Powder X-ray Diffraction

Powder X-ray Diffraction

  • Jong-Ku Park added an answer:
    What can cause significant shift of a single peak in powder XRD?

    I have synthesized a compound by two different methods.  Both methods give a powder pattern that matches well with the calculated data, with the exception of a single peak that shifts from 20.3 (which matches the calculated value) to 21.8 degrees in method A vs method B. 

    Could this peak shift indicate macrostrain?  From what I have studied macrostrain normally occurs to a lesser degree and is more pronounced at higher 2thetas.

    Jong-Ku Park · Korea Institute of Science and Technology

    Macrostrain can be a cause to make a shift for a certain peak among several peak. In this case, however, there should be an appropriate reason to explain it because, generally speaking, macrostrain affects (relatively) homogeneously over the sample due to three-dimensional topography. Therefore, macrostrain has special relationship with a particular crystallographic direction. (Here, the special relationship means that the macrostrain is evolved independantly only along the specific direction.) Anyway your case is not usual.  In case of bulk with a textured microstructure, your question can be explained more easily (this is not your case),

  • Theeranun Siritanon added an answer:
    How can I improve the peak shape fitting in Rietveld refinements using TOPAS software?

    The data was collected on powder XRD (Bruker) with 0.02/2s scan, Ka2 and probably some Kb are there.

    I am currently getting Rexp = 2.766 Rwp= 12.327, GOF = 4.723. This is the result after anisotropic refinement (in Launch mode) is performed. I think, by looking at the graphic of the fit, that peak shape and broadening seem to be the main problem?. Is there anything I can do to improve this? So far I have refined the basic parameters and structure-related parameters. The sample is 30%doped of the parent compound but the pattern looks really really similar so I use the model of the parent compound. The doping ion is Bi3+ and having lone pair electrons and being quite lager might cause much strain, could this be the reason?

    Theeranun Siritanon · Suranaree University of Technology

    Thank you for the comments. 

    In that case, I did use the fundamental parameters approach. 

    I will try on preferred orientation and also other suggestions as well.

  • Maykel Manawan added an answer:
    Lattice parameter of rhombohedral phase from XRD data?

    Apart from using the equations manually, is there any simple software to find lattice parameter of rhombohedral phase from XRD data?

    Thank you

    Maykel Manawan · University of Indonesia

    Continue the refinement with the hexagonal lattice, safe the .cif than use the link below to transform to rhombohedral.

    http://www.cryst.ehu.es/cryst/setstru.html

  • Alfred Amon added an answer:
    Comparing the XRD patterns of mixtures containing CaCO3, how can I just roughly prove that one sample contains more aragonite than another one?

    I have the XRD patterns of two samples which mainly contains calcite and aragonite (S1 and S2, see the attachments). How can I just roughly say that S2 has more amount of aragonite than S1?

    Alfred Amon · Vienna University of Technology

    Also look at this related discussion:

  • V. A. Parfenov added an answer:
    Can you help me with interpretation of this XRD data?

    Hello,

    I have this XRD pattern for two ceramic materials - nanoparticles (see file added to the question). Both supposed to be the same material, but one of them (black curve) was synthesized with addition of surfactant which probably bonds to the surface of resulting nanoparticles. Is it possible that presence of this surfactant may distort the XRD pattern as much as it is visible? Or maybe other effects cause this differences in XRD patterns of both samples?

    The red curve is for the commercially available material.

    Thank you for your contribution!

    Best regards,

    Michał W.

