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1.
Phosphide-based materials have been investigated as promising candidates for solid electrolytes, among which the recently reported Li9AlP4 displays an ionic conductivity of 3 mS cm−1. While the phases Li–Al–P and Li–Ga–P have already been investigated, no ternary indium-based phosphide has been reported up to now. Here, we describe the synthesis and characterization of the first lithium phosphidoindate Li3InP2, which is easily accessible via ball milling of the elements and subsequent annealing. Li3InP2 crystallizes in the tetragonal space group I41/acd with lattice parameters of a = 12.0007(2) and c = 23.917(5) Å, featuring a supertetrahedral polyanionic framework of interconnected InP4 tetrahedra. All lithium atoms occupy tetrahedral voids with no partial occupation. Remarkably, Li3InP2 is not isotypic to the previously reported homologues Li3AlP2 and Li3GaP2, which both crystallize in the space group Cmce and feature 2D layers of connected tetrahedra but no supertetrahedral framework. DFT computations support the observed stability of Li3InP2. A detailed geometrical analysis leads to a more general insight into the structural factors governing lithium ion mobility in phosphide-based materials: in the non-ionic conducting Li3InP2 the Li ions exclusively occupy tetrahedral voids in the distorted close packing of P atoms, whereas partially filled octahedral voids are present in the moderate ionic conductors Li2SiP2 and Li2GeP2.

Li3InP2 exhibits a polyanionic framework of corner-sharing InP4 tetrahedra and DFT computations reveal the stability trend for indium in the tetragonal structure compared to the orthorhombic structure of the lighter homologues.  相似文献   

2.
With Li7Si2NO6, a new member of the family of lithium oxonitridosilicates with a so far unseen structure type could be synthesized. Using a high-temperature solid-state reaction in open nickel crucibles under nitrogen flow, it was possible to obtain single crystals from the starting materials SiO2, Li3N, and Li2O at temperatures of 900 °C. Single crystal X-ray diffraction data yielded lattice parameters of a=5.0934(2), b=7.4128(2), c=8.5918(2) Å, α=75.16(1)°, β=87.36(1)°, γ=73.01(1)° and a cell volume of V=299.75(2) Å3. The compound, crystallizing in the triclinic space group P (no. 2), consists of a highly condensed anionic network built up by [SiNO3]-, [LiO4]-, and [LiN2O2]-tetrahedra as well as lithium in octahedral coordination as completing cation. With an activation barrier of 695 meV for lithium migration, Li7Si2NO6 is a potential lithium-ion conductor. The structure allows a classification not only as a sorosilicate but also as a tecto-lithosilicate and most precisely as a lithium oxonitridolithosilicate, when the different coordinations of the lithium ions are taken into account. Interestingly, the new compound is none of the several proposed representatives of the lithium oxonitridosilicates, thus expanding this substance class unexpectedly.  相似文献   

3.
The preparation of novel technetium oxides, their characterization and the general investigation of technetium chemistry are of significant importance, since fundamental research has so far mainly focused on the group homologues. Whereas the structure chemistry of technetium in strongly oxidizing media is dominated by the anion, our recent investigation yielded the new anion. Brown single crystals of Ba[TcO3N] were obtained under hydrothermal conditions starting from Ba(OH)2 ⋅ 8H2O and NH4[TcO4] at 200 °C. crystallizes in the monoclinic crystal system with the space group P21/n (a=7.2159(4) Å, b=7.8536(5) Å, c=7.4931(4) Å and β=104.279(2)°). The crystal structure of consists of isolated tetrahedra, which are surrounded by Ba2+ cations. XANES measurements complement the oxidation state +VII for technetium and Raman spectroscopic experiments on Ba[TcO3N] single crystals exhibit characteristic Tc−O and Tc−N vibrational modes.  相似文献   

