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Organic–inorganic metal halides (OIMHs) have various crystal structures and offer excellent semiconducting properties. Here, we report three novel OIMHs, (PPA)6InBr9(PPA = [C6H5(CH2)3NH3]+), (PBA)2SbBr5, and (PBA)2SbI6(PBA = [C6H5(CH2)4NH3]+), showing typical zero-dimensional (0D) structure, octahedra dimers, and corner-sharing one-dimensional chains and crystallized in the monoclinic system with P21, P21/c, and C2/cspace groups, respectively. (PPA)6InBr9, (PBA)2SbBr5, and (PBA)2SbI6have experimental optical band gaps of ∼3.16, ∼2.24, and 1.48 eV, respectively. (PPA)6InBr9exhibits bright-orange light emission centered at 642 nm with a full-width at half-maximum of 179 nm (0.51 eV) and a Stokes shift of 277 nm (1.46 eV). After Sb3+doping, the peak position did not change, and the photoluminescence quantum yield increased significantly from 9.2 to 53.0%. The efficient emission of Sb:(PPA)6InBr9stems from the isolated ns2luminescent center and strong electron–phonon coupling, making the spin-forbidden 3P1–1S0observable. By combining commercial blue and green phosphors with orange-red-light-emitting (PPA)6In0.99Sb0.01Br9, a white-light-emitting diode was constructed, with the color-rendering index reaching up to 92.3. Our work highlights three novel 0D OIMHs, with chemical doping of Sb3+shown to significantly enhance the luminescence properties, demonstrating their potential applications in solid-state lighting.

The carbon dissolution in solvent plays a key role in the process of solution growth route for SiC single crystal, which could determine the growth rate and quality of the products. However, the carbon dissolving ability of binary alloy solvent still needs to be improved. Here, we demonstrate the improved carbon dissolution and enlarged carbon supersaturation in Cr–Ce–Si ternary solvent, showing great potential for SiC solution growth. The phase relations of Cr–Ce–Si–C system were determined by using CALPHAD method based on thermodynamic parameters of CeCr2Si2C. It is indicated that the Cr–Ce–Si ternary solvent shows much larger carbon solubility in temperature range from 1700 to 2000 °C compared to Cr–Si binary one. Furthermore, the carbon supersaturation in solvent is also significantly increased in low temperature range after the addition of Ce, leading to a rapid growth rate. Our work not only demonstrates the feasibility of adding Ce in the alloy solvent for rapid growth of SiC crystal, but also provides an example for investigating the C solubility in ternary solvent.

A new series of compounds, ANi5Bi5.6+δ(where A = K, Rb, and Cs) are discovered with a quasi-one-dimensional (Q1D) [Ni5Bi5.6+δ]−double-walled column and a coaxial inner one-dimensional Bi atomic chain. The columns are linked to each other by intercolumn Bi–Bi bonds and separated by an A+cation. Typical metallic behaviors with strong correlation of itinerant electrons and the Sommerfeld coefficient enhanced with the increasing cationic radius were experimentally observed and supported by first-principles calculations. Compared to AMn6Bi5(where A = K, Rb, and Cs), the enhanced intercolumn distances and the substitution of Ni for Mn give rise to strong diamagnetic susceptibilities in ANi5Bi5.6+δ. First-principles calculations reveal possible uncharged Ni atoms with even number of electrons in ANi5Bi5.6+δ, which may explain the emergence of diamagnetism. ANi5Bi5.6+δ, as Q1D diamagnetic metals with strong electron correlation, provide a unique platform to understand exotic magnetism and explore novel quantum effects.