    V. A. Parfenov · Russian Academy of Sciences

    Michal,
    It is clear that the red X-Ray pattern received for true crystalline material. But the second material is obviously amorphous. Black pattern does not contain any signs of surfactant-ceramic bonding. But, there are some variants. What about the crystallinity of pure surfactant? If pure surfactant is amorphous, than it can't be stated in XRD pattern in any case. On the other hand, if surfactant is crystalline, than it could be stated as individual surfactant phase (surfactant precipitated without any interaction with ceramic components) or it could form some crystalline phase with one of ceramic component. But no: there are no any sharp XRD reflections. Therefore, IF surfactant is presented in this material, than it is in amorphous state. And the only way to influence on roentgenogram consists in decrease of XRD profile intensity. You can find it out by TGA, IR-spectroscopy, CHNS-analysis or else. Or You can heat this material in air above 300°C (2-3 hours) and remove it.
    It is important to understand that surfactant presence in synthesis mixture can put obstacles in the way of true crystalline particles formation. It is more precisely to speak about obstacles for crystalline particles growth, because surfactant do can stabilize nanoparticles in reaction mixture forming preventing layer in their surface. So, my answer to “Is it possible that presence of this surfactant may distort the XRD pattern as much as it is visible?” is “NO”. And the answer to “Or maybe other effects cause this differences in XRD patterns of both samples?” presented above and concerned with ceramic formation (particles growth) in reaction mixture, but not with XRD patterning. It can be supposed that ceramic particles are too small.
    By the way, what about the ceramic/surfactant molar or weight ratio(s) and both ceramic’s specific surfaces?

    I do tender my apologies for my extremely poor English.

  • N. Civici added an answer:
    How reliable is energy dispersive X-ray spectroscopy (EDS) for elemental analysis of powder sample?

    Is EDS sufficient to confirm the elemental composition of powder samples (composite) or is it necessary to go for advanced techniques like X-ray fluorescence (XRF) or XPS.

    N. Civici · University of Tirana

    In general the reliability of any technique depends on to many factors and EDS if used in the proper way is considered as reliable as any other technique. Regarding the analysis of powders, as the other colleagues mentioned, it depends on what kind of powder you like to analyze, what elements you are interested in and what kind of equipment you have. It is difficult to analyze low Z elements and almost impossible to analyze elements bellow Na, unless you can use electron microprobe. The main advantage is that you can measure your powder without any special sample preparation. You can measure your powder as it is, as pressed pellet or as a thin sample by depositing a small amount of the powder on a filter on any other substrate.  

  • Biserka Grzeta added an answer:
    I got a peak at below 38 (around 36) for Ag. can anyone help with the interpretation?

    Please have a look at the image. I am unable to interpret and reason the peak shift towards left. Moreover the 2nd peak at around 30 is of silver oxide ?

    the peak is supposed to be of Silver nano particles that have been synthesized from algae.

    Need your valuable comments.

    Biserka Grzeta · Ruder Boskovic Institute

    Dear Uzair,

    Please perform XRD measurement of the empty sample holder (without sample) for comparison. Also, please provide an information about the anode material of your X-ray tube. Diffraction lines in your present XRD pattern are narrow, so they do not belong to nano particles.

    Regards, Biserka

  • Prashant Sahu added an answer:
    Are there any free programs to make several XRD-plots in the same picture for comparison (stacked)?

    I have several .raw files which I want to analyze in the same plot. Is it possible to do this in any free available programs?

    Prashant Sahu · Indian Institute of Technology Bombay

    Microcal Origin, my long time favourite. :-)

  • B. Mallick added an answer:
    How can one determine the instrumental resolution of a X-ray diffractometer better?

    I observe less broadened peaks from a diffractogram of deformed aluminum than those observed from a LaB6 standard powder (SRM-660b).

    B. Mallick · Institute of Physics, Bhubaneswar

    Hi!

    You can refer these papers/books to improve the resolution of your existing diffractometer also.

    B. D. Cullity, Elements of X-ray Diffraction, (Addition-Weseley Publishing Company, Inc. London, 1978).

    W. R. McIntire, Phys. Rev., B14, (1976), 4386.
    N. Shiotani, N. Sakai, F. Itoh, M. Sakurai, H. Kawata, Y. Amemiya and M. Ando, Nucl. Instrum. Methods., A275,(1989), 447.

