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A series of spinel-type MnxNi1-xCo2O4 (x = 0, 0.3, 0.5, 0.7, 1) oxides were synthesized by using a citrate sol-gel technique. The structural, magnetic and electronic properties of the oxides with different Mn content were investigated using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). The XRD and FTIR studies revealed that MnxNi1-xCo2O4 formed in a cubic structure for all the compositions synthesized. Transmission electron microscopy (TEM) studies show cubic nano-plates for x = 0 and on increasing Mn concentration, agglomerated nanoparticles with sphere-like shape are observed with a particle size in the range of 11.7 nm–22.1 nm. This is in close agreement with the results of XRD analysis. The Mn 2p, Ni 2p, and Co 2p XPS spectra reveal the coexistence of Mn2+, Mn3+, Ni2+, Ni3+, Co2+, and Co3+ species on the surface of MnxNi1-xCo2O4 samples in differing proportions. The measurements of magnetic properties at room temperature show that the samples have some ferromagnetic behaviour. The saturation magnetization, remnant magnetization, and coercivity of the nanoparticles vary significantly with a concentration of Mn, which tends to be distributed in both tetrahedral and octahedral positions of the spinel lattice.

One of the pathways responsible for the deactivation of Fischer-Tropsch catalysts is the loss of active metal surface area due to nanoparticle agglomeration. To combat this effect efforts have been made to increase the interaction between the metal nanoparticles and the support using materials like silica. In this study, the supported metal particles were covered with a highly porous layer of silica to stabilize the Co nanoparticles on a titania support both during reduction and under reaction conditions. Co3O4 nanoparticles (size range: 8–12 nm) supported on titania were stabilized by coating them with a thin layer of mesoporous silica ( ∼ 4 nm) to make Fischer-Tropsch catalysts that are less prone to sintering (Co/TiO2@mSiO2). To mitigate the strong metal support interactions brought about by the titania and silica a Ru promoter was loaded together with the cobalt nanoparticles onto the titania (CoRu/TiO2@mSiO2). Temperature programmed XRD studies on the evolution of the Co metal nanoparticles showed that there was no significant particle size growth under reduction conditions in the temperature range from 30 to 600 °C. Chemisorption studies following reduction under hydrogen at 350 °C and 450 °C gave results consistent with the in situ XRD data when compared to the Co/TiO2. Fischer-Tropsch synthesis on the Co/TiO2@mSiO2 and CoRu/TiO2@mSiO2 catalysts encapsulated inside the mesoporous silica shell exhibited good catalytic performance without any display of significant mass transport limitations that might arise due to a silica shell coating of the active sites. For these two catalysts the Fischer-Tropsch activity increased with reduction temperature without any significant negative changes in their selectivity due to sintering, while the activity on Co/TiO2 decreased due to Co nanoparticle sintering.

The thermal production of 4PbO·PbSO4 was comprehensively studied and characterized for two syntheses routes, i.e. either heating 3PbO·PbSO4·H2O, or a mixture of 4PbO:PbSO4, in air to about 700 °C. In the 3PbO·PbSO4·H2O approach, the formation of an intermediate amorphous phase occurred at around 210 °C with the loss of H2O from the hydrated structure. Formation of 4PbO·PbSO4 initiated at around 270 °C with predominantly 4PbO·PbSO4 and 13% residual PbO·PbSO4 existing at 700 °C. With the synthesis route of mixing a stoichiometric ratio of 4PbO with PbSO4, an intermediate phase of PbO·PbSO4 formed at around 300 °C, before the 4PbO·PbSO4 phase started to form at around 500 °C. Upon further heating, 4PbO·PbSO4 was the predominant phase with 8% of PbO·PbSO4 remaining. Both samples decomposed upon further heating to 850 °C. Powder neutron diffraction studies of the final 4PbO·PbSO4 products from the two different synthesis routes showed similar crystallographic unit cell lattice parameters with slight differences in the PbO:PbSO4 contents. This could possibly be linked to differences observed in the microscopic crystallite shapes from the two synthesis routes.

The phase behaviour of Fe and Co particles, supported on CaCO3 was studied using mainly in situ PXRD and Mossbauer spectroscopy. This is of interest as these systems can be used as catalysts to produce multi-walled carbon nanotubes (MWCNTs) following appropriate heat treatment and reduction. The Fe–Co/CaCO3 samples were prepared by deposition of the metallic particles from solution onto the support. The study indicated that the CaCO3 support reacted in air or N2 with the iron and cobalt present in all three samples studied (10% Fe/CaCO3, 10% Co/CaCO3 and 10% Fe–Co/CaCO3) to give a brownmillerite structure with the general formula Ca2M2O5 (M = Fe, Co or Fe + Co). Reduction of the bimetallic catalyst gave Fe2Co alloy and Co. This confirms earlier reports by other authors that implicated this alloy as the active phase in the synthesis of the MWCNTs. The bimetallic catalyst was easier to reduce than the mono-metallic catalysts.

