Download - Fullprof Refinement
PXRD AND RIETVELD REFINEMENT
By Saurav Chandra Sarma and Dundappa MumbaraddiSolid State and Inorganic Chemistry Lab, NCU,
JNCASR
What Rietveld can do..???
• Analysis of the whole diffraction pattern.• Phase purity and identification.
• Refinement of the structure parameters from diffraction data.• Quantitative phase analysis.• Lattice parameters.• Atomic positions and Occupancies.• Isotropic and anisotropic thermal vibrations.
• Grain size and micro-strain calculation.• Magnetic moments (Neutron diffraction).
PHASE PURITY
Lattice parameter
sCe2AgGe3 Pr2AgGe3 Nd2AgGe3
Single crystal XRD
Reitveld refinement
Single crystal XRD
Reitveld refinement
Single crystal XRD
Reitveld refinement
a = b 4.2754(3) 4.2733(1) 4.2401(6) 4.2270(1) 4.1886(6) 4.1876(3)
c 14.6855(16) 14.7976(1) 14.611(3) 14.6457(1) 14.557(3) 14.5343(2)
PHASE IDENTIFICATION
What Rietveld can do..???
• Analysis of the whole diffraction pattern.• Phase purity and identification.
• Refinement of the structure parameters from diffraction data.• Quantitative phase analysis.• Lattice parameters.• Atomic positions and Occupancies.• Isotropic and anisotropic thermal vibrations.
• Grain size and micro-strain calculation.• Magnetic moments (Neutron diffraction).
QUANTITATIVE PHASE ANALYSIS
With high quality data, you can determine how much of
each phase is present
The ratio of peak intensities varies linearly as a function
of weight fractions for any two phases in a mixture.
Experimental Data
Fitted Data
Model 1
Model 2
Difference between experimental and fitted data
CRYSTALLITE SIZE
Crystallites smaller than ~120nm create broadening of diffraction peaks. (scherrer’s equation)
Where,D-Size of ordered domainsK-dimentionless Shape factorLamda-X-ray wavelengthβ-Line broading at FWHMTheta-Brage angle
MICROSTRAIN
Ref:A. Khorsand Zak et al. / Solid State Sciences 13 (2011) 251-256
Microstrain may also create peak broadening (analyzing the peak widths over a long range of 2theta using a Williamson-Hull plot can let you separate microstrain and crystallite size)
PREFERRED ORIENTATION (TEXTURE)
Preferred orientation of crystallites can create a systematic
variation in diffraction peak intensities.
DOI: 10.1038/srep03679
PREFERREDCRYSTALLOGRAPHIC ORIENTATION
AVAILABLE FREE SOFTWARE
GSAS- Rietveld refinement of crystal structures
FullProf- Rietveld refinement of crystal structures
Rietan- Rietveld refinement of crystal structures
PowderCell- crystal visualization and simulated
diffraction patterns
JCryst- stereograms
PANalytical HighScore Plus
FULLPROF- RIETVELD REFINEMENT OF CRYSTAL STRUCTURES
REITVELD REFINEMENT USING FULLPROF SOFTWARE
Necessary files: High quality PXRD pattern
.dat file.xy file .raw file
Structural model.cif (from database)
Step 1:Create a new folder and paste the .dat and .cif files in that folderStep2:In the FullProf window click on ‘WinPlotr’ option.
OPEN WINPLOTR
SELECT DATA FILE
SELECT BACKGROUND
SELECTION OF PEAKS
OPEN EDITOR OF PCR FILE
Click on <Ed PCR> followed by cif PCR.
Click on <X ray> , <Default Values>, write the space group with proper spacing
PROFILE FITTING BY USING PCR FILE
PROFILE FITTING
Red line => observed dataBlack line => Calculated pattern by the programme.Blue line => Difference pattern
AFTER PROFILE FITTING
REITVELD REFINEMENT
REITVELD REFINEMENT
REITVELD REFINEMENT
AFTER FITTING
DESCRIPTION OF THE .PCR FILE
Title (lines 1-3) COMM:Will use original, single phase format Job parameter flags (line 4) Job: Radiation type
0 X-rays1 Neutrons, CW-1 Neutrons, TOF2 Pattern calc (X-rays)3 Pattern calc (neutrons, CW)-3 Pattern calc (neutrons, TOF)
Npr: Default profile shape0 Gaussian1 Cauchy (Lorentzian)2 Modified 1 Lorentzian3 Modified 2 Lorentizian4 Tripled pseudo-Voigt5 pseudo-Voigt6 Pearson VII7 Thompson-Cox-Hastings8 Numerical profile9 TOF conv. pseudo-Voigt10 TOF, similar to 911 Split pseudo-Voigt12 conv. Pseudo-Voigt13 TOF Ikeda-Carpenter
Nph:Number of phases Nba: Background type 0 Refine with polynomial 1 Read from CODFIL.bac N >1Linear interpolation -1 Refine with Debye+polynomial -2 Treated iteratively with Fourier filtering -3 Read addition 6 additional polynomial coeffs. Nex:Number of regions to exclude Nsc:Number of user defined scattering factors Nor:Preferred orientation function type 0 Function No. 1 1 Function No. 2
Dum:Control of divergence 1 If some phases are treated in Profile Matching,
convergence criterion with stand. dev. not applied 2 Program stopped for local divergence: chi2(i-
cycle+1)>chi2(i-cycle) 3 Reflections near excluded regions excluded from
Bragg R-factor Iwg:Refinement weighting scheme 0 Standard least squares 1 Maximum likelihood 2 Unit weights Ilo: Lorentz and polarization corrections 0 Standard Debye-Scherrer or Bragg Brentano 1 Flat plate PSD geometry -1 Lorentz-polarization correction not performed 2 Transmission geometry 3 Special polarization correction
