| 1. |
- Bell, Thomas, et al.
(författare)
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Tb3Pd2, Er3Pd2 and Er6Co5-x : structural variations and bonding in rare-earth-richer binary intermetallics
- 2018
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Ingår i: Acta crystallographica. Section C, Structural chemistry. - 2053-2296. ; 74:9, s. 991-996
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Tidskriftsartikel (refereegranskat)abstract
- The three binary Tb/Er-rich transition metal compounds Tb3Pd2 (triterbium dipalladium), Er3Pd2 (trierbium dipalladium) and Er6Co5-x (hexaerbium pentacobalt) crystallize in the space groups Pbam (Pearson symbol oP20), P4/mbm (tP10) and P6(3)/m (hP22), respectively. Single crystals of Tb3Pd2 and Er6Co5-x suitable for X-ray structure analysis were obtained using rare-earth halides as a flux. Tb3Pd2 adopts its own structure type, which can be described as a superstructural derivative of the U3Si2 type, which is the type adopted by Er3Pd2. Compound Er6Co5-x belongs to the Ce6Co2-xSi3 family. All three compounds feature fused tricapped {TR6} (R = rare-earth metal and T = transition metal) trigonal prismatic heterometallic clusters. R3Pd2 is reported to crystallize in the U3Si2 type; however, our more detailed structure analysis reveals that deviations occur with heavier R elements. Similarly, Er6Co5-x was assumed to be stoichiometric Er4Co3 = Er6Co4.5. Our studies reveal that it has a single defective transition-metal site leading to the composition Er6Co4.72(2). LMTO (linear muffin-tin orbital)-based electronic structure calculations suggest the strong domination of heteroatomic bonding in all three structures.
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| 2. |
- Celania, Chris, et al.
(författare)
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Crystal structures and new perspectives on Y3Au4 and Y(14)Au51
- 2017
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Ingår i: Acta crystallographica. Section C, Structural chemistry. - 2053-2296. ; 73, s. 692-696
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Tidskriftsartikel (refereegranskat)abstract
- Y3Au4 (triyttrium tetragold) and Y14Au51 (tetradecayttrium henpentacontagold), two binary representatives of Au-rich rare earth (R) systems crystallize with the space groups R (3) over bar and P6/m, adopting the Pu3Pd4 and Gd14Ag51 structure types, respectively (Pearson symbols hR(42) and hP(65)). Avariety of binary R-Au compounds have been reported, although only a few have been investigated thoroughly. Many reports lack information or misinterpret known compounds reported elsewhere. The Pu3Pd4 type is fairly common for group 10 elements Ni, Pd, and Pt, while Au representatives are restricted to just five examples, i.e. Ca3Au4, Pr3Au4, Nd Au-3(4), Gd3Au4, and Th3Au4. Sm6Au7 is suspected to be Sm3Au4 due to identical symmetry and close unit-cell parameters. The Pu3Pd4 structure type allows for full substitution of the position of the rare earth atom by more electronegative and smaller elements, i.e. Ti and Zr. The Gd14Ag51 type instead is more common for the group 11 metals, while rare representatives of group 12 are known. Y3Au4 can be represented as a tunnel structure with encapsulated cations and anionic chains. Though tunnels are present in Y14Au51, this structure is more complex and is best described in terms of polyhedral 'pinwheels' around the tunnel forming polyhedra along the c axis.
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| 3. |
- Cheng, Erbo, et al.
(författare)
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Porous ZnO/Co3O4/N-doped carbon nanocages synthesized via pyrolysis of complex metal-organic framework (MOF) hybrids as an advanced lithium-ion battery anode
- 2019
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Ingår i: ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY. - : INT UNION CRYSTALLOGRAPHY. - 2053-2296. ; 75, s. 969-978
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Tidskriftsartikel (refereegranskat)abstract
- Metal oxides have a large storage capacity when employed as anode materials for lithium-ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge-discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO-Co3O4 nanocomposites embedded in N-doped carbon (ZnO-Co3O4@N-C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal-organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N-doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as-prepared ZnO-Co3O4@N-C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO-Co3O4@N-C shows a discharge capacity of 2373 mAh g(-1) at the first cycle and exhibits a retention capacity of 1305 mAh g(-1) even after 300 cycles at 0.1 A g(-1). In addition, a reversible capacity of 948 mAh g(-1) is obtained at a current density of 2 A g(-1), which delivers an excellent high-rate cycle ability.
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| 4. |
- Huang, Ruting, et al.
(författare)
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Construction of SnS2-SnO2 heterojunctions decorated on graphene nanosheets with enhanced visible-light photocatalytic performance
- 2019
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Ingår i: ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY. - : INT UNION CRYSTALLOGRAPHY. - 2053-2296. ; 75, s. 812-821
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Tidskriftsartikel (refereegranskat)abstract
- Heterostructures formed by the growth of one kind of nanomaterial in/on another have attracted increasing attention due to their microstructural characteristics and potential applications. In this work, SnS2-SnO2 heterostructures were successfully prepared by a facile hydrothermal method. Due to the enhanced visible-light absorption and efficient separation of photogenerated holes and electrons, the SnS2-SnO2 heterostructures display excellent photocatalytic performance for the degradation of rhodamine (RhB) under visible-light irradiation. Additionally, it is found that the introduction of graphene into the heterostructures further improved photocatalytic activity and stability. In particular, the optimized SnS2-SnO2/graphene photocatalyst can degrade 97.1% of RhB within 60 min, which is about 1.38 times greater than that of SnS2-SnO2 heterostructures. This enhanced photocatalytic activity could be attributed to the high surface area and the excellent electron accepting and transporting properties of graphene, which served as an acceptor of the generated electrons to suppress charge recombination. These results provide a new insight for the design and development of hybrid photocatalysts.
