Synthesis and crystal structure analysis of Sr8Cu3In4N5 and Sr0.53Ba0.47CuN

Single crystals of new quaternary compounds Sr₈Cu₃In₄N₅ and Sr_0.53Ba_0.47CuN were prepared, respectively, from a Sr–Cu–In–Na melt under 7 MPa of N₂ and from a Sr–Ba–Cu–In–Na melt under 0.5 MPa of N₂ by slow cooling from 1023 to 823 K. The crystal structures were determined by single-crystal X-ray diffraction. Sr₈Cu₃In₄N₅ has an orthorhombic structure (space group, Immm, Z=2, a=3.8161(5) Å, b=12.437(2) Å, c=18.902(2) Å), and is isostructural with Ba₈Cu₃In₄N₅. It contains nitridocuprates of isolated units ⁰[CuN₂] and one-dimensional linear chains _∝¹[CuN_2/2] and one-dimensional indium clusters _∝¹[In₂In_2/2]. Sr_0.53Ba_0.47CuN crystallizes in an orthorhombic cell, space group Pbcm, Z=4, a=5.4763(7) Å, b=9.2274(12) Å, c=9.0772(12) Å. The structure contains infinite zig-zag chains _∝¹[CuN_2/2] which kink at every second nitrogen atom.     

High-Pressure High-Temperature Synthesis of Mixed Nitridosilicatephosphates and Luminescence of AESiP3N7:Eu2+ (AE=Sr,Ba)

Tetrahedra-based nitrides with network structures have emerged as versatile materials with a broad spectrum of properties and applications. Both nitridosilicates and nitridophosphates are well-known examples of such nitrides that upon doping with Eu²⁺ exhibit intriguing luminescence properties, which makes them attractive for applications. Nitridosilicates and nitridophosphates show manifold structural variability; however, no mixed nitridosilicatephosphates except SiPN₃ and SiP2N4NH have been described so far. The compounds AESiP₃N₇ (AE=Sr, Ba) were synthesized by a high-pressure high-temperature approach using the multianvil technique (8 GPa, 1400–1700 °C) starting from the respective alkaline earth azides and the binary nitrides P₃N₅ and Si₃N₄. The latter were activated by NH₄F, probably acting as a mineralizing agent. SrSiP₃N₇ and BaSiP₃N₇ were obtained as single crystals. They crystallized in the barylite-1O (M=Sr) and barylite-2O structure types (M=Ba), respectively, with P and Si being occupationally disordered. Cation disorder was further supported by solid-state NMR spectroscopy and energy-dispersive X-ray spectroscopy (EDX) mapping of BaSiP₃N₇ with atomic resolution. Upon doping with Eu²⁺, both compounds showed blue emission under UV excitation.     

Synthese und Kristallstruktur des ersten Oxonitridoborates — Sr3[B3O3N3]

Synthesis and Crystal Structure of the First Oxonitridoborate — Sr₃[B₃O₃N₃] The cyclotri(oxonitridoborate) Sr₃[B₃O₃N₃] was synthesized at 1450 °C as coarsely crystalline colourless crystals by the reaction of SrCO₃ with poly(boron amide imide) using a radiofrequency furnace. The structure was solved by single‐crystal X‐ray diffractometry (Sr₃[B₃O₃N₃], Z = 4, P2₁/n, a = 663.16(2), b = 786.06(2), c = 1175.90(3) pm, η = 92.393(1)°, R1= 0.0441, wR2 = 0.1075, 1081 independent reflections, 110 refined parameters). Besides Sr²⁺ there are hitherto unknown cyclic [B₃O₃N₃]^6— ions (B—N 143.7(10) — 149.1(9) pm, B—O 140.5(8) — 141.4(8) pm).     

