Hiya all.
A joint introduction and question. I'm a PDF with Canada's National
Research Council working on cathode materials for lithium ion batteries (yes
we do use neutrons!). My background is in oxides of various types and I
have an interest in time resolved diffraction studies. I use GSAS (w
Hiya all
I was wondering if anyone has had any experience with the Bruker D8 system
with the Hi-Star area detector and Goebel mirrors? We're trying to weigh up
the advantages and disadvantages for different users, and as I'm the one who
does the Rietveld work I need to fight my corner! How does
Hiya all
We are now the proud owners of a new Bruker D8 system with the twin Goebel
mirror setup (Guinea Pigs R Us!). This has given me a few headaches with
regard to modelling the instrumental broadening effects (not all of them
solved) but that's another story. However, for Rietveld work with
Natale (and others!)
We have a very new D8 equipped with dual Goebel mirrors (40mm primary and
secondary), but have no experience with the Vario monochromator (very fiddly
to keep well aligned so I'm told). We've just used the reflection geometry
so far, as we haven't even got around to mounting
Postdoctoral Fellowship
position, Institute for Chemical Process and
Environmental Technology (ICPET), National Research Council, Ottawa ON,
Canada
ICPET (http://icpet-itpce.nrc-cnrc.gc.ca/research.html) requires a postdoctoral fellow to undertake a
research project on immobilization of h
Robert
As previously mentioned many Rietveld programs will do what you want if
you're willing to do the amorphous content calculations by hand afterwards.
Some commercial software has it built in.
I've done work in this area, and there are some pitfalls of which you must
be aware, or your results
Jim
Excellent news! This amorphous standard issue has been driving me nuts.
When you say phase purity do you mean purity in terms of crystalline phase
content?
Pam
Dr Pamela Whitfield CChem MRSC
Energy Materials Group
Institute for Chemical Process and Environmental Technology
Building M12
Nati
Nandini
The best people to reply on behalf of fundamental parameters would be Alan
Coehlo or Arnt Kern.
But until they do here goes
The more general form is convolution-based profile fitting. This can be
used for all peak profile types, whereas 'pure' fundamental parameters has
only been
nal Message-
From: Nandini Devi Radhamonyamma [mailto:[EMAIL PROTECTED]
Sent: June 4, 2004 9:46 AM
To: [EMAIL PROTECTED]
Thanks, Pam and Jon for the clarifications.
Again, does this approach take care of low angle peak
asymmetry better?
thanks,
nandini
--- "Whitfield, Pamela"
<
Our system has double mirrors and I could never get FCJ to give as good a
fit, but then that may be a peculiarity of these optics. My memory is a bit
hazy so I can't remember what function the simple axial model uses, but I
don't think it's a function of diffractometer characteristics. Topas is
f
ariet or topas by Dr. Coehlo et al. Do
you know a web site where we can down load a bunch of .str files for
minerals, as BGMN.de has the .str files for BGMN.
Thanks.
jilin zhang
omni labs
8845 fallbrook
houston tx 77064
phone 832-237-4000
-----Original Message-
From: Whitfield, Pamela [mailto
>In addition, the raytracing fundamental
>approach describes at now (planar) transmission geometry and
>capillar geometry.
Don't know about the planar transmission (never done it), but I can happily
fit capillary data off my system. I have no quibbles about the
effectiveness of ray-tracing, but w
Oooo, picking up where Friday left off..
Must go and put the coffee pot on :-)
- refining of "fundamental parameters" is nonsense, unless one is not
familiar with his diffractometer or want/must "absorb" any unkown effects
or weaknesses of his model :-)
In a perfect world this would be the c
Domain size work is a bit of a can of worms. It's something I looked at
more carefully a while back for nanoparticle work, and the deeper I got into
it the worse it got.
Peak broadening methods tend to give 'apparent' sizes, either area or volume
weighted, and require corrections (usually not don
yclotron Centre
Kolkata 700 064
phone: 91-33-2337-1230 (extn. 3190)
Fax: 91-33-2334-6871
INDIA
- Original Message -
From: "Whitfield, Pamela" <[EMAIL PROTECTED]>
Date: Monday, June 7, 2004 10:04 pm
>
> Domain si
Hiya
all
I find myself having
to do some work with materials containing Ni4+ and Co4+. Unfortunately
there are no form factors that I can find for these ions. In the absence
of hard numbers, what would be the best fudge to use to get sensible and
defensible results? BTW my data is from
Hiya
all
I have a bit of a
brainache for a Monday morning.
