Results on disordered materials from the GEneral Materials diffractometer, GEM, at ISIS ☆

The GEneral Materials diffractometer, GEM, at the ISIS Facility pulsed neutron source is the most advanced materials neutron diffractometer in the world. A full description of GEM is given from the point of view of structural studies of disordered materials. The key component for these studies is the highly stable detector array, which covers a very wide range in scattering angles and a very large solid angle, leading to a wide dynamic range and a high count rate. The high real-space resolution of GEM, due to a high maximum momentum transfer of 55 A ˚ � 1 , is illustrated by data on bioactive phosphate glasses, where bonds from phosphorus to bridging and non-bridging oxygens (which differ in length by approximately 0.12 A ˚ ) are clearly resolved. The low momentum transfer ability of GEM is demonstrated by a measurement on amorphous Si77D23, which yields reliable data down to 0.1 A ˚ � 1 . The first successful isotopic substitution experiment on sol–gel materials has been performed on GEM in a study of amorphous titanium silicates, showing the suitability of the instrument for both isotopic substitution, and for studies of complex materials, even in the presence of hydrogen. Studies of the structures of disordered group 11 cyanide crystals show the power of GEM to reveal the nature of disorder in crystalline systems as well as glassy materials. The crystal structure of high temperature CuCN has been solved for the first time. The disorder in AuCN, AgCN and high temperature CuCN arises from random displacements of the linear –M–(CRN)– chains relative to each other, and the one-dimensional negative thermal expansion is due to long wavelength cooperative motions of the chains.

[1]  J. Hanna,et al.  The Structure of Solid Copper(I) Cyanide: A Multinuclear Magnetic and Quadrupole Resonance Study , 1999 .

[2]  S. Heathman,et al.  Radial collimator system for reducing background noise during neutron diffraction with area detectors , 1981 .

[3]  Mark E. Smith,et al.  New insights into medium-range order around titanium in sol–gel derived silica through isotope difference neutron diffraction and reverse Monte Carlo modelling , 2004 .

[4]  G. Frenking,et al.  Molecular structures, bond energies, and bonding analysis of group 11 cyanides TM(CN) and isocyanides TM(NC) (TM = Cu, Ag, Au) , 2003 .

[5]  T. Proffen,et al.  Local Atomic Strain in ZnSe1 xTex from High Real Space Resolution Neutron Pair Distribution Function Measurements , 2000, cond-mat/0009364.

[6]  J. Dore,et al.  Model-based computation of powder diffraction patterns for carbon nanotubes , 2003 .

[7]  Edwin D. Mares,et al.  On S , 1994, Stud Logica.

[8]  A. Wright,et al.  A small angle neutron scattering (SANS) study of hydrogen in hydrogenated amorphous silicon , 1996 .

[9]  W. Howells,et al.  Microstructural study of joule heated nanocrystalline alloys using in situ neutron diffraction , 2003 .

[10]  Simon J L Billinge,et al.  Beyond crystallography: the study of disorder, nanocrystallinity and crystallographically challenged materials with pair distribution functions. , 2004, Chemical communications.

[11]  J. Nagy,et al.  Radial distribution function analysis of spatial atomic correlations in carbon nanotubes , 2003 .

[12]  W. Howells,et al.  The analysis of liquid structure data from time-of-flight neutron diffractometry , 1989 .

[13]  Mark E. Smith,et al.  Synthesis, characterisation and performance of (TiO2)0.18(SiO2)0.82 xerogel catalysts , 2000 .

[14]  S. Hibble,et al.  CuCN: a polymorphic material. Structure of one form determined from total neutron diffraction. , 2002, Inorganic chemistry.

[15]  P. Hartmann,et al.  The structure of zinc polyphosphate glass studied by diffraction methods and 31P NMR , 2004 .

[16]  E. Lorch.  Neutron diffraction by germania, silica and radiation-damaged silica glasses , 1969 .

[17]  A. Wright,et al.  Boroxol groups in vitreous boron oxide: new evidence from neutron diffraction and inelastic neutron scattering studies , 1994 .

[18]  John C. Lindon,et al.  Encyclopedia of spectroscopy and spectrometry , 2000 .

[19]  G. P. Johari,et al.  CuCN: An orientational glass , 2002 .

[20]  C. Bradley.  Coming on board : Electronic innovations for the new millennium , 2000 .

[21]  Martin T. Dove,et al.  An introduction to the use of neutron scattering methods in mineral sciences , 2002 .

[22]  D. Keen,et al.  MCGRtof: Monte Carlo G(r) with resolution corrections for time-of-flight neutron diffractometers , 2001 .

[23]  María Vallet-Regí,et al.  Ceramics for medical applications , 2001 .

[24]  G. Placzek.  The Scattering of Neutrons by Systems of Heavy Nuclei , 1952 .

[25]  J. Neuefeind,et al.  Structure of zinc phosphate glasses probed by neutron and X-ray diffraction of high resolving power and by reverse Monte Carlo simulations , 2005 .

[26]  A. Soper,et al.  Scientific Reviews: GEM: The General Materials Diffractometer at ISIS-Multibank Capabilities for Studying Crystalline and Disordered Materials , 2004 .

[27]  S. Hibble,et al.  Total neutron diffraction: the correct way to determine the true structure of crystalline materials? , 1999 .

[28]  Martin T. Dove,et al.  Neutron total scattering method: simultaneous determination of long-range and short-range order in disordered materials , 2002 .

[29]  H. Krutter,et al.  FOURIER ANALYSIS OF X‐RAY PATTERNS OF VITREOUS SiO2 AND B2O3* , 1936 .

[30]  R. Walton,et al.  Local order of amorphous zeolite precursors from 29Si[1H] CPMAS and 27Al and 23Na MQMAS NMR and evidence for the nature of medium-range order from neutron diffraction , 2004 .

[31]  C. Rüssel,et al.  Structure of zinc and niobium tellurite glasses by neutron and x-ray diffraction , 2004 .

[32]  P. Jóvári,et al.  Structure of tellurite glasses—effects of K2O or P2O5 additions studied by diffraction , 2005 .

[33]  Brendan J. Kennedy,et al.  Crystal Structures of AuCN and AgCN and Vibrational Spectroscopic Studies of AuCN, AgCN, and CuCN. , 1998, Inorganic chemistry.

[34]  Hyunmin Kim.  Bioactive Ceramics: Challenges and Perspectives. , 2001 .

[35]  T. Nakai,et al.  Effect of tetrahedral Ti in titania–silica mixed oxides on epoxidation activity and Lewis acidity , 1995 .

[36]  John C. Dore,et al.  Paracrystalline nature of saccharose- and anthracene-based carbons studied by wide-angle scattering , 2003, Saratov Fall Meeting.

[37]  W. Howells,et al.  LAD, 1982 - 1998: the first ISIS diffractometer , 1999 .

[38]  M. Divadeenam,et al.  Neutron resonance parameters and thermal cross sections , 1981 .

[39]  S. Hibble,et al.  Structure of AuCN determined from total neutron diffraction. , 2003, Inorganic chemistry.

[40]  Mark E. Smith,et al.  The Structure of TiO2−SiO2 Sol−Gel Glasses from Neutron Diffraction with Isotopic Substitution of Titanium and 17O and 49Ti Solid-State NMR with Isotopic Enrichment , 2004 .

[41]  Zhufang Liu,et al.  Titania−Silica: A Model Binary Oxide Catalyst System , 1997 .

[42]  A. Baiker,et al.  Nature of Active Sites in Sol–Gel TiO2–SiO2 Epoxidation Catalysts , 2001 .

[43]  Uwe Hoppe,et al.  Structural specifics of phosphate glasses probed by diffraction methods: a review , 2000 .

[44]  S. L. Stebbings,et al.  The structure of lithium–ammonia and sodium–ammonia solutions by neutron diffraction , 2003 .

[45]  C. Rüssel,et al.  Structure of vanadium tellurite glasses studied by neutron and X-ray diffraction , 2002 .

[46]  S. Hibble,et al.  Beyond Bragg scattering: the structure of AgCN determined from total neutron diffraction. , 2002, Inorganic chemistry.

[47]  A. Wright,et al.  Neutron scattering from vitreous silica IV. Time-of-flight diffraction☆ , 1990 .

[48]  Alfred Schultze.  Notiz , 1890, Tschermaks mineralogische und petrographische Mitteilungen.

[49]  A. Wright.  Scientific opportunities for the study of amorphous solids using pulsed neutron sources , 1985 .

[50]  P. A. Egelstaff,et al.  Neutron Cross-Sections , 1956, Nature.

[51]  A. Cowley,et al.  Copper(I) cyanide: a simple compound with a complicated structure and surprising room-temperature reactivity. , 2004, Angewandte Chemie.

[52]  C. Brinker,et al.  Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing , 1990 .

[53]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[54]  A. Wright,et al.  Neutron scattering from vitreous silica II. Twin-axis diffraction experiments , 1983 .

[55]  A. Wright,et al.  Static approximation distortions and neutron time-of-flight diffraction using the Harwell Linac , 1974 .

[56]  D. L. Bryce,et al.  Insight into the structure of silver cyanide from (13)C and (15)N solid-state NMR spectroscopy. , 2002, Inorganic chemistry.