Inverse-Tunable Red Luminescence and Electronic Properties of Nitridoberylloaluminates Sr2−xBax[BeAl3N5]:Eu2+ (x=0–2)

The nitridoberylloaluminate Ba₂[BeAl₃N₅]:Eu²⁺ and solid solutions Sr_2−xBa_x[BeAl₃N₅]:Eu²⁺ (x=0.5, 1.0, 1.5) were synthesized in a hot isostatic press (HIP) under 50 MPa N₂ atmosphere at 1200 °C. Ba₂[BeAl₃N₅]:Eu²⁺ crystallizes in triclinic space group (no. 2) (Z=2, a=6.1869(10), b=7.1736(13), c=8.0391(14) Å, α=102.754(8), β=112.032(6), γ=104.765(7)°), which was determined from single-crystal X-ray diffraction data. The lattice parameters of the solid solution series have been obtained from Rietveld refinements and show a nearly linear dependence on the atomic ratio Sr : Ba. The electronic properties and the band gaps of M₂[BeAl₃N₅] (M=Sr, Ba) have been investigated by a combination of soft X-ray spectroscopy and density functional theory (DFT) calculations. Upon irradiation with blue light (440–450 nm), the nitridoberylloaluminates exhibit intense orange to red luminescence, which can be tuned between 610 and 656 nm (fwhm=1922–2025 cm⁻¹ (72–87 nm)). In contrast to the usual trend, the substitution of the smaller Sr²⁺ by larger Ba²⁺ leads to an inverse-tunable luminescence to higher wavelengths. Low-temperature luminescence measurements have been performed to exclude anomalous emission.     

Sr5[NbN4]N ‐ A Nitridoniobate(V) Nitride Containing Isolated [NbN4]7‐ Tetrahedra and Octahedral Chains 1(Sr4Sr2/2N7+)

Sr₅[NbN₄]N (transparent, red single crystals) was synthesized by reaction of Sr2N with Nb under nitrogen at ambient pressure and 1223 K. The crystal structure was solved and refined in the space group Pbcm (no. 57), Z = 4, with lattice constants a = 646.6(3) pm, b = 1792.5(9) pm, c = 729.8(4) pm, and R = 0.019, wR² = 0.034. The crystal structure contains both isolated tetrahedra [NbN₄]^7‐ as well as chains of corner sharing octahedra 1(Sr₄Sr_2/2N⁷⁺). Strontium is irregularly coordinated by nitrogen (CN = 4 ‐ 6, Sr‐N: 252.3(4) ‐ 340.8(3) pm); nitrogen is located in a distorted octahedral environment by strontium and niobium (Nb‐N: 194.5(4) ‐ 199.2(2) pm). By formal reduction of the structural building units to their centers a close structural relationship to both the NiAs and the CaSi type structure is evident.     

Fabrication of novel Ag/g-C3N4 electrode for resveratrol sensors

Ag/g-C₃N₄ is fabricated and used as an electrode for determining trans-resveratrol concentration. The compositional and structural characteristics of the as-fabricated Ag/g-C₃N₄ are studied through X-ray diffraction, transmission electron microscopy, and energy dispersive spectroscopy. Additionally, the electrochemical behavior of Ag/g-C₃N₄ is investigated using cyclic voltammetry. According to the experimental results, 1 wt%Ag/g-C₃N₄ exhibits an oxidation peak at 0.48 V, with a low detection limit (1.88 × 10⁻⁷ M) and satisfactory correlation coefficient (0.9975), suggesting that the proposed Ag/g-C₃N₄ electrode can be successfully used for detecting trans-resveratrol.     

Structural Influence of Lone Pairs in GeP2N4, a Germanium(II) Nitridophosphate

Owing to their widespread properties, nitridophosphates are of high interest in current research. Explorative high-pressure high-temperature investigations yielded various compounds with stoichiometry MP₂N₄ (M=Be, Ca, Sr, Ba, Mn, Cd), which are discussed as ultra-hard or luminescent materials, when doped with Eu²⁺. Herein, we report the first germanium nitridophosphate, GeP₂N₄, synthesized from Ge₃N₄ and P₃N₅ at 6 GPa and 800 °C. The structure was determined by single-crystal X-ray diffraction and further characterized by energy-dispersive X-ray spectroscopy, density functional theory calculations, IR and NMR spectroscopy. The highly condensed network of PN₄-tetrahedra shows a strong structural divergence to other MP₂N₄ compounds, which is attributed to the stereochemical influence of the lone pair of Ge²⁺. Thus, the formal exchange of alkaline earth cations with Ge²⁺ may open access to various compounds with literature-known stoichiometry, however, new structures and properties.     