    P. Pattison, P. Suorti and W. Weyrich, J. Appl. Cryst., 19, (1986), 353.
    E. Straube, D. Hohlwein and Th. Zeiske, J. Appl. Cryst., 31, (1998), 169.

  • Venkataraman Abbaraju added an answer:
    Is there any relationship between the size of nanoparticles and broadening of PXRD peak?

    My PXRD analysis of gold nanoparticle adsorbed silica matrix has shown different widths in their peaks for different sizes of gold nanoparticles. I wish to know what is the relation between peak shape and size of metallic nanoparticle.

    Venkataraman Abbaraju · Gulbarga University

    The Debye_Scherrer equation is useful for spherical particles, so you will have to be careful and as suggested by others.

  • Ganesh Kotnana added an answer:
    I am getting negative value for Uiso in GSAS-EXPGUI. Can any one tell me how to refine atomic positions and to not get the negative value to Uiso?

    I am getting negative value for Uiso in GSAS-EXPGUI. Can any one tell me how to refine atomic positions and to not get the negative value to Uiso?

    Ganesh Kotnana · Indian Institute of Technology Hyderabad

    What type of Absorption function I can put for XRD refinement in EXPGUI?

  • Fabrizio Guzzetta added an answer:
    Where can i get XRD patterns about anatase and rutile?

    I want to compare my samples with the XRD patterns to identify the phases in each one.

  • Khaled Abou-El-Sherbini added an answer:
    Is there any free software for finding out the lattice parameters of a XRD powder pattern?

    ready to be downloaded and can use ASCII files

    Khaled Abou-El-Sherbini · National Research Center, Egypt

    Hi Igor

    Thank you very much for your kind help.

    Best wishes and regards

    Dupra Ye Otra

  • Simon Sembiring added an answer:
    What is the best technique of GAXRD for thin film?

    Since Grazing angle techniques have different configurations (and this creates a lot of confusion): as shown bellow.


    (i) fixed angle between specimen and incoming beam and 2theta scan
    (ii) fixed angle between specimen and outgoing beam and theta scan
    (iii) fixed angle between specimen normal and scattering vector, with conventional coupled scan.


    Which one is th best technique and what are the angles I have to take for oxide thin film?

    Simon Sembiring · Lampung University

    The best technique can be used for thin film is Grazing Incidence Synchrotron radiation diffraction (GISRD).  GISRD can be expected to provide more detailed descriptions near-surface phases.GISRD offers considerably enhanced diffraction patten intensities and superior pattern resolution thus offering superior major phase discrimination plus superior ability to reveal the presence of minor phases greater. Also pattern complexity is reduced for GISRD due to the use of monochromatic radiation, and it is usually used Co or Cr target tube due to the relatively high penetration depth.  The selection of a wavelength is important to provide depth of some 10 micrometre for angle operating of several degrees. 

    The penetration depth (or information depth, when the angle incidence a is very small can be calculated:

    D=angle (a)/ mass attenuation coefficient X the material density.
    If the angle of incidence a is less than the critical angle of total reflection ac where total internal reflection occurs, the penetration depth reduces dramaticall according to the equation (Vineyard, 1982)
    D = radian x wavelength/ (a2c- a2)1/2
    The critical angle for total reflection ac can be approximated by (Barner, 1982):
    critical angle (ac) = 1.6 x 10-3 density of material  X wavelength
    So from equation above, you can arrangge the angle which you need
    Refferences
    Barner, P (1982)< Dynamic Diffraction Studies on the synthesis of ceramic Using Synchrotron Radiation, Tran. J. Br.Ceram. Soc., 91(1), 26-29)
    Vineyard, G.H (1982), Grazing incidence Diffraction and Distorted-Wave Approximation for the of surface, Physical Review (B), 26, 4146-4158

  • Lawrence Margulies added an answer:
    Does capillary diameter influence the resolution reached when measuring X-ray powder diffraction of organics in Deby-Scherrer configuration?

