: Thursday, 6 February 2014 5:25 PM
To: Breogan Pato Doldan; rietveld_l@ill.fr
Subject: Re: Preferred orientation and lattice parameters
Dear Breogan,
just three small additions:
(i) .25 Å is a lot, if the lattice parameter in that direction is 4 Å, but much
less if it is 40 Å
(ii) Definitely
ot;Breogan Pato Doldan" ,
"rietveld_l@ill.fr"
*Enviados: *Miércoles, 5 de Febrero 2014 11:55:59
*Asunto: *Re: Preferred orientation and lattice parameters
How much mismatch? If you're getting a good profile fit, I'd be
inclined to doubt that it is a consequence of pre
Hi! Be careful with LeBail. There is a paper (I can send it to you)
showing, that this method may give some errors (so is probably also for
Pawley method).
Best regards!
Btw: preferred orientation should not influence the c parameter, but the
intensity of an reflection. It can be influenced by sa
ot;
Para: "Breogan Pato Doldan" , "rietveld_l@ill.fr"
Enviados: Miércoles, 5 de Febrero 2014 11:55:59
Asunto: Re: Preferred orientation and lattice parameters
How much mismatch? If you're getting a good profile fit, I'd be inclined to
doubt that it is a consequence
How much mismatch? If you're getting a good profile fit, I'd be inclined
to doubt that it is a consequence of preferred orientation. You could mix
your sample with another material (corundum powder, cork) to try to reduce
the degree of preferred orientation, and see if that makes a difference.
I
Dear Ross,
I presume on the flat sample you measured regular theta-2theta diagrams,
then only probed those planes parallel to the sample plane. In such a
situation, you do not probe correctly the texture, and all the models
you could envisage are just giving back parameters that have been
ref
> From a theoretical point of view, preferred orientation
> means orientational texture. There may be size textures,
> strain textures, grain boundary textures, dislocation textures
> etc. as well, although seldom in practical use. Therefrom, in
> practical use, texture is meant orientational textu
: 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
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
Dear all,
If, I can to obtain the data from Bragg-Brentano geometry, obtained by very
slowly steps (maybe to 20-30 seconds), Can I make a microstructure analysis
(crystalline sizes and residual tensions) using Rietveld refinament?
Best regards,
Mario Macias
UIS, Colombia
---
>From a theoretical point of view, preferred orientation
means orientational texture. There may be size textures,
strain textures, grain boundary textures, dislocation textures
etc. as well, although seldom in practical use. Therefrom, in
practical use, texture is meant orientational texture and t
> If you want it, it's texture. If you don't want it, it's preferred
> orientation!
Preferred orientation is what you get with X-rays; neutrons are good for
measuring texture :-)
Seriously, "texture" is a term best applied to solid materials, where
crystallites have preferred orientation due to t
The texture versus preferred orientation difference has some
signficant blurry edges from a practical point of view.
If you want it, it's texture. If you don't want it, it's preferred
orientation!
The discussion seems not for a nervous.
A naive question of a baby watching adults in the mailing
_
From: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
The texture versus preferred orientation difference has some signficant
blurry edges from a practical point of view.
If you want it, it's texture. If you don't want it, it's preferred
orientation!
Matthew
Matt
Martin wrote:
PS For anyone interested in an explanation of texture vs. PO, see:
http://pd.chem.ucl.ac.uk/pdnn/inst1/texture1.htm
http://pd.chem.ucl.ac.uk/pdnn/inst1/texture2.htm
I disagree! The web page has confused "texture" with "granularity". See:
http://en.wikipedia.org/wiki/Texture_(c
see:
http://pd.chem.ucl.ac.uk/pdnn/inst1/texture1.htmhttp://pd.chem.ucl.ac.uk/pdnn/inst1/texture2.htm
PPS for anyone interested in the TV ad that came to mind during this
discussion, see:
http://www.nationalarchives.gov.uk/films/1964to1979/filmpage_lonely.htmMartin
Subject: RE: Preferred o
_
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
er.. - sorry - making things worse here - quite right, large particles can lead
to PO. I meant crystallites . 'umble apologies.
M
Subject: RE: Preferred orientation?From: [EMAIL PROTECTED]: [EMAIL PROTECTED];
[EMAIL PROTECTED]: Fri, 16 May 2008 15:47:31 +
Hi,
decouple orientation,
statistcs and microabsorption as they are all related to size.
Pam
From: Martin [mailto:[EMAIL PROTECTED]: Fri 16/05/2008 10:04 AMTo: Whitfield,
Pamela; [EMAIL PROTECTED]: RE: Preferred orientation?
In fact I think you might find it helps quite a bit. Have a
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
Subject: RE: Preferred orientation?Date: Thu, 8 May 2008 10:55:12 -0400From:
[EMAIL PROTECTED]: rietveld_l@ill.fr
I do that myself but it doesn’t always help
> Dear Reinhard,
If I want make a microstructure analysis of data from Bragg-Brentano scan.
Can I use spherical harmonic model and Rietveld refinament content into
Fullprof?
Best regars,
Mario Macias
UIS, Colombia.
Luca,
> I understood Gerard's problem to have a measurement of a powder (of
>
Luca,
I understood Gerard's problem to have a measurement of a powder (of
unknown particle shape) in Bragg-Brentano geometry, for structure
refinement. As you said the graininess problem can be minimized
primarily by grinding and to a certain extent by rotation and enhancing
the divergence, ax
ubject: Re: Preferred orientation?
