AW: Hyper-Lorentzian effect on quantitative analysis

[Uwe Kolitsch]

> But with some electronic transmission analysis no amorphous is observed.

Could the TEM investigation have led to recrystallisation?
Have you tried polarised-light microscopy to check the character of the 
amorphous phase?

Cheers, Uwe


-Ursprüngliche Nachricht-
Von: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] Im Auftrag 
von Wörle Michael
Gesendet: Mittwoch, 03. März 2021 15:32
An: rietveld_l@ill.fr
Betreff: AW: Hyper-Lorentzian effect on quantitative analysis

Dear François,
Maybe you have a strongly disordered system. Depending on the type of disorder 
and the distribution of diffuse intensity, it can also have an influence on the 
reflection profile (thermal diffuse scattering).
Michael


Dr. Michael Wörle
Head Small Molecule Crystallography Center Laboratorium für Anorganische Chemie 
ETH Zürich HCI H103 Vladimir-Prelog-Weg 1
CH-8093 Zürich

Tel.:   +41 44 632 5684
FAX:  +41 44 632 1149
email: woe...@inorg.chem.ethz.ch
http://www.smocc.ethz.ch


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-Ursprüngliche Nachricht-
Von: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] Im Auftrag 
von François Goutenoire
Gesendet: Wednesday, 3 March 2021 13:34
An: rietveld_l@ill.fr
Betreff: Hyper-Lorentzian effect on quantitative analysis

Dear Rietveld users,

I have some industrial compound presenting a strong hyper-Lorentzian peak shape 
(eta=1.1 with HighScore). When we calculate the amorphous content after an 
internal standard addition, the result is 40%. The micro-absorption effect has 
been minimized (mu of the internal standard is closed to the compound).

But with some electronic transmission analysis no amorphous is observed.

The question is : Does a strong hyper-Lorentzian peak shape could influence 
quantitative analysis ?

François

--
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FAX: 02.43.83.35.06
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Département des Oxydes et Fluorures
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Bibliographie
https://scholar.google.fr/citations?hl=fr=qC-lmN4J_op=list_works=1=title
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AW: Stoichiometry and occupancy fractions of solid solutions

[Uwe Kolitsch]

Dear Othman,

You should check if the synthesised grains in your powder are chemically
homogeneous of if they show any zonation due to growth processes. Variable
chemistry will cause broadened and/or asymmetric peaks

Are vacancies known to occur in this class of compounds? The conditions of
preparation might be important (synthesis in air or something else?).

 

Uwe

 

 

Von: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] Im Auftrag
von Othman Al Bahri
Gesendet: Montag, 19. Dezember 2016 09:54
An: rietveld_l@ill.fr
Betreff: Stoichiometry and occupancy fractions of solid solutions

 

Dear all,

 

I've made a series of solid solution powders using a solid state reaction in
the form A2B3-xCxO12 at x= 0.5 steps. A2B3O12 is orthorhombic while A2C3O12
is monoclinic. I'm refining the XRD data to find the atomic distribution of
the solute. 

 

I've constrained the sum of the occupancy fractions for each relevant site
to equal 1. At low concentrations of the solute, I initially set the
solute's occupancy fractions to 0 and keep the solvent's occupancy at 1 then
refine the fractions (after following the usual Rietveld refinement steps).
This seems to give reasonable occupancy fraction values (no big numbers or
negative values) but the stoichiometry is way off. This is probably because
each site has different Wykoff multiplicities so constraining the sum of
each site's fractions to 1 is insufficient.

 

Let's assume that I knew the stoichiometry from Mass Spectroscopy or XPS -
is there a way to constrain the stiochiometry in a Rietveld refinement? I'm
using GSAS-II and comfortable with FullProf but feel free to give advice for
any other open-source software.

 

I've seen a few papers where the authors mention, typically in the
supplementary info, that their refinements' stoichiometry was off and that
it should be ignored. However I'm not comfortable with this approach and
would appreciate your advice.