4.
All-solid-state batteries are promising candidates for safe energy-storage systems due to non-flammable solid electrolytes and the possibility to use metallic lithium as an anode. Thus, there is a challenge to design new solid electrolytes and to understand the principles of ion conduction on an atomic scale. We report on a new concept for compounds with high lithium ion mobility based on a rigid open-framework boron structure. The host–guest structure Li6B18(Li3N) comprises large hexagonal pores filled with Li7N] strands that represent a perfect cutout from the structure of α-Li3N. Variable-temperature 7Li NMR spectroscopy reveals a very high Li mobility in the template phase with a remarkably low activation energy below 19 kJ mol−1 and thus much lower than pristine Li3N. The formation of the solid solution of Li6B18(Li3N) and Li6B18(Li2O) over the complete compositional range allows the tuning of lithium defects in the template structure that is not possible for pristine Li3N and Li2O.  相似文献   

5.
The aluminosilicate Li2Na3AlSi2O8 was crystallized from the Li2CO3–H3BO3 flux system. It crystallizes in the orthorhombic space group Cmca, with cell dimensions a = 14.1045 (19) Å, b = 14.7054 (19) Å, c = 7.0635 (9) Å, and Z = 8. The crystal structure consists of a two‐dimensional infinite layer, which is composed of [Al2Si2O12] groups and [SiO4] tetrahedra. The lithium and sodium atoms filling in the interlayer and intralayer link the layers together and balance the charge. IR spectroscopy and BVS calculations were used to verify the validity of the structure. The calculated band structures and the density of states of Li2Na3AlSi2O8 suggest that its direct gap is 4.28 eV.  相似文献   

6.
The layered compound Sn2.8(4)Bi20.2(4)Se27 exhibits an extraordinarily long-periodic 150R stacking sequence. The crystal structure contains three different building blocks, which form upon the addition of Sn to a Bi-rich bismuth selenide. Sn-doped Bi2 double (“2”) layers similar to those in elemental bismuth, Sn0.3Bi1.7Se3 quintuple (“5”) layers and Sn0.4Bi2.6Se4 septuple (“7”) layers are arranged in a 7525757525|7525757525|7525757525 sequence, which corresponds to a structure with a=4.1819(4) and c=282.64(6) Å in space group R m. The structure of a microcrystal was determined using microfocused synchrotron radiation and refined as a formally commensurately modulated structure in (3+1)D superspace (superspace group R m(00γ)00), with a trivial basic structure that contains just one atom. The stacking sequence as well as the cation distribution are confirmed by aberration-corrected scanning transmission electron microscopy (STEM) in combination with chemical mapping by X-ray spectroscopy with atomic resolution. Stacking faults are not typical but have been observed occasionally.  相似文献   

7.
[Br3][SbF6] and [Br3][IrF6] were synthesized by interaction of BrF3 with Sb2O3 or iridium metal, respectively. The former compound crystallizes in the orthorhombic space group Pbcn (No. 60) with a=11.9269(7), b=11.5370(7), c=12.0640(6) Å, V=1660.01(16) Å3, Z=8 at 100 K. The latter compound crystallizes in the triclinic space group P (No. 2) with a=5.4686(5), b=7.6861(8), c=9.9830(9) Å, α=85.320(8), β=82.060(7), γ=78.466(7)°, V=406.56(7) Å3, Z=2 at 100 K. Both compounds contain the cation [Br3]+, which has a bent structure and is coordinated by octahedron-like anions [MF6] (M=Sb, Ir). Experimentally obtained cell parameters, bond lengths, and angles are confirmed by solid-state DFT calculations, which differ from the experimental values by less than 2 %. Relativistic effects on the structure of the tribromonium(1+) cation are studied computationally and found to be small. For the heaviest analogues containing At and Ts, however, pronounced relativistic effects are found, which lead to a linear structure of the polyhalogen cation.  相似文献   

8.
The experimental and computational characterization of a series of dialkylterphenyl phosphines, PR2Ar′ is described. The new P-donors comprise five compounds of general formula PR2Ar (R=Me, Et, iPr, c-C5H9 and c-C6H11); Ar = 2,6-C6H3-(3,5-C6H3-(CMe3)2)2), and another five PR2Ar′ phosphines containing the bulky alkyl groups iPr, c-C5H9 or c-C6H11, in combination with Ar′=Ar , Ar , or Ar ( L1 – L10 ). Steric and electronic parameters have been determined computationally and from IR and X-ray data obtained for the phosphines and for some derivatives, including tricarbonyl and dicarbonyl nickel complexes, Ni(CO)3(PR2Ar′) and Ni(CO)2(PR2Ar′). In the solid state, the free phosphines PR2Ar′ adopt one of the three possible structures formally related by rotation around the Cipso−P bond. Details on their relative energies and on the influence of the free phosphine structure on its coordination chemistry towards Ni(CO)n (n = 2, 3) fragments has been obtained by experimental and computational methods.  相似文献   

