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Industrial Group of the BCA
July 1995 NewsletterContents
EditorialIn this issue we have news of forthcoming meetings, reports on recent meetings and details of committee changes following the elections at the AGM.Also there is an introduction to a round-robin calibration exercise in which all members in the UK are invited to participate. Following changes by the BCA in the way t hey allocate funds to the Groups, detailed in the last newsletter, the committee is considering various alternatives in attracting Group membership. A discussion paper is enclosed on a proposal which the committee is considering. If you have any views on the subject please let us know. Trevor Carter JCPDS ADVANCED PHASE IDENTIFICATION COURSEThe Advanced Phase Identification Course combining lectures and practical sessions was presented by Ron Jenkins, Principal Scientist of the ICDD. The interesting and instructive lectures recapped the theory of XRD, optimum instrument and data collection parameters as well as the various search strategies available for phase identification. The lectures were supported by a new phase identification course workbook which contains a number of examples to illustrate the various approaches available and problems which may be encountered in practice. The prac tical sessions used computing facilities supplied by Cardiff University. The large number of course participants allowed for two users per terminal and this was satisfactory. The facilities enabled us to try out the latest versions of JCPDS database software whilst attempting examples from the range of XRD problems from the workbook. The course was well presented and accessible to attendees with a range of experience. The novice users of XRD were able to follow Ron Jenkins' down to earth a pproach and the more experienced benefitted from new tips and looking again at the basics of the technique. Barbara Middlemiss - ICI Wilton Research Centre QUANTITATIVE PHASE ANALYSIS - part IThe workshop meeting was held at Sir William Siemens House in Manchester on 7th June 1995. The sessions were chaired by Jo Jutson and opened by Gareth Cullen of Siemens who gave a brief overview of Siemens history and current operati ons in the UK and worldwide. The first paper concerning Sample Methods and Reproducibility of Data was due to be presented by Walter Gutteridge (British Cement Association). Due to unavoidable last minute committments by Walter, the paper was presented by David Dyson who was able to add some additional detail from his own laboratory to notes supplied by Walter. Illustrated examples from the BCA laboratory included extensive data on the effect of sieving and grinding times during sample pre paration. Factors such as the difference between wet and dry grinding were discussed. It was stressed that the backloading technique was essential for accurate results. Data on reproducibility of sample preparation was also presented. Dieter Bertelmann of Siemens gave a brief overview of methods available for analysis (Chung I and II, Rietveld). He then continued by discussing modifications to the diffractometer setup in order to obtain maximum intensity, i.e. 'tuning your hardware' to get better counting statistics. Removal of secondary monochromators and soller slits plus the choice of wider slits can dramatically increase intensity./ Judith Shackleton of Philips gave an in depth presentation covering aspects of instrument setup and data collection parameters. In order to achieve the highest possible count rate, a low background and reasonable resolution, several compromises have to be addressed. Careful choice of x-ray tube anode and focus, x-ray detector, filt ers, monochromators and slits were all described in order to achieve good peak to background ratios without producing poor resolution. The importance of regular machine checks using a standard such as NIST 1976 was stressed. The paper concluded with a section concerning data collection and counting statistics. Judith emphasised the importance of counting for a reasonable time on the background region, especially if the background is substantial. Glyn Carter of Geochem presented a paper on t he effects of particle size, texture and surface finish. He gave detailed information on sample preparation techniques to negate such factors as preferential sorting in mixed phase samples. He concluded with remarks to the effect that it is possible to obtain high precision with modern XRD methods, but only poor accuracy. His final plea was that in most cases there is no set analytical procedure in the open literature for quantification. Whereas within one laboratory there may be excellent precision , there is often no reproducibility throughout the Industrial community. He urged us to publish our methods in the open literature in order to remedy this situation. Jo Jutson of BICC Cables gave the first of the final two contributions discussing problems encountered with specific industrial laboratory samples. In analysing fillers, especially alumina trihydrate, in cable sheathing, problems exist with lack of reliable standards and the non ideal shape of the 'as received' cable samples. After investigation suitable standards were made up by powdering a standard cable, mixing with spectroblend and pressing to shape. Quantitative analysis of alumina trihydrate content was successfully accomplished so long as the polymer type was known and suitable calibration data was available. David Dyson of British steel reminded the audience that it was possible to obtain meaningful results from 'non ideal' samples , eg non powder, preferentially orientated steels, typically of cubic ma terials with overlapping peaks. Determination of the amount of austenite in steels is a typical example. Reliable answers were presented after derivation of 'P factors' along with a demonstration of software utilised. The formal part of the workshop was concluded with an open discussion session. The workshop was exceptionally well attended with over 60 registered participants. Our thanks are extended to Marcus Winter and Siemens for the successful hosting of the event at their off ices in Manchester. A second workshop on quantitative analysis, hosted by Philips in February 1996, will expand and broaden the themes discussed in Part I and include additional topics such as choice of method. Tim Hyde BCA MEMBERSHIPThe Industrial Group Committee are considering a proposal to offer automatic membership of the BCA to delegates at Industrial Group meetings. The proposal is aimed at attracting new members a nd giving existing members the ability to retain membership by simply attending one of the IG meetings each year. BCA membership runs from 1st January to 31st December.The BCA Spring Meeting would be excluded from the scheme because of administrative difficulties but, for those who only attend that meeting, membership could be retained by paying the additional non-members fee and completing a membership form at the meeting. Scheme proposals for all other meetings are as follows:-
The current methods of payment of the 81 BCA members with IG
as main interest are as follows:-
* * * * * * * * * * * * * * * * * * ROUND-ROBINDIFFRACTOMETER CALIBRATION
- - Is your diffractometer correctly aligned - -
- - Is it accurate - -
The group is proposing to organise a 'round-robin' exercise to
enable members resident in the UK to check their diffractometers.
This will follow along the lines of similar exercises o
rganised
in several countries over the last few years by Ron Jenkins and
the ICDD. The exercise will require each participant to make
measurements on the internationally available NIST standard
reference material SRM1976. This is a plate of sintered alumina
which can be made with very reproducible properties.
Plans are not yet complete and we may either purchase a number of standards and circulate these to all participants or we may encourage each participant to purchase their own standards. Th e first option ensures that everyone measures the same sample whilst the second would be a lot quicker. If you are interested in participating please let us know. The form below shows the preliminary information we need. Please either post, fax or e-mail the information to the address given.,p> David Taylor will be giving an introductory talk on the Round-Robin at the Autumn Meeting.
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DIFFRACTOMETER STANDARDS - Round-Robin Exercise 1995/96
Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Address _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Post Code _ _ _ _ _ _ _
Telephone _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Fax _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Make and model of Diffractometer_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Sample holder (dimensions if non-standard) _ _ _ _ _ _ _ _ _ _ _
I already have a NIST SRM1976 standard yes/no
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Send to:- Mr D J Taylor
Pilkington Technology Centre
Hall Lane
Lathom, Ormskirk
Lancs L40 5UF Fax
01695 54596
or e-mail to [email protected]
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