共查询到20条相似文献,搜索用时 31 毫秒
1.
Y. Akishige H. Shigematsu T. Tojo H. Kawaji T. Atake 《Journal of Thermal Analysis and Calorimetry》2005,81(3):537-540
Summary Specific heats on the single crystals of Sr2Nb2O7, Sr2Ta2O7 and (Sr1-xBax)2Nb2O7 were measured in a wide temperature range of 2-600 K. Heat anomalies of a λ-type were observed at the incommensurate phase transition of TINC (=495 K) on Sr2Nb2O7 and at the super-lattice phase transition of TSL (=443 K) on Sr2Ta2O7; the transition enthalpies and the transition entropies were estimated. Furthermore, a small heat anomaly was observed at the low temperature ferroelectric phase transition of TLOW (=95 K) on Sr2Nb2O7. The transition temperature TLOW decreases with increasing Ba content x and it vanishes for samples of x>2%. 相似文献
2.
Ming‐Liang Tong Shao‐Liang Zheng Xiao‐Ming Chen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):960-962
The title compound, poly[[diaquadibromocadmium‐μ‐(1,3,5,7‐tetraazatricyclo[3.3.1.13,7]decane‐N1:N5)‐aquacadmium‐di‐μ‐bromo‐aquacadmium‐μ‐(1,3,5,7‐tetraazatricyclo[3.3.1.13,7]decane‐N1:N5)‐di‐μ‐bromo] dihydrate], [Cd3Br6(C6H12N4)2(H2O)4]·2H2O, is made up of two‐dimensional neutral rectangular coordination layers. Each rectangular subunit is enclosed by a pair of Cd3(μ2‐Br)6(H2O)3 fragments and a pair of (μ2‐hmt)Cd(H2O)2Br2(μ2‐hmt) fragments as sides (hmt is hexamethylenetetramine). The unique CdII atom in the Cd2Br2 ring in the Cd3(μ2‐Br)6(H2O)3 fragment is in a slightly distorted octahedral CdNOBr4 geometry, surrounded by one hmt ligand [2.433 (5) Å], one aqua ligand [2.273 (4) Å] and four Br atoms [2.6409 (11)–3.0270 (14) Å]. The CdII atom in the (μ2‐hmt)Cd(H2O)2Br2(μ2‐hmt) fragment lies on an inversion center and is in a highly distorted octahedral CdN2O2Br2 geometry, surrounded by two trans‐related N atoms of two hmt ligands [2.479 (5) Å], two trans‐related aqua ligands [2.294 (4) Å] and two trans‐related Br atoms [2.6755 (12) Å]. Adjacent two‐dimensional coordination sheets are connected into a three‐dimensional network by hydrogen bonds involving lattice water molecules, and the aqua, bromo and hmt ligands belonging to different layers. 相似文献
3.
The solid-phase interaction in the V2O5-Nb2O5-MoO3 system has been investigated, and the formation of a solid solution bounded by the compositions MoNb2V4O18 ? δ, Mo2NbV5O21 ? δ, Mo2Nb3V3O21 ? δ, and Mo4Nb9V9O57 ? δ has been found (δ is nonstoichiometry). In the V2O5?Nb2O5 system, the formation of three compounds is verified, namely, VNbO5 (tetragonal structure), VNb9O25, and V2Nb23O62.5. The first two compounds are isostructural and form a continuous solid solution with tetragonal symmetry. A new compound of the composition Mo3NbVO14 ? δ has been synthesized. This compound is isostructural to the Mo3Nb2O14 compound described in the literature and forms a tetragonal solid solution with it. The phase equilibria in the V2O5-Nb2O5-MoO3 system in the subsolidus region have been determined. 相似文献
4.
Shu‐Mei Chen Can‐Zhong Lu Ya‐Qin Yu Quan‐Zheng Zhang Xiang He 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):m549-m550
The title compound, [NaLaMo8O26(C3H7NO)7]n, contains infinite chains of [Mo8O26]4− units supporting dimethylformamide‐coordinated LaIII cations and linked by Na+ cations. The lanthanum center adopts a nine‐coordinate geometry and the Na atom is sandwiched between two β‐[Mo8O26]4− units. 相似文献
5.
Ming‐Lin Guo Hong‐Xia Cao 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):m431-m433
The title complex, [Ba2Ni(C3H2O4)2(NO3)2(H2O)10]n, has a two‐dimensional layer structure. The Ni atom lies on a crystallographic centre of symmetry in an octahedral NiO6 environment, and is coordinated by four malonate O atoms in a planar arrangement and by two water molecules in axial positions. The coordination of the unique Ba atom involves two nitrate O atoms, five water molecules and three malonate O atoms. 相似文献
6.
A. S. Kalyuzhnaya A. M. Abakumov M. G. Rozova H. D’Hondt J. Hadermann E. V. Antipov 《Russian Chemical Bulletin》2010,59(4):706-711
The complex oxide Ca7Mn2.14Ga5.86O17.93 was synthesized by the solid-state reaction in a sealed evacuated quartz tube at 1000 °C. Its crystal structure was determined
by electron diffraction and X-ray powder diffraction. The structure can be represented as a tetrahedral framework, viz., the
polyanion [(Mn0.285Ga0.715)15O29.86]19- stabilized by the incorporated cation [Ca14GaO6]19+. The polycation consists of the GaO6 octahedra surrounded by the Ca atoms, which are arranged to form a cube capped at all places. The tetrahedral framework is
partially disordered due to the presence of tetrahedra with two possible orientations in the positions (0, 0, 0) and (x, x,
x) with x ≈ 0.15 and 0.17. The relationship between the Ca7Mn2.14Ga5.86O17.93 structures and related ordered phases with the symmetry F23, as well as the influence of the oxygen content on the ordering
in the tetrahedral framework, are discussed. 相似文献
7.
Thiruneelakantan Lakshmanan Desikan Sriram Duraikannu Loganathan 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):825-826
The crystal structure of the title compound, C14H25NO11·2H2O, has been determined. The glucose and galactose residues are in a 4C1 conformation. The N‐acetyl group has a Z‐anti conformation. 相似文献
8.
Poly[[μ2‐aqua‐bis[(1,10‐phenanthroline)nickel(II)]]‐di‐μ2,μ4‐5‐nitro‐1,3‐benzenedicarboxylato]
Hong‐Yin He Yi‐Li Zhou Long‐Guan Zhu 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):m569-m571
The reaction of Ni(CH3COO)2·4H2O, 5‐nitro‐1,3‐benzenedicarboxylic acid (H2nmbdc), 1,10‐phenanthroline and water under hydrothermal conditions yields the first reported two‐dimensional nickel coordination polymer with water‐ and carboxylate‐bridged dimeric units, viz. [Ni2(C8H3NO6)2(C12H8N2)2(H2O)]n. The coordination polyhedron of the NiII ion in the title structure is an octahedron defined by an N2O4 donor set. The water molecule is positioned on a mirror plane and the 5‐nitro‐1,3‐benzenedicarboxylate group is located on a twofold axis. Two types of nmbdc2− coordination mode are observed: one is a bis‐monodentate mode, μ2‐nmbdc2−, and the other is a bis‐bridging mode, μ4‐nmbdc2−. The dimeric unit in the title compound is similar to the structural moiety in urease. In the two‐dimensional framework in the title compound, strong stacking interactions between benzene rings (μ2‐nmbdc2− and μ4‐nmbdc2−) and 1,10‐phenanthroline ligands are observed. 相似文献
9.
Hong Yin Xiang-Xiang Yu Han Zhao Chong Li Ming-Qiang Zhu 《Journal of Solid State Electrochemistry》2018,22(8):2395-2403
Zn-doped LiNi0.8Co0.2O2 exhibits impressive electrochemical performance but suffers limited cycling stability due to the relative large size of irregular and bare particle which is prepared by conventional solid-state method usually requiring high calcination temperature and prolonged calcination time. Here, submicron LiNi0.8Co0.15Zn0.05O2 as cathode material for lithium-ion batteries is synthesized by a facile sol-gel method, which followed by coating Al2O3 layer of about 15 nm to enhance its electrochemistry performance. The as-prepared Al2O3-coated LiNi0.8Co0.15Zn0.05O2 cathode delivers a highly reversible capacity of 182 mA h g?1 and 94% capacity retention after 100 cycles at a current rate of 0.5 C, which is much superior to that of bare LiNi0.8Co0.15Zn0.05O2 cathode. The enhanced electrochemistry performance can be attributed to the Al2O3-coated protective layer, which prevents the direct contact between the LiNi0.8Co0.15Zn0.05O2 and electrolyte. The escalating trend of Li-ion diffusion coefficient estimated form electrochemical impedance spectroscopic (EIS) also indicate the enhanced structural stability of Al2O3-coated LiNi0.8Co0.15Zn0.05O2, which rationally illuminates the protection mechanism of the Al2O3-coated layer. 相似文献
10.
A. M. Potapova G. V. Zimina I. N. Smirnova F. M. Spiridonov P. P. Fedorov 《Russian Journal of Inorganic Chemistry》2011,56(9):1453-1457
The 950°C isothermal section of the InPO4-Na3PO4-Li3PO4 ternary system was studied and constructed; one-, two, and three-phase fields are outlined. Five solid-solution regions exist
in the system: solid solutions based on the complex phosphate LiNa5(PO4)2 (olympite structure), the indium ion stabilized high-temperature Na3PO4 phase (Na3(1 − x)In
x
(PO4); space group Fm
[`3]\bar 3
m), the complex phosphate Na3In2(PO4)3, and the α and β phases of the compound Li3In2(PO4)3. A narrow region of melt was found in the vicinity of eutectic equilibria. All the phases detected in the system are derivatives
of phases existing in the binary subsystems. Isovalent substitution of lithium for sodium in Na3In2(PO4)3 leads to a significant increase in the region of a NASICON-like solid solution. 相似文献
11.
I. I. Aliev I. G. Aliev A. A. Farzaliev Dzh. A. Veliev 《Russian Journal of Inorganic Chemistry》2008,53(6):962-964
The TlAs2Se4-Tl3As2S3Se3 system was investigated by physicochemical methods (DTA, X-ray powder diffraction, microstructural analysis), and its phase diagram was constructed. The TlAs2Se4-Tl3As2S3Se3 join is a quasi-binary internal section of the As-Tl-S-Se quaternary system. The solubility range of TlAs2Se4-based solid solutions is extended to 7 mol %, and the region of Tl3As2S3Se3-based solid solutions is extended to 15 mol %. 相似文献
12.
Hiroyuki Hosomi Shigeru Ohba Yoshikatsu Ito 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e260-e261
In the title two adducts, C3H12N22+·2C9H6NO4?, (I), and C6H16N22+·2C9H6NO4?, (II), hydrogen bonds between the diammonium and carboxylate ions form a two‐dimensional network parallel to the ab plane in (I) and one‐dimensional chains along the c axis in (II). The cyclohexanediammonium ion in (II) has a crystallographic twofold axis. 相似文献
13.
Glen B. Deacon Pauline Pearson Brian W. Skelton Leone Spiccia Allan H. White 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):m537-m539
The syntheses and crystal structure determinations of a pair of `sawhorse' dimers are reported, viz. [Ru2(C6H5CO2)2(C5H5N)2(CO)4] [a new polymorph, cf. Kepert, Deacon, Spiccia, Fallon, Skelton & White (2000). J. Chem. Soc. Dalton Trans. pp. 2867–2874] and [Ru2(CF3CO2)2(C5H5N)2(CO)4]. The Ru⋯Ru distances are 2.6724 (2) and 2.7122 (5) Å, respectively. 相似文献
14.
What is “Molybdic Acid” or “Polymolybdic Acid”? According to a comparative study of the literature, supplemented by well-aimed experimental investigations and equilibrium calculations, the terms “molybdic acid” or “polymolybdic acid”, used for many substances, species, or solutions in the literature, are applicable to a species, a solution, and two solids:
- a) The monomeric molybdic acid, most probably having the formula MoO2(OH)2(H2O)2(? H2MoO4, aq), exists in (aqueous) solution only and never exceeds a concentration of ≈ 10?3 M since at higher concentrations it reacts with other monomemeric molybdenum (VI) species to give anionic or cationic polymers.
- b) A concentrated (>0.1 M MoVI) aqueous molybdate solution of degree of acidification P = 2 (realized, e. g., by a solution of one of the MoVI oxides; by any molybdate solutions whose cations have been exchanged by H3O+ on a cation exchanger; by suitable acidification of a molybdate solution) contains 8 H3O+ and the well-known polyanion Mo36O112(H2O)168? exactly in the stoichiometric proportions.
- c) A glassy substance, obtained from an alkali metal salt-free solution prepared according to (b), refers to the compound (H3O)8[Mo36O112(H2O)16]·xH2O, x = 25—29.
- d) A solid having the ideal composition [(H3O)Mo5O15(OH)H2O·H2O]∞ consists of a polymolybdate skeleton (the well-known ?decamolybdate”? structure), in the tunnels of which H3O+ and H2O are intercalate. The structure is very unstable if only H3O+ cations are present, but it is enormously stabilized by a partial exchange of H3O+ by certain alkali or alkaline earth metal cations.
15.
Zao‐Zao Qiu Xin‐Ping Hui Peng‐Fei Xu 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(8):o475-o476
The structure of the title compound, C22H24N2O9S2, is described. This compound consists of a sugar ring and a heterocyclic base linked unusually by an S atom. The sugar is in a 4C1 chair conformation and forms dihedral angles of 49.54 (4) and 33.42 (5)° with the thiadiazole and phenyl rings, respectively. The S atom occupies an equatorial position of the sugar ring and lies 1.807 (2) Å out of the corresponding mean plane. 相似文献
16.
T. V. Belysheva G. N. Gerasimov V. F. Gromov E. Yu. Spiridonova L. I. Trakhtenberg 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(9):1554-1559
The conductivity of films consisting of a mixture of SnO2 and In2O3 nanocrystals at 200–500°C was studied. Based on the experimental data, it was assumed that in films containing less than
20 wt % In2O3, the current flows along SnO2 nanocrystals. A model of conductivity in these films is presented; it includes an electron transfer from In2O3 to SnO2, which forms positively charged In2O3 nanocrystals that contact the negatively charged SnO2 nanocrystals. In the presence of In2O3 nanocrystals, the activation energy of the electron transfer between SnO2 nanocrystals decreased substantially because of a decrease in the barrier of electron transfer between SnO2 crystals under the action of the negative charge. As a result, a percolation cluster of charged SnO2 crystals formed. At high contents of In2O3 (over 20 wt %), the conductivity increased dramatically. The curve of the temperature dependence of conductivity changed
because of the appearance of a percolation cluster of In2O3 nanocrystals, in which the current passed. The conductivity of a mixed film of this kind differed from that of the nanocrystalline
film of pure In2O3. 相似文献
17.
Youxin Yao Wenju Zeng Bin Zhang Yunqi Liu Daoben Zhu 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):e90-e91
The title complex, C14H20O4S8+.BF4?, is a charge‐transfer complex with typical charges for the donor and anion of +1 and ?1, respectively. Two centrosymmetrically related donors form a face‐to‐face π‐dimer with a strong intermolecular S?S interaction. These π‐dimers stack along the a axis to form a donor column. The structure is extensively hydrogen bonded. 相似文献
18.
Xu‐Cheng Fu Xiao‐Yan Wang Ming‐Tian Li Xiao‐Tao Deng Cheng‐Gang Wang 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(8):m343-m345
The title complex, {[Cu2(C8H4O4)2(C3H4N2)4(H2O)]·H2O}n, is a three‐dimensional polymer formed through bridging by phthalate dianions of two different CuII cations and a network of O(N)—H⋯O hydrogen bonds. The Cu—O and Cu—N interaction distances are in the ranges 2.0020 (16)–2.4835 (17) and 1.968 (2)–1.9855 (19) Å, respectively. The structure is composed of alternating polymer chains parallel to the c axis, with a shortest Cu⋯Cu distance of 6.3000 (5) Å. 相似文献
19.
G. B. Kunshina I. V. Bocharova V. I. Ivanenko 《Russian Journal of Applied Chemistry》2016,89(6):909-915
Compatibility of the lithium-titanium spinel Li4Ti5O12 in contact with precursors of lithium-conducting solid electrolytes of composition Li1.3Al0.3Ti1.7(PO4)3 (LATP), Li1.5Al0.5Ge1.5(PO4)3 (LAGP), Li0.5La0.5TiO3 (LLT) was studied. It was found that, in sintering of Li4Ti5O12 brought in contact with LATP and LAGP, a solid-phase reaction occurs to give nonconducting phases (TiO2 and Li3PO4). The conductivity of the stable composite Li4Ti5O12/LLT (10%) is higher than that of the starting Li4Ti5O12, which makes it possible to regard the composite as a promising anode material for lithium-ion batteries. 相似文献
20.
I. B. Bakhtiyarly A. V. Neimatova F. M. Mamedov 《Russian Journal of Inorganic Chemistry》2010,55(4):620-625
Phase equilibria in the La2S3-Bi2S3-La2O3 ternary system were studied by differential thermal, X-ray powder diffraction, and microstructure analyses. Phase diagrams
of five vertical sections and a liquidus surface projection were plotted for the La2S3-Bi2S3-La2O3 system. The regions of primary crystallization of phases and coordinates of non- and monovariant equilibria were determined
for the system. 相似文献