    I'm thinking in modern diffractometers like Panalytical MPD or Bruker Advance with fast detectors like Pixcel and Lynxeye respectively. 

    Manufacturers say that, virtually, the diameter of the capillary doesn't affect the resolution reached in the new diffractometers.

    I would like to know what is your experience and if you have some example on that.

    Lawrence Margulies · University of Guelph

    The reference you need to calculate broadening is a high school trigonometry text. No x-ray diffraction text would contain something that simple. It would only give you information of how to make absorption corrections to structure factors, which is not your question.

  • Anahita Bashardoust added an answer:
    How can I get the percent of crystallinity from Powder XRD data?
    I have done XRD and having data file and drawn xrd patterns using Powder X software. I need % crystallinity.
    Anahita Bashardoust · Amirkabir University of Technology

    i didn't understand. how do i fit of XRD peaks by gaussian or lorentizan function?
    and then how i get % crystallinity? would you please explain more? in XPowder softeware. thank you

  • Shashwat Shukla added an answer:
    Is it possible a sample did not obey the Williamson-Hall plot or is it general?

    for example:magnetite ferrofluids

    Shashwat Shukla · Nanyang Technological University

    Williamson-Hall (W-H) plot works well as long as the peak shape is purely Lorentzian or purely Gaussian.

    W-H (for Lorentzian profile): {βobs − βinst}cosθ = λ/D + 4εstr{sinθ}

    W-H (for Gaussian profile): {β2obs − β2inst}cos2θ = λ2/D2 + 16εstr2 {sin2θ}

    obs: integral breath of observed reflection, βinst: instrumental broadening, D: volume averaged crystallite size and εstr: strain)

    In W-H method, depending upon the peak shape, we plot 1) {βobs − βinst}cosθ vs 4sinθ or 2) {β2obs − β2inst}cos2θ vs 16sin2θ. If the peak is a pure Lorentzian or Gaussian, either plot 1) or plot 2) will be linear and we will be able to extract the size and strain simply by measuring the y-intercept and slope of the straight line.

    However, the difficulty would arise when the peak shape is more complex. For example, if the peak shape is a convolution of a Lorentzian and a Gaussian, the mathematical expressions given above will not apply. As a result, both plot 1) and plot 2) will start to deviate from a straight line and the W-H method will no longer be useful for extracting the size/ strain data.

    Balzar has developed analytical models to describe such complex convoluted peak shapes. You might find his papers useful: http://mysite.du.edu/~balzar/lbap.htm.

  • Nikolaos Kourkoumelis added an answer:
    How can I convert the XRD pattern taken using Cobalt-K alpha to Copper-K alpha?
    I recorded XRD pattern using Cobalt-K alpha, but I have the PANalytical software with data base which was with Cu-K ALPHA radiation. Using POWDLL, I cannot convert it. Can you help me convert XRD pattern from Co-K alpha to Cu-K alpha?
    Nikolaos Kourkoumelis · University of Ioannina

    Dear Dirk,

    sure! Just send me (via email?) some relevant data. Thanks for your kind words. Best regards, Nikos  

  • Jason Potticary added an answer:
    How can I resolve a low temp pXRD pattern?

    I have taken various powder XRD patterns at different temperatures (every 10 degrees from 300 - 10 K) and I have a beautiful surface plot with peaks changing intensity as slowly shifting in 2Theta. I also have a cif of the solved structure at 100 K and have been trying to use CCDC DASH software to resolve what the unit cell looks like at each temperature. This software, however appears to not allow me to index the peaks manually so it has issues building the new .cif.

    Does anyone know of a program that allows one to input initial structural info and will modify that based on experimental data? Or is there any other way that I'm missing?

    Jason Potticary · University of Bristol

    Thanks all for your answers. I'll have a look at the free programs 1st and see how I get on...batch processing sounds amazing as there are 100 of patterns to do this on.

    Cristobal: The issue with dash is that takes the .mol file and mashes it together to make a messy .cif, thus I'm not sure I can trust the output.