 

This is my first time working with solid solutions so please feel free to
offer any general advice on what I should be careful with. I've tested for
phase mixtures (insolubility) by visually comparing my XRD patterns with the
sum of simulated XRD patterns of molar mixtures and through Rietveld
refinements with two phases. The system I'm working with has been reported
but the original authors didn't do Rietveld refinements - they were
interested in physical property measurements.

 

Kind Regards,

 

Othman

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Re: peak position of W L-alpha for Cu X-ray tube

[uwe . kolitsch]

http://xray.uu.se/hypertext/XREmission.html

 can you remind me what the peak position of the tungsten L-alpha for the Cu
 X-ray tube? 


*
Univ.-Doz. Dr. Uwe Kolitsch
Institut für Mineralogie und Kristallographie
Geozentrum, Universität Wien
Althanstr. 14 
A-1090 Wien
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
website: http://www.univie.ac.at/mineralogie/kolitsch.htm
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Re: Bazhenovite

[Uwe Kolitsch]

Dear Armel,
obviously the structure of bazhenovite is unknown (although bright 
orange to yellow, tabular xls up to 5 mm were reported). 
The mineral is said to be the monoclinic analog of the synthetic 
rhombic compound CaS5.CaS2O3.6Ca(OH)2.20H2O (Lutz, H. D. 
et al, 1969). 
I don't know about the stability - maybe it's discussed in the 
original publication. I could give you the contact address of a 
Russian colleague who should know more about this mineral 
(contact me off-list then). 

Regards, Uwe




 Hello,
 
 Any opinion of the eminent mineralogists members
 of this mailing list welcome about bazhenovite (ICDD-JCPDS
 card No 42-1361 and 22-0154) Ca8S5(S2O3)(OH)12.(H2O)20
 
 Is the structure determined ?
 If not, are the cell and space group dubious or not ?
 Anyway, is the compound stable in air ?
 
 Thanks a lot,
 
 Armel Le Bail
 http://www.cristal.org/course/
 





Dr. Uwe Kolitsch
Institut für Mineralogie und Kristallographie 
Geozentrum 
Universität Wien 
Althanstr. 14 
A-1090 Wien 
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
home page: http://www.univie.ac.at/mineralogie/kolitsch.htm

Re: Site occupation factor in atoms

[Uwe Kolitsch]

No, there is no way, unfortunately (referring to V. 5.0). This also 
means that you have to be careful when you calculate a powder 
pattern with ATOMS - it doesn't take into account mixed 
occupancies, vacancies, etc.. 
(You may be able to trick the program a bit by choosing an 
element with an 'equivalent' no. of electrons.)

Uwe

 
   Dear All,
 
   is there any way of defining the site occupation factor of an atom in
 the software ATOMS??
 
   Gracias!!
 
   ana
 
 -- 
 Ana Isabel Becerro
 ICMSE (CSIC)
 Avda. Américo Vespucio s/n
 41092 Sevilla (Spain)
 Tel: 34-95 4489576
 Fax: 34 95 4460665
 





Dr. Uwe Kolitsch
Institut für Mineralogie und Kristallographie 
Geozentrum 
Universität Wien 
Althanstr. 14 
A-1090 Wien 
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
home page: http://www.univie.ac.at/mineralogie/kolitsch.htm

Re: Information in Atom Program

[Uwe Kolitsch]

Dear Irini,
do you mean the program ATOMS by Eric Dowty?
Defining polyhedra in ATOMS is pretty straight forward by using 
Input1/Polyhedra (I am referring to version 5.0). 
Defining the no. of atoms or the size of the structure fragment 
drawn is done in Input1/Boundary. 

If you want to draw different polyhedra for identical cations then it 
would be easiest to just change the type of atoms. 

The inbuilt manual will help you in any other questions.

Uwe





Dr. Uwe Kolitsch
Institut für Mineralogie und Kristallographie 
Geozentrum 
Universität Wien 
Althanstr. 14 
A-1090 Wien 
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
home page: http://www.univie.ac.at/mineralogie/kolitsch.htm

Re: Database stories

[Uwe Kolitsch]

In the latest edition of the ICSD there is actually the entry of 
khademite you found (Bachet et al., 1981). The ICSD collection 
code is 41-562. 

