Reports and publications

 Publications

Browse the list of publications in the library for ID31.

The review committees are paying increasing attention to the quality of publications resulting from work carried out at the ESRF. Please remember to note on the proposal form the complete references of your most recent papers appearing in print, based on measurements made at the ESRF. Remember to send a reprint for the Joint ESRF/ILL library.

Experimental reports

Browse the list of experimental reports for ID31.

If you have been allocated beam time for an experiment you are required to provide a report of your experiment. Deadlines for submissions of experimental reports are: 1st March for experiments carried out up to July of the previous year 1st September for experiments carried out up to January. If you are submitting a proposal for a new project, or to continue a project for which you have previously been allocated beam time, you must attach a report, if necessary, a preliminary report on your measurements. For detailed instructions for preparing your report, please look at the user office pages.

Recent ID31 highlights

Methane Adsorption in a Supramolecular Organic Zeolite

C. Tedesco, L. Erra, M. Brunelli, V. Cipolletti, C. Gaeta, A. N. Fitch, J. L. Atwood, and P. Neri

Chem. Eur. J., 16, 2371 (2010).

An eight-membered ring: The methane adsorption properties of a new microporous organic zeolite have been studied by volumetric adsorption analysis and high-resolution powder XRD. Methane molecules have been located inside the host channels and a ring of eight methane and eight calixarene molecules is formed through CH π bonds.

 Response of the Crystal Structure and Electronic Properties to Calcium Substitution in NdFeAsO

P. Ghigna, M. Scavini, C. Mazzoli, M. Brunelli, C. Laurenti, and C. Ferrero

Phys. Rev. B, 81, 073107 (2010).

The melting of the cooperative Jahn-Teller distortion (cJTd) in KCu_1−xMg_xF₃ has been studied by high-resolution x-ray powder diffraction. A first-order phase transition relaxing the cJTd is detected at temperatures increasing monotonically with x. From the transition temperatures, an estimate of the cJTd stabilization energy is derived and found to be linearly increasing with x. By extrapolating to x=0, the cJTd energy in the parent compound KCuF₃ is determined. It is argued how, in the light of current theories, the cJTd rather than orbital polarization controls the peculiar physics of KCuF₃.

Fullerenium Salts: A New Class of C₆₀-Based Compounds

M. Riccò, D. Pontiroli, M. Mazzani, F. Gianferrari, M, Pagliari, A. Goffredi, M. Brunelli, G. Zandomeneghi, B. H. Meier, and T. Shiroka

J. Am. Chem. Soc., 132, 2064 (2010).

We report here on the preparation and characterization of a fullerenium salt in the solid state, where the fullerene is in the 2+ oxidized state. To succeed in this long-standing challenge, we exploit the oxidizing power of one of the strongest Lewis acids, AsF₅. The weak nucleophilic character of its conjugate base is essential in stabilizing the fullerene dication in a crystal lattice. High-resolution structural analysis of this compound, with the formula C₆₀(AsF₆)₂, indicates that the highly reactive C₆₀²⁺ units are arranged according to a novel 1D “zigzag” polymer structure. The molecules are connected by an alternating sequence of four-membered carbon rings ([2+2] cycloaddition) and single C−C bonds. The long awaited high-T_c superconductivity and magnetism, expected in a hole-doped C₆₀ compound, are replaced instead by a semiconducting behavior, quite probably originating from the reduced crystal and molecular symmetry upon polymerization. The small value of the energy gap (approximately 70 meV) suggests, nevertheless, the proximity of a metallic phase.

Superconductivity in NdFe_1−xCo_xAsO (0.05<x<0.20) and rare-earth magnetic ordering in NdCoAsO

A. Marcinkova, D. A. M. Grist, I. Margiolaki, T. C. Hansen, S. Margadonna, and J.-W. G. Bos

Phys. Rev. B, 81, 064511 (2010).

