August 2001 Newsletter

Contents

1. Editorial
2. BCA Spring meeting - Reports April 2001, Reading
3. Chairman's Report for 2000 Delivered at the 2001 AGM
4. Newsletter mailing list
5. Bruker AXS User Group Meeting Report
6. Pharmaceutical SIG June 2001 Report
7. Autumn Meeting 1/11/01 Pilkington, Lathom - Programme
8. Committee Members and Addresses (2001)

Thanks to Philips Analytical w ho sponsored the distribution of the paper edition of this Newsletter.

Forthcoming Events
Autumn Meeting - 1^st November 2001, Pilkington, Lathom

2002 BCA Spring Meeting - Nottingham University, 25 - 28^th March. Look out for details in Crystallography News and the next newsletter

Editorial

This is my first newsletter as editor, so any comments on the layout and co ntent would be welcome. Thanks to Colin Small for his efforts over the past couple of years. Things are now getting back to normal after the Spring Meeting at Reading. For those of you who couldn't make it, this was an excellent meeting with good attendance at the IG sessions. Thanks to all those who spoke and especially the three speakers at the basic powder diffraction workshop. To be able to stand up and talk for a couple of hours requires a great deal of thought and preparation.

I know that we are all under pressure at work these days; but would you think about submitting a technical article about your work. This could be a short description of some work recently carried out, tips on sample preparation or advice on a particular technique. This type of article has been well received in previous newsletters. Also, if you attend a conference or meeting, which has some crystallographic content, please consider sending in a short report.

Possible changes to the Industrial G roup Constitution?

As Steve Norval mentioned in his article, it is becoming increasingly difficult to attract new committee members. It seems that the time has come to consider changes to the way that new committee members are elected and their terms of office. This would require changes to be made to the Industrial Group Constitution.

This is YOUR chance to have a say in how the group is run and organised. Please have a look at the Constitution on the IG web site, and let me have your comments or ideas for changes.

Philip Holdway

Editor

Newsletter Mailing list.

To keep cost down and to ensure that the newsletter gets to the appropriate people it is essential that we know your correct address. Also if there is a more appropriate contact in your organisation or if you no longer require a copy please let us know by contacting any of the committee officers.

If you would like an e-mail notification of the WEB posting of future IG Newsletters then send an E-mail to [email protected] - with the title SUBSCRIBE WEB NEWS

Dave Taylor

Bruker AXS Ltd - User Group Meeting

30th April - 1st May 2001

Bruker AXS held an XRD User Group Meeting at The Bank House Hotel, Bransford, Worcester on Monday 30^th April and Tuesday 1st May 2001which was attended by around 40 delegates. Andrew Keir, DERA Malvern, gave the first presentation on Monday on the high resolution X-ray diffractometry of semiconductor alloys. One example of the use of a high-resolution diffractometer was in the measurement of the lattice parameters of GaAs (a=5.6533) and AlAs (a=5.6523). Another application described was the measurement of lattice parameters to characterise the composition of the GaN/AlN system. This semiconductor has a sapphire substrate (Al₂O₃), a layer of GaN and then a layer of AlGaN. The AlGaN layer has built in strain due to its attempts to fit to the lattice parameters of the underlying layers. This strain shows as a small change in lattice parameter which can be detected using high-resolution diffractometry

The second presentation was from Phil Holdway, DERA Oxford. Phil described the hardware and software used to measure strain in helicopter blades. Wi th an XYZ sample stage and small collimators it is possible to analyse large samples from the blades and at various positions on the samples. The software used measured strain from diffraction peak shifts and residual stress calculated from the strain. Phil pointed out that the need to take into account variations in texture when analysing the data.

Chris Morgan from Johnson Matthey, followed with a presentation on the post-mortem characterisation of autocatalysts. A utocatalysts consist of a precious metal sprayed on a high surface support material such as Al₂O₃ which is then coated onto a ceramic or metallic substrate. XRD can be used to identify the crystalline components of autocatalysts under different conditions. These include the initial state of the autocatalyst, thermally induced changes during ageing and the effect of poisoning. XRD is also used in the development of new autocatalysts. Chris described a case study for a customer w here XRD analysis was used to determine the thermal history of an autocatalyst under test.

