The Topochemical Pseudomorphosis of a Chloride into a Bismuthide

The heterogeneous reaction of crystals of the novel intermetallic subhalide Bi₁₂Rh₃Cl₂ with a solution of n‐butyllithium at 70 °C led to the complete topochemical exchange of chloride ions for bismuth atoms, that is, the transformation into the isostructural metastable intermetallic superconductor Bi₁₄Rh₃. The crystals underwent the reductive pseudomorphosis almost unchanged except some fissures perpendicular to the a‐axis. Detailed inspections of the transformed crystals by electron microscopy indicated no volume defects that would indicate internal chemical reactions. Thus, extensive mass transport must have occurred through the seemingly dense crystal structure. An efficient transport mechanism, based on an unusual breathing mode of the three‐dimensional network formed by edge‐sharing [RhBi₈] cubes and antiprisms, is proposed. The replacement of ionic interaction in the chloride by metallic bonding in the binary intermetallic compound closes the pseudo gap in the density of states at the Fermi level. As a result, the rod‐packing of conducting, yet electrically isolated strands of [RhBi₈] cubes in Bi₁₂Rh₃Cl₂ turns into the three‐dimensional metal Bi₁₄Rh₃.     

Low‐Temperature Topochemical Transformation of Bi13Pt3I7 into the New Layered Honeycomb Metal Bi12Pt3I5

Ordered single‐crystals of the metallic subiodide Bi₁₃Pt₃I₇ were grown and treated with n‐butyllithium. At 45 °C, complete pseudomorphosis to Bi₁₂Pt₃I₅ was achieved within two days. The new compound is air‐stable and contains the same ${{{\hfill 2\atop \hfill \infty }}}$ [(PtBi_8/2)₃I]ⁿ⁺ honeycomb nets and iodide layers as the starting material Bi₁₃Pt₃I₇, but does not include ${{{\hfill 1\atop \hfill \infty }}}$ [BiI₂I_4/2]^? iodidobismuthate strands. Electron microscopy and X‐ray diffraction studies of solid intermediates visualize the process of the topochemical crystal‐to‐crystal transformation. In the electronic band structures of Bi₁₃Pt₃I₇ and Bi₁₂Pt₃I₅, the vicinities of the Fermi levels are dominated by the intermetallic fragments. Upon the transformation of Bi₁₃Pt₃I₇ into Bi₁₂Pt₃I₅, the intermetallic part is oxidized and the Fermi level is lowered by 0.16 eV. Whereas in Bi₁₃Pt₃I₇ the intermetallic layers do not interact across the iodidobismuthate spacers (two‐dimensional metal), they couple in Bi₁₂Pt₃I₅ and form a three‐dimensional metal.     

An Ultrastable Anode for Long‐Life Room‐Temperature Sodium‐Ion Batteries

Sodium‐ion batteries are important alternative energy storage devices that have recently come again into focus for the development of large‐scale energy storage devices because sodium is an abundant and low‐cost material. However, the development of electrode materials with long‐term stability has remained a great challenge. A novel negative‐electrode material, a P2‐type layered oxide with the chemical composition Na_2/3Co_1/3Ti_2/3O₂, exhibits outstanding cycle stability (ca. 84.84 % capacity retention for 3000 cycles, very small decrease in the volume (0.046 %) after 500 cycles), good rate capability (ca. 41 % capacity retention at a discharge/charge rate of 10 C), and a usable reversible capacity of about 90 mAh g^?1 with a safe average storage voltage of approximately 0.7 V in the sodium half‐cell. This P2‐type layered oxide is a promising anode material for sodium‐ion batteries with a long cycle life and should greatly promote the development of room‐temperature sodium‐ion batteries.     

Scalable Room‐Temperature Synthesis of Mesoporous Nanocrystalline ZnMn2O4 with Enhanced Lithium Storage Properties for Lithium‐Ion Batteries

In this work, we put forward a facile yet efficient room‐temperature synthetic methodology for the smart fabrication of mesoporous nanocrystalline ZnMn₂O₄ in macro‐quality from the birnessite‐type MnO₂ phase. A plausible reduction/ion exchange/re‐crystallization mechanism is tentatively proposed herein for the scalable synthesis of the spinel phase ZnMn₂O₄. When utilized as a high‐performance anode for advanced Li‐ion battery (LIB) application, the as‐synthesized nanocrystalline ZnMn₂O₄ delivered an excellent discharge capacity of approximately 1288 mAh g^?1 on the first cycle at a current density of 400 mA g^?1, and exhibited an outstanding cycling durability, rate capability, and coulombic efficiency, benefiting from its mesoporous and nanoscale structure, which strongly highlighted its great potential in next‐generation LIBs. Furthermore, the strategy developed here is very simple and of great importance for large‐scale industrial production.     