We ran a couple of
samples on a Scintag Bragg-Brentano diffractometer and found some weak
reflections that would correspond to a doubled c-axis supercell. I
was a bit wary, so I ran it on our twin mirror D8 this weekend - and fou
Hiya
all
I seem to be
unfortunate in my choice of materials. I've been looking at the bond
lengths and bond valence for some battery materials that contain some transition
metals in low spin states. From what I understand, all of the bond valence
coefficients that I have are for high sp
Hiya
all
I've come across a
unit cell that seems to give alot of software a headache when generating the
powder patterns. I've tested 6 software packages with this (including
commercial) and found only a 50% success rate in generating a good pattern with
correct relative intensities. No
-itpce.nrc-cnrc.gc.ca
-Original Message-
From: Jacco van de Streek [mailto:[EMAIL PROTECTED]
Sent: October 18, 2004 1:32 PM
To: [EMAIL PROTECTED]
Whitfield, Pamela wrote:
> I've come across a unit cell that seems to give alot of software a
> headache when generating the powder p
> - The matrices representing the space-group operators are no longer
> diagonal, and the distinction between R*h and h*R (where R is the
> rotation matrix and h is the reciprocal space vector [h,k,l]) becomes
> important when calculating systematic absences.
This does make sense. Many of the pro
Alan
I agree - I found them as well, but this particular P3112/P3212 group is
very rare. Given that software tends to deal with space group
interpretation on a case-by-case basis it does mean that problems can be
specific to a particular group - especially if it hasn't been tested before.
Some so
as per instructions) "p 31 1
2" and not "p3112".
Bob
R.B. Von Dreele
IPNS Division
Argonne National Laboratory
Argonne, IL 60439-4814
-Original Message-----
From: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
Sent: Monday, October 18, 2004 12:50 PM
To: '[EMAIL PROTECTED]
AlanI'm afraid that the cif files weren't overly good
ones - I don't normally use them. For the R-3m the Li 1/2 fractional
coordinate is for the z, not y. The structures are related by a Ö3a x Ö3a relationship with Z = 3
for the R-3m and Z = 9 for the P3112.Here are the STR files. You can
Bob
I worked through all of the various operators used in the programs I have
(including Topas) and they are equivalent in each case. Topas works for
this one just as well as GSAS.
Pam
Dr Pamela Whitfield CChem MRSC
Energy Materials Group
Institute for Chemical Process and Environmental Technol
g the bond lengths.
My
guess is that the other programs may have conventions that are also not
obvious.
it
is always good to do some checking
cheers
alan
-Original Message-From: Whitfield,
Pamela [mailto:[EMAIL PROTECTED] Sent: Monday,
Our library has Z. Phys. back to volume 1 so I should be able to order it.
Pam
Dr Pamela Whitfield CChem MRSC
Energy Materials Group
Institute for Chemical Process and Environmental Technology
Building M12
National Research Council Canada
1200 Montreal Road
Ottawa ON K1A 0R6
CANADA
Tel: (613)
I just
have a few of points to make here.
Firstly, using the Scherrer equation leaves a bad taste due to all
the potential issues that it ignores. If you go this route, doing a
Williamson-Hall plot will give much more information and avoids some of the
problems.
Secondly, remember to al
This is where the real fun starts (if you're a masochist!). I just finished
doing some work along those lines this afternoon, and managed to get it to
work(ish) eventually. The double-Voigt analysis can give you Dv (volume
weighted domain size) and Ds (surface weighted domain size). If you assum
Title: RE: rietveld refinement
>There was a strong size anisotropy. The X-ray study cannot
>gives the shape (you see that I agree with you on that point),
>an electron microscopy study showed that the coherently
>diffracting domains are plate-like crystallites aggregated along
>the c axis.