Ias: Reflections reordering 0 Reordering performed only at first cycle 1 Reordering at each cycle Res: Resolution function 0 Not given 1—4 For CW data, profile is Voigt function and different
functions available Ste: Number of data points reduction factor 1,2..NIf Ste>1, number of data points and therefore step size
reduced by factor Ste Nre: Number of constrained parameters Cry: Single crystal job 0 Only integrated intensity given, no profile parameters 1 Refinement with single crystal data or int. intensities 2 Montecarlo search for starting configuration, no least
squares 3 Simulated annealing optimization method
Uni:Scattering variable unit 0 2θ in degrees 1 TOF in sec 2 Energy in keV Cor:Intensity correction0 No correction is applied1 File with intensity corrections2 File with empirical function Opt:Calculation optimization0 General procedures used1 Optimizes calculations to proceed faster Aut: Automatic mode for refinement codes
numbering0 Codewords treated as usual.1 Codewords treated automatically by program
REFINEMENT OUTPUT CONTROLS (LINE 7)
Ipr: Profile integrated intensities 0 No action 1 Observed and calculated profiles in .out
file 2 Calculated profiles for each phase in
n.sub files 3 Like 2 but background added to each
profile Ppl: Types of calc output-I 0 No action 1 Line printer plot in .out file 2 Generates background file 3 Difference pattern included in .bac file
Ioc: Types of calc output-II 0 No action 1 List of observed and calculated
integrated intensities in .out file 2 Reflection from 2nd wavelength if
different Mat:Correlation matrix 0 No action 1 Correlation matrix written in .out file 2 Diagonal of LS matrix printed before
inversion at every cycle
Pcr: Update of .pcr 0 after refinement 1 .pcr re-written with updated parameters 2 New input file generated called .new Ls1: Types of calc output-III 0 No action 1 Reflection list before starting cycles
written in .out file Ls2: Types of calc output-IV 0 No action 1 Corrected data list written in .out file 4 Plot of diffraction pattern displayed on
the screen at each cycle
LS3:Types of calc output-V 0 No action 1 Merged reflection list written in .out file Prf: Output format of Rietveld plot file 0 1 For WinPLOTR 2 For IGOR 3 For KaleidaGraph and WinPLOTR 4 For Picsure, Xvgr
Ins: Data file format 0 Free format, 7 comments ok = 1 D1A/D2B, original Rietveld = 2 D1B old format = 3 ILL instruments D1B, D20 = 4 Brookhaven, pairs of lines with 10 items = -4 DBWS program = 5 GENERAL FORMAT for TWO AXIS = 6 D1A/D2B format prepared by SUM, ADDET
or MPDSUM = 7 From D4 or D20L = 8 DMC at Paul-Scherrer Inst. = 10 X, Y, sigma format = 11 Variable time XRD = 12 GSAS
Rpa:Output .rpa/.sav file = 0 = 1 Prepares output file CODFIL.rpa = 2 Prepares file CODFIL.sav Sym:Output .sym file = 0 = 1 Prepares CODFIL.sym Hkl: Output of reflection list = 0 No action = 1 Code, h, k, l, mult, d_hkl, 2, FWHM, I_obs,
I_calc, I_obs-calc = 2 h, k, l, mult, sinq/l, 2, FWHM, F2, s(F2) = 3 Real and imaginary parts of structure factors,
h, k, l, mult, F_real, F_imag, 2, intensity = 4 h, k, l, F2, (F2) = 5 h, k, l, mult, F_calc, T_hkl, d_hkl, Q_hkl
Fou:Output of CODEFIL.fou = 0 No action = 1 Cambridge format = 2 SHELXS format = 3 FOURIER format = 4 GFOURIER Sho:Reduced output during refinement = 0 = 1 Suppress out from each cycle, only last
printed
EXPERIMENTAL SET UP CONTROLS (LINE 8) Lamda1:wavelength 1 Lamda2:wavelength 2 Ratio:I2/I1 If <0, parameters U,V,W for l2 read
separately Bkpos: Origin of polynomial for background Wdt:Cut off for peak profile tails in FWHM
units ~4 for Gaussian ~20-30 for Lorentzian ~4—5 for TOF Cthm:Monochromator polarization correction
muR:Absorption correction m = effective absorption coeff. R= radius or thickness of sample AsyLim: Limit angle for asymmetry
correction Rpolarz:Polarization factor Iabscor:Absorption correction for TOF data = 1 Flat plate perp. to inc. beam = 2 Cylindrical
REFINEMENT CONTROLS (LINE 9) NCY:Number of refinement cycles Eps:Control of convergence precisionForced termination when
shifts < EPS x e.s.d R_at Relaxation factor of shifts of atomic parameters: coordinates, moments, occupancies, Uiso’s R_an Relaxation factor for shifts of anisotropic displacement
parameters R_pr: Relaxation factor of profile parameters, asymmetry,
overall displacement, cell constants, strains, size, propagation vectors, user-supplied parameters
R_gl: Relaxation factor of Global parameters, zero-shift, background, displacement and transparency
Thmin:Starting scattering variable value (2θ/TOF/Energy) Step:Step in scattering variable Thmax: Last value of scattering variable PSD: Incident beam angle Sent0: Maximum angