R. Lindsay Davis

Refinement of the structure of Na0.74CoO2 using neutron powder diffraction

Abstract Refinement of the structure of Na 0.74(2) CoO 2 was carried out using neutron diffraction data. The material was indexed using the hexagonal P6 3 /mmc space group with lattice parameters a = 2.840(1) A and c = 10.811(1) A. High resolution neutron powder diffraction data of the layered metal oxide were analysed ab initio to reveal a structure with alternating sodium layers intercalated between octahedral sheets of cobalt oxide (CoO 6 ). The two sites available for occupancy by the sodium ion in the sodium layer of the unit cell are ( 2 3 , 1 3 , 1 4 ) and (0, 0, 1 4 ). The sodium ions occupy the two available sites unequally (the probability of finding sodium ions at one site being approximately twice that for the other site) due to the influence of second nearest neighbour cobalt ions.

STRUCTURE OF CALCIUM ALUMINATE SULFATE CA4AL6O16S

The commensurately modulated structure of polycrystalline calcium aluminate sulfate was determined using spectroscopic and electron microscopic information and calculations with the bond-valence method. The neutron powder diffraction data were refined by the Rietveld profile technique. Calcium aluminate sulfate, Ca4Al6O16S, MW = 2440 Da, orthorhombic, Pcc2, a = 13.028(3) Angstrom, b = 13.037(3) Angstrom, c = 9.161(2) Angstrom, U = 1556(1) Angstrom(3), Z = 4, Dc = 2.60 g cm(3), lambda (neutron) = 1.893 Angstrom (Ge monochromated), mu R(neutron) = 0.42, R(Bragg) = 0.046, R(p) = 0.06, R(wp) = 0.08 is a twofold superstructure of sodalite which is generated by z modulation of the framework along [1 1 0] of the cubic subcell

Structure of sodium tetradeuteroborate, NaBD4

The structure of NaBD was determined from powder neutron data and refined using Rietvelds method. The compound has a sodium chloride-type structure, in space group F43m, a = 6.137(7), A, BD, 1.160(7); angle DBD, 109.5(2)° at 295 K, with D atoms tetrahedrally oriented about B (at 1 2,0,0, etc.), and along all cube diagonals. This gives a random distribution of BD tetrahedra in two different configurations.

The structure of Li0.43Na0.36CoO1.96 using neutron powder diffraction

Abstract A new layered alkali-transition metal oxide was prepared by the solid state reaction of LiCoO 2 and Na 0.7 CoO 1.96 in air at 850°C. Its chemical formula is Li 0.43 Na 0.35 CoO 1.96 as determined by atomic absorption spectrophotometry and high resolution neutron powder diffraction. X-ray and neutron diffraction data of the material were indexed using the hexagonal P6 3 mc space group with lattice parameters a = 2.839(4) A and c = 20.36(3) A . High resolution neutron powder diffraction data of the layered metal oxide were analysed ab initio to reveal a structure with alternating lithium and sodium layers intercalated between octahedral sheets oxide (CoO 6 ). The lithium ions are sited within an octahedral oxygen framework whereas the sodium ions are within a trigonal prismatic oxygen environment (between the CoO 6 layers). The sodium ions occupy two available sites unequally (the probability of finding sodium ions at one site being approximately twice that for the other site) due to the influence of second nearest neighbour cobalt ions.

On the nature of the host–guest interaction between cyclam and 4-tert-butylbenzoic acid—a system pre-assembled for metal complex formation

The host–guest interaction between cyclam and 4-tert-butylbenzoic acid has been investigated by NMR titration, X-ray diffraction, neutron diffraction and semi-empirical MO calculation; the product represents a system preassembled for metal-ion complexation.

On the short C–C bond lengths in macrocyclic ligand systems incorporating ether donors: a comparative neutron and X-ray diffraction study of an O2N3 donor macrocycle: 6,7,8,9,10,11,12,13,19,20-decahydro-5H-dibenzo[e,p][1,4,8,11,14]dioxatriazacycloheptadecine

The neutron diffraction structure of a 17-membered macrocyclic ligand incorporating an O2N3-donor set has been determined in order to investigate whether the C–C bond in the –OCH2CH2O– atom string remains short as found in the corresponding X-ray structure of this compound; the evidence suggests that the short bond found by X-ray diffraction in this as well as in many other polyether compounds is largely an artefact with the ‘real’ component of the shortening being quite minor.

Self-assembly directed by NH···O hydrogenbonding: a neutron study of a trilayered supramolecular array formedbetween 1,2-diaminoethane and benzoic acid

The supramolecular array formed by co-crystallisation of 1,2-diaminoethane and benzoic acid is investigated by neutron diffraction; the system self-assembles into an unusual layered structure composed of two-dimensional hydrogen-bonded networks sandwiched between layers of edge-to-face stacked aromatic systems; the number of hydrogen-bond donors and acceptors is balanced in the structure.

Thermal parameters for lithium halides

The thermal parameters for LiF, LiCl, LiBr, LiI have been determined using a high-resolution neutron powder diffractometer (λ = 1.500 A), and found to be 1.17(5), 0.73(3); 2.39(7), 1.18(2); 3.16(8), 1.46(3); 4.08(11), 1.84(5) A2, respectively, for (Li, X) at 294 K.