Archive of Reports on IG meetings
1983-1986
Contents This file gives access to reports
in:
- 1986
- Workshop - QUANTITATIVE ANALYSIS BY XRD,
1 May 1986, Cement and Concrete Association
- Spring Meeting, Symposium April 9 198
6,
York University
- Spring Meeting, Workshop April 9 1986,
York University
- 1985
- 1984
- 1983
Page last updated by IG Web Editor 13 Nov 2000
QUANTITATIVE ANALYSIS BY XRD
A one-day meeting was held at the Cement and Concrete
Association on Thursday the 1st of May to discuss procedures for
quantitative analysis by X-ray diffraction.
The meeting was attended by 16 delegate
s, mainly from
industrial establishments, but also included representatives from
Hatfield polytechnic, and Birmingham University.
The morning session took the form of presentations, by Walter
Gutteridge (C & CA) and Dermott Wood (BP), reviewing sample
preparation procedures, and quantitative analysis using both the
Chung and internal standard methods.
An excellent lunch followed by a guided tour of the
magnificent gardens, was the precursor to a stimulating afternoon
session.
This consisted of a presentation on QXDA of overlapping
peaks followed by in depth discussions of the days
proceedings.
S.E. LOVELL
April 8th 1986, University of York
A workshop organised and co-ordinated by the industrial Group
was held on the afternoon of April 8th as part of the 1986 BCA
Spring Meeting.
The number of people attending being in the region of
100.
The first session chaired by Alun Bowen (RAE Farnborough)
opened with II contribution from Ron Jenkins (JCPDS) on recent
developments in the use of personal computers for XRD data base
searching and provoked interesting comments and discussion. This
was followed by contributions from various manufacturers. Rag
Nicholls (Pye Unicam) described the 4-crystal Bartels
monochromator and Wilhaim Issenborg (Siemens) and David Brown
(Stoe) spoke about the new developments in their respective
c
ompanies. The first session was completed by a contribution from
David Rendle (Met. Police Forensic Lab.) on the
microodiffractometer designed by him for the examination of vary
small amounts of sample. This micro-diffractometer is now
available commercially from GTP Engineering, Swindon.
The second session with Ed Metcalfe (CEGB) in the chair opened
with a contribution from John Harding (British Rail) on the
examination of very small amounts of sample using conventional
powder diffractomet
ry. The technique being very nicely
illustrated with a clever piece of detective work in 'The Case of
the Exploding Knob'.
Keith Bowen (University of Warwick) described some simple but
very novel ways of making ones own collimators and Ian Wood
(Rothamsted) described the effect of variations of ambient
temperature on the position of diffraction peaks. This latter
paper provoking much comment from the floor. The session ended
with a general discussion co-chaired by Alun Bowen and Ed
Metcalf
e where comments and questions were invited from the
audience resulting in some very lively cross talk and
interchanges.
It is in no doubt that the workshop was a success and the
Industrial Group will co-ordinate a similar workshop at the 1987
Spring Meeting in Edinburgh incorporating the lessons learnt from
this one. It should be stressed that the workshop is not just an
Industrial Group workshop. It will be co-ordinated by the group
on behalf of and for the convenience of all members of t
he BCA
and all are strongly encouraged to actively participate.
Brian Bellamy
BCA SPRING MEETING, YORK April 9 1986
The style and content of the Industrial Group Symposium
followed that which had successfully evolved during previous
meetings; a morning session of oral presentations and a large
number of posters which were on display throughout the
meeting.
Whilst the
BCA meetings appear to concentrate on X-ray
diffraction the Industrial Group has always tried to introduce
other crystallographic techniques. Thus past presentations have
covered convergent beam electron diffraction and neutron
diffraction.
This approach was continued with the first invited
presentation by Dr E D Boyes (University of Oxford) and concerned
direct imaging of crystal lattices by high resolution
transmission electron microscopy (HREM) and field ion microscopy
(FIM). The basis
and present capabilities of HREM and FLM were
reviewed and illustrated by examples of applications in materials
science, geology, and semiconductor technology. The preparation
of suitable samples and interpretation of results are important
constraints, but direct imaging at the level of individual atomic
columns with a resolution of <1 5A has recently become
available. Despite the superficial attractiveness of an image
with atomic resolution it is essential to use computer image
calculations for
reliable interpretation. The complementary
nature of direct 'real space' imaging to reciprocal space
diffraction information was emphasised particularly where defects
or small features are important components of crystallographic
analysis.
The next talk was given by Dr J D McConnell (Schlumberger
Cambridge Research) on the origin and structure of incommensurate
phases. The paper was primarily concerned with the situation
which arises in certain incommensurate phases where it is
necessary t
o describe the structure in terms of component
structures each of which exists within the modulated structure of
its own symmetry. The thermodynamic stability of such
incommensurate structures was explained in terms of local
favourable interactions between component structures which are
such that free energy is minimised. Symmetry rules and free
energy considerations were used to explain the incommensurate
structure of mullite, and the nature of the interactions which
leads to enthalpy stabilization
for this high temperature phase
was also described. I suspect that, like myself, a number of the
audience knew far more about such phases after the cogent and
lucid lecture than they did before, but did not yet fully
understand such phases because of the complexity of the
subject.
There then followed a nice juxtaposition of two papers
covering surface stress analysis techniques which appear to be
attracting a resurgence of interest at present. The first paper
by Professor E J Mittemeijer
(Delft University, Netherlands)
concerned X-ray diffraction in surface engineering. It dealt with
X-ray diffraction analysis of residual macro and micro-stresses
in surface layers (mainly of steels) following thermo-chemical
surface treatments such as nitriding, boriding and chemical
vapour deposition. The differences and relative importance of
macro and micro-stresses were emphasised and the development of
single line profiling methods such as the Voight method were
presented. The general conclusio
ns were that residual
macrostresses in the layers are dominantly caused by cooling from
the treatment temperatures but relaxation phenomena occur, and
that the occurrence of significant residual microstresses are
often unjustifiably ignored.
The second paper by Dr W Pfieffer (Fraunhofer Iristitut fur
Werkstoffmechanik, Freiburg, West Germany) concerned the
determination of surface stresses of high temperature ceramic
materials. The paper concentrated on residual stress measurements
for sil
icon nitride and silicon carbide, and the importance of
determining X-ray elastic constants was emphasised. A four point
bending rig for use on a Siemens D500 was described. Examples of
surface residual stress determination of finished parts for high
temperature applications were given.
The final talk was given by J Dodson (Diatech, London) and
concerned the automatic orientation and capture of topograms for
the identification of round brilliant cut diamonds. These are
essentially 'fingerpr
ints' for the diamond and enable individual
identifications. The development of the technique and the
production of the equipment to take such topographs at an
economic rate was described. This was a flamboyant but somewhat
superficial presentation of an elegantly engineered solution to a
difficult problem. A little more detailed description of the
crystallographic input by Dineen and Isherwood would have been a
nice counterbalance to the anecdotal style. Notwithstanding this,
the presentation encap
sulated the essence of industrial
crystallography by this example of the development of a technique
such as Lang topography via good engineering to provide a
practical tool for the unique identification of diamonds.
The series of lectures were supported by a comprehensive and
wide-ranging display of 33 posters. Many of the posters were of
such a quality and content that it seems a little unfair not to
review them in the same detail as the verbal presentations but
space does not permit this.
Suffice is to say that in spite of
their rather remote location they amply rewarded the attention
which was paid to them by the conference delegates.
The York BCA demonstrates the clear quality and breadth of
crystallographic studies carried out in industrial laboratories
and the organisers are to be congratulated on the symposium.
E METCALFE
1985 Autumn Meeting, AERE Harwell
The Indus
trial Group of the B.C.A held its Autumn meeting on
November the 14th at AERE Harwell. The theme of the meeting was
"Crystallography in Industry" and was attended by some fifty
delegates from Industrial, Government and University
laboratories. The welcoming address was given by Dr Ron Sowden -
Director of Industrial Research at Harwell. In his address Dr
Snowden briefly outlined the history of materials research at
Harwell which had recently celebrated it's 40th anniversary,
Despite being equipped w
ith a variety of large nuclear machines,
it was always recognised that Harwell's role would be to study
basic material's problems, rather than fundamental physics and
that in accomplishing this task: it would interact very closely
with industry on a wide materials front.