9.
Structural and electronic properties of Li3GaP2 and Li3GaN2 have been investigated by the first-principles calculations within the density functional theory. The calculated lattice parameters of the two compounds are in excellent agreement with the available experimental data. Both Li3GaP2 and Li3GaN2 are direct band gap semiconductors with the band gaps of 1.26 eV and 2.37 eV, respectively. The Ga–P (Ga–N) and Li–P bonds consist of a mixture of ionic character and covalent nature, while the Li–N bond exhibits almost ionic. The bonds in the Li3GaP2 are shown to have stronger covalency and weaker ionicity as compared to the corresponding ones in the Li3GaN2.  相似文献   

10.
The crystal structures of α-F2 and β-F2 have been reinvestigated using neutron powder diffraction. For the low-temperature phase α-F2, which is stable below circa 45.6 K, the monoclinic space group C2/c with lattice parameters a=5.4780(12), b=3.2701(7), c=7.2651(17) Å, β=102.088(18)°, V=127.26(5) Å3, mS8, Z=4 at 10 K can now be confirmed. The structure model was significantly improved, allowed for the anisotropic refinement of the F atom, and an F−F bond length of 1.404(12) Å was obtained, which is in excellent agreement with spectroscopic data and high-level quantum chemical predictions. The high-temperature phase β-F2, stable between circa 45.6 K and the melting point of 53.53 K, crystallizes in the cubic primitive space group Pm n with the lattice parameter a=6.5314(15) Å, V=278.62(11) Å3, cP16, Z=8, at 48 K. β-F2 is isotypic to γ-O2 and δ-N2. The centres of gravity of the F2 molecules are arranged like the atoms in the Cr3Si structure type.  相似文献   

11.
12.
The nitridoberylloaluminate Ba2[BeAl3N5]:Eu2+ and solid solutions Sr2−xBax[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.  相似文献   

13.
Transition-metal borides (TMBs) containing Bn-fragment (n>3) have recently gained interest for their ability to enable exciting magnetic materials. Herein, we show that the B4-containing TiFe0.64(1)Os2.36(1)B2 is a new ferromagnetic TMB with a Curie temperature of 523(2) K and a Weiss constant of 554(3) K, originating from the chain of M3-triangles (M=64 %Fe+36 %Os). The new phase was synthesized from the elements by arc-melting, and its structure was elucidated by single-crystal X-ray diffraction. It belongs to the Ti1+xOs2−xRuB2-type structure (space group P 2 m, no. 189) and contains trigonal-planar B4 boron fragments [B−B distance of 1.87(4) Å] interacting with M3-triangles [M–M distances of 2.637(8) Å and 3.0199(2) Å]. The experimental results were supported by computational calculations based on the ideal TiFeOs2B2 composition, which revealed strong ferromagnetic interactions within and between the Fe3-triangles. This discovery represents the first magnetically ordered Os-rich TMB, thus it will help expand our knowledge of the role of Os in low-dimensional magnetism of intermetallics and enable the design of such materials in the future.  相似文献   