Low‐Temperature Solution Synthesis of Few‐Layer 1T ′‐MoTe2 Nanostructures Exhibiting Lattice Compression

Molybdenum ditelluride, MoTe₂, is emerging as an important transition‐metal dichalcogenide (TMD) material because of its favorable properties relative to other TMDs. The 1T ′ polymorph of MoTe₂ is particularly interesting because it is semimetallic with bands that overlap near the Fermi level, but semiconducting 2H‐MoTe₂ is more stable and therefore more accessible synthetically. Metastable 1T ′‐MoTe₂ forms directly in solution at 300 °C as uniform colloidal nanostructures that consist of few‐layer nanosheets, which appear to exhibit an approx. 1 % lateral lattice compression relative to the bulk analogue. Density functional theory calculations suggest that small grain sizes and polycrystallinity stabilize the 1T ′ phase in the MoTe₂ nanostructures and suppress its transformation back to the more stable 2H polymorph through grain boundary pinning. Raman spectra of the 1T ′‐MoTe₂ nanostructures exhibit a laser energy dependence, which could be caused by electronic transitions.     

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

Little is known about the pathway of room‐temperature formation of ternary CdTeSe magic‐size clusters (MSCs) obtained by mixing binary CdTe and CdSe induction period samples containing binary precursor compounds (PCs) of MSCs, monomers (Ms), and fragments (Fs). Also, unestablished are dispersion effects that occur when as‐mixed samples (without incubation) are placed in toluene (Tol) and octylamine (OTA) mixtures. The resulting ternary MSCs, exhibiting a sharp optical absorption peak at 399 nm, are labelled CdTeSe MSC‐399, and their PCs are referred to as CdTeSe PC‐399. When the amount of OTA is relatively small, single‐ensemble MSC‐399 evolved without either binary CdTe or CdSe MSCs. When the OTA amount is relatively large, CdTe MSC‐371 appeared initially and then disappeared, while single‐ensemble MSC‐399 developed more deliberately. The larger the OTA amount, the more slowly these changes proceeded. The substitution reaction of CdTe PC + CdSe M/F?CdTeSe PC‐399 + CdTe M/F is proposed to be rate‐determining for the MSC‐399 formation in a Tol and OTA mixture. This study provides further understanding of the transformation pathway between MSCs.     

Type-II Clathrate Na24-δGe136 from a Redox-Preparation Route

The metastable type-II clathrate Na_24-δGe₁₃₆ was obtained from Na₁₂Ge₁₇ by applying a two-step procedure. At first, Na₁₂Ge₁₇ was reacted at 70 °C with a solution of benzophenone in the ionic liquid (IL) 1,3-dibutyl-2-methylimidazolium-bis(trifluoromethylsulfonyl) azanide. The IL was inert towards Na₁₂Ge₁₇, but capable of dissolving the sodium salts formed in the redox reaction. By annealing at 340 °C under an argon atmosphere, the X-ray amorphous intermediate product was transformed to crystalline Na_24-δGe₁₃₆ (δ≈2) and α-Ge in an about 1 : 1 mass ratio. The product was characterized by X-ray powder diffraction, chemical analysis, and ²³Na solid-state NMR spectroscopy. Metallic properties of Na_24-δGe₁₃₆ were revealed by a significant Knight shift of the ²³Na NMR signals and by a Pauli-paramagnetic contribution to the magnetic susceptibility. At room temperature, Na_24-δGe₁₃₆ slowly ages, with a tendency to volume decrease and sodium loss.     

Single Lithium‐Ion Conducting Polymer Electrolytes Based on a Super‐Delocalized Polyanion

A novel single lithium‐ion (Li‐ion) conducting polymer electrolyte is presented that is composed of the lithium salt of a polyanion, poly[(4‐styrenesulfonyl)(trifluoromethyl(S‐trifluoromethylsulfonylimino)sulfonyl)imide] (PSsTFSI^?), and high‐molecular‐weight poly(ethylene oxide) (PEO). The neat LiPSsTFSI ionomer displays a low glass‐transition temperature (44.3 °C; that is, strongly plasticizing effect). The complex of LiPSsTFSI/PEO exhibits a high Li‐ion transference number (t_Li⁺=0.91) and is thermally stable up to 300 °C. Meanwhile, it exhibits a Li‐ion conductivity as high as 1.35×10^?4 S cm^?1 at 90 °C, which is comparable to that for the classic ambipolar LiTFSI/PEO SPEs at the same temperature. These outstanding properties of the LiPSsTFSI/PEO blended polymer electrolyte would make it promising as solid polymer electrolytes for Li batteries.     