  • Karimat El-sayed added an answer:
    If 200 plane diffraction of fcc cancels out that of 100, why do we still see that of 200?

    I am trying to understand the systematic absences that occur for certain symmetry. The explantion above was given for fcc but I would have thought that both of them would not be seen if the above was the case.

    does 200 planar diffraction have 2 or 3 times the intensity of 100 plane

    Karimat El-sayed · Ain Shams University

    all the previous answers are corrct , but the answer of Marcin Perzanowski is correct also and simple for those who are not crystallographer

  • Subrat kumar Das added an answer:
    Can you help me on the Rietveld refinement by X'Pert Highscore plus?

    Using X'PERT highscore plus to perform Rietveld refinements, where can I find the reliability factors: rf, rb, rexp. And where can I find the graph where the difference between EXP-CALC is illustrated? Thank you.

    Subrat kumar Das · Institute for Plasma Research

    Dear hassan

    Can you share X'pert High-score setup file.

  • Ubirajara Rodrigues Filho added an answer:
    Has anyone observed the formation of polyhedral oligomeric sesquisiloxane (POSS) in acid catalyzed organosilane polycondensation?
    We are working with inorganic-organic hybrid ormosils using alkoxyorganosilane and diferent polymers. During the synthesis we used phosphotungstic acid as an acid catalyst in ethanol, DMAC or ketone solvent. The Powder XRD and WAXS difractograms display a peak between 6 and 8 degrees (2 theta). We believe this peak is due to formation of POSS in our material, however, we could not find any articles reproting their synthesis in acid catalyzed hydrolysis/polycondensation conditions.
    Ubirajara Rodrigues Filho · University of São Paulo

    Dear Mateuz,

    We have just published an article claiming the formation of POSS in ormosil materials. Please, see http://dx.doi.org/10.1016/j.matchemphys.2015.01.035.

  • Suchinder K. Sharma added an answer:
    Can anybody suggest the suitable software for assigning (h,k,l) in the XRD peaks and also its matching with JCPDS no.?

    I want to characterize the prepared crystal samples on the basis of XRD spectra. I have XRD spectra with me and I want to assign their (h,k,l) planes and  also to match these spectras with their standard JCPDS no.

    Suchinder K. Sharma · Chimie ParisTech

    Match! can be good option for the purpose. They provide free database too. check on website crystalimpact.com 

  • Ricardo Sousa added an answer:
    What free software do you use to analyze XRD data?
    There is many free software to analyze XRD data but what is the best, if I have raw, dat, cpi, sd , rd data?
    Ricardo Sousa · University of Porto

    To work with a .rd file, what software do you advise?

  • Evgeni B. Starikov added an answer:
    How can I calculate crystallinity index (CI) from XRD data?

    I have seen some methods in web but it seems to be difficult. I am a beginner to this kind of work. Any suggestions from your side would be very helpful. Thanks in advance. 

    Evgeni B. Starikov · Chalmers University of Technology

    Dear Arun,

    in this paper you'll find the answer to your question:

    A. Person et al. (1995), Journal of Archeological Science, v. 22, pp. 211-221.

    Respectfully yours,

    Evgeni B. Starikov

  • Bojidarka B. Ivanova added an answer:
    How can I estimate the uncertainty in structure factors derived from X-ray diffraction experiments?

    I have some high quality synchrotron powder XRD data, gathered in a Debye-Scherrer geometry.  I've calculated relative peak areas by fitting Gaussian/Lorentzian peaks using Igor and calculated structure factors using

        I = |F|2p (1 + cos2 2θ) / (sin2θ cos θ)

    where I is the relative intensity, F is the structure factor, p is the multiplicity factor and θ is the Bragg angle.  (This is Eq. (4-19) in Cullity, 2nd Ed.)

    I now need to estimate an uncertainty in these structure factors.  Can anyone provide an expression for this, or point me towards some relevant references?