14.
The redetermination of the crystal structure of trigonal UCl6, which is the eponym for the UCl6 structure type, showed that certain atomic coordinates had been incorrectly reported. This led to noticeably different U−Cl distances within the octahedral UCl6 molecule (2.41 and 2.51 Å). Within the revised structure model presented here, which is based on single crystal data as well as quantum chemical calculations, all U−Cl distances are essentially equal within standard uncertainty (2.431(5), 2.437(5), and 2.439(6) Å). This room temperature modification, called rt-UCl6, crystallizes in the trigonal space group P m1, No. 164, hP21, with a=10.907(2), c=5.9883(12) Å, V=616.9(2) Å3, Z=3 at T=253 K. A new low-temperature (lt) modification of UCl6 is also presented that was obtained by cooling a single crystal of rt-UCl6. The phase change occurs between 150 and 175 K. lt-UCl6 crystallizes isotypic to a low-temperature modification of SF6 in the monoclinic crystal system, space group C2/m, No. 12, mS42, with a=17.847(4), b=10.8347(18), c=6.2670(17) Å, β=96.68(2)°, V=1203.6(5) Å3, Z=6 at 100 K. The Cl anions form a close-packed structure corresponding to the α-Sm type with uranium atoms in the octahedral voids. During the synthesis of UBr5 a new modification was obtained that crystallizes in the triclinic crystal system, space group P , No. 2, aP36, with a=10.4021(6), b=11.1620(6), c=12.2942(7) Å, α=68.3340(10)°, β=69.6410(10)° and γ=89.5290(10)°, V=1231.84(12) Å3, Z=3 at T=100 K. In this structure the UBr5 units are dimerized to U2Br10 molecules. The Br anions also form a close-packed structure of the α-Sm type with adjacent uranium atoms in the octahedral voids. Comparisons of the crystal structures of the compounds MX5 (M=Pa, U; X=Cl, Br) show that the crystal structure of monoclinic α-PaBr5 is probably not correct.  相似文献   

15.
Spin Hamiltonian parameters of a pentanuclear Os Ni cyanometallate complex are derived from ab initio wave function based calculations, namely valence-type configuration interaction calculations with a complete active space including spin-orbit interaction (CASOCI) in a single-step procedure. While fits of experimental data performed so far could reproduce the data but the resulting parameters were not satisfactory, the parameters derived in the present work reproduce experimental data and at the same time have a reasonable size. The one-centre parameters (local matrices and single-ion zero field splitting tensors) are within an expected range, the anisotropic exchange parameters obtained in this work for an Os−Ni pair are not exceedingly large but determine the low-T part of the experimental χT curve. Exchange interactions (both isotropic and anisotropic) obtained from CASOCI have to be scaled by a factor of 2.5 to obtain agreement with experiment, a known deficiency of such types of calculation. After scaling the parameters, the isotropic Os−Ni exchange coupling constant is cm−1 and the D parameter of the (nearly axial) anisotropic Os−Ni exchange is −1, so anisotropic exchange is larger in absolute size than isotropic exchange. The negative value of the isotropic J (indicating antiferromagnetic coupling) seemingly contradicts the large-temperature behaviour of the temperature dependent susceptibility curve, but this is caused by the negative g value of the Os centres. This negative g value is a universal feature of a pseudo-octahedral coordination with configuration and strong spin-orbit interaction. Knowing the size of these exchange interactions is important because Os(CN) is a versatile building block for the synthesis of / magnetic materials.  相似文献   

16.
Heterobimetallic complexes with inequivalent bridging alkyl chains are very often invoked as key intermediates in many catalytic processes, yet their interception and structural characterization are lacking. Such complexes have been prepared from reactions of the cationic cyclometalated hafnocene [CpPrCp Hf][B(C6F5)4] ( 1 ) with main group metal alkyls to afford the corresponding hetero-bridged cationic products, [CpPrCp Hf(μ-R)E(R)n][B(C6F5)4] (E=Al or Zn; R=Me, Et, or iBu). NMR and DFT studies demonstrate that both bridging alkyls establish agostic interactions with Hf, which are appreciably stronger for ethyl rather than methyl groups. Hf–Al and Hf–Zn distances are surprisingly short and only slightly longer than computed Hf–Al or Hf–Zn single bond lengths (2.80 Å). Finally, a reaction of [CpPrCp Hf(μ-Me)Zn(Me)][B(C6F5)4] with excess ZnMe2 yields an unprecedented heterotrimetallic species, [(CpPr)2Hf(μ-Me)(ZnMe)(μ3-CH2)ZnMe][B(C6F5)4], the detailed structure of which is elucidated by a combination of NMR spectroscopic methods and molecular calculations.  相似文献   

