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Three europium chalcogenides, Cu2EuSiS4 (1), Cu2EuGeS4 (2), and Cu2EuGeSe4 (3) were obtained by a high-temperature solid-state method. They crystallize in the noncentrosymmetric space groups P3121 (1), P3221 (2), and Ama2 (3), respectively. Their structures can be described as EuQ8 bicapped trigonal prisms (btps) constructed 3D frameworks, and Cu and Si/Ge atoms occupying the tetrahedral cavities. The 3D network built by CuQ4 and Si/GeQ. 4 tetrahedra in 3 is different from that in 1 and 2. Their energy band gaps are determined to 2.36, 2.32, and 1.74 eV for 1–3, respectively. Compound 1 shows typical photoluminescence of Eu2+ ion. All of them show antiferromagnetic-like behaviors, and are not second-harmonic generation-active. Theoretical calculations indicate that 1 and 2 show direct band gaps, while 3 indirect.

Chalcohalides are attractive infrared (IR) nonlinear optical (NLO) materials because they can take advantages of the large second-harmonic generation (SHG) responses of chalcogenides and high laser-induced damage thresholds (LIDTs) of halides simultaneously, which are two correlated while contradictory indicators of the NLO performance. Here, a new chalcohalide, K2Ba3Ge3S9Cl2, was synthesized by a high temperature solid-state reaction, and it crystallizes in the polar noncentrosymmetric space group P63. The fundamental structural unit [Ge3S9]6– rings formed by three corner-sharing [GeS4]4– tetrahedra establish the framework, which further connects with {[KS3Cl]6–}∞ chains to build up the structure with Ba and K/Ba cations occupying the cavities. It exhibits a widest band gap of 3.69 eV among all Ba-based chalcohalides, and a high LIDT (339.3 MW/cm2), which is 28.8 times that of AgGaS2. It also exhibits a SHG intensity around 0.34 times that of AGS. These experimental results are verified by theoretical calculations on its electronic structure and optical properties.

Iron sulfides receive special interests as anode materials for lithium or sodium ion batteries in view of their low-cost, environmental benign, and high conductivities. Here, a combination of FeS2 microspheres and Fe3S4 microcubes with reduced graphene oxides (iron sulfides@rGO) is prepared by a facile in-situ hydrothermal method. As an anode material for lithium ion batteries, iron sulfides@rGO exhibits excellent lithium storage ability. It delivers a high initial discharge capacity of 1476.2 mA h/g at 100 mA/g, and 1189.6 mA h/g capacity can be maintained after 100 cycles. Most impressively, 800 mA h/g capacity can be remained after 1000 cycles even at 1 A/g.

Effective utilization of energy requires the storage and conversion device with high ability. For well-developed lithium ion batteries (LIBs) and highly developing sodium ion batteries (SIBs), this ability especially denotes to high energy and power densities. It's believed that the capacity of a full cell is mainly contributed by anode materials. So, to develop inexpensive anode materials with high capacity are meaningful for various rechargeable batteries' better applications. Iron is a productive element in the crust, and its oxides, sulfides, fluorides, and oxygen acid salts are extensively investigated as electrode materials for batteries. In view of the importance of electrode materials containing iron, this review summarizes the recent achievements on various binary iron sulfides (FeS, FeS2, Fe3S4, and Fe7S8)-type electrodes for batteries. The contents are mainly focused on their crystal structures, synthetic methods, and electrochemical performance. Moreover, the challenges and some improvement strategies are also discussed.

The all-solid-state lithium batteries using solid electrolytes are considered to be the new generation of devices for energy storage, which might be a key solution for power electric and hybrid electric vehicles in the future. This review focuses on the crystal structures and electrochemical properties of sulfide solid electrolytes. They are classified to several subgroups according to their chemical compositions, namely thiophosphates, halide thiophosphates, sulfide without phosphorus, and glassy sulfides electrolytes, which might be potential solid electrolytes in lithium batteries and may replace the currently used polymeric electrolytes for LIBs. Through discussion, this review provides an insight into future promising sulfide electrolytes.

