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Instruments / Technical Area	Publication Details	Published
I22-Small angle scattering & Diffraction	A template-free and low temperature method for the synthesis of mesoporous magnesium phosphate with uniform pore structure and high surface area Jorn Hovelmann , Tomasz M. Stawski , Rogier Besselink , Helen M. Freeman , Karen M. Dietmann , Sathish Mayanna , Brian R. Pauw , Liane G. Benning Nanoscale 11, 6939 - 6951 DOI: 10.1039/C8NR09205B Diamond Proposal Number(s): [16256] Open Access Show Abstract ▼ Abstract: Mesoporous phosphates are a group of nanostructured materials with promising applications, particularly in biomedicine and catalysis. However, their controlled synthesis via conventional template-based routes presents a number of challenges and limitations. Here, we show how to synthesize a mesoporous magnesium phosphate with a high surface area and a well-defined pore structure through thermal decomposition of a crystalline struvite (MgNH4PO4·6H2O) precursor. In a first step, struvite crystals with various morphologies and sizes, ranging from a few micrometers to several millimeters, had been synthesized from supersaturated aqueous solutions (saturation index (SI) between 0.5 and 4) at ambient pressure and temperature conditions. Afterwards, the crystals were thermally treated at 70–250 °C leading to the release of structurally bound water (H2O) and ammonia (NH3). By combining thermogravimetric analyses (TGA), scanning and transmission electron microscopy (SEM, TEM), N2 sorption analyses and small- and wide-angle X-ray scattering (SAXS/WAXS) we show that this decomposition process results in a pseudomorphic transformation of the original struvite into an amorphous Mg-phosphate. Of particular importance is the fact that the final material is characterized by a very uniform mesoporous structure with 2–5 nm wide pore channels, a large specific surface area of up to 300 m2 g−1 and a total pore volume of up to 0.28 cm3 g−1. Our struvite decomposition method is well controllable and reproducible and can be easily extended to the synthesis of other mesoporous phosphates. In addition, the so produced mesoporous material is a prime candidate for use in biomedical applications considering that magnesium phosphate is a widely used, non-toxic substance that has already shown excellent biocompatibility and biodegradability.	Apr 2019
I22-Small angle scattering & Diffraction	Simultaneous SAXS and SANS Analysis for the Detection of Toroidal Supramolecular Polymers Composed of Noncovalent Supermacrocycles in Solution Martin J. Hollamby , Keisuke Aratsu , Brian R. Pauw , Sarah E. Rogers , Andrew J. Smith , Mitsuaki Yamauchi , Xu Lin , Shiki Yagai Angewandte Chemie 128, 10044 - 10047 DOI: 10.1002/ange.201603370 Diamond Proposal Number(s): [11969] Show Abstract ▼ Abstract: Molecular self-assembly primarily occurs in solution. To better understand this process, techniques capable of probing the solvated state are consequently required. Small-angle scattering (SAS) has a proven ability to detect and characterize solutions, but it is rarely applied to more complex assembly shapes. Here, small-angle X-ray and neutron scattering are applied to observe toroidal assemblies in solution. Combined analysis confirms that the toroids have a core–shell structure, with a π-conjugated core and an alkyl shell into which solvent penetrates. The dimensions determined by SAS agree well with those obtained by (dried-state) atomic force microscopy. Increasing the number of naphthalene units in the molecular building block yields greater rigidity, as evidenced by a larger toroid and a reduction in solvent penetration into the shell. The detailed structural analysis demonstrates the applicability of SAS to monitor complex solution-based self-assembly.	Aug 2016
I11-High Resolution Powder Diffraction	In situ synchrotron X-ray diffraction study of the sol-gel synthesis of Fe3N and Fe3C Zoe Schnepp , Ashleigh Danks , Martin Hollamby , Brian Pauw , Claire Murray , Chiu Tang Chemistry of Materials 27 (14), 5094–5099 DOI: 10.1021/acs.chemmater.5b01811 Diamond Proposal Number(s): [9566] Show Abstract ▼ Abstract: Sol-gel chemistry is a powerful tool for the synthesis of porous or nanocrystalline structures of a wide range of materials. The morphology and composition of the final product can depend strongly on the mechanism that operates during the heating step, as has been demonstrated in many investigations of binary, ternary and quaternary metal oxides. We demonstrate the complex phase transformations occurring in a transition metal carbide (Fe3C, cementite) synthesis using in situ synchrotron X-ray diffraction. Our new study proves the existence of multiple intermediate phases and elucidates how oxide-nitride and nitride-carbide phase transformations can occur. This is particularly important as many transition metal nitrides and carbides are metastable, which renders their stability windows sensitive to small changes in sol-gel methodology	Jul 2015

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