOI
TL;DR: In this paper, a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water was reported.

Journal ArticleDOI
TL;DR: In this article , a multi-light-stimulus response with high down-conversion photoluminescence quantum yield (PLQY) value of near unity is reported, which can also be activated by near-infrared light and X-ray.
Abstract: Anti‐counterfeiting has become a serious issue around the global world; fluorescence‐based tags are praised for the low‐cost and facile decryption process. However, the high‐level anti‐counterfeiting application requires incorporating multifunctional luminescent materials with response to different excitation sources. Herein, a dimeric Cu(I)‐halide‐clusters‐assembled single‐crystal (AEP)2Cu2I6·2I·2H2O (AEP = N‐aminoethylpiperazinium) concerning a high down‐conversion photoluminescence quantum yield (PLQY) value of near unity is reported (λex = 305 nm), which can also be activated by the near‐infrared light and X‐ray. The ultrafast spectroscopy and density functional theory calculations reveal that the broad‐band emission originates from the recombination of self‐trapped excitons. Remarkably, the high PLQY and excellent attenuation capability for X‐ray confers an outstanding light yield of 55 650 photons MeV−1 to (AEP)2Cu2I6·2I·2H2O, which is 5.25 times higher than the standard bismuth germaniumoxide scintillator. Such multi‐light‐stimulus response endows (AEP)2Cu2I6·2I·2H2O with great application potential in anti‐counterfeiting, solid‐state lighting devices, and digital radiography.

Journal ArticleDOI
TL;DR: In this paper , a novel family of centimeter-sized 2D perovskitoid single crystals, (3AP)PbX4 (3-amidinopyridine, X = Cl, Br, and I), was synthesized based on an amidino-based organic spacer.
Abstract: Metal-halide perovskitoids with corner-, edge-, and face-sharing octahedra provide a fertile “playground” for structure modulation. With low defect density, low ion migration, and high intrinsic stability, two-dimensional (2D) perovskitoid single crystals are expected to be ideal materials for room-temperature semiconductor detectors (RTSDs) as high-energy radiation. However, there is no report yet on the use of 2D perovskitoid single crystals for X-ray detection, as well as on how the halide-modulated molecular assembly would affect their structure and properties. Herein, based on an amidino-based organic spacer, we successfully synthesized a novel family of centimeter-sized 2D perovskitoid single crystals, (3AP)PbX4 (3AP = 3-amidinopyridine, X = Cl, Br, and I). This is the first time that centimeter-sized 2D perovskitoid single crystals are demonstrated for X-ray photoresponse. Detailed investigations reveal a unique crystal packing with corner-sharing and edge-sharing octahedra of inorganic frameworks and 3AP cations lying between adjacent inorganic layers in a parallel and antisymmetric manner. Changing the halide from I to Br and Cl results in greater Pb–X–Pb angles and stronger hydrogen bonding in perovskitoids and therefore consequently a better elastic recovery under stress, a more efficient charge transport in the inorganic layer, and a lower ionic migration. By varying halide substitution, an efficient X-ray photoresponse is achieved with a sensitivity up to 791.8 μC Gyair–1 cm–2 for (3AP)PbCl4 and a low detection limit of 1.54 μGyair s–1. These results reveal that the large 2D perovskitoid single crystals provide a promising platform for high performance optoelectronics.

Journal ArticleDOI
TL;DR: In this article , two types of MAPbI3 single-crystal films with dominant (001) and (100) surface orientations for solar cells were synthesized and shown to have efficient hole transfer into poly(triaryl)amine (PTAA).
Abstract: We synthesized two types of MAPbI3 single-crystal films with dominant (001) and (100) surface orientations for solar cells. We found that both MAPbI3 (001) and (100) single-crystal films have efficient hole transfer into poly(triaryl)amine (PTAA), as evident from the reduced photoluminescence (PL) intensity and lifetime, as well as the type-II energy alignment. Unlike a MAPbI3 (100) single-crystal film with a strong PL quenching due to efficient electron transfer to phenyl-C61-butyric acid methyl ester (PCBM), the MAPbI3 (001) single-crystal film exhibits an increase in PL intensity in the presence of PCBM, which can be attributed to surface passivation. Interestingly, different from the conventional MAPbI3 (100) that suffers from a significant decrease in the PCE (from 19.3 to 14.4%), the MAPbI3 (001) single-crystal film shows an increase in the PCE (from 16.0 to 17.2%) and much better stability under ambient conditions thanks to the dual passivation on the PbI2-rich surface by PCBM and O2.

Journal ArticleDOI
TL;DR: In this paper , a universal route for synthesizing arrays of unidirectionally orientated monolayer TMDs ribbons (e.g., MoS2, WS2, MoSe2, WSe2 and MoSxSe2-x) was presented.
Abstract: Two-dimensional (2D) semiconductors, especially transition metal dichalcogenides (TMDs), have been envisioned as promising candidates in extending Moore's law. To achieve this, the controllable growth of wafer-scale TMDs single crystals or periodic single-crystal patterns are fundamental issues. Herein, we present a universal route for synthesizing arrays of unidirectionally orientated monolayer TMDs ribbons (e.g., MoS2, WS2, MoSe2, WSe2, MoSxSe2-x), by using the step edges of high-miller-index Au facets as templates. Density functional theory calculations regarding the growth kinetics of specific edges have been performed to reveal the morphological transition from triangular domains to patterned ribbons. More intriguingly, we find that, the uniformly aligned TMDs ribbons can merge into single-crystal films through a one-dimensional edge epitaxial growth mode. This work hereby puts forward an alternative pathway for the direct synthesis of inch-scale uniform monolayer TMDs single-crystals or patterned ribbons, which should promote their applications as channel materials in high-performance electronics or other fields.

Journal ArticleDOI
TL;DR: In this article, a dioxomolybdenum Schiff base complex was synthesized by the reaction of MoO2(acac)2 and an ONO donor base ligand (H2L: (E)-4-amino-N'-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide) derived by the condensation of 4-aminobenzohydraide and 3-ethoxysalicylaldehyde.


Journal ArticleDOI
TL;DR: In this paper , a universal route for synthesizing arrays of unidirectionally orientated monolayer TMDs ribbons (e.g., MoS2, WS2, MoSe2, WSe2 and MoSxSe2-x) was presented.
Abstract: Two-dimensional (2D) semiconductors, especially transition metal dichalcogenides (TMDs), have been envisioned as promising candidates in extending Moore's law. To achieve this, the controllable growth of wafer-scale TMDs single crystals or periodic single-crystal patterns are fundamental issues. Herein, we present a universal route for synthesizing arrays of unidirectionally orientated monolayer TMDs ribbons (e.g., MoS2, WS2, MoSe2, WSe2, MoSxSe2-x), by using the step edges of high-miller-index Au facets as templates. Density functional theory calculations regarding the growth kinetics of specific edges have been performed to reveal the morphological transition from triangular domains to patterned ribbons. More intriguingly, we find that, the uniformly aligned TMDs ribbons can merge into single-crystal films through a one-dimensional edge epitaxial growth mode. This work hereby puts forward an alternative pathway for the direct synthesis of inch-scale uniform monolayer TMDs single-crystals or patterned ribbons, which should promote their applications as channel materials in high-performance electronics or other fields.