The morning session was chaired by Dr Brian Isherwood
(GEC-HRC) who in introducing the first speaker, Dr Tony Hughes
(Harwell) pointed out that it was now becoming a tradition that
the host establishment provide the opening
speaker. Dr Hughes
paper entitled ' Some Recent Applications of X-Ray and Neutron
Diffraction at Harwell ' amply demonstrated the wide experience,
range of techniques and special skills available at Harwell by
describing the results of a variety of studies undertaken on
various materials. Amongst the topics covered in Dr Hughes' paper
were included the measurement of texture and stress in
sputter-ion plated TiN films on tool steels, in-situ studies; of
the growth of second phases in steels and the
characterisation of
the pore structure of cements to give information relating to the
stability of packaged radioactive waste.
The second paper given by Dr Paul Tempest (CEGB Berkeley)
entitled 'Crystallographic Aspects of the Oxidation of Uranium
Dioxide Nuclear Fuel' reviewed the current understanding of the
crystallography and chemistry of uranium oxide at the high
temperatures encountered in advanced gas cooled and pressurised
water reactors.
In the final paper of the morning
session, Dr Keith Bowen
(University of Warwick) described a novel application of an X-Ray
Interferometer to calibrate sensitive engineering transducers in
the sub nanometre range. The lattice spacing of silicon had
recently been related to the krypton wavelength to 1:10. Dr Bowen
pointed out that since semiconductor grade silicon usually has a
lattice parameter reproducible to about 1:10 it's lattice
effectively comprises a portable absolute length standard with
discrimination down to a fraction of
the lattice spacing. The
interferometer, machined from a block of single crystal silicon,
comprises three single crystals, two of which are fixed with
respect to one another, whilst the third is constructed in the
block so as to be capable of being translated (albeit over very
small distances) behind the other two. When correctly oriented
and irradiated with a beam of x-rays, anomalously transmitted
beams interfere resulting in either maxima or minima of intensity
depending on the position of the th
ird crystal. Results presented
to the meeting were extremely impressive and the elegance and
apparent simplicity of the techniques being developed by Dr Bowen
and his colleagues was generally acknowledged.
The afternoon session, chaired by Brian Bellamy (Harwell)
opened with a review by Dr Alun Bowen (RAE Farnborough) of the
Denver X-Ray Conference and a preview of the 1986 BCA York
Conference. The Denver meeting had been organised into a series
of workshop and formal sessions with one even
ing poster session
on stress measurement. Dr Bowen then briefly summarised the main
topics discussed in the sessions that he attended. In previewing
the BCA spring meeting, Dr Bowen issued a call far papers for the
oral and poster sessions and for the active participation of all
industrial crystallographers in the special workshop on Practical
Powder Diffraction.
In the second paper of the afternoon Dr Rona Highcock (BP
Research Centre) described the elucidation of the structure of
the nov
el zeolite theta-1. This had proved to be a particularly
difficult but intellectually rewarding study since the zeolite
crystals were too small for conventional single crystal structure
techniques. The structure was eventually being solved and refined
using X-Ray powder data and confirmed by high resolution
transmission electron microscopy.
The final paper of the day was presented by Dr Steve Tarling
(Birkbeck). Illustrating his contribution by reference to a
recent very detailed study of t
he production of Ultramarine - a
synthetic blue pigment, Dr Tarling described the establishment of
a high temperature X-ray diffraction facility to mimic industrial
furnacing processes and undertake in situ studies of the
structural changes which take place, thus permitting process
optimisation. From both an academic, and in the context of the
meeting, from an industrial viewpoint, this would appear to be a
most timely development and we look forward to hearing, at future
meetings of further work: c
arried out using this facility.
The organisation of the meeting was excellent and judged by
the discussion following each paper, during lunch and at tea, was
very successful. All the speakers are to complimented on the very
high standard of presentation of the papers.
C Dineen
Click here to return to Contents
THE USE OF POSlTION SENSITIVE DETECTORS IN POWDER
D
IFFRACTOMETRY
On the 24th September 1985, Dr. Brian Isherwood welcomed
thirty seven crystallographers, mainly from industry and
universities, to the Hirst Research Centre, Wembley. He pointed
out that the aim of the meeting was to encourage discussion on
the subject and that participation of delegates in the discussion
session was essential.
Pat McAllister (BICC) introduced the subject with a review of
the advances in powder diffraction techniques from film cameras,
through early
diffractometers, to modern instruments with on-line
minicomputers. Data processing time with the new instruments was
of the order of minutes whilst data collection time was typically
two hours or longer in certain cases. The principles of operation
of Position Sensitive Detectors (PSD) were briefly described with
reference to the 10o 2theta flat detector which is
scanned, and the 50o 2theta curved detector which Is
positioned sequentially, to cover the full angular range. These
detectors collect data up to 100 times faster than conventional
scintillation and proportional counters and hence data collection
time with PSDs and data processing times are similar. Work on
polymers had established that peak to background ratios with PSD
systems were as good as with conventional systems but with a
considerable time advantage.
David Puxley (British Gas Corporation) described his
experiences with a 50o 2theta PSD system over the past
six months. The system was
now carrying out work which had
previously been dealt with by film cameras, with an increased
throughput of about four times. The accuracy of the PSD system
was better than 0.2o 2theta. The weight of sample
required for a conventional diffractometer was about 0.1g whereas
the PSD system produced similar data with 0.1mg. Data collection
time with a conventional diffractometer was 20 mins to 2hrs;
similar quality data was collected in 3 mins on the PSD system
with useful data being availabl
e in 10s for certain samples. The
improved spatial resolution of the PSD system was illustrated by
the examination of structural changes occurring across a weld in
polyethylene gas main pipe.
Dr Herbert Gobel (Siemens Central Research Laboratories)
described some of his work with the 10o 2theta PSD
system. His research had concentrated on dynamic experiments
including rapid heating of samples, an example of which was the
investigation of phase changes occurring in low and high ca
rbon
steels using a heating time from ambient to melting of 15s. By
using a pulsed radiation source, he had established that the time
resolution of the PSD system was better than 20ns. For cyclic
change phenomena, he had developed a stroboscopic method for the
examination of samples. Applications included domain wall
movement in piezo-ceramics, determination of electrostrictive
coefficients in PZT telephone membranes and measurements of
lattice distortions in a steel test piece oscillating at 200Hz.
Many of the examples were illustrated using three dimensional
plotting techniques.
Professor Erich Wolfel (Stoe et Cie) outlined the history of
the development of the 50o 2theta system. He described
a number of applications of the PSD system to dynamic experiments
which showed an intermediate state of disorder between changes
from one phase to another. Routine examination of mine dust
filters has shown a detection limit for quartz of 0.02mg. He
showed numerous examples illustra
ting the speed at which data
could be collected and interpreted using the on-line computer
system. He also described work on the examination of gallstones
which illustrated how, with the PSD system, examination and
interpretation of results from an unknown could be carried out in
a single day.
The discussion session concentrated mainly on instrumentation,
with the resolution and reliability of the detectors being of
major interest. The o 2theta detector was quoted as
having an u
ltimate resolution of 0.02o 2theta and a
maximum life of 1012 counts between counter wire
changes. The resolution of the 50o 2theta detector
appeared to be slightly inferior but could be improved by
increasing the specimen to detector distance with some loss in
data collection speed. The 50o 2theta detector was
less beam sensitive than the 10o 2theta detector and
had not shown any deterioration after some years of use. However,
with very strong
beams, the 50o 2theta detector was
subject to ion saturation and required brief interruptions of the
X-ray beam to allow the charge to dissipate. The 10o
2theta detector is a flow counter running at over 10 atmospheres.
The 50o 2theta detector is a sealed detector with a
gas pressure of 5 atmospheres. Both detectors appear to have the
same counting efficiency.
Trevor Carter (BICC) reported the results of line broadening
studies using the Warren-Averbach tech
nique. The data had been
collected using the 10o 2theta system with
transmission geometry and an incident beam K-alpha one
monochromator. Satisfactory results were obtained with a total
data collection and processing time for two samples of less than
an hour.
In the next year, several PSD systems scheduled for installation
in laboratories in the UK. It was agreed by the delegates that a
further meeting on this topic should be held in two years
time.