Influences of Sr2+ Doping on Microstructure,Giant Dielectric Behavior,and Non-Ohmic Properties of CaCu3Ti4O12/CaTiO3 Ceramic Composites

The microstructure, dielectric response, and nonlinear current-voltage properties of Sr²⁺-doped CaCu₃Ti₄O₁₂/CaTiO₃ (CCTO/CTO) ceramic composites, which were prepared by a solid-state reaction method using a single step from the starting nominal composition of CCTO/CTO/xSrO, were investigated. The CCTO and CTO phases were detected in the X-ray diffraction patterns. The lattice parameter increased with increasing Sr²⁺ doping concentration. The phase compositions of CCTO and CTO were confirmed by energy-dispersive X-ray spectroscopy with elemental mapping in the sintered ceramics. It can be confirmed that most of the Sr²⁺ ions substituted into the CTO phase, while some minor portion substituted into the CCTO phase. Furthermore, small segregation of Cu-rich was observed along the grain boundaries. The dielectric permittivity of the CCTO/CTO composite slightly decreased by doping with Sr²⁺, while the loss tangent was greatly reduced. Furthermore, the dielectric properties in a high-temperature range of the Sr²⁺-doped CCTO/CTO ceramic composites can be improved. Interestingly, the nonlinear electrical properties of the Sr²⁺-doped CCTO/CTO ceramic composites were significantly enhanced. The improved dielectric and nonlinear electrical properties of the Sr²⁺-doped CCTO/CTO ceramic composites were explained by the enhancement of the electrical properties of the internal interfaces.     

钾离子掺杂对石墨型氮化碳光催化剂能带结构及光催化性能的影响

以双氰胺和氢氧化钾为原料制备了能带可控的钾离子掺杂石墨型氮化碳(g-C3N4)光催化剂,并与碱处理的g-C3N4及g-C3N4/KOH复合催化剂进行了对比。采用X射线衍射(XRD)光谱、紫外-可见(UV-Vis)光谱、傅里叶变换红外(FTIR)光谱、N2吸附、电感耦合等离子体-原子发射光谱(ICP-AES)、荧光(PL)光谱、X 光电子能谱(XPS)等分析手段对制备的催化剂进行了表征。结果表明,钾离子含量对氮化碳催化剂的价带及导带位置有显著影响。此外,钾离子的引入抑制了氮化碳晶粒的生长,提高了氮化碳的比表面积以及对可见光的吸收,降低了光生电子-空穴对的复合几率。以染料罗丹明B的降解为探针反应系统研究了钾离子掺杂对g-C3N4在可见光下催化性能的影响,研究了光催化反应机理。结果表明,钾离子掺杂后氮化碳的光催化性能显著提高。制备的钾离子掺杂氮化碳催化剂表现出良好的结构及催化稳定性。     

C/g-C3N4/MoS2复合材料的制备及光催化性能

首先以尿素和葡萄糖为前驱体,通过热缩合方法制备了C/g-C₃N₄,然后利用溶剂热法合成C/g-C₃N₄/MoS₂三元复合材料。通过不同的手段对其进行了表征,结果表明,与C/g-C₃N₄相比,该三元复合材料不仅具有更强的光吸收性能和更大的表面积,而且更有利于电子的转移。同时对其可见光催化降解甲基橙性能进行研究,结果发现,C/g-C₃N₄/MoS₂-2.0%复合材料(含有质量分数为2.0%的MoS₂)表现出最高的反应速率常数(0.0086 min^-1),分别为g-C₃N₄/MoS₂-2.0%(0.0015 min^-1)和C/g-C₃N₄(0.0036min^-1)的5.7倍和2.3倍。     

Ammonothermal Synthesis,Crystal Structure,and Vibrational Properties of the Doubly Deprotonated Calcium Guanidinate,CaC(NH)3

We report the synthesis of the doubly deprotonated calcium guanidinate, CaC(NH)₃, from liquid ammonia and its crystal structure as determined from powder X-ray and neutron diffraction, and confirmed using CNH elemental analysis and infrared (IR) spectroscopy data. CaC(NH)₃ crystallizes in the hexagonal system with space group P6₃/m (no. 176) with Z = 2 and a = 5.2666(13) Å, c = 6.5881(6) Å and V = 158.25(4) ų. We also compare the structural similarities and differences of this phase with the isotypical strontium and ytterbium compounds.     