Zero-dimensional (0D) In-based organic–inorganic metal halides (OIMHs) have received growing interest in recent years as promising luminescent materials. However, the high efficiencies of 0D In-based OIMHs are all dependent on Sb doping in the existing literature. Here, we report a novel 0D In-based OIMH (C10H22N2)2In2Br10, which exhibits intrinsic broadband emission (610 nm), and the photoluminescence quantum yield (PLQY) can reach 70% without Sb doping. (C10H22N2)2In2Br10shows a typical 0D structure with three different In–Br polyhedra (two octahedra and one tetrahedron) separated by large organic cations. Based on the optical property measurements and theoretical calculations, we demonstrate that (C10H22N2)2In2Br10is an indirect semiconductor with a band gap of 3.74 eV, and the In–Br inorganic moiety is primarily responsible for the intense emission of (C10H22N2)2In2Br10. Interestingly, the unique double octahedral configuration in (C10H22N2)2In2Br10may enhance the structural distortion and stimulate the self-trapped excitons (STEs), leading to the related high PLQY. Our work provides a novel 0D In-based OIMH with high-efficiency intrinsic emission, which is helpful for understanding the structure–PL relationships of hybrid halides.

Hybrid tetrahedral Mn(II)-based halides show great potential for narrow-band green emitters, which could be applied in the liquid crystal display field. However, the strategy to improve the chemical stability of tetrahedral Mn hybrids has not been fully investigated. Here, we demonstrate that Zn doping can be an effective route to significantly improve the stability of tetrahedral Mn hybrids under air conditions without compromising the luminous efficiency. A new bromide (ABI)2MnBr4(ABI = 2-aminobenzimidazole) is synthesized, which exhibits a typical zero-dimensional structure with isolated [MnBr4]2–tetrahedra in the P1̅ space group. Under 450 nm excitation, a narrow-band green-emitting peak at 516 nm is observed with a full width at half maximum of 42 nm. It is indicated that spontaneous phase transition from the tetrahedral to octahedral motif occurs in this Mn hybrid driven by humidity, combined with the emission color change from green to red. Interestingly, this phase transition could be strongly suppressed by Zn doping with a very low doping amount (5%), leading to the significantly improved chemical stability of (ABI)2MnBr4without reducing the photoluminescence quantum yield. Our work provides a simple and feasible strategy to enhance the chemical stability of the green-emitting (ABI)2MnBr4, and it may also be applicable for other tetrahedral Mn-based hybrids.

The participation of organic cations plays an important role in tuning broad-spectra emissions. Herein, we synthesized a series of Mn(II)-based two-dimensional (2D) halide perovskites with arylamine cations of different lengths having the general formula (C6H5(CH2)xNH3)2MnCl4(x= 1–4), with the x= 4 compound reported here for the first time. With the increase in the −(CH2)– in organic cations, the distance between adjacent inorganic layers increases, causing the title compounds to exhibit different structural distortions. As the Mn–Cl–Mn angular distortion increases, the experimental optical band gaps of the title compounds increase correspondingly. When the angle distortion between the octahedrons of the compounds is similar, the band gaps may also be affected by the distortion of the octahedron itself (the bond-length distortion of 2is greater than that of 4). Under UV-light irradiation at 298 K, all of the compounds exhibit two emission peaks centered at 480–505 and 610 nm, corresponding to the organic-cation emission and the 4T1(G) to 6A1(S) radiative transition of Mn2+ions, respectively. Among these title compounds, (PPA)2MnCl4[(PPA)+= C6H5(CH2)3NH3+] exhibits the strongest photoluminescence (PL). The study of the title compounds contributes to an in-depth understanding of the relationship between the structural distortion and optical properties of 2D Mn(II)-based perovskite materials.

The ferromagnetic shandite Co3Sn2S2has attracted great attention in physics and chemistry communities owing to its Kagome net, magnetism, and topological property. Here, for the first time, we report the effect of Sb doping on the crystal structure, magnetic interaction, and transport behavior of this ferromagnetic Weyl semimetal. A relatively low doping limit has been determined as x= 0.1 in a Co3Sn2–xSbxS2system. Single-crystal X-ray diffraction indicates that the Sb doping shows a preferred occupation at the Sn sites between Kagome layers (Sn(1)) rather than the intralayer sites (Sn(2)), leading to the anisotropic contraction of the lattice. The ferromagnetic interaction is weakened upon Sb doping with the Curie temperature decreased from 172 to 146 K, which resulted from the shifting of the Fermi level toward high energy. Due to the electron injection, the Sb-doped sample shows the declined thermoelectric property with the reduced absolute value of the Seebeck coefficient compared to the parent compound. The anomalous Hall effect is still maintained in Co3Sn1.9Sb0.1S2with the increased anomalous Hall resistivity based on the measurement on polycrystalline samples. Our work provides a new electron doping system to understand the interplay between the magnetism and quantum properties of this Weyl semimetal.

The newly discovered AMnBi2(A = Ca, Sr, Ba, Eu, and Yb) materials composed of two-dimensional Bi square nets provide an excellent platform to investigate the effect of magnetism on topological band structures. Effectively tuning the magnetic interaction in AMnBi2is of great importance to advance this issue. Here, we describe an effective route to tune the magnetism in Dirac semimetal CaMnBi2through Cu doping. Structural analysis on CaMn1–xCuxBi2single crystals indicates that Cu atoms occupy the Mn sites randomly, with the maximum doping level of 25%. After Cu doping, the Bi square net in charge of the Dirac band is still retained, but the Bi–Bi bond distance is markedly shortened. The antiferromagnetic interaction of CaMnBi2is strongly weakened in the Cu-doped crystals, with the transition temperature decreased from 260 to 85 K. On the contrary, the ferromagnetic component that originated from the canted AFM is enhanced, suggesting that the spin canting in this system is tunable. In addition, the magnetoresistance is decreased upon Cu doping, probably due to the disorder in structure. Our work suggests that the CaMn1–xCuxBi2(0 ≤ x≤ 0.25) system can offer a suitable playground to address the interplay between magnetism and the topological state.

The Pb-free hybrid-layered-double perovskites (HLDPs) have been proposed as green and stable semiconducting materials for optoelectronic devices, but the synthesized members are still limited. Here, we report the synthesis of three new HLDPs, (C8H20N2)2AgMBr8(M = In, Sb, and Bi), by a solution method using 1,4-bis(ammoniomethyl)cyclohexane (C8H20N22+) as the organic spacing cation. All three of these HLDPs show ⟨100⟩-oriented layered structures with Ag and In/Sb/Bi order arranged in corner-sharing octahedral layers. The first-principle calculations indicate the indirect-gap nature of (C8H20N2)2AgInBr8and (C8H20N2)2AgSbBr8, while their Bi counterpart shows a direct band gap after considering spin–orbit coupling. The band gaps obtained by diffuse-reflectance spectroscopy are 3.11, 2.60, and 2.70 eV for M = In, Sb, and Bi, respectively. (C8H20N2)2AgInBr8shows a broadband red emission centered at 690 nm, and it is mainly attributed to the self-trapped-excitons mechanism. Our results not only provide a series of new “Pb-free” HLDPs with chemical diversity but also help us to further understand the structure–property relationships of HLDP materials.

It is known that as the FeAs4tetrahedron in the Fe-based superconductor is close to the regular tetrahedron, critical temperature (Tc) can be greatly increased. Recently, a Co-based superconductor of LaCoSi (4 K) with “111” structure was found. In this work, we improve the Tcof LaCoSi through structural regulation. Tccan be increased by the chemical substitution of Co by Fe, while the superconductivity is suppressed by the Ni substitution. The combined analysis of neutron and synchrotron X-ray powder diffractions reveals that the change of the Si–Co–Si bond angles of the CoSi4tetrahedron is possibly responsible for the determination of superconducting properties. The Fe chemical substitution is favorable for the formation of the regular tetrahedron of CoSi4. The present new Co-based superconductor of LaCoSi provides a possible method to enhance the superconductivity performance of the Co-based superconductors via controlling Co-based tetrahedra similar to those well established in the Fe-based superconductors.