P.B.McAllister
Click here to return to Contents
BCA SPRING MEETING, BRISTOL MARCH 26 1985
As in previous years, the Industrial Group symposium covered a
wide range of techniques, materials and phenomena, and attracted
a large attendance throughout. The symposium consisted of a
morning session of oral presentations and a large number of
posters which were on display througho
ut the meeting.
The oral session started with a talk by Graeme Davies
(University of Sheffield) on crystallite orientation distribution
functions. Prof Davies began by outlining the Bunge and Roe
systems for representing the probability of a crystal having a
particular ideal orientation (described by three Euler angles),
how these are represented as a specific point in Euler space and
how the distribution about each ideal orientation is represented
by a contoured function showing the intens
ity levels.
Experimental problems in data collection were then touched upon
and the advantages of the composite specimen emphasised. The
derivation of quantitative data, such as volume fractions of
ideal orientations and severity parameters, were given, followed
by a wide-ranging survey of their applications. These included
deformation textures, crystallographic slip and shear and the
inheritance of texture through phase transformations. The final
part of the talk was concerned with the prediction o
f physical
and mechanical properties from the crystallite orientation
distributions, particularly the degree of anisotropy, as well as
yield loci and forming parameters.
The next talk was given by Dermot Wood (BP Research Centre) on
quantitative analysis of North Sea well core samples, where X-ray
diffraction was one of the techniques used to characterise 1000
samples of sandstone. Reasons for the choice of X-ray diffraction
and the approach necessary for analyses of the 11 candidate
compo
unds were highlighted. This careful and systematic approach
was particularly commendable in view of the pressure of time,
whereby two diffractometers were committed to solving the problem
in 170 days: Each stage in the process: sample preparation, data
collection and data processing, was optimised until consistent
results were achieved on both control and real samples. The final
quantitative data, calculated by the Chung method, were good, so
much so that the reward was another 1000 samples to analys
e
John Steeds (University of Bristol) then gave a presentation
on convergent beam electron diffraction, which is a uniquely
powerful tool for investigating crystalline materials: to
determine lattice parameters to an accuracy at least as good as
with X-ray diffraction; to study point symmetry and space groups;
and to measure strain. The limitations of the conventional
selected-area diffraction patterns were given and this led into a
presentation of how convergent-beam patterns are formed wh
en one
utilises the probe-forming capabilities of scanning transmission
electron microscopes. The Ewalds' Sphere construction was
described together with an explanation of HOLZ lines and the
extensive detail contained within diffracted cones. The remainder
of the talk was concerned with a wide range of examples to
illustrate the technique. These included: ordering in
superalloys; phase analysis in steels and semi-conductors,
including the identification of new phases; and the analysis of
borides, c
arbides, oxides and nitrides. Future developments, such
as HOLZ rings and their very strong dependence on strain, were
touched upon. Much of the work illustrated has just been
published in an atlas of convergent beam electron diffraction
patterns.
There then followed two papers on semi-conductor
materials.
The first was by Mary Halliwell (British Telecom Research
Laboratories) on the growth of single crystal layers of IIl-V
compounds. The aim of the work was to match the lattice
parameters of the layer and substrate. The advantages and
disadvantages of the four methods available for preparation were
given and the results on material prepared by one of these,
MOVPE, were then described. These were for 200 layer samples of
InP and GaInAs, each layer being ~180A thick. Transmission
electron microscopy showed high dislocation densities at the
interfaces while rocking curves were very wide and asymmetric.
Subsequent modifications to the process overcame these problems
and device
s with low defect levels at the interfaces are now
being produced.
The second talk was by Paul Fewster (Philips Research
Laboratories) on multiple quantum well structures made up of
alternate layers of GaAs and GaAlAs. These were grown by
molecular beam epitaxy to form sandwich layers of ~34A GaAs (to
form the wells) and ~100A GaAlAs (to form the barriers). The
means of assessing the layer thickness, uniformity and
composition by X-ray diffraction were described and some of the
complexitie
s, such as extra peaks around the mean peaks, were
illustrated. Interpretation of data was assisted by comparing
experimental diffractograms with those simulated from theory. The
change from well to barrier is not clear-cut and defects and
non-standard layers form in these regions. It is difficult to
define the lattice parameters at the well-barrier interface and
for a few layers on either side; a problem which would not seem
to be amenable to transmission electron microscopy because of low
contrast
.
