Report Industrial Group Autumn Meeting 2006

The Impact of Crystallography in an Industrial Environment

The meeting began with an introduction by Jeremy Cockcroft, the Industrial Group Chair, who thanked Pilkington for hosting the meeting and providing lunch. He commented that it was good to see the meeting return to the site of an industrial company. The sessions started with an introduction to Pilkington by Mary Ormsby, a senior manager on site. Fairly recently, Pilkington was taken over by the Japanese glass company NSG - half its size - and the two organisations are slowly merging. Whereas Pilkington had in recent years majored on building and automotive products, NSG has a lot of hi-tech applications. The next few months will be an interesting time as the cultures merge.

The first scientific talk of the day was by Gordon Barr (U. of Glasgow), who spoke about high throughput screening with XRPD and Raman. In both cases, full profile patterns are compared, using both parametric and nonparametric statistics. Correlation coefficients are calculated from which a distance matrix is set up. Finally various techniques for cluster analysis are applied. The result is a robust and rapid method of grouping data on large groups of samples.

The next speaker was an old friend, Ian Ferguson, who described the characterisation of SiC coatings on nuclear reactor fuel pellets. This amounted to an interesting reminder of the value of relatively simple approaches to strain analysis. Some of this work went back a long way - how many of us remember computer data entry on 5-hole punch tape? - but it is still relevant.

The last speaker in the morning session was Ivan Parkin (UCL) who talked about XRPD mapping of CVD coatings on glass. WO₃ coatings are always the same polymorph, but crystallite morphology and orientation vary with the reagent used to hydrolyse WCl₆. The surfaces can be highly hydrophilic: on the other hand, if the coating is of WSe₂, then the surface will be very hydrophobic. This comparison led on to a discussion of different models for the hydrophilic/hydrophobic nature of surfaces, and a comparison with various TiO₂-based films.

During the lunch break, we enjoyed a tour of the exhibition area - so interesting did we find it that two of the three parties were late back, and the afternoon session got under way a little behind schedule. Mark Farnworth (Pilkington) led with a description of how XRPD and X-ray reflectivity can be used in the glass industry. Estimation of the proportion of amorphous material is important but because it is always compositionally similar, a simple method can be used. Silver in coatings on glass shows marked preferred orientation, which can be seen by XRD at different angles of incidence.

Andrew Hodge (BP) spoke next, describing some of the varied work he carries out on a wide range of samples associated with chemicals, oils and their applications. He compared the use of XRD in its 80's heyday of seven instruments and 9 staff to today's two instruments and one staff. Recent modernisation and migration to new instruments includes an old high temperature 30 bar pressure + temperature chamber with a sophisticated reactive gas flow system used for catalyst studies.

Richard Morris (Morris Analytical X-Ray) had chosen the title "Dog Food 'n Diffraction" for an interesting talk; the various reactions of members of the audience made an amusing study in human nature. Polyphosphates find a lot of uses in meat products, but some of them have undesirable properties. Trisodium hydrogen pyrophosphate is useful but not easily prepared, and Richard had been involved with a project that found a route to a crystalline form of it. The product is analysed by XRPD, the results from which agree well with ³¹P NMR.

Chris Staddon (U. of Nottingham) had a similarish title, "XRD 'n Chips" - silicon chips to be precise, and other semiconductors, particularly III-V's but especially Ga(As,N). This occurs in the two ZnS structures and, with doping, atoms on unexpected lattice or interstitial sites and so on, form a complex group of species. The determination of Mn, and of where in the lattice it is to be found in GaMnAs, is a complex task for which a combination of XRF and XRD has proved reasonably successful.

Graham Smith (Shell, Thornton) told us about some of the work he has done over the years on samples associated with the application of oil products. Pitting of a valve from an aero-engine was found to be associated with a deposit of Pb₂CrO₅, a high-temperature oxidation product of the valve material, whose presence indicated excessive engine temperatures. Fuel starvation in a petrol engine was found to be due to a blocked filter in the petrol tank. The blockage was shown by XRPD to contain Fe₃O₄, Cu, CuO and graphite. The first was rust, but the others derived from wear of the (totally immersed) electric fuel pump's commutator and brushgear. These and other examples made this a fascinating talk. Another old technique which had come in handy was a Debye-Scherrer camera, useful with very small samples.

The last talk was by Peter Stacey (HSL, Buxton) who also talked about his work. The main topic of his talk was the quantification of crystalline SiO₂ in air samples. The recently-reduced WEL is now 0.1 mg m^-3; while there are calls for lower limits, the difficulty of analysis would make them hard to enforce. At the proposed level of 0.04 mg m^-3, the interlaboratory uncertainty would lead to relative 95 % confidence limits around ± 50 % for 4 hours measurement. Large samples require corrections for absorption of X-rays, which would be an added complication. He concluded with further examples relating to asbestos and calcium phosphates.

All in all, it was an interesting meeting in an excellent venue, and the thirty-odd participants went home well satisfied.

David Beveridge
HARMAN Technology Limited (ILFORD Photo)

Last updated 22-November-2006

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