    Bojidarka B. Ivanova · Technische Universität Dortmund

    Mr. Howie,

    The equation in the previous attachment has shown the app. relationship between the calculated structura factor F, where has contribution a factor B. Therefore uncertaiity in this factor B shoud presumably have contribution to the uncertainty of the function Fcalc, which should determine the error of its value.
    But as I have understood, Fcalc do not represent interest. Therefore, with above reflections in mind let us focuse our attention on Eq. (1) in the new attachment, particularly visualizing the real part. So that, if this equation is true, I hoe so, then there have two factors phases and scattering factor. In this respect if we are looking for origin of uncertainities in Fh,k,l than this means to search about the uncertainities in those two factors.
    For plane having indexes h,k,l 0,0,0 the F factor has been given bz Eq. (2). In this equation to expect some uncertainities has sense if describing onlz the Ym, but at small number of electrons, to expect so significant uncertainities, I do not think so (or may be yes?).
    For may electron systems, however, there has observable Tscherenkow phenomenon, due to the relativistic effect. Is your interest is to account quantitatively of this effect and it contribution to the determination of Fh,k,l? If this is the essesnce of your question, that I have found, but this literature research is only scarce, Monte Carlo simulations studying the fluctuations of the phase and the scattering factor. These are refs. [1,2]. Most probably they should be useful for you, if the systems studied fit exactly to your one/s.

  • Apramita Chand added an answer:
    What is the explanation if experimental PXRD patterns fail to match that of your simulated PXRD pattern of single crystal data,in case of cocrystals?

    While studying cocrystals,I ball milled the starting materials with a few drops of solvent (with proper frequency,time-1hr).However,I notice the peaks of starting materials in my experimental pattern. While some peaks match with my simulated pattern from SCXRD data,there are still lots of peaks from my starting materials.All my cocrystals are anhydrous. Are there any references which suggest that  some anhydrous co-crystals may require higher temperature or more amount of solvent to form which may not always be satisfied by mechanochemical methods?

    Apramita Chand · Indian Institute of Technology Bhubaneswar

    Crystallinity was retained in the powder..Also,both measurements(SCXRD and PXRD) were recorded at room temperature. It may be due to insufficient reaction time or inhomogenous mixture...

    Thanks a lot !..

  • Brahim Orayech added an answer:
    How to correct baleline of Powder XRD data in crysalis pro software?

    We have single crystal instrument of agilent technologies supernova model with crysalis software. Initially we done powder XRD in same instrument it given good data with all peaks were detected but it has lack of baseline. Let me know how to correct the baseline in this software. Help me please. The XRD graph is attached here.

    thanks in advace

    Brahim Orayech · Universidad del País Vasco / Euskal Herriko Unibertsitatea

    Hi Raj Kumar, you can do that using Fullprof package-Winplotr. You make your background points (selected or automatic) then you substract that background from your data. In that way you will have a linear baseline.
     

  • Amin Hodaei added an answer:
    How could it be possible that the formation of barium-monoferrite bypassed during the formation of barium hexaferrite?

    In the conventional solid-state synthesis of barium hexaferrite (BaFe12O19) before complete crystallization of BaFe12O19, an intermediate phase of barium-monoferrite (BaFe2O4) was formed. In some process (e.g. mechanical activation) this phenomenon was not occurred and BaFe12O19 formed without formation of BaFe2O4 phase. Indeed, formation of barium-monoferrite bypassed

    Amin Hodaei · University of Tehran

    Dear Doctor Klimm,

    I would like to thank you so much for sharing such valuable information.

    Sincerely yours,

    Amin Hodaei

  • Manish Kr Mishra added an answer:
    Can I get XRD .CIF file of ZnAl2O4 (Cubic) JCPDS number: 01-074-1138 ?
    I need it for HR-TEM analysis.
    Manish Kr Mishra · Central Glass and Ceramics Research Institute

    Geoffrey Tse! can you please send me .CIF files of CdS (cubic, hexagonal), TiO2 (anatase) and Al2O3 (gama)?

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