Low-dimensional organic–inorganic metal halides (OIMHs), as emerging light-emitting materials, have aroused widespread attention owing to their unique structural tunability and photoelectric characteristics. OIMHs are also promising materials for optoelectronic equipment, light-emitting diodes, and photodetectors. In this study, (C3H12N2)2Sb2Cl10(C3H12N22+is an N-methylethylenediamine cation), a new zero-dimensional OIMH, has been reported, and (C3H12N2)2Sb2Cl10possesses a P21/nspace group. The (C3H12N2)2Sb2Cl10structure contains [Sb2Cl10]4–dimers (composed of two edge-sharing [SbCl6]3–octahedra) that are surrounded by C3H12N22+cations. The experimental band gap of (C3H12N2)2Sb2Cl10is 3.80 eV, and density functional theory calculation demonstrates that (C3H12N2)2Sb2Cl10possesses a direct band gap, with the edge of the band gap mainly contributed from the inorganic units. (C3H12N2)2Sb2Cl10exhibits good ambient and thermal stability. Under 395 nm excitation at room temperature, (C3H12N2)2Sb2Cl10exhibits a broad emission with a full width at half-maximum of ∼114 nm, peaking at 480 nm, and the broad emission was ascribed to self-trapped exciton emission.

It is known that few Co-based superconducting compounds have been found compared with their Fe- or Ni-based counterparts. In this study, we have found superconductivity of 4 K in the LaCoSi compound for the first time. The combined analysis of neutron and synchrotron X-ray powder diffractions reveals that LaCoSi exhibits an isostructure with the known Fe-based LiFeAs superconductor, which is the first “111” Co-based superconductor. First-principles calculation shows that LaCoSi presents a quasi-two-dimensional band structure that is also similar to that of LiFeAs. The small structural distortion may be more conducive to the emergence of superconductivity in the LaCoSi compound, which provides a direction for finding new Co-based superconducting compounds.

Layered sulfides with high selectivity for binding heavy metal ions and radionuclide ions are promising materials in effluent treatment and water purification. Here we present a rationally designed layered sulfide Kx[Bi4–xMnxS6] (x= 1.28) deriving from the Bi2Se3-structure type by targeted substitution to generate quintuple [Bi4–xMnxS6]x−layers and K+cations between them. The material has dual functionality: it is an attractive semiconductor with a bandgap of 1.40 eV and also an environmental remediation ion-exchange material. The compound is paramagnetic, and optical adsorption spectroscopy and DFT electronic structure calculations reveal that it possesses a direct band gap and a work function of 5.26 eV. The K+ions exchange readily with alkali or alkaline-earth ions (Rb+, Cs+, and Sr2+) or soft ions (Pb2+, Cd2+, Cr3+, and Zn2+). Furthermore, when the K+ions are depleted the Mn2+ions in the Bi2Se3-type slabs can also be replaced by soft ions, achieving large adsorption capacities. The ion exchange reactions of Kx[Bi4–xMnxS6] can be used to create new materials of the type Mx[Bi4–xMnxS6] in a low temperature kinetically controlled manner with significantly different electronic structures. The Kx[Bi4–xMnxS6] (x= 1.28) exhibits efficient capture of Cd2+and Pb2+ions with high distribution coefficient, Kd(107mL/g), and exchange capacities of 221.2 and 342.4 mg/g, respectively. The material exhibits excellent capacities even in high concentration of competitive ions and over a broad pH range (2.5–11.0). The results highlight the promise of the Kx[Bi4–xMnxS6] (x= 1.28) phase to serve not only as a highly selective adsorbent for industrial and nuclear wastewater but also as a magnetic 2D semiconductor for optoelectronic applications.