17.
We report the first examples of metal-promoted double geminal activation of C(sp3)−H bonds of the N−CH2−N moiety in an imidazole-type heterocycle, leading to nickel and palladium N-heterocyclic carbene complexes under mild conditions. Reaction of the new electron-rich diphosphine 1,3-bis((di-tert-butylphosphaneyl)methyl)-2,3-dihydro-1H-benzo[d]imidazole ( 1 ) with [PdCl2(cod)] occurred in a stepwise fashion, first by single C−H bond activation yielding the alkyl pincer complex [PdCl(PC HP)] ( 3 ) with two trans phosphane donors and a covalent Pd−C bond. Activation of the C−H bond of the resulting α-methine C H−M group occurred subsequently when 3 was treated with HCl to yield the NHC pincer complex [PdCl(PCNHCP)]Cl ( 2 ). Treatment of 1 with [NiBr2(dme)] also afforded a NHC pincer complex, [NiBr(PCNHCP)]Br ( 6 ), but the reactions leading to the double geminal C−H bond activation of the N−CH2−N group were too fast to allow identification or isolation of an intermediate analogous to 3 . The determination of six crystal structures, the isolation of reaction intermediates and DFT calculations provided the basis for suggesting the mechanism of the stepwise transformation of a N−CH2−N moiety in the N−CNHC−N unit of NHC pincer complexes and explain the key differences observed between the Pd and Ni chemistries.  相似文献   

18.
The new phosphidosilicates Li2SiP2 and LiSi2P3 were synthesized by heating the elements at 1123 K and characterized by single‐crystal X‐ray diffraction. Li2SiP2 (I41/acd, Z=32, a=12.111(1) Å, c=18.658(2) Å) contains two interpenetrating diamond‐like tetrahedral networks consisting of corner‐sharing T2 supertetrahedra [(SiP4/2)4]. Sphalerite‐like interpenetrating networks of uniquely bridged T4 and T5 supertetrahedra make up the complex structure of LiSi2P3 (I41/a, Z=100, a=18.4757(3) Å, c=35.0982(6) Å). The lithium ions are located in the open spaces between the supertetrahedra and coordinated by four to six phosphorus atoms. Temperature‐dependent 7Li solid‐state MAS NMR spectroscopic data indicate high mobility of the Li+ ions with low activation energies of 0.10 eV in Li2SiP2 and 0.07 eV in LiSi2P3.  相似文献   

19.
A new series of lanthanide ( 1 – 5 ) and uranyl ( 6 ) complexes with a tetra-substituted bifunctional calixarene ligand H2L is described. The coordination environment for the Ln3+ and UO22+ ions is provided by phosphoryl and salicylamide functional groups appended to the lower rim of the p-tert-butylcalix[4]arene scaffold. Ligand interactions with lanthanide cations (light: La3+, Pr3+; intermediate: Eu3+ and Gd3+; and heavy: Yb3+), as well as the uranyl cation (UO22+) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2 : 2 M : L , [Ln2( L )2(H2O)]2+ ( 1–5 ), in solution, whereas uranyl formed a 1 : 1 M : L complex [UO2( L )(MeOH)] ( 6 ) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H2L was found to be an effective extracting agent for UO22+ over La3+ and Yb3+ cations. The separation factors at pH 6.0 are: βUO /La =121.0 and βUO /Yb =70.0.  相似文献   

20.
Molybdenum disulfide (MoS2) is an intensively studied anode material for lithium-ion batteries (LIBs) owing to its high theoretical capacity, but it is still confronted by severe challenges of unsatisfactory rate capability and cycle life. Herein, few-layer MoS2 nanosheets, vertically grown on hierarchical carbon nanocages (hCNC) by a facile hydrothermal method, introduce pseudocapacitive lithium storage owing to the highly exposed MoS2 basal planes, enhanced conductivity, and facilitated electrolyte access arising from good hybridization with hCNC. Thus, the optimized MoS2/hCNC exhibits reversible capacities of 1670 mAh g−1 at 0.1 A g−1 after 50 cycles, 621 mAh g−1 at 5.0 A g−1 after 500 cycles, and 196 mAh g−1 at 50 A g−1 after 2500 cycles, which are among the best for MoS2-based anode materials. The specific power and specific energy, which can reach 16.1 kW and 252.8 Wh after 3000 cycles, respectively, indicate great potential in high-power and long-life LIBs. These findings suggest a promising strategy for exploring advanced anode materials with high reversible capacity, high-rate capability, and long-term recyclability.  相似文献   

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