共查询到20条相似文献,搜索用时 15 毫秒
1.
V. Ya. Kavun V. I. Sergienko N. F. Uvarov T. F. Antokhina 《Journal of Structural Chemistry》2002,43(3):429-435
The dynamics of fluoride and ammonium ions in Na(NH4)6Zr4F23 (I) and Li(NH4)6Zr4F23 (II) was studied by 1H and 19F NMR in the temperature range 170-440 K. Types of ionic motion were determined, and their activation energies were evaluated. In I, phase transitions were found in the temperature ranges 360-370 and 410-415 K. The experimental values of conductivity of Na(NH4)6Zr4F23 and Li(NH4)6Zr4F23 ( 4 × 10-3 S/cm at T = 420 K) permit one to attribute these fluorides to the class of superionic conductors. 相似文献
2.
The liquid-solid phase diagram of the binary systems AlPO4?M3PO4(M=Li, Na, K) have been established. The additional compounds Na3Al(PO4)2, Na3Al2(PO4)3 and K3Al2(PO4)3 have been found again. A new compound K3Al(PO4)2 is observed. The melting point of Na3PO4 is 1545°C and K3PO4 does not melt up to 1700°C. 相似文献
3.
O. A. Gapurenko T. N. Gribanova R. M. Minyaev V. I. Minkin 《Russian Journal of Inorganic Chemistry》2008,53(10):1605-1613
The electronic and geometric structures of M4NO 4 + compounds (M = Li, Na, K) in classical and nonclassical isomeric forms were studied by the ab initio (MP2(full)/6-311+G**) and density functional theory (B3LYP/6-311+G**) methods. For all M atoms, structurally stable nonclassical isomers were found with octacoordinated nitrogen atoms and tetracoordinated oxygen atoms. For Li4NO 4 + , the classical structure with the tetracoordinated nitrogen atom is energetically more stable, whereas nonclassical structures with the octacoordinated nitrogen center are more stable for Na4NO 4 + and K4NO 4 + . 相似文献
4.
High-energy milling of Y(BH(4))(3) (containing LiCl as a by-product, which has not been removed) with MBH(4) (M = Li, Na, K, (CH(3))(4)N) leads to the first two examples of quasi-ternary yttrium borohydrides: KY(BH(4))(4) and (CH(3))(4)NY(BH(4))(4), while no chemical reaction is observed for LiBH(4) and NaBH(4). KY(BH(4))(4) is isostructural to NaSc(BH(4))(4) (Cmcm, a = 8.5157(4) ?, b = 12.4979(6) ?, c = 9.6368(5) ?, V = 1025.62(9) ?(3), Z = 4), while (CH(3))(4)NY(BH(4))(4) crystallises in primitive orthorhombic cell, similarly to KSc(BH(4))(4) (Pnma, a = 15.0290(10) ?, b = 8.5164(6) ?, c = 12.0811(7) ?, V = 1546.29(17) ?(3), Z = 4). The thermal decomposition of hydrogen-rich KY(BH(4))(4) (8.6 wt.% H) involves the formation of an unidentified intermediate at 200 °C and recovery of KBH(4) at higher temperatures; at 410 °C, KCl and YH(2) are observed. The thermal decomposition of (CH(3))(4)NY(BH(4))(4) occurs via two partly overlapping endothermic steps with concomitant emission of H(2) and organic compounds. Heating of a NaBH(4)/Y(BH(4))(3) mixture above 165 °C results in a mixed-cation mixed-anion borohydride, NaY(BH(4))(2)Cl(2), but not NaY(BH(4))(4). The reduced reactivity of Y(BH(4))(3) towards borohydride Lewis bases when compared to hypothetical scandium borohydride can be explained by the lower Lewis acidity of Y(BH(4))(3) than Sc(BH(4))(3). 相似文献
5.
氢能是一种新型的清洁能源,有望替代碳经济,而氢的储存是氢能应用的关键。近年来,研究集中在具有储氢容量高和可逆性好等优点的固态储氢材料上。许多新型储氢材料不断出现,其中以MAlH4(M=Li, Na)为代表的金属复合氢化物体系被认为是最有前景的储氢材料之一。本文综述了MAlH4(M=Li, Na)作为可逆储氢材料的研究现状,主要从吸放氢反应、储氢性能、反应机理、理论计算和存在的问题等方面进行了讨论,并指出其相关发展趋势。 相似文献
6.