In the final talk the emphasis returned to metals and the
measurement of residual stresses in welds using neutron
diffraction. Colin Windsor (AERE Harwell) emphasised the
advantages of neutrons over X-rays, for example the ease of
in-situ experiments, deep penetration and full stress tensor
analysis. The distribution of stresses in steel tubes welded to
tubes and plates were shown followed by those in stainless steel
welds containing austenite and ferrite. In the latter, texture
proved t
o be a problem and specimens had to be cut correctly.
Strains in both the austenite and ferrite were determined and
differences explained in terms of the differences in elastic and
plastic responses of the two phases. The advent of the Spallation
Neutron Source held out the promise of an increase in resolution
of about a factor of five.
The lectures were complemented very aptly by a display of 27
posters. This number was well in excess of those presented at
Nottingham and exhibited a remark
ably diverse range of work. The
same high standard set in previous years was clearly evident in
the posters and contributors to future meetings would do well to
emulate both the duality and quantity of this work.
The Bristol BCA proved yet again that high quality science is
very much the norm in industrial crystallography laboratories.
The organisers and contributors to the oral and poster sessions
are therefore to be congratulated on providing a wide-ranging and
well-balanced symposium.
ALUN BOWEN
The Autumn meeting of the industrial group, held on 9 November
1984 at the Central Electricity Generating Board, North East
Region Scientific Services Department was a greet success. The
varied and interesting programme organised by Drs Ed. Metcalfe
(CEGB), Brian Isherwood (GEC), Brian Bellamy (UKAEA, Harwell) and
John Herding (British Rail) attracted thirty-eight members to
Ha
rrogate. Dr Richard Jack, Head of the Chemistry and Materials
Division in welcoming the group to the CECB complex at Harrogate
told members that CEGB was at the forefront of scientific
endeavour.
Dr Ed Metcalfe (CEGB) presented the first paper. He described
the organisational structure of CECB in which some fifty five
thousand people are employed. The facilities of eight research
laboratories cope with the demands of this large organisation.
Whilst the workforce is diminishing, the demand f
or electricity
is increasing. Events such as miners strike pose technical
problems for the Board. Concentrating on aspect of x-ray
diffraction, Dr Metcalfe described some applications such as the
characterisation of coal; study and identification of the phase
changes which occur within the metal of turbine shafts and the
detection of metal fatigue. The lattice parameter technique is
widely used in the study of oxides and carbides.
Dr Derek Thompson (University of Newcastle) presented a
fas
cinating paper on the topic of nitrogen in ceramics. Single
crystals of such materials are not easy to produce but
nevertheless Dr Thompson seems to have overcome the difficulty in
the many examples of structures which he described. He showed how
in the study of the polytypes in the Aluminium Silicon Oxygen
Nitrogen system the metal to non-metal ratio was related to the
ratio of the c-spacing to the number of layers in the polytype.
Lattice parameter measurements allow one to relate the MX2 layer
co
ncentration to the cell size. Using a series of trial and error
approaches Dr Thompson showed how polytypes could be described by
using layers of octahedra between the basic layers to tetrahedra.
One dimensional lattice imaging was used to support his findings
but in extending to the more demanding two dimensional imaging he
showed some of the shortcomings relating to the detection of
ordering. He completed his presentation with a description of a
phase which he termed 'nitrogen mullite'. This phase
exists in
two forms (low and high). Again by applying a trial and error
approach coupled with stereochemical requirements the structures
were elucidated. TEM gave direct evidence of the faulting which
occurs in the structure.
Dr Peter Doig (CECB) described a mobile x-ray machine capable
of producing precision data for use in the determination of
stress in metal components. The equipment can be used either in a
laboratory or in an industrial area. It comprises a Siemens
transportable x-ray
diffractometer in which the incident beam can
be rotated with respect to the metal surface of the item being
examined. A linear position sensitive detector records diffracted
intensity data over an angular range of ten degrees (2-theta) and
it takes only four minutes to obtain a value for the stress
within a metal. Dr Doig described the computer software which he
now uses and whilst fifty psi-steps can be handled he suggested
that there was no reel benefit in using more than ten such
steps.