制备方法对Al2O3掺杂Pt/WO3-ZrO2催化剂上正庚烷异构化反应的影响

采用恒pH法和非恒pH法制备了Al₂O₃掺杂的Pt/WO₃/ZrO₂催化剂,并用N₂吸附-脱附、X射线衍射、紫外-可见漫反射、CO化学吸附、X射线光电子能谱、²⁷Al魔角旋转核磁共振和吡啶吸附红外等技术对催化剂进行了表征.结果表明,相比于非恒pH法制备的催化剂,恒pH法制备的催化剂具有较高的比表面积和Pt分散度,在H₂气氛中产生更多的B酸位,从而表现出更高的催化正庚烷临氢异构化反应活性; 在200℃和质量空速0.9h^-1的反应条件下,正庚烷转化率达70.0%,明显高于非恒pH法制备的催化剂(43.5%).     

Neue anorganische Ringsysteme. XV. Die sechsgliedrigen Ringsysteme PIIISi2N3, [PvSi2N3]⊕ und PvSi2N3

Novel Inorganic Ring Systems. XV. The Sixmembered Ring Systems P^IIISi₂N₃, [P^VSi₂N₃]^⊕ and P^VSi₂N₃ Compounds I–X of the sixmembered ring system PSi₂N₃ with phosphorus in different oxidation and bond numbers, collected in scheme 1, have been prepared for the first time and confirmed in their structure by elemental analysis as well as by infrared and ¹H and ³¹P spectroscopy.     

MoS2/g-C3N4复合材料的制备及可见光催化性能

首先在N-甲基吡咯烷酮溶液中超声剥离得到少层的MoS₂,将其与石墨相氮化碳（g-C₃N₄）复合,制得MoS₂/g-C₃N₄复合材料。采用X射线衍射（XRD）,扫描电镜（SEM）,X射线光电子能谱（XPS）,傅里叶变换红外光谱（FTIR）,Raman光谱,紫外-可见漫反射吸收光谱（DRS）和光致荧光（PL）技术对复合材料进行表征。可见光下考察MoS₂/g-C₃N₄复合材料光催化降解罗丹明B（RhB）的活性,结果表明：将少量MoS₂与g-C₃N₄复合可明显提高光催化活性,且1%（w/w）MoS₂/g-C₃N₄复合物的光催化活性最高,可能的原因是MoS₂和g-C₃N₄匹配的能带结构,增大了界面间电荷的传输,降低了光生电子-空穴的复合,进而提高了光催化活性。     

A new iron oxophosphate SrFe3(PO4)3O with chain-like structure

A new strontium iron oxophosphate SrFe₃(PO₄)₃O was synthesized by the solid state method and its structure was studied by single-crystal X-ray and electron diffraction, high-resolution electron microscopy, Mössbauer and IR spectroscopy. The compound crystallizes in a monoclinic system (space group P2₁/m) with unit-cell parameters: a = 7.5395(7), b = 6.3476(7) c = 10.3161(13) Å, β = 99.740(9)°. The structure of SrFe₃(PO₄)₃O represents a new structural type and is made up of isolated PO₄ tetrahedra and FeO_n polyhedra connected via common vertices and edges to form a 3D framework. Iron cations occupy three crystallographically independent sites with different oxygen environment: Fe1 and Fe2 occupy two octahedral sites, and Fe3 is five-coordinated. Two particularities of this structure are remarkably mentioned: the isolated {FeO₆}_n octahedral chains along the b direction and the five coordinated environment for the Fe3 position. Mössbauer spectroscopy confirmed the presence of only high-spin Fe³⁺ cations in two types of coordination environment. The IR-data show the presence of only PO₄³⁻ groups.     

MoS_2/g-C_3N_4复合材料的制备及可见光催化性能

首先在N-甲基吡咯烷酮溶液中超声剥离得到少层的MoS_2,将其与石墨相氮化碳(g-C_3N_4)复合,制得MoS_2/g-C_3N_4复合材料。采用X射线衍射(XRD),扫描电镜(SEM),X射线光电子能谱(XPS),傅里叶变换红外光谱(FTIR),Raman光谱,紫外-可见漫反射吸收光谱(DRS)和光致荧光(PL)技术对复合材料进行表征。可见光下考察MoS_2/g-C_3N_4复合材料光催化降解罗丹明B(Rh B)的活性,结果表明:将少量MoS_2与g-C_3N_4复合可明显提高光催化活性,且1%(w/w)MoS_2/g-C_3N_4复合物的光催化活性最高,可能的原因是MoS_2和g-C_3N_4匹配的能带结构,增大了界面间电荷的传输,降低了光生电子-空穴的复合,进而提高了光催化活性。     