Chalcogenides are extensively studied as infrared nonlinear optical materials, while rare-earth-based ones are scarcely explored. Here, two ternary rare-earth sulfides Ho3GaS6 (1) and Er3GaS6 (2), are obtained by high-temperature solid-state reactions. They are isostructural and crystallize in the orthorhombic noncentrosymmetric space group Cmc21. Their structures can be described as rare earth–S bonds constructed 3D framework, providing tetrahedral cavities for Ga atoms. Their optical band gaps are determined to be 3.03 (1) and 3.08 (2) eV, and their powder samples have no infrared absorption peaks between 400 and 4000 cm–1. Size-dependent second-harmonic generation measurements suggest that both of them are phase-matchable, and have the effects around 0.4 and 0.6 times that of AgGaS2 for their 150–210 μm samples. The structure-property relationship is also studied by structural analysis and theoretical calculations.

Recently, inorganic functional materials containing multiple anions have received extensive attention in view of their comprehensive physical performances, and chalcogenide borates are such one type of rarely explored novel materials. The combination of chalcogenides and borates are attractive in view of their advantages as potential second-order nonlinear optical materials. Here, borate sulfide Zn4B6O12S crystallized with the I 4 ¯ 3 m structure is synthesized using a solid-state reaction, and its structure features truncated octahedron. Its powder sample presents a largest second-harmonic generation around 1.9 × KDP at 1.604 μm, and its photocurrent is 2.1 μA/cm2, much higher than that of classical photoelectric material TiO2 (0.4 μA/cm2). Theoretical calculations on its electronic structure and optical properties are also performed.

Given the collaborative effect between different anions, compounds containing two types of anions can have improved physical performance compared with some aspects of those containing only one type of anion. To date, many such compounds have been investigated. This review focuses on metal chalcogenide halides, namely, M–Q–X (M = metal element; Q = S, Se, Te; X = F, Cl, Br, I) compounds. Although they have similar atomic radii, chalcogen atoms have much smaller electronegativities than those of its neighboring halogen atoms, which results in their different bonding styles. The inclusion of X − into chalcogenides can move their optical band gaps to higher values and their coordination polyhedra can become more distorted, albeit with little density change. These structural effects make metal chalcogenide halides a good choice to fine-tune the structures and physical properties of chalcogenides or halides. Several hundreds of metal chalcogenide halides already have been discovered. They demonstrate rich structures and versatile physical properties, enabling their diverse applications in the fields of solid-state electrolytes, second-order non-linear optics and thermoelectricity. Considering their flourishing development, this paper provides an overview of recent achievements in the structural chemistry and physical properties of metal chalcogenide halides.

In the past several years, many efforts have been made to develop polyanion-type cathode materials for sodium ion batteries by chemists and material scientists. These materials are one of the main types of promising cathodes though the studies are still in their infancy. This paper reviews almost all the important advances of polyanion-type cathodes on their syntheses, crystal structures, morphologies, electrochemical performance and Na redox mechanisms. It specifically focuses on their crystal chemistry and electrochemical behaviors. The contents are divided into several categories according to their chemical compositions. After introduction of the synthetic methods, phosphates (ortho-, pyro- and fluoro-), silicates, sulfates, and mixed anions type cathodes are summarized and discussed successively.

Cu3Mo2O9 nanorods (NRs) have been prepared via a facile hydrothermal method with subsequent heat treatment. The sample is characterized by the XRD, SEM, TEM, and XPS techniques. The results indicate that Cu3Mo2O9 NRs crystallize in the orthorhombic space group Pnma and have the diameters at around 100 nm. As the anode material for lithium-ion batteries, Cu3Mo2O9 NRs can deliver an initial discharge capacity of 1209 mAh/g at a current density of 300 mA/g in the potential window of 0.005–3 V, and a reversible capacity of 440 mAh/g can be maintained after 400 cycles. Furthermore, Cu3Mo2O9 NRs still have the capacity of 437 mAh/g even at 1 A/g. The improved electrochemical performance of Cu3Mo2O9 can be attributed to the effect of enhanced contact area and shortened Li+ ions’ transport distance between the Cu3Mo2O9 NRs and the electrolyte.