Title: RE: rietveld refinement
I'm afraid that you got the wrong end of the stick -I wasn't talking about the application of peak broadening to size distribution, I was commenting that determining crystallite shape is perfectly possible (some comments were flying that said otherwise), and I've
A
couple of things that can cause mischief are surface roughness and beam
overspill in lab data. The first you can deal with in software, GSAS
included. The second simply requires care in data collection,
especially with Bragg-Brentano reflection data, where the beam footprint
increases a
Since we're on the subject of battery materials, we published some work
recently where we didn't assume that it was the Ni that went to the Li site in
LiMn1/3Ni1/3Co1/3O2. It's logical if it's Ni2+ but we had the data to test it
in the form of resonant scattering data to add some more informat
Strictly speaking you shouldn't trust Rietveld results
with that particle size whether there is microabsorption or not. If you
look at a cement sample with a microdiffraction system it becomes really obvious
how grainy some of the stuff really is. If you have a Co system microabsorption
its
Title: Message
This
seems to have moved away from polarisation onto something far more
touchy. :-)
I tend
to look upon things from an practical/experimental point of view, so
here's my ha'penny's worth.
As far
as lab instruments are concerned, finding either divergence or linear absorpt
I'm not sure exactly what your description of your setup means - do you have a
single or twin mirror system? I'm hoping that it's single because your
background is way too high for a properly aligned twin mirror system. I'm
assuming that you're using GSAS given the data format.
Your pattern r
Hold that thought.
On closer examination of the difference plot at high angles you have something
that looks like sample displacement, and refining it improves the fit, although
the values for zero point and shift become quite large. Mirrors shouldn't give
you this kind of error so make sure it
Stephane
Just one small point - strictly speaking you should be using integral breadth
rather than FWHM for size/strain analysis.
Pam
-Original Message-
From: Von Dreele, Robert B. [mailto:[EMAIL PROTECTED]
Sent: June 29, 2006 2:24 PM
To: rietveld_l@ill.fr
Stephanie,
The GSAS routine
Afternoon all
After spending over 2 days making up a single file, I'd like to hear some other opinions on the practical aspects of CIF files for structures from powder data. This is partly a moan from trying to get a 11000 line file to pass the CheckCIF when all of the items it complains about
maybe they won't miss a
few terms!
Pam
From: Favre-Nicolin Vincent [mailto:[EMAIL PROTECTED]
Sent: Wed 12/07/2006 5:30 AM
To: rietveld_l@ill.fr
Hi,
On Tuesday 11 July 2006 19:13, Whitfield, Pamela wrote:
> After spending over 2 days mak
n, single crystal,
powder & restraints all mixed together) capabilities of GSAS? Pam, as you
probably know, gsas2cif writes out template cif files which you can "edit once"
and reuse. Would this help your problem? Bob
From: Whitfield, Pamela [mailto:[
This is a known issue and we battled with for years. The explanation that
seems to make most sense is that the high energy X-rays from the tube cause the
formation of ozone that attacks the mirror surface. Moisture will speed this
up (probably why you noticed it after the summer) but having dr
For some reason the original email never made it to me so I can't see the data
- so apologies if this is way off base. However, it's not impossible for
perfect single crystal material to produce forbidden reflections from multiple
diffraction effects if the crystallites are big enough.
Pam
_
There are two seperate issues here - coding the restraint and then having
enough information to theoretically solve what is a effectively a simultaneous
equation problem with 3 or more variables.
The CCP14 website tells you how to code it (the same approach works just as
well in programs other
The selection rule for R-3m is h-k =3n +- 1.
Are you per chance working with delithiated or charged lithium battery
materials? You can get some rather wierd broadening effects that we looked at
a couple of years ago (which is why I know the selection rule!)
Pam
___
I try and avoid this, but as the scenario Leo describes is identical to those
that I deal with, I'll self-cite. Whitfield et al, Solid State Ionics, v175
(2005), 463-471 describes a relatively simple (R-3m) application using lab,
neutron, off-edge and resonant patterns simultaneously. A paper
I have to disagree with that; at least on a practical front with lab XRD. I
have done measurements myself with samples containing large portlandite plates
(granted, not a silicate but lovely-looking plates in a SEM) for quantitative
analysis. The whole point of the work was to see if capillary
cates.
Dipo Omotoso
From: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
Sent: Wednesday, March 21, 2007 7:51 AM
To: rietveld_l@ill.fr
Subject: RE: Re: Problems using TOPAS R (Rietveld refinement)
I have to disagree with that; at least on a practical front wit
Been there and got a wardrobe full of T-shirts as the saying goes. 4 years is
pretty good going if the machine is heavily used. Ours went alot faster but
the machine was used 24/7. We went through about a mirror a year for a while.