To: [EMAIL PROTECTED]
Copies to: rietveld_l@ill.fr
[ Double-click this line for list subscription options ]
Reinhard,
I stick with what Gerard said:
"But i have no other information that supports the e
aries visitors to my lab must sometimes think I'm very vain!
Pam
From: Peter Y. Zavalij [mailto:[EMAIL PROTECTED]
Sent: May 8, 2008 12:48 PM
To: 'Kurt Leinenweber'
Cc: rietveld_l@ill.fr
Subject: RE: Preferred orientation?
Kurt,
An old way used for alloys is:
greas
Reinhard,
I stick with what Gerard said:
"But i have no other information that supports the existence of
preferred orientation"
so what information give you the confirmation it is the powder mount
responsible of preferred orientation. I work almost exclusively with
image plate detectors
Leinenweber [mailto:[EMAIL PROTECTED]
Sent: Thursday, May 08, 2008 12:37 PM
To: rietveld_l@ill.fr
Subject: RE: Preferred orientation?
Hi all,
This thread gives me a chance to ask a question I've had for a long time.
I've heard about these large chambers where you can mix your sample wit
ay, 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
From: Kurt Leinenweber [mailto:[EMAIL PROTECTED]
Sent: May 8, 2008 12:12 PM
To: Whitfield, Pamela
Subject
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
Forget all that long winded stuff. Just collect the data on capillary
transmission geometry and avoid all (well, most of) the fuss.
Martin Vickers
_
Be a Hero and Win with Iron Man
http://clk.atdmt.com/UKM/go/msnnkmgl001009ukm/d
Pam
-Original Message-
From: William Bisson [mailto:[EMAIL PROTECTED]
Sent: May 8, 2008 9:29 AM
To: rietveld_l@ill.fr
Subject: Re: Preferred orientation?
Another way to check or convince yourself of preferred orientation is to
take note what is happening when grinding the sample.
Another way to check or convince yourself of preferred orientation is to
take note what is happening when grinding the sample.
Some crystallite samples will fracture along a particular plane upon
grinding and this summed up for the whole sample may produce preferred
orientation. Alternatively, b
Luca,
speaking about powder samples, Frank is right. The PO of powder mounts
is seldom reproducible and the filling technique is responsible for
particle orientation, depending on particle shape, filling direction,
pressure... In practice it is a nice trick to repeat the filling of the
powder
On May 8, 2008, at 12:30 AM, May, Frank wrote:
You can check for texture effects (preferred orientation) by
obtaining multiple patterns of the material. It's realistic to
expect some differences, but preferred orientation is manifest by
not being able to replicate the pattern.
Not true,
You can check for texture effects (preferred orientation) by obtaining multiple
patterns of the material. It's realistic to expect some differences, but
preferred orientation is manifest by not being able to replicate the pattern.
That's the simple test. Let us know what you find.
Another i
Dear Gerard,
The low-angle intensity problem might come from disordered
regions, like water or solvent molecules occupying some voids.
Also, poor modeling of weakly scattering atoms, like hydrogen,
may lead to the similar problem.
Best regards,
Yaroslav
http://filinchuk.com
===
> my question is : how can I get the preferred orientation direction
> (pr1,pr2,pr3) from an X-ray pattern expressed in reciprocal space?
You may try to analyse the shape of the (0,0,0) peak on the Patterson
map. In the case of a preferred orientation it usually elongates in the
directions per
At 12:04 19/01/99 +0100, Lubo wrote:
>Hi Armel,
>I am sure you will not be satisfied by this answer, but my solution to
>this problem is : USE transmission geometry. We have been doing it for
>years getting nice results for kaolinites, micas, vermiculites and
>smectites, not to
>speak of some orga
Armel,
We use a gadget marketed by McCrone that is not a ball mill, but has small,
cylindrical elements. (It's relatively inexpensive, ~2500$US, I think.)
These can be of either agate or alumina. There are 56 elements close packed
in a canister w/ a capacity of ~100 mL. We use these w/ ~2 gm of s
At 15:55 19/01/99 +0100, Lubo wrote:
>No need for a capillary - just transmision geometry.
Levitation geometry ?
Armel
On Tue, 19 Jan 1999, Armel Le Bail wrote:
> It is really not expensive (buying 250g will cost you a few $ and
> you will have enough for the rest of your life).
I don't like the idea of admixtures, so I think I'll spare those few $ for
a quite expensive meeting in Glasgow.
> orders of magnitude
Lubo wrote :
>No need to add -osils (what's that, BTW).
Cab-osil (M-5 Fluka) is glassy SiO2 with high specific surface
(200+-25m**2/g). It pertains to the category of "solid filler
materials" used for surrounding particles in a non-orienting medium.
For a list of other possibilities, see : M
> And then, problems with preferred orientation occured.
[...]
> Even
> after mixing 25% biotite and 75% Cab-osil, in volume,
> one cannot expect to be able to pack the sample : the
> 75% Cab-osil tends to decrease to a few percent after
> packing, so that the preferred orientation is not reduced
Hi Armel,
I am sure you will not be satisfied by this answer, but my solution to
this problem is : USE transmission geometry. We have been doing it for
years getting nice results for kaolinites, micas, vermiculites and
smectites, not to
speak of some organic plates. No need to add -osils (what's t
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