A Versatile Room‐Temperature Route to Di‐ and Trisubstituted Allenes Using Flow‐Generated Diazo Compounds

A copper‐catalyzed coupling reaction between flow‐generated unstabilized diazo compounds and terminal alkynes provides di‐ and trisubstituted allenes. This extremely mild and rapid transformation is highly tolerant of several functional groups.     

A Room‐Temperature Verwey‐type Transition in Iron Oxide,Fe5O6

Functional oxides whose physicochemical properties may be reversibly changed at standard conditions are potential candidates for the use in next‐generation nanoelectronic devices. To date, vanadium dioxide (VO₂) is the only known simple transition‐metal oxide that demonstrates a near‐room‐temperature metal–insulator transition that may be used in such appliances. In this work, we synthesized and investigated the crystals of a novel mixed‐valent iron oxide with an unconventional Fe₅O₆ stoichiometry. Near 275 K, Fe₅O₆ undergoes a Verwey‐type charge‐ordering transition that is concurrent with a dimerization in the iron chains and a following formation of new Fe?Fe chemical bonds. This unique feature highlights Fe₅O₆ as a promising candidate for the use in innovative applications. We established that the minimal Fe?Fe distance in the octahedral chains is a key parameter that determines the type and temperature of charge ordering. This model provides new insights into charge‐ordering phenomena in transition‐metal oxides in general.     

一种新型氧离子导体：La3GaMo2O12

A new oxide ion conductor,La_3GaMo_2O_(12),with a bulk conductivity of 2.7×10~(-2)S·cm~(-1) at 800 ℃ in air at-mosphere was prepared by the traditional solid-state reaction.The room temperature X-ray diffraction data could beindexed on a monoclinic cell with lattice parameters of a=0.5602(2) nm,b=0.3224(1) nm,c=1.5741(1) nm,β=102.555(0)°,V= 0.2775(2) nm~3 and space group Pc(7).Ac impedance measurements in various atmospheres furthersupport that it is an oxide ion conductor.This material was stable in various atmospheres with oxygen partial pres-sure p(O_2)ranging from 1.0×10~5 to 1.0×10~(-7) Pa at 800 ℃.A reversible polymorphic phase transition occurred atelevated temperatures as confirmed by the differential thermal analysis and dilatometric measurement.     

Room‐Temperature Columnar Mesophases in Triazine–Gold Thiolate Metal–Organic Supramolecular Aggregates

Supramolecular mono‐ and dinuclear liquid‐crystalline gold(I) aggregates have been synthesized by means of hydrogen bond interactions of 2,4,6‐triarylamino‐1,3,5‐triazine with thiolate moities of gold metalloacids [Au(PR₃)(SC₆H₄COOH)] or [μ‐(binap){Au(SC₆H₄COOH)}₂], in 1:1 and 2:1 molar ratio, respectively. All of the supramolecular aggregates display a stable columnar hexagonal mesophase (Col_h) at room‐temperature. The supramolecular arrangement within the columns consists of the one‐dimensional stacking of triazine units, with the core of the attached metallic thioacid fragments acting as the fourth branch. The phosphine‐containing moieties of the metallic thioacid protrude out in the aliphatic continuum. These complexes do not show metallophilic interactions, but this strategy appears very promising for the future design of room‐temperature LC mesophases containing interacting metallic fragments.     

A Stable Room‐Temperature Luminescent Biphenylmethyl Radical

There is only one family of room‐temperature luminescent radicals, the triphenylmethyl radicals, to date. Herein, we synthesize a new stable room‐temperature luminescent radical, (N‐carbazolyl)bis(2,4,6‐tirchlorophenyl)methyl radical (CzBTM), which has improved properties compared to the triphenylmethyl radicals. X‐ray crystallography, electron paramagnetic resonance spectroscopy, and magnetic susceptibility measurements confirmed the radical structure. CzBTM shows room‐temperature deep‐red to near‐infrared emission in various solutions. Both thermal and photo stability were significantly enhanced by the replacement of trichlorobenzene by the carbazole moiety. The electroluminescence results of CzBTM verify its potential application to circumvent the problem of triplet harvesting in traditional fluorescent OLEDs. A new family of stable luminescent radicals based on CzBTM is anticipated.