In this work, we report the discovery of a new Ni-based quasi-one-dimensional selenide: Cs0.9Ni3.1Se3. This compound adopts the TlFe3Te3-type structure with space group P63/m, which consists of infinite [Ni3Se3] chains with face-sharing Ni6octahedra along the cdirection. The lattice parameters are calculated as a= 9.26301(4) Å and c= 4.34272(2) Å, with the Ni–Ni distance in the abplane as 2.582(3) Å, suggesting the formation of a Ni–Ni metallic bond in this compound. Interestingly, it has been found that Cs0.9Ni3.1Se3is nonstoichiometric, which is different from the other TlFe3Te3-type phases reported so far. Structure refinement shows that the extra Ni atom in the structure may occupy the 2c site, together with Cs atoms. Cs0.9Ni3.1Se3shows metallic behavior with monotonously decreased resistivity with temperatures from 300 to 0.5 K. Measurements on the magnetic susceptibility display a spin-glass state below 7 K. The specific heat curve gives a Sommerfeld coefficient of 14.6 mJ·K–2·mol–1and a Debye temperature of 143.6 K. The discovery of this new compound enriches the diversity of low-dimensional materials in a transition-metal-based family and also sheds light on the structure–property relationship of this system.

The search for new materials with Dirac points has been a fascinating subject of condensed matter physics. Here we first report the growth and band structure of HfGe0.92Te single crystals featuring three different types of Dirac points. HfGe0.92Te crystallizes in a nonsymmorphic tetragonal space group P4/nmm(No. 129), having a square Ge-atom plane with vacancies of about 8%. Using angle-resolved photoemission spectroscopy (ARPES), the Dirac nodal line composed of conventional Dirac points vulnerable to spin-orbit coupling (SOC) is observed, accompanied by robust Dirac points protected by the nonsymmorphic symmetry against SOC and vacancies. In particular, spin-orbit Dirac points (SDPs) originating from the surface formed under significant SOC could exist based on ARPES and calculations. Quasi-two-dimensional (quasi-2D) characteristics are confirmed by angular-resolved magnetoresistance. HfGe0.92Te bulk crystals can be easily exfoliated to flakes with a thickness of approximately 5 nm for the quasi-2D nature. Thus, HfGe0.92Te provides a good platform to explore exotic topological phases or topological properties with three different types of Dirac points, which is a potential candidate to achieve novel 2D SDPs.

Transition metal subchalcogenides involve electron-rich metals and can facilitate an in-depth understanding of the relationships among quantum properties such as superconductivity, charge density wave, and topological band structures. However, effective experimental routes toward synthesizing transition metal subchalcogenides are still lacking, hindering the development of new quantum materials. Herein, we propose a eutectic polytelluride flux strategy as an excellent solution to address phase discovery and crystal growth in transition metal subtelluride systems. We report new phases easily and selectively synthesized using a eutectic “K3Te4” polytelluride flux upon adjusting the ratio of Nb metal to flux in the starting materials (K/Nb/Te = 3:x:4). Using a high Nb content in the solvent (x= 2 and 1), crystals of KNb3Te3O0.38and K0.9Nb3Te4are obtained. Both subtellurides exhibit diverse Nb clusters, including face-sharing and edge-sharing Nb6octahedral columns and zig-zag Nb chains. Reducing the Nb content to x= 0.33 leads to the formation of a layered compound, K1.06NbTe2. This compound comprises a NbTe6trigonal prism with K intercalated between the layers. Single crystals of known binary Nb tellurides can also be grown using another eutectic flux “KTe3.2”, and the obtained NbTe2exhibits a new polymorphism with extra trimerization along the b-axis in the Nb–Nb bonded double zig-zag cluster. Precise control over the structural dimensionality and oxidation state, combined with the facile crystal growth process, makes our synthetic strategy an efficient route to explore quantum materials in transition metal subchalcogenides.