The phase diagram of NdFe_1−xCo_xAsO for low cobalt substitution consists of a superconducting dome (0.05<x<0.20) with a maximum critical temperature of 16.5(2) K for x=0.12. The x=1 end member, NdCoAsO, is an itinerant ferromagnet (T_C=85 K) with an ordered moment of 0.30(1) μ_B at 15 K. Below T_N = 9 K, Nd spin ordering results in the antiferromagnetic coupling of the existing ferromagnetic planes. Rietveld analysis reveals that the electronically important twofold tetrahedral angle increases from 111.4° to 115.7° in this series. Underdoped samples with x=0.046(2) and x=0.065(2) show distortions to the orthorhombic Cmma structure at 72(2) and 64(2) K, respectively. The temperature dependences of the critical fields H_c2(T) near T_c are linear with almost identical slopes of 2.3(1) T K⁻¹ for x=0.065(2), x=0.118(2), and x=0.172(2). The estimated critical field H_c2(0) and correlation length for optimally doped samples are 26(1) T and 36(1) Å. A comparison of the maximum reported critical temperatures of well-characterized cobalt-doped 122- and 1111-type superconductors is presented.

Anisotropic microstrain broadening of minium, Pb₃O₄, in a high-pressure cell: interpretation of line-width parameters in terms of stress variations

A. Leineweber and R. E. Dinnebier

J. Appl. Cryst., 43, 17 (2010).

The diffraction-line broadening exhibited by three different Pb₃O₄ phases was studied at ambient and elevated pressures. The broadening indicates strongly anisotropic microstrain, which was interpreted in terms of (local) stress variations in association with strongly anisotropic elastic properties. In particular, making use of the anisotropic compressibility of Pb₃O₄ determined on the basis of the present data, the pressure fluctuations in the employed diamond anvil cell due to non-hydrostatic conditions of the sample were estimated.

Molecular and crystalline structures of three (S)-4-alkoxycarbonyl-2-azetidinones containing long alkyl side chains from synchrotron X-ray powder diffraction data

L. E. Seijas, A. J. Mora, G. E. Delgado, F. López-Carrasquero, M. E. Báez, M. Brunelli, and A. N. Fitch

Acta. Cryst., B65, 724 (2009).

> The (S)-4-alkoxo-2-azetidinecarboxylic acids are optically active β-lactam derivatives of aspartic acid, which are used as precursors of carbapenem-type antibiotics and poly-β-aspartates. The crystal structures of three (S)-4-alkoxo-2-azetidinecarboxylic acids with alkyl chains with 10, 12 and 16 C atoms were solved using parallel tempering and refined against the X-ray powder diffraction data using the Rietveld method. The azetidinone rings in the three compounds display a pattern of asymmetrical bond distances and an almost planar conformation; these characteristics are compared with periodic solid-state, gas-phase density-functional theory (DFT) calculations and MOGUL average bond distances and angles from the CSD. The compounds pack along [001] as corrugated sheets separated by approximately 4.40 Å and connected by hydrogen bonds of the type N-H···O.

Charge ordering driven metal-insulator transition in the layered cobaltite HoBaCo₂O_5.5

L. Malavasi, M. Brunelli, Y. Diaz-Fernandez, B. Pahari, and P. Mustarelli.

Phys. Rev. B, 80, 153102 (2009).

In this Brief Report we report high-resolution synchrotron x-ray diffraction and x-ray pair-distribution-function analysis as a function of temperature on the HoBaCo₂O_5.5 cobaltite. These investigations provided a direct evidence of a structural phase transition from an orthorhombic to a monoclinic phase in the HoBaCo₂O_5.5 layered cobaltite which occurs concomitantly with the metal to insulator transition. The structural data suggest a possible charge ordered state in the monoclinic phase which may be responsible for the insulating character at low temperature.

[Al₄(OH)₂(OCH₃)₄(H₂N-bdc)₃]·x H₂O: A 12-Connected Porous Metal-Organic Framework with an Unprecedented Aluminum-Containing Brick

T. Ahnfeldt, N. Guillou, D. Gunzelmann, I. Margiolaki, T. Loiseau, G. Férey, J. Senker and N. Stock.

Angew. Chem. Int. Ed., 48, 5163 (2009).

Al together now! A new stable aluminum aminoterephthalate system contains octameric building blocks that are connected by organic linkers to form a 12-connected net (see picture). The structure adopts a cubic centered packing motive in which octameric units replace individual atoms, thus forming distorted octahedral (red sphere) and tetrahedral cages (green spheres) with effective accessible diameters of 1 and 0.45 nm, respectively.