William T. A. Harrison

A powder neutron diffraction determination of the structure of Sr6Co5O15, formerly described as the low-temperature hexagonal form of SrCoO3–x

The structure of Sr6Co5O15 is determined by Rietveld analysis of powder neutron diffraction data and identified as the low-temperature hexagonal form of SrCoO3–x.

Tetrahedral-atom zincophosphate structures: synthesis and structural characterization of two novel anionic eight-ring frameworks containing cationic 1,4-diazabicyclo[2.2.2]octane guests

The synthesis and structures of two new microporous, anionic zincophosphates whose channels contain cationic organic cations are described.Zn2(HPO4)3·H2N2C6H12(ZnPO/dab-A) crystallizes in the triclinic space group P with a= 9.933(2)A, b= 9.966(2)A, c= 9.518(2)A, α= 98.022(3)°, β= 114.805(3)°, γ= 107.696(3)°, V= 775.0 A3 and Z= 2, with R(F)= 3.94% for 3417 observed reflections, according to the criterion I > 3σ(I).Zn4(PO4)2(HPO4)2·3H2O·H2N2C6H12(ZnPO/dab-B) is also centric triclinic, P, with a= 9.515(2)A, b= 12.297(2)A, c= 9.461(2)A, α= 91.030(4)°, β= 98.658(4)°, γ= 93.714(4)°, V= 1091.7 A3, Z = 2, with R(F)= 6.38% for 4150 observed reflections [I > 3σ(I)].Both these new phases consist of a three-dimensional network of ZnO4 and PO4 tetrahedra, linked through oxygen vertices, to form two different open structures containing one-dimensional eight-ring channels, occupied by cationic, protonated diazabicyclo[2.2.2]octane, or dabco [(H2N2C6H12)2+] molecules and water. Some of the zinc and phosphorus polyhedra contain ‘hanging’ OH2 and OH groups: guest–framework and framework–framework hydrogen-bonds are a key structural feature of these new phases. These new phases are briefly compared with other open-framework topologies.

The crystal structure and magnetic properties of the synthetic langbeinite KBaFe2(PO4)3

Powder neutron diffraction data have been used to refine the crystal structure of KBaFe2(PO4)3 at 4.2 K; space group P213, a0 = 9.8732(1) A. The material is isostructural with the mineral langbeinite, having two crystallographically distinct, octahedrally coordinated Fe3+ ions in the asymmetric unit. Mossbauer effect spectroscopy and magnetic susceptibility measurements show that KBaFe2(PO4)3 orders as an L-type ferrimagnet with 3.9 < TC < 4.2 K. The variation of Hint has been monitored by Mossbauer spectroscopy in the temperature range 1.3 < T < 4.2 K.

Organic templates in zincophosphate synthesis: Zn5(PO4)2(HPO4)4·H2O·2H2N2C6H12, containing two distinct eight-ring channels and Zn3(PO4)(HPO4)2· HN2C6H12, containing tetrahedral three-rings and Zn–N bonds

The hydrothermal syntheses, single-crystal X-ray structures and some properties of two new microporous, anionic, zinc phosphate frameworks encapsulating organic cations are described. Zn5(PO4)2(HPO4)4·H2O·2H2N2C6H12(ZnPO/dab-C) crystallizes in the triclinic space group P(No. 2) with a= 9.366(1)A, b= 9.882(1)A, c= 19.183(2)A, α= 85.406(3)°, β= 85.029(3)° and γ= 114.485(3)°, V= 1596.51 A3 and Z= 2, with R(F)= 7.11% for 4095 observed reflections [I > 3σ(I)], Zn3(PO4)(HPO4)2·HN2C6H12(ZnPO/dab-D) is orthorhombic, space group P212121(No. 19), a= 11.095(2)A, b= 16.413(2)A, c= 8.263(1)A, V= 1505.61 A3, Z= 4, with R(F)= 5.71% for 1321 observed reflections [I > 3σ(I)].Both of these new materials consist of a three-dimensional network of tetrahedrally coordinted zinc and phosphorus atoms, linked through oxygen atom vertices, to form two different open structures. ZnPO/dab-C contains two distinct one-dimensional eight-ring channels (one regular, one squashed), occupied by extraframework, protonated, 1,4-diazabicyclo[2.2.2]octane (DABCO, [H2N2C6H12]2+) molecules. ZnPO/dab-D is a new framework type containing ‘bridged’ three-rings of tetrahedra. The DABCO molecule coordinates to the framework in this phase via Zn–N links. 31P MAS NMR data for these two materials are presented, and may be interpreted using a simple bond-strength model.

Synthesis and crystal structure of a novel beryllium phosphate open-framework structure

The synthesis and crystal structure of a new beryllophosphate (BePO) open-framework structure are reported. The new anionic BePO framework contains regular, one-dimensional eight-ring channels occupied by an organic cation, and secondary channels containing pendant P—OH and Be(OH2) units. Framework–framework and framework–guest hydrogen bonds are key structural features of this new phase.

Manganese-doped bismuth vanadate solid electrolytes

The solid solution series Bi 2 V 1-x Mn x O 5.5-x (0.10≤x≤0.25) has been prepared by conventional solid-state reaction and by crystallization from the melt. After additional subsolidus annealing both procedures yielded tetragonal phases with similar structures and lattice constants, as determined by X-ray powder diffraction. Partial substitution of manganese on the vanadium sites stabilizes Bi 2 V 1-x Mn x O 5.5-x in the high-temperature tetragonal (γ) structure of Bi 2 VO 5.5 for compositions in the range 0.10≤x ≤0.25. The structures of four compositions have been investigated by combined Rietveld refinements of X-ray and neutron powder diffraction data. Further characterization studies by transmission electron microscopy, magnetic susceptibility measurements and differential thermal analysis are described.

Synthesis and crystal structure of the two-dimensional polymer K3Co(CN)6·2Rh2(O2CMe)4

The two-dimensional coordination polymer K3Co(CN)6·2Rh2(O2CMe)4, with a square lattice forms on reaction of an aqueous solution of K3Co(CN)6 with a thf solution of Rh2(O2CMe)4.

The crystal structure of a new sodium zinc arsenate phase solved by “simulated annealing”

Abstract The framework structure of a new sodium zinc arsenate, produced by dehydration of the Na 6 (ZnAsO 4 ) 6 ·8 H 2 0 sodalite analog, has been solved by a simulated annealing method. This method utilizes typical tetrahedral-atom bonding schemes with possible space group and unit cell dimensions to randomly generate possible continuous frameworks and their calculated energies. The Rietveld refinement of the Na 6 (ZnAsO 4 ) 6 solution phase was initially performed on room temperature X-ray data and then continued on low-temperature constant wavelength neutron data. This sodium zinc phosphate is a hexagonal polycrystalline material: space group P6 3 (no. 173), with a = b =9.005 (2) A, c = 8.161 (2) A, a = β = 90°, γ = 120°, V = 573.1 A, and Z = 2, with R = 12.35% and R w = 9.76% for 2756 (CW neutron) powder data points. This tridymite structural analog undergoes a room-temperature transformation to the open-framework sodalite structure.

The structure and magnetic properties of chromium(III) molybdate

Abstract Magnetic susceptibility measurements have shown that Cr 2 (MoO 4 ) 3 orders magnetically at 42 K. Powder neutron diffraction experiments at 295 and 5 K indicate that Cr 2 (MoO 4 ) 3 is chemically and magnetically isostructural with the L-type ferrimagnet Fe 2 (MoO 4 ) 3 , and has a magnetic moment of 2.5 ± 0.2 μ B per cation at 5 K. The limitations imposed on powder neutron diffraction methods by particle-size effects are discussed.

Syntheses and structures of the open-framework phases (CH3NH3)3·Zn4O(AsO4)3 and (CH3NH3)3·Zn4O(PO4)3 related to the M3Zn4O(XO4)3·nH2O family

The solution-mediated syntheses and single crystal structures of the new open-framework phases (CH3NH3)3·Zn4O(AsO4)3 and (CH3NH3)3·Zn4O(PO4)3 are reported. These compounds are built up from vertex-sharing three-dimensional “OZn4” + ZnO4 + AsO4/PO4 tetrahedral frameworks encapsulating methylammonium cations in three-dimensional channel systems. These phases are closely related to the zeolite-like M3Zn4O(XO4)3·nH2O family of phases.