α -LiFeO 2 and its nanocomposite with porous carbon ( α- LiFeO 2 / PC) is prepared by a simple one-step solid-state method. They are characterized by powder X-ray diffraction, scanning electron microscope, transmission electron microscope, thermogravimetry, differential scanning calorimetry, X-ray photoelectron spectroscopy, Raman spectrum, and BET surface area analysis techniques. When composited with PC, α- LiFeO 2 particles with smaller sizes locate on the surface or insert in the pores of PC. α- LiFeO 2 /PC can deliver the first discharge capacity of 1830 mAh/g, and 792 mAh/g can be maintained after 120 cycles at 0.1 C. Its capacity can reach to 570 mAh/g after 120 cycles even at 1C. The facile preparation method and nice electrochemical data, together with cheap and eco-friendly iron sources, make α- LiFeO 2 /PC a promising anode material for lithium-ion batteries.

Four isostructural europium chalcogenides, EuZnGeS4 (1), EuGa2S4 (2), EuIn2S4 (3) and EuIn2Se4 (4), have been synthesized using a high-temperature solid-state method. Single-crystal X-ray diffraction analysis indicates that they crystallize in the orthorhombic space group Fddd with Z = 32. Their structures feature an MQ4 (M = Zn, Ge, Ga and In; Q = S and Se) tetrahedrally constructed 3D network, and Eu2+ ions occupy the bicapped trigonal prismatic cavities. Compounds 1–3 have optical band gaps of 2.26, 2.32 and 2.37 eV, respectively. Theory calculations indicate that 2, with an indirect band gap, can be tuned to 1, with a direct band gap, via simple chemical substitution.

Metal chalcogenides are extensively studied as infrared second-order nonlinear optical (NLO) materials. Among the candidates, ones containing cations with lone-pair electrons in the structure have received great interest in view of the lone-pair electrons’ special contribution to the NLO property. Here, we revisit such a sulfide Sb6Sb6S17 and study its NLO property, which represents a novel structure-type of NLO material. It exhibits phase-matchable second-harmonic generation activity, and the powder sample shows a laser-induced damage threshold (LIDT) around 3.2 times that of AgGaS2 when both have the particle sizes of 75–110 ​μm. Its optical energy gap is measured to be 1.92 ​eV and the powder sample has a transparency range from 0.65 to 25 ​μm. The electronic structure and optical property calculations are also performed.

Ferrous sulfide (FeS) particles dispersed in the pores of carbon (FeS/PC) from the polyacrylonitrile carbonization were prepared via a facile one-pot solid-state method, which was extensively characterized by XRD, SEM, TEM, Raman spectrum, and XPS techniques. As an anode material for lithium-ion batteries, this FeS/PC composite can achieve a high initial discharge capacity of 1428.8 mAh/g at 0.1 C, and can maintain 624.9 mAh/g capacity after 150 cycles. The porous carbon accommodates the volume change during the cycling, and the special structure of the FeS/PC composite results in its advanced electrochemical performance by enhancing the structure stability.

The γ-LiFeO2 micro-cubes were synthesized using a simple solid-state method. Their electrochemical performance as anode material for lithium ion batteries was firstly investigated. Pure γ-LiFeO2 without nanosizing or carbon coating can deliver the first discharge capacity of 1055.3 mAh/g, and 611.5 mAh/g can be maintained after 50 cycles, around 80 % of the second discharge capacity. γ-LiFeO2 also demonstrates nice rate capabilities. These results indicate that γ-LiFeO2 is a promising anode material candidate for lithium ion batteries. The charge/discharge mechanism was also investigated.

The Fe2SSe particles dispersed in the pores of carbon (Fe2SSe/PC) were prepared using a simple one-pot solid-state method, which were then characterized by XRD, SEM, TEM, XPS, and Raman spectrum techniques. As the anode material for lithium-ion batteries, Fe2SSe/PC displays an initial discharge capacity as high as 699.5 mAh/g at 0.1 C, and 327.9 mAh/g can be maintained after 200 cycles, much enhanced than those of pure Fe2SSe. The small particles of Fe2SSe wrapped in carbon can effectively buffer the volume expansion during charging/discharging to improve the electrochemical performance.