Antokhina T. F. Ignat'eva L. N. Kaidalova T. A. Savchenko N. N. 《Russian Journal of Coordination Chemistry》2003,29(3):157-162
Monoclinic crystals of ammonium hydrofluoride fluoro complexes of zirconium and hafnium (NH4)4M(Zr(Hf))3F17 · 2HF (M = Li, Na) are synthesized and studied. Their unit cell parameters are determined. IR spectra of the synthesized compounds are measured in the range of 350–4000 cm–1. 相似文献
7.
The MCl/AlCl3/SO2 Systems (M = Li, Na, K, NH4) Phase diagrams of the ternary systems of the type MCl/AlCl3/SO2 were determined by measurement of SO2 pressure, solubilities, and by thermal analysis. The complete phase diagram in the range from ?30 to +50°C is given for the case M = Na, partial diagrams for M = Li, K, NH4. There exist solid compounds of the type MAlCl4 · nSO2 (M = Li, Na; n = 1.5 and 3) (M = K; n = 1.5 and 5) (M = NH4; n = 5). Liquid phases can be obtained at room temperature and atmospheric pressure in the NaCl or LiCl containing systems. 相似文献
8.
Marcelle Gaune-Escard A. Bogacz L. Rycerz W. Szczepaniak 《Journal of Thermal Analysis and Calorimetry》1995,45(5):1117-1124
Present work is a part of thermodynamic research program on the MX?LnX3 system (M=alkali metal,X=Cl, Br andLn=lanthanide). Molar enthalpies of mixing in the LiBr?NdBr3, NaBr?NdBr3 and KBr?NdBr3 liquid binary systems have been determined at temperature 1063 K by direct calorimetry in the whole range of composition. Investigated systems are generally characterized by negative enthalpies of mixing with minimum atX NdBr3≈0.3–0.4. These enthalpies decrease with decrease of ionic radii of alkali metals. Molar enthalpies of solid-solid and solid-liquid phase transitions of K3NdBr6 and Cs3NdBr6 have been also determined by differential scanning calorimetry (DSC). K3NdBr6 is formed at 689 K from KBr and K2NdBr5 with enthalpy of 44.0 kJ·mol?1 whereas Cs3NdBr6 is stable at ambient temperature and undergoes phase transition in the solid state at 731 K with enthalpy of 8.8 kJ·mol?1. Enthalpies of melting have been also determined. 相似文献
9.
《Solid State Sciences》2012,14(7):828-832
While systems K3TaF8 and K3ZrF7 were prepared by modified molten salt method modified wet pathway was used for reproducible preparation of Na7Zr6F31. Its congruently melting character was demonstrated on simultaneous TG/DSC measurements and XRD patterns. X-ray photoelectron spectroscopy was applied for identification of differently bonded fluorine atoms in series of compounds NaF, K2TaF7, K3TaF8, K2ZrF6, Na7Zr6F31 and K3ZrF7. Three different types of fluorine atoms were described qualitatively and quantitatively. Uncoordinated fluorine atoms (F−) provide signals at lowest binding energies, followed by signals from terminally coordinated fluorine atoms (M–F) and then bridging fluorine atoms (M–F–M) at highest energy. Based on XPS F 1s signals assigned to fluorine atoms in compounds with correctly determined structure it was suggested that fluorine atoms in K3ZrF7 have partially bridging character. 相似文献
10.
Shurdumov B. K. Trunin A. S. Kuchukova M. A. 《Russian Journal of General Chemistry》2002,72(5):675-677
Thermal analysis of the pseudoternary systems Na4P2O7-WO3-NaCl and K4P2O7-WO3-KCl was performed, and the crystallization fields were revealed of sodium and potassium pyrophosphates, incongruently melting compounds Na4P2O7·3WO3 and K4P2O7·3WO3, and of products formed by reactions of WO3 with NaCl and KCl. Low-melting compositions were revealed, which are of interest for preparing Na(K)-W oxide bronzes. 相似文献
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12.
A large number of new phases have been prepared and characterized in the MFTlF3 system: Na3TlF6 isostructural with cryolite, Na3Tl2F9, NaxTl1−xF3−2x (0.425 ? x ? 0.565 at 500°C) and Na5Tl9F32 related to the fluorite type, K3TlF6 with a structure similar to that of (NH4)3FeF6, K5Tl3F14 with the chiolite structure, NayTl1−yF3−2y (0.12 ? y ? 0.14 at 500°C) and K2Tl7F23 affiliated to α-UO3, KTlF4, and KTl2F7. 相似文献
13.