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| 5. |
- Małecka, Magdalena, et al.
(författare)
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The relationship between Hirshfeld potential and cytotoxic activity : a study along a series of flavonoid and chromanone derivatives
- 2020
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Ingår i: Acta Crystallographica Section C: Structural Chemistry. - 2053-2296. ; 76:8, s. 723-733
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Tidskriftsartikel (refereegranskat)abstract
- The present study examines a series of six biologically-active flavonoid and chromanone derivatives by X-ray crystal structure analysis: (E)-3-benzylidene-2-phenylchroman-4-one, C22H16O2, I, (E)-3-(4-methylbenzylidene)-2-phenylchroman-4-one, C23H18O2, II, (E)-3-(3-methylbenzylidene)-2-phenylchroman-4-one, C23H18O2, III, (E)-3-(4-methoxybenzylidene)-2-phenylchroman-4-one, C23H18O3, IV, (E)-3-benzylidenechroman-4-one, C16H12O2, V, and (E)-3-(4-methoxybenzylidene)chroman-4-one, C17H14O3, VI. The cytotoxic activities of the presented crystal structures have been determined, together with their intermolecular interaction preferences and Hirshfeld surface characteristics. An inverse relationship was found between the contribution of C⋯C close contacts to the Hirshfeld surface and cytotoxic activity against the WM-115 cancer line. Dependence was also observed between the logP value and the percentage contribution of C⋯H contacts to the Hirshfeld surface.
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| 6. |
- Ovchinnikov, Alexander, et al.
(författare)
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Electronic stabilization by occupational disorder in the ternary bismuthide Li3-x-yInxBi (x similar or equal to 0.14, y similar or equal to 0.29)
- 2020
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Ingår i: Acta crystallographica. Section C, Structural chemistry. - 2053-2296. ; 76, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- A ternary derivative of Li3Bi with the composition Li3-x-yInxBi (x similar or equal to 0.14, y similar or equal to 0.29) was produced by a mixed In+Bi flux approach. The crystal structure adopts the space group Fd (3) over barm (No. 227), with a = 13.337 (4) angstrom, and can be viewed as a 2 x 2 x 2 superstructure of the parent Li3Bi phase, resulting from a partial ordering of Li and In in the tetrahedral voids of the Bi fcc packing. In addition to the Li/In substitutional disorder, partial occupation of some Li sites is observed. The Li deficiency develops to reduce the total electron count in the system, counteracting thereby the electron doping introduced by the In substitution. First-principles calculations confirm the electronic rationale of the observed disorder.
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| 7. |
- Prodius, Denis, et al.
(författare)
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Synthesis, structural characterization and luminescence properties of 1-carboxymethyl-3-ethylimidazolium chloride
- 2018
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Ingår i: Acta crystallographica. Section C, Structural chemistry. - 2053-2296. ; 74, s. 653-658
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Tidskriftsartikel (refereegranskat)abstract
- A microcrystalline carboxyl-functionalized imidazolium chloride, namely 1-carboxymethyl-3-ethylimidazolium chloride, C7H11N2O2+center dot Cl-, has been synthesized and characterized by elemental analysis, attenuated total reflectance Fourier transform IR spectroscopy (ATR-FT-IR), single-crystal X-ray diffraction, thermal analysis (TGA/DSC), and photoluminescence spectroscopy. In the crystal structure, cations and anions are linked by C-H center dot center dot center dot Cl and C-H center dot center dot center dot O hydrogen bonds to create a helix along the [010] direction. Adjacent helical chains are further interconnected through O-H center dot center dot center dot Cl and C-H center dot center dot center dot O hydrogen bonds to form a (10(1) over bar) layer. Finally, neighboring layers are joined together via C-H center dot center dot center dot Cl contacts to generate a three-dimensional supramolecular architecture. Thermal analyses reveal that the compound melts at 449.7 K and is stable up to 560.0 K under a dynamic air atmosphere. Photoluminescence measurements show that the compound exhibits a blue fluorescence and a green phosphorescence associated with spin-allowed ((1)pi <- (1)pi*) and spin-forbidden ((1)pi <- (3)pi*) transitions, respectively. The average luminescence lifetime was determined to be 1.40 ns for the short-lived ((1)pi <- (1)pi*) transition and 105 ms for the long-lived ((1)pi <- (3)pi*) transition.
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| 8. |
- Shtender, Vitalii, et al.
(författare)
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Variants of the X-phase in the Mn-Co-Ge system
- 2021
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Ingår i: ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY. - : International Union Of Crystallography. - 2053-2296. ; 77, s. 176-180
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Tidskriftsartikel (refereegranskat)abstract
- We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.
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