Three new ternary rare-earth zirconium chalcogenides, Ce 2 ZrSe 5 ( 1 ), Pr 2 ZrSe 5 ( 2 ) and Nd 2 ZrSe 5 ( 3 ), have been synthesized by a facile solid-state route with boron as the reducing reagent. They crystallize in the space group Pnma of the orthorhombic system, belonging to the U 3 Se 5 structure type. Their 3-D structures are constructed by parallel polyanionic {[ZrSe 5 ] 6– } n chains and LnSe 8 bicapped trigonal prisms. The magnetic susceptibilities' data indicate their antiferromagnetic-like behavior without magnetic order down to 2 K. The structural relationships among several similar structures are discussed, together with the lanthanide contraction in the Ln 2 ZrSe 5 system.

Novel 3-D network SeS x /NCPAN (nitrogen-doped carbonized polyacrylonitrile) ( x = 0.1 and 0) composites were prepared by one-step in situ solid-state method, directly heated the mixture of Se, S and PAN sealed in a quartz tube under vacuum, which was characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrum and X-ray photoelectron spectroscopy (XPS) techniques. It is discovered that SeS 0.1 is dispersed in the 3-D network of NCPAN. The reversible electrode operation of SeS 0.1 at ca. 1.1 V vs Li was identified with the capacity of 1387 mAh/g and around 600 mAh/g maintained after 20 cycles, demonstrating much better electrochemical performance than Se/NCPAN. This is the first study on one-step in-situ preparation of SeS x /NCPAN composites as the active cathode material for lithium–ion battery.

A series of CexFebalB6 ( $x=12$ , 14, 17, 19, and 23 wt%) ternary ribbons was prepared by melt-spinning. Magnetic properties and the microstructure of the Ce–Fe–B ribbons with different Ce contents were investigated. The X-ray diffraction results indicated that multiphase coexisted in the as-spun Ce–Fe–B ribbons, which contained Ce2Fe17, CeFe2, Ce-rich phase, Fe-rich phase, cerium oxide, and iron oxide. The magnetic properties, microstructure, and phase composition of the ribbons were directly affected by the cerium content. The magnetic properties could be obtained by exchange coupling between the hard and soft magnetic phases in the pure ternary Ce–Fe–B ribbons. Furthermore, by heat treatment, the magnetic properties of the as-spun Ce–Fe–B ribbons could be optimized. The highest magnetic properties of $H_{{\mathrm{cj}}}=6.2$ kOe, $B_{\mathrm{ r}}=6.9$ kGs, and $(BH)_{\mathrm{ m}}=8.6$ MGOe were obtained in Ce17FebalB6 magnets.

Inorganic compounds with mixed anions attract broad interest recently in view of their rich structural chemistry and physical performance. Specifically, chalcogenide borates are receiving increasing attention though they are in their infancy. Here, the chalcogenide borate Zn8Se2(BO2)12 is revisited by focusing on its second-harmonic generation (SHG) activity. Its sodalite cage structure is elucidated in detail and correlates with the SHG behavior. Its optical band gap is determined to be 4.42 ​eV. Theoretical calculations on its electronic structure and optical properties are performed and the results are well consistent with the experimental ones. Besides, the structural chemistry with related structures and possible SHG improvement strategies are discussed.

Second-order nonlinear optical (NLO) materials in the middle infrared (MIR) region have attracted widespread interest in view of their importance and deficiency to the laser market’s requirement. Here, we report a new MIR NLO material Eu8Sn4Se20 (1), which represents a new structure type one and the pioneer of the (MII2MIVQ5)n (MII ​= ​divalent alkali-earth metal, Eu, Yb, Pb, and Sn; MIV ​= ​Si, Ge, Sn; Q ​= ​S, Se, Te. n ​= ​1, 2, 4) family. It demonstrates obvious second-harmonic generation (SHG) activity. Its optical band gap is determined to be 1.30 ​eV and its magnetic data exhibits antiferromagnetic-type behavior. Its electronic structure is performed as well.