From solutions containing 2–17 wt % TiO2 at the molar ratios M/Ti = 1–4, F/Ti = 2–4, and PO 4 3? /Ti = 0.5–10 under mild conditions, fluoro- and oxo(hydroxo) fluorophosphate titanates were isolated: crystalline M2TiF6 (M = K, Rb, Cs) and K2Ti2O2.5F2PO4 · 2H2O, and amorphous K3Ti4O(OH)F7(PO4)3 · 5H2O, Cs2Ti3O2F7PO4 · 6H2O, and CsTi3O3F4PO4 · 3H2O. In a mixture with M2TiF6 and KCl, phosphate-ion-containing crystalline phases of unidentified composition were detected. The phases were studied by elemental, crystal-optical, X-ray powder diffraction, thermal, IR spectroscopic, and electron microscopic analyses. Annealing fluorophosphate titanates gives a mixture of MTiOPO4 and TiO2. All the mentioned alkali metal fluorophosphates contain the tetrahedral ion PO 4 3? and titanium polyhedra with bonds Ti-F and Ti-O; some of them also contain bridging oxygen connecting titanium atoms: Ti-O-Ti; i.e., these substances are polymeric. 相似文献
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15.
L. A. Zemnukhova R. L. Davidovich V. N. Rykovanov S. I. Kuznetsov 《Russian Chemical Bulletin》1987,36(5):1051-1053
Conclusion A study of the temperature dependence of the123Sb NQR parameters for MSbClF3 complexes (M=K, Cs, NH4) at from 77 to 390K shows temperature ranges with anomalous change in the electric field gradient asymmetry parameter for the antimony atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1136–1139, May, 1987.The authors express their gratitude to G. K. Semin for a useful discussion of this work. 相似文献
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S. S. Yarovoi Yu. V. Mironov S. V. Tkachev V. E. Fedorov 《Russian Journal of Inorganic Chemistry》2009,54(2):299-304
Phase formation in the Re-Se-Br-MBr systems (M = K, Rb, Cs) was studied by NMR spectroscopy and powder X-ray diffraction.
The reactions taking place in alkali metal halide melts were found to give, among the series of cluster anions [{Re6Se8 − n
Br
n
}Br6](4 − n)− (0 ≤ n≤ 4), polymeric complexes Re6Se8Br 2 and M2Re6Se8Br4 (M = Cs, Rb) and salts containing cluster anions [Re6Se6Br8]2− and [Re6Se7Br7]3− as the major products. The effect of the alkali metal cation on the product composition and ratio was established.
Original Russian Text ? S.S. Yarovoi, Yu.V. Mironov, S.V. Tkachev, V.E. Fyodorov, 2009, published in Zhurnal Neorganicheskoi
Khimii, 2009, Vol. 54, No. 2, pp. 344–349. 相似文献
18.
K. Kitadai M. Takahashi M. Takeda 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(2):311-314
121Sb Mössbauer spectra for M3Sb (M3 = Na3, K3, Na2K, Rb3) were measured at 12 K. The values of isomer shift (d) and quadrupole coupling constant suggest that the valence state of antimony in M3Sb is –3. The d values increase in the order Rb3Sb<K3Sb<Na3Sb<Na2KSb. The differences in d values are discussed by examining M–Sb distances and bond valence for M–Sb interactions. Some covalent interactions between alkali metal atoms and antimony atom are suggested. 相似文献
19.
Ab initio calculations reveal that all-metal antiaromatic molecules like Al4M4 (M = Li, Na and K) can be stabilized in half sandwich (Al4M4)Fe(CO)3 and full sandwich (Al4M4)2Ni complexes. The formation of the full sandwich complex [(Al4M4)2Ni] from its organometallic precursor depends on the stability of the organic-inorganic hybrid (C4H4)Ni(Al4Li4). 相似文献
20.
A series of novel borates, MM'4(BO3)3 (M = Li, M' = Sr; M = Na, M' = Sr, Ba), have been successfully synthesized by standard solid-state reaction. The crystal structures have been determined from powder X-ray diffraction data. They crystallize in the cubic space group Iad with large lattice parameters: a = 14.95066(5) A for LiSr4(BO3)3, a = 15.14629(6) A for NaSr4(BO3)3, and a = 15.80719(8) A for NaBa4(BO3)3. The structure was built up from 64 small cubic grids, in which the M' atoms took up the corner angle and the BO3 triangles or MO6 cubic octahedra filled in the interspaces. The isolated [BO3]3- anionic groups are perpendicular to each other, distributed along three 100 directions. The anisotropic polarizations were counteracting, forming an isotropic crystal. Sr and Ba atoms were found to be completely soluble in the solid solution NaSr(4-)xBax(BO3)3 (0 < or = x < or = 4). The photoluminescence of samples doped with the ions Eu2+ and Eu3+ was studied, and effective yellow and red emission was detected, respectively. The results are consistent with the crystallographic study. The DTA and TGA curves of them show that they are chemically stable and congruent melting compounds. 相似文献