Dave Stewart, BNFL Magnox, described the wide range of irradiated and uniradiated materials that are analysed by XRD at the Berkeley Technology Centre. Examples of analyses included the oxidation of welds, the quantification of magnetite, haematite, retained austenite and sigma phase in steels, the oxidation of copper and the investigation of magnox combustion products. He also presented a cas e study describing how XRD was used to identify changes in the lattice parameter and crystallinity of graphite moderator samples caused by irradiation damage.

Joe Hriljac, University of Birmingham gave a presentation on XRD studies of Bismuth Molybdovanadates in the system Bi _1-x/3(V _1-x Mo _x)O ₄. Part of the studies involved determining the range of x for which solid solutions existed. At high values of x a solid solution existed with a su perlattice. High temperature studies indicated that BiVO4 undergoes a phase transition to give a CaWO₄ type structure.

Ian Slipper, University of Greenwich gave a talk entitled "Determination of Glass content of ground granulated blast furnace slag GGBS". This slag is a by-product of the steel industry and used as an admixture to cement. If the crystallinity of the slag is too high (above 67%) it cannot be used as cement additive. The BS Standard method of measuring the cr ystallinity of the slag is to profile fit the X-ray diffraction pattern to separate the crystalline and amorphous components, print the pattern, cut out the amorphous and crystalline peaks and weigh the paper cut outs. With PC based pattern evaluation software (EVAL) it is now possible to remove the amorphous component and then calculate the area of the crystalline peak directly.

Judith Shackleton, University of Manchester Materials Science Centre, looked at XRD Stress Mapping of Ine rtial welds using a GADDS system. Inertial welding is carried out by slamming a spinning component into a stationary component and allowing friction to form the weld. Neutron diffraction had been used to analyse a test piece of Ni superalloy welded in this way and the lattice parameters calculated from whole pattern fitting. As the hoop, axial and radial residual stresses calculated by neutron diffraction were not as expected analysis was also carried out on slices of weld areas from this sample usi ng the GADDS system at Manchester. It was possible to see the weld with the video camera on the GADDS system and determine exactly where to carry out analysis. Happily, the results obtained were found to be in agreement with the neutron diffraction results

Jo Jutson (ex BICC Cables) described how microdiffraction could be carried out using a GADDS system, allowing the analysis of very small samples from cable components. Sample preparation time and analysis time was greatly reduced compared with analysis using a conventional diffractometer. Typical analyses carried out were variations in phase composition of cable components and identification of impurities. The technique had a particular application in the analysis of superconductor tapes. These tapes are typically 3mm wide and 0.5mm thick and could contain about 30 filaments of conducting material in a silver casing. With microdiffraction it was possible to analyse individual filaments about 500m m wide. Variations in phase composition of filaments across the tapes could be determined from the ratio of 2223/2212 superconductor peaks and variations in texture could also be measured.

David Taylor (ICDD) closed the presentations with a talk on ICDD developments. At present there is a reduction in the number of powder diffraction patterns being published in papers and ICDD now pay diffractionists to produce new patterns via the Grant-in-Aid program. Some patterns are calculated f rom single crystal data. To date there are over 130,000 patterns in the PDF (powder diffraction file); sets 1-50 are from experimental data and sets 70-88 calculated from ICSD data.

Software for the PDF has been updated with PCPDFWin allowing windows accessibility and PCSIWin software is an alternative to the paper search manual. The new Relational DataBase (RDB) will give a more flexible search environment and allow easier updating of information. Metals and Alloys is the first RDB to be marketed.

The Bruker AXS technical presentations on the second day of the meeting covered a wide range of new and improved hardware and software products and their applications. All of the presentations over the two days of the meeting were very interesting. Many thanks to Bruker AXS for organising the meeting.

Jo Jutson