Cheers, Uwe



Dr. Uwe Kolitsch
Institut fr Mineralogie und Kristallographie 
Geozentrum 
Universitt Wien 
Althanstr. 14 
A-1090 Wien 
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
home page: http://www.univie.ac.at/mineralogie/kolitsch.htm

Re: Natrite - Na2 CO3

[Uwe Kolitsch]

  0.0230  0.
 (1) (5) (3)(10)
  Na 30.0050  0.0148  0.0157  0.  0.0030  0.
 (1) (4) (3) (1)
  C  10.0025  0.0073  0.0059  0.  0.0010  0.
 (1) (6) (4) (2)
  O  10.0031  0.0190  0.0115  0.  0.0035  0.
 (1) (6) (3) (2)
  O  20.0058  0.0093  0.0135  0.0014  0.0020 -0.0008
 (2) (7) (3) (4) (2) (4)
 REM  MOD (modulated/incommensurate structure)
 REM  M PDF 37-451
 RVAL 0.108
 TEST Calculated density unusual but tolerable. (Code 23)






Dr. Uwe Kolitsch
Institut für Mineralogie und Kristallographie 
Geozentrum 
Universität Wien 
Althanstr. 14 
A-1090 Wien 
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
home page: http://www.univie.ac.at/mineralogie/kolitsch.htm

Re: Calcium iron titanium oxide

[Uwe Kolitsch]

Dear Bruce,
the following is from the ICSD database (only one entry for the 
compound):

COL  ICSD Collection Code 203100
 DATE Recorded Dec 27, 1990
 NAME Tricalcium titanium diiron(III) oxide
 FORM Ca3 Ti Fe2 O8
  = Ca3 Fe2 O8 Ti
 TITL Perovskite Threefold Superlattices: A Structure Determination 
of 
  the A3 M3 O8 Phase
 REF  Materials Research Bulletin
  MRBUA 24 (1989) 423-430
 AUT  Rodriguez Carvajal J, Vallet RegiÿM, Gonzalez CalbetÿJÿM
 CELL a=5.530(0) b=11.205(1) c=5.438(0) à=90.0 á=90.0 ç=90.0
  V=336.9 Z=2
 SGR  P c m 21  (26) - orthorhombic
 CLAS mm2   (Hermann-Mauguin) - C2v (Schoenflies)
 PRS  oP28
 ANX  A3B3X8
 PARM Atom__No OxStat  Wyck -X- -Y- -Z-  -SOF-
  Fe 1  3.0002a  0.309(2)0.  0.050(2)
  Ti 1  4.0004c  0.258(1)0.3303(5)   0.0.5
  Fe 2  3.0004c  0.258(1)0.3303(5)   0.0.5
  Ca 1  2.0002b  0.234(2)1/2 0.486(4)
  Ca 2  2.0004c  0.225(1)0.1884(5)   0.526(3)
  O  1 -2.0002a  0.398(6)0.  0.410(6)
  O  2 -2.0002b  0.316(5)1/2-0.010(7)
  O  3 -2.0004c  0.169(3)0.144(2)   -0.018(5)
  O  4 -2.0004c -0.010(5)0.353(2)0.227(7)
  O  5 -2.0004c  0.469(5)0.300(2)0.281(6)
 WYCK c5 b2 a2
 ITF  Fe  1   B=0.57(4)
 ITF  Ti  1   B=0.57(4)
 ITF  Fe  2   B=0.57(4)
 ITF  Ca  1   B=0.57(4)
 ITF  Ca  2   B=0.57(4)
 ITF  O   1   B=0.57(4)
 ITF  O   2   B=0.57(4)
 ITF  O   3   B=0.57(4)
 ITF  O   4   B=0.57(4)
 ITF  O   5   B=0.57(4)
 REM  XDP (X-ray diffraction from a powder)
 RVAL 0.128




Dr. Uwe Kolitsch
Institut für Mineralogie und Kristallographie 
Geozentrum 
Universität Wien 
Althanstr. 14 
A-1090 Wien 
Austria 
Tel +43-1-4277-53239
Fax +43-1-4277-9532
e-mail: [EMAIL PROTECTED]
home page: http://www.univie.ac.at/mineralogie/kolitsch.htm