Recently, excellent optical properties of low-dimensional organic–inorganic metal halides, stemming from their tunable structure and optoelectronic properties, have been demonstrated. The synthetic method is critical because it is highly related to the structure and properties of the halide. Herein, we obtain two different antimony bromides, (Bmpip)2SbBr5and (Bmpip)3Sb2Br9, which both possess the P21/cspace group having different crystal structures, and this confirms the important influence of synthesis on the single-crystal structure. (Bmpip)2SbBr5contains Bmpip+and [SbBr5]2–pyramids, and (Bmpip)3Sb2Br9consists of Bmpip+and Sb-based dimers [Sb2Br9]3–. Under 400 nm excitation, (Bmpip)2SbBr5exhibits a 640 nm orange emission with a quantum yield of ∼11.5% owing to Sb 5s2electron luminescence. A diode was fabricated by (Bmpip)2SbBr5and commercial phosphors and showed a high color render index of 92. Our work reveals the effect of the preparation method on the crystal structure. A luminescent material was finally identified.

The reaction of MnTe with AgSbTe2in an equimolar ratio (ATMS) provides a new semiconductor, AgMnSbTe3. AgMnSbTe3crystallizes in an average rock-salt NaCl structure with Ag, Mn, and Sb cations statistically occupying the Na sites. AgMnSbTe3is a p-type semiconductor with a narrow optical band gap of ∼0.36 eV. A pair distribution function analysis indicates that local distortions are associated with the location of the Ag atoms in the lattice. Density functional theory calculations suggest a specific electronic band structure with multi-peak valence band maxima prone to energy convergence. In addition, Ag2Te nanograins precipitate at grain boundaries of AgMnSbTe3. The energy offset of the valence band edge between AgMnSbTe3and Ag2Te is ∼0.05 eV, which implies that Ag2Te precipitates exhibit a negligible effect on the hole transmission. As a result, ATMS exhibits a high power factor of ∼12.2 μW cm–1K–2at 823 K, ultralow lattice thermal conductivity of ∼0.34 W m–1K–1(823 K), high peak ZTof ∼1.46 at 823 K, and high average ZTof ∼0.87 in the temperature range of 400–823 K.

Metal cluster compounds have garnered renewed interest in the search for novel superconductors and topological semimetals owing to structural instabilities of metal-cluster geometries and broken symmetries. Here we synthesized needle-like crystals of the V-cluster-based quasi-one-dimensional (Q1D) materials AV3Q3Oδ(A = K, Rb, Cs, Q = Se, Te) which can also be viewed as being composed of parallel nanowires. We examine how changes in their average and local structure control their electronic properties. All compounds crystallize in the TlFe3Te3-type structure (P63/mspace group) with infinite (V3Q3)−double-walled columnar chains separated by A+cations. Our single-crystal and synchrotron powder diffraction studies indicate oxygen atoms partially occupy the center site of the V6octahedral metal cluster cages in KV3Te3O0.33, RbV3Te3O0.32, and CsV3Te3O0.35, whereas KV3Se3is structurally oxygen-free. Our synchrotron X-ray pair distribution function (PDF) analyses indicate that the oxygen-free V6cluster octahedra in KV3Se3are highly distorted perpendicular to the chain direction even at room temperature, reducing the symmetry of the average structure from hexagonal P63/mto monoclinic P21/m. Our theoretical calculation supports this P21/mdistortion and suggests the structure further distorts to P21or P21/cat lower temperatures. In contrast, the oxygen-centered V-cluster in KV3Te3O0.33exhibits a V3-triangle-trimerization along the chain direction. This feature is discernible from the local PDF and is consistent with lattice dynamical calculations based on density functional theory. Resistivity measurements indicate that KV3Se3exhibits metallic behavior, whereas a dramatic metal–semiconductor–metal transition emerges in KV3Te3O0.33, RbV3Te3O0.32, and CsV3Te3O0.35because of oxygen disorder and changes in local structure captured from our electronic structure analyses of the Fermi surface. Our investigation of the AV3Q3Oδfamily demonstrates the importance of understanding local changes in structure driven by electronic instabilities, which can guide the search for new quantum materials in other low-dimensional cluster-compound materials.