As a novel composite material, metal-organic frameworks have a great application in supercapacitor. In the current study, based on mixed ligands of 5-nitroisophthalic acid (H2NIPA) and 1,3-di(4-pyridyl)propane (1,3-dpp), [Zn3(NIPA)3(1,3-dpp)(H2O)2·H2O]n HU14 and two isostructural [M(NIPA)(1,3-dpp)(H2O)·2H2O] (M ​= ​Zn for HU15, M ​= ​Ni for HU16) were prepared by hydrothermal reaction. The single crystal X-ray diffraction determined that HU14 contains three different zinc ions to construct a non-porous 3D network, while the isostructure HU15 and HU16 display different center metal ions but identical porous frameworks with large brick-like channels. Due to different cations and diverse architectures, these three materials show different electrochemical properties, Ni-MOF(HU16) displays a better performance (The specific capacitance of the complexes HU14, HU15 and HU16 are 22.8 ​F ​g−1, 27.86 ​F ​g−1 and 307.4 ​F ​g−1 at 1 ​A ​g−1 and remains 60.35%,71.79% and 51% of their capacitance at a high current density of 8 ​A ​g−1, respectively.) The excellent electrochemical property may be ascribed to the intrinsic nature of Ni-MOF, unique structural feature and the particles of nanoscale size.

Mixed transition metal sulfides attract much interests for their potentials as electrode materials for rechargeable batteries in view of their high theoretical specific capacities, low costs, and environmental friendliness. Combining the porous structure and high stability of ZIF, here we obtain a CuCo2S4 material with zeolite imidazole ester structure by using ZIF-67 as the precursor. The obtained particles are hollow dodecahedra with size of about 500 nm and shell thickness of about 30 nm. As an anode material for lithium ion batteries, CuCo2S4@C dodecahedra can deliver an initial discharge capacity of 1715.0 mAh g−1 at 100 mA g−1, and a reversible capacity of 1100.8 mAh g−1 can be maintained after 200 cycles. The reason caused the high-performance electrochemical activities is also explored. This work presents a nice routine to synthesize metal–organic frameworks–derived carbon-based nanocomposites for energy storage.

This study is concerned with the ternary compounds RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x

In our investigation of rare earth sulfides in the AE-RE-Sn-S (AE = alkaline-earth, RE = rare earth) system, three isostructural quaternary sulfides have been obtained. These compounds adopt the Eu5Zr3S12 structure type and crystallize in the P-62m space group (no. 189); the crystal data are as follows: Sr2Y2.67Sn3S12, a = 11.600(7) A, c = 3.948(3) A, Z = 1; Ca3La2Sn3S12, a = 11.5997(6) A, c = 3.9407(4) A, Z = 1; Ca3Er2Sn3S12, a = 11.448(3) A, c = 3.8780(11) A, Z = 1. Single-crystal analysis indicated that the crystal structures consist of three types of building block: RES7, AES6, and SnS6 units. The structure of Sr2Y2.67Sn3S12 is characterized by the [ Y 3 S ( 1 ) 12 / 2 S ( 2 ) 3 S ( 3 ) 3 ] 1 ∞ trimer-chains along the c direction, which are connected into a 3-dimensional framework by the Sn atoms via S(1), S(2), and S(3), with Sr atoms filling in the channels along the c direction. The optical band gap of 1.45 eV for Ca3La2Sn3S12 was deduced from the diffuse reflectance spectrum.

Fe2SiS4 and its composite with porous carbon from carbonization of PAN porous carbon (PC) were synthesized using one-pot method, which were characterized by XRD, SEM, TEM, XPS and Raman spectrum techniques. Their electrochemical data as anode materials for lithium-ion batteries were firstly studied. The results indicate that the Fe2SiS4 particles dispersed on the surface or in the pores of PC has the 1st capacity of 961.9[Formula: see text]mAh/g, and around 400[Formula: see text]mAh/g capacity can be still maintained after 50 cycles at 0.2C, much enhanced electrochemical performance than those for pure Fe2SiS4.