The old 1st generation mirrors could be cleaned in-house with
Hiya all
Sorry for doing this on the list but I'm out of options. I'm trying to reply
to an email from Maxim Lobanov but his server won't let messages from any of my
accounts through to either of his addresses. Is anyone in email contact with
him? If so could I get you to forward an email to
At first glance it looks like a classic microabsorption problem, but I
don't have the linear absorption coefficients to hand. Using an
internal standard with a too small absorption will tend to over-estimate
the amorphous content. Ce versus Zn is a pretty big contrast for CuKa,
even if the parti
This is a can of worms that keeps cropping up now and again. Rather than go
into masses of detail I'd suggest looking at the Rietveld mailing list archive
for some fairly detailed discussions on the subject. I'd go with Bob's route
as it's applicable in a laboratory environment but foolproof i
Polymers are not a good example for the spiking method as it is
difficult to find a standard with a good absorption match (although
diamond and LiF are possibilities), people don't usually hand them to
you as nice micron-sized powders (poor particle stats on a lab system),
and a few other issues.
If you have one, stick the sample on a GADDS system or similar with a 2D
detector and a large collimator. You'll find out if your sample is
grainy (or rocks in dust as Reinhard put it) in less than a minute. A
nicely micronized sample should give nice even rings with a 1mm
collimator.
Pam
---
I do that myself but it doesn't always help much if you've got something
like wollastonite! J
From: Martin [mailto:[EMAIL PROTECTED]
Sent: May 8, 2008 10:51 AM
To: rietveld_l@ill.fr
Subject: RE: Preferred orientation?
Forget all that long winded stuff. Just collect the data on capillary
tr
- Kurt
________
From: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
Sent: Thursday, May 08, 2008 9:16 AM
To: Kurt Leinenweber
Subject: RE: Preferred orientation?
It's one of the classic needle-shaped materials - it gives lovely SEM
images if you can avoid charging
Fr
__
From: Martin [mailto:[EMAIL PROTECTED]
Sent: Fri 16/05/2008 10:04 AM
To: Whitfield, Pamela; rietveld_l@ill.fr
Subject: RE: Preferred orientation?
In fact I think you might find it helps quite a bit. Have a look at:
http://img.chem.ucl.ac.uk/www/vickers/po/po.htm
Martin
__
_
From: Martin [mailto:[EMAIL PROTECTED]
Sent: Fri 16/05/2008 11:47 AM
To: Whitfield, Pamela; rietveld_l@ill.fr
Subject: RE: Preferred orientation?
Hi, happy Rietvelders
Some elements of confusion creeping in here. I think you said, Pam that
transmission wont help much if it's wolla
ometer and doing the maintenance on two others so no time today
for any jousting by email.
Pam
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: May 18, 2008 7:44 PM
To: Whitfield, Pamela; [EMAIL PROTECTED]
Cc: rietveld_l@ill.fr
Subject: RE: Preferred o
: May 20, 2008 9:38 AM
To: Whitfield, Pamela
Subject: RE: Preferred orientation?
Well said, Pamela! Come to St. Louis and I'll buy you a Budweiser!
By the way, do you know of any need for an old Scintag/Seifert
diffractometer - just the theta and 2-theta box? It's vintage 1982 or
Hi Jose
Errors in the region of 1wt% aren't unheard of in complex mixtures (and the
liklihood of the second decimal place being meaningful is very slim). However
there are other possible explanations and one in particular comes to mind.
Did you micronize your sample? If yes then feel free to
osé Carlos Cordeiro [mailto:[EMAIL PROTECTED]
Sent: May 29, 2008 5:07 PM
To: Whitfield, Pamela; rietveld_l@ill.fr
Cc: Mitchell, Lyndon
Subject: RES: ADS
My samples are cements (fine samples with 30 microns) and don't need micronize
its. The problem in my refinements is that periclase quantified
; ===
>>
>> José Carlos Cordeiro
>>
>> Diretoria Técnica - Laboratório Central
>>
>> Centro Técnico - Curitiba
>>
>> Rodovia PR-092, 1303, Abranches, 82130-570 Curitiba-PR
>>
>> Votorantim Cimentos
&g
>> Sorry for my bad English!!!
>>
>>
>>
>> regards
>>
>>
>>
>> ===
>>
>> José Carlos Cordeiro
>>
>> Diretoria Técnica - Laboratório Central
>>
>> Centro Técnico - Curitib
y other effects. Maybe my logic is flawed but
I don't think so! Having said that it has been demonstrated that the situation
isn't quite as bad practically as it is theoretically.