钙铝石涂层对整体型钙钛矿氧化物催化剂活性和热稳定性的影响

 采用固相反应法合成了钙铝石材料 12SrO•7Al2O3, 并以此作为涂层制备了堇青石蜂窝陶瓷型 La0.8Sr0.2MnO3 整体催化剂, 在不同温度 (850~1 050 oC) 下对该催化剂进行了热处理, 并采用 N2 吸附-脱附、X 射线衍射和扫描电镜等手段对其进行了表征, 考察了其催化甲基丙烯酸甲酯燃烧反应的活性. 结果表明, 12SrO•7Al2O3 作为涂层明显改善了整体催化剂的热稳定性, 在 850 oC 下焙烧 6 h 后, 含有 12SrO•7Al2O3 涂层的整体催化剂在 260 oC 即可将甲基丙烯酸甲酯完全转化. 12SrO•7Al2O3 涂层可避免 La0.8Sr0.2MnO3 活性组分与堇青石的接触, 减轻了活性组分在催化剂表面的烧结, 有利于保持 La0.8Sr0.2MnO3 活性组分的晶体结构和分散度, 提高整体催化剂的活性和热稳定性.     

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M2+ (M=Ca,Sr) by Sc3+ and U3+

Based on the known linking options of their fundamental building unit, that is the SiN₄ tetrahedron, nitridosilicates belong to the inorganic compound classes with the greatest structural variability. Although facilitating the discovery of novel Si–N networks, this variability represents a challenge when targeting non‐stoichometric compounds. Meeting this challenge, a strategy for targeted creation of vacancies in highly condensed nitridosilicates by exchanging divalent M²⁺ for trivalent M³⁺ using the ion exchange approach is reported. As proof of concept, the first Sc and U nitridosilicates were prepared from α‐Ca₂Si₅N₈ and Sr₂Si₅N₈. Powder X‐ray diffraction (XRD) and synchrotron single‐crystal XRD showed random vacancy distribution in Sc_0.2Ca_1.7Si₅N₈, and partial vacancy ordering in U_0.5xSr_2?0.75xSi₅N₈ with x≈1.05. The high chemical stability of U nitridosilicates makes them interesting candidates for immobilization of actinides.     

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M2+ (M=Ca,Sr) by Sc3+ and U3+

Based on the known linking options of their fundamental building unit, that is the SiN₄ tetrahedron, nitridosilicates belong to the inorganic compound classes with the greatest structural variability. Although facilitating the discovery of novel Si–N networks, this variability represents a challenge when targeting non‐stoichometric compounds. Meeting this challenge, a strategy for targeted creation of vacancies in highly condensed nitridosilicates by exchanging divalent M²⁺ for trivalent M³⁺ using the ion exchange approach is reported. As proof of concept, the first Sc and U nitridosilicates were prepared from α‐Ca₂Si₅N₈ and Sr₂Si₅N₈. Powder X‐ray diffraction (XRD) and synchrotron single‐crystal XRD showed random vacancy distribution in Sc_0.2Ca_1.7Si₅N₈, and partial vacancy ordering in U_0.5xSr_2?0.75xSi₅N₈ with x≈1.05. The high chemical stability of U nitridosilicates makes them interesting candidates for immobilization of actinides.     

BaP6N10NH:Eu2+ as a Case Study–An Imidonitridophosphate Showing Luminescence

Barium imidonitridophosphate BaP₆N₁₀NH was synthesized at 5 GPa and 1000 °C with a high-pressure high-temperature approach using the multianvil technique. Ba(N₃)₂, P₃N₅ and NH₄Cl were used as starting materials, applying a combination of azide and mineralizer routes. The structure elucidation of BaP₆N₁₀NH (P6₃, a=7.5633(11), c=8.512(2) Å, Z=2) was performed by a combination of transmission electron microscopy and single-crystal diffraction with microfocused synchrotron radiation. Phase purity was verified by Rietveld refinement. ¹H and ³¹P solid-state NMR and FTIR spectroscopy are consistent with the structure model. The chemical composition was confirmed by energy-dispersive X-ray spectroscopy and CHNS analyses. Eu²⁺-doped samples of BaP₆N₁₀NH show blue emission upon excitation with UV to blue light (λ_em=460 nm, fwhm=2423 cm⁻¹) representing unprecedented Eu²⁺-luminescence of an imidonitride.