<
p>Dr David Dyson (British Steel Corporation) described a
computer based procedure which he and Dr Steve Butler have
devised to interpret electron diffraction patterns produced from
compounds commonly detected in steels
The procedure is now widely used in their laboratories by
persons who are not necessarily crystallographers, but who
require to identify the inclusions etc. which they detect when
using an electron microscope. The procedure is user interactive
and all requests for specific in
formation are displayed on the
VDU. By requesting information for four vectors the software will
offer solutions which allow the user to identify the phase or
phases which have produced the particular diffraction
pattern.
Dr Craig Adams (Unilever Research) uses a 64k microcomputer to
assist in the quantitative analysis of inorganic hydrates. The
procedure includes the Chung approach in which overlapping
profiles are used. Standard intensity data for one hundred and
twenty standards have be
en collected and are stored by the
computer. A least-squares procedure is used to determine the
relative proportion of the hydrates in a mixture and a graphical
output comparing the observed intensity with that calculated is
produced.
The role of infrared spectroscopy in mineralogy was described
by Dr Jim Russell of the Macaulay Institute. He showed with
numerous examples, how infrared spectroscopy can be used in the
identification of minerals, particularly clay minerals. He showed
that th
e technique would give information on such materials as
whinstone where the presence of smectite, albite, chlorite and
calcite could be detected in under five minutes by a skilled
operator.
Dr David Blundell (ICI) presented the final paper of the
meeting and dealt with the crystallinity in PEEK/carbon fibre
composites, He showed that one could obtain a value for the
crystallinity index of such a composite which
correlates well with density. By using information obtained
from low a
ngle scattering and x-ray diffraction, values for the
crystal thickness can be obtained. Techniques such as wide angle
x-ray scattering and multiple internal reflection infra red are
used to study these composites. Dr Blundell showed that cooling
rate used in the fabrication process of the thermoplastics was
related to the crystallinity of the final product.
W A Gutteridge
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The first one-day meeting of the Industrial Group of the BCA
was held at the BP Research Centre on 10th November. It was very
well attended with over 50 delegates from a wide variety of
industrial research laboratories and universities spread all over
Britain. The Chairman, Brian Isherwood, said in his opening
address that he hoped it would set a precedent for future
meetings - first of all in being held at an industrial research
centre, and secondly as an informal and fri
endly meeting.
Glen Smith gave the first paper in which he described the type
of work done at BP. This covers a wide variety of samples, such
as corrosion and engine deposits, hydrocarbons, catalysts,
minerals and polymers, for identification, quantitative analysis
and structure determination. The following discussion included
questions on powder sample preparation. Then Brian Beagley spoke
about the structure service at UMIST with reference to structure
determination of zeolites in control
led atmospheres from powder
data. This is a topic of growing interest to many people and
evoked much discussion.
Unfortunately, Terry Willis (Harwell) was not well so his
paper was withdrawn. However, there was another contribution from
Harwell by Mike Hutchings, about the use of neutrons for strain
measurement.
Paul Fewster (Philips) presented a clear description of how
back reflection Laue photographs are solved using a program which
runs on a microcomputer, giving possible solu
tions in about 12
minutes.
Jean Holt (GEC) gave a brief description of Lang X-ray
topography and then showed how it has been used to assess the
quality of synthetically grown quartz crystals.
lan Ferguson (Springfield Nuclear Power) presented a paper
based on Carl Bilsby's work on the characterisation of thin oxide
films on stainless steel using micro- diffraction and elemental
analysis.
This led into the workshop chaired by Ed Metcalfe (CERL), on
X-ray diffraction - its
relationship to competing techniques,
cost effectiveness and expediency versus rigour. It seems that
over the years the technique has not lost but probably gained
some ground from other techniques. The use of off-site facilities
such as Daresbury was discussed.
Sue Kipling (ICI) briefly described her thorough exercise to
prove the cost effectiveness of automated equipment, and the
importance of good communication between the customer and the
crystallographer was repeatedly emphasised.
If the support and interest shown at this meeting is
sustained, the future of the Industrial Group looks good. MEV
On behalf of those who attended the Industrial Group meeting
at Sunbury, I would like to thank the Staff of BP Research for
arranging such a splendid meeting, and especially the members of
the X-ray Diffraction Group: Rona Highcock, G. W. Smith, B. H.
Stringer, Mary Vickers and D. Wood. MM
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