Pam
-Original Message-
From: Reinhard Kleeberg [mailto:[EMAIL PROTECTED]
Sent: May 30, 2008 10:10 AM
ietveld
program - a happy note for repeatability! On a less happy note that doesn't
mean that something like severe microabsorption doesn't come along and mess up
your accuracy.
Pam
-Original Message-
From: Kurt Leinenweber [mailto:[EMAIL PROTECTED]
Sent: May 30, 2008 11:11 AM
I'm only going to stick my big toe in here on a practical note for
lab-based studies.
I managed to get the Bruker Vantec detector to work with MoKa quite
nicely for some non-ambient work and decided to see if I could get
useful data for PDF from some battery cathode materials (I think it was
up to
Apologies for this pitch as it's not what this mailing list is for, but
unusual measures are required due to serious time issues.
Some of you may be aware that we have been developing a gas-pressure
cell to ASME pressure code for a lab diffractometer rated to 300bar and
300oC for CO2 sequestratio
While my coffee pot gurgles away here's my tuppence worth
As mentioned by previous answers prevention is MUCH better than cure.
Having said that a couple of comments. If there's significant PO then it's a
pretty sure thing that the particles are not spherical - so you can forget the
Brindley c
I'll put my tuppence worth in here as there can be another consideration with
high backgrounds.
Normally I wouldn't touch the background, but there are times when a high
background causes an artificially shallow minimum and the refinement isn't
going very far (Rietveld software is usually mini
Afternoon all
Tomorrow is the abstract deadline for the Toronto ACA meeting and there
is a severe lack of abstracts for the powder/materials sessions. We
have been trying hard to push the agenda of powder and materials
diffraction within the ACA and more generally but if we don't get
abstracts t
Morning/afternoon all
Apologies to anyone who gets this twice...
The web address www.iucr-cpd.org now redirects to the new CPD website
located on the central IUCr servers. All the old content is there with
some updates. The webpages for the Quantitative Phase Analysis round
robin have bee
Hiya folks
Just a quick notice.
All the retrievable presentation videos (flash video format) from the Erice
powder diffraction school have been collected together and are now available to
view on the CPD website at
http://www.iucr.org/resources/commissions/powder-diffraction/schools/erice2011
Nelson (and others)
The Scherrer equation is a quick and easy method to get a feel for relative
sizes for data from the same instrument and is still a useful tool in that
regard. However, beware of relying on absolute values from the Scherrer
equation in work to be submitted for peer review. De
Now, now no need to be prickly
To be fair to Julian he didn't ask what the polarization was - he asked how it
was calculated. Given that Goebel mirrors are graded multilayers (i.e. not a
fixed diffracting angle) it's a fair question and one I asked myself in 2001.
As the 'minute quote' demonstr
nt: Monday, 07 April, 2014 3:14 PM
To: Whitfield, Pamela S.
Cc: Julian R Tolchard; rietveld_l@ill.fr
Subject: Re[4]: Polarization factor por Ge (111) monochromator
Hi everybody,
Nobody is trying to be prickly (at all)!
The topic has been started with particular case for Panalytical machines, an
calculate a value via ray-tracing?
It strikes me as a little surprising that we are all buying these, but the
associated corrections are not well documented...
jools
____
From: Whitfield, Pamela S. [whitfiel...@ornl.gov]
Sent: 07 April 2014 21:31
To: Art
You would be well advised to do some background reading on microabsorption as
it will be pretty bad with those two phases and limit the accuracy you may
realistically expect in your quantification
Pam
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of
Nelson
Sent:
After reading the slew of emails that landed in my inbox over the last couple
of days I'll put my hat on as CPD chair and put my head above the parapet
(hopefully not to be shot at)
The IUCr (and others) have tried to get journals to use powder cifs and
checkcif for structures for some time
How about 'brute force with some educated guesswork'!
Brute force is a nicer way of putting it than blind luck :-)
See how that goes with reviewers!
Pam
-Original Message-
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of
A. van der Lee
Sent: Thursday, 17 D
This is a very sad day for the powder diffraction community. Any words I write
here cannot add in any meaningful way to the email that was received by members
of the mailing list earlier today.
What I can say is that discussions will start behind the scenes (and sometimes
in front of them) to co
Many, many, many years ago in a galaxy far away I wrote a paper that probably
no-one read that had some systematic data on this for a double mirror parallel
beam system (second mirror as an ‘analyzer’) in flat-plate theta-theta
geometry. This setup is much more sensitive to displacement than mos
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