The vibrational mode for the cubic symmetry of boron nitride (BN) has been produced by boron ion implantation of hexagonal boron nitride (h-BN). The optimum fluence at 150 keV was found to be 5 × 1014 ions/cm2. The presence of the c-BN phase was inferred using glancing incidence XRD (GIXRD) and Fourier Transform Infrared Spectroscopy (FTIR). After implantation, Fourier Transform Infrared Spectroscopy indicated a peak at 1092 cm−1 which corresponds to the vibrational mode for nanocrystalline BN (nc-BN). The glancing angle XRD pattern after implantation exhibited c-BN diffraction peaks relative to the implantation depth of 0.4 μm.

The synthesis and thermoresponsive behaviour of high purity CuTi2(PO4)3 (CTP) was examined while heating in air and nitrogen at atmospheric pressure. It is known that a spontaneous redox reaction involving the Cu+ cations that are contained in the Ti2(PO4)3− crystal structure converts the CTP phase to the related Cu0.5Ti2(PO4)3 (CTP2) phase when heated in air. However, the extent of this reaction and the effect that it has on the CTP crystal structure has not been established. Using in situ powder X-ray diffraction it was found that during heating in air, the migration of Cu+ cations out of the Ti2(PO4)3− crystal lattice results in the growth of a CuO phase. To quantify the extent of the migration of the Cu+ cations out of the Ti2(PO4)3− crystal lattice, quantitative phase analysis was used to show that the redox reaction converts the CTP phase to the CTP2 phase in the temperature region from 450 to 530 °C. When increasing the temperature above 530 °C it was found that the CTP phase was spontaneously regenerated forming a high temperature form of the parent CTP phase. Previously heat-treated CTP samples were subjected to further heat treatments and produced different quantitative phase behaviour when compared to a fresh CTP sample. Most significantly it was found that the CTP2 phase was prevalent over a broader temperature range. Comparison of the high temperature and parent CTP phases showed differences between the Cu+ site occupancies. Further heat treatment under nitrogen suppressed the redox reaction and stabilized the CTP phase. This allowed the calculation of the coefficients of thermal expansion (CTE) of CTP across a broad temperature range (30–900 °C). Analysis of the CTP lattice constants via Parametric Rietveld refinement showed that the compound exhibited moderate thermal expansion up to 900 °C.

High pressure–temperature (P–T) phases of the ZrxHf1−xO2 (x = 0.5) solid-solution have been stabilised in a CO2 laser heated diamond anvil cell. At room-temperature the monoclinic to orthorhombic-I structural transformation is initiated at 5–8 GPa. The X-ray diffraction (XRD) studies show these two phases coexist to above ∼15 GPa. A progressive increase in the orthorhombic-I phase abundance occurs, to culminate in full conversion at ∼20 GPa. At this lower threshold of ∼20 GPa transformation to the orthorhombic-II (cotunnite) structure can be initiated by heating in the range of 600–1200 °C. Substantial conversion to the cotunnite phase occurs in the same temperature range at 25–30 GPa. Raman signatures have been assigned to the two orthorhombic high-pressure phases, aided by the qualitative assessment of the complementary XRD data. Decompression experiments show that phase mixture composites of these high pressure structures, possibly with enhanced tribological properties, can be recovered to ambient conditions.

Distorted square pyramidal complexes of molybdenum (η 5 -C 5 H 4 Me)Mo(CO) 2 (PR 3 )I (R 3 = PhMe 2 ( 2a ); PhEt 2 ( 3a ) and Et 3 ( 4a )) have been synthesized and the structures of the lateral ( cis ) isomers have been determined by X-ray diffraction. The cone ( Θ ) and solid ( Ω ) angles as well as the angular profiles of the phosphine ligands in the complexes have been computed using the program steric . Values for the crystallographic cone and solid angles calculated for 2a , 3a and 4a are Θ (129°, 135° and 139°) and Ω (2.73, 2.99 and 2.93 sr), respectively. A search of the Cambridge Structural Database (CSD) was made for piano stool, 5- and 6-coordinate complexes containing the title phosphine ligands. Results from this study show a wide range of sizes for each of the ligands and even the seemingly simple PPhMe 2 ligand exhibited a wide range of values for the cone (113–137°) and solid (2.49–3.07 sr) angles. These observations have been rationalized and related to the possible group conformations from the crystallographic data.

The crystal structure of complex 3, a Ni(II)(dppe) ligated in a square planar arrangement by a novel S, N-ligand, has been determined at 123 K. The neutral and air stable complex is of interest as it shows an apparently zwitterionic structure, one counter-anion to the Ni(II) being delocalised into the backbone of the ligand. Support for this conclusion comes from an analysis of bond lengths in the complex 3, the crystal structure of which is presented and the result of a density functional calculation performed on the complex. A discussion of the mechanism leading to the observed product is presented.

The cis and trans monosubstituted cyclopentadienyl tungsten and molybdenum complexes (η 5 -C 5 H 4 R)M(CO) 2 (L)I ( 1 ) (M=W, R=Me, t Bu, L=P(O i Pr) 3 , PPh 3 ; M=Mo, R=Me, L=PPh 3 ) have been synthesised and fully characterised by elemental analysis and IR and NMR spectroscopy. It was found that 1 underwent a thermal solid-state ligand isomerisation reaction and that the favoured direction of the isomerisation reaction is related to the melting points of the cis and trans isomers, i.e., with intermolecular forces in the solid state. No obvious relationship between the melting point and the metal, the ring-substituent or the ligand was observed. Crystal structure determinations of the cis and trans isomers of (η 5 -C 5 H 4 Me)W(CO) 2 (PPh 3 )I reveal that a limited amount of isomer conversion can be accommodated in the unit cell of the trans isomer, prior to crystal fragmentation. The rearrangement of the molecules within the unit cell, during isomerisation, also leads to disorder in the crystal.

The isomerisation of ttt -RuCl 2 (RNC) 2 (PPh 3 ) 2 (R=2,6-xylyl, t Bu, i Pr, benzyl, 2-OMe-4-Clphenyl) to cct -RuCl 2 (RNC) 2 (PPh 3 ) 2 has been carried out in the solid state. The reaction is first order and kinetic measurements have yielded activation energies of 210 kJ mol −1 (R= t Bu) and 221 kJ mol −1 (R=benzyl) for reactions performed between 160 and 180 °C. XRD analysis of the solid state reaction of ttt -RuCl 2 ( t BuNC) 2 (PPh 3 ) 2 has revealed that the cct -isomer produced is a polymorph of that produced by recrystallisation of the pure cct -RuCl 2 ( t BuNC) 2 (PPh 3 ) 2 isomer. A possible mechanism for the isomerisation reaction involving rotation of the two small groups (Cl, RNC) is proposed.

Powder neutron and X-ray diffraction data for indium sulfide are reported. The lattice parameters obtained from a Rietveld refinement for the neutron data are: a=7.5937 (6) A; c=32.352 (3) A; V=1865.6 (3) A3 and for X-ray data are: a=7.6172 (1) A; c=32.3307 (8) A; V=1875.86 (6) A3. The crystal system was taken to be tetragonal (space group I41/amd).

Reaction of (η5-C5H5)MoMn(CO)8 (1) with P(OMe)3 and t-BuNC in the presence of Me3NO results in facile MoMn bond cleavage products as well as the synthesis of (η5-C5H5)Mo(CO)3Mn(CO)4[P(OMe3)] (3) in which the P(OMe)3 occupies a site trans to the MoMn bond. The crystal structure of 3 is reported (space group P21/c, a=13.064(4), b=7.1325(8), c=22.227(5) A β=104.91(1)°. Final R and Rw, values were 0.058 and 0.048 (w=Kσ2(F)). The non-bridged MoMn bond length is the largest reported to date (3.112(1) A) and the equatorial MnCO bond lengths are longer than those in the patent unsubstituted dimer (1).

The molecular structure of [1,1′-bipyrrolidine]-2,2′-dithione (1) has been determined by single-crystal X-ray crystallography. The compound crystallizes in the orthorhombic system: Pbca, a = 9.314(12), b = 13.213(2), c = 16.321(3) A, V = 2008.4 A3, Z = 8, Dc = 1.33 g cm−3, R = 0.042 for 2583 unique reflections and 140 variable parameters. The dihedral angle between the mean planes of the rings is 104.2(7)°. The conformations of the rings themselves are presented in terms of normalized linear combinations of the primitive envelope and twist forms. Certain bond distances are rationalized in terms of the screening of nuclear repulsion. The rorational barrier about the NN bond has been calculated from variable temperature nuclear magnetic resonance (NMR) measurements in deuterated toluene as 73 kJ mol−1. All measured parameters are contrasted with those found in the literature for the 2,2′-dioxo analogue (2), for which the rotational barrier has been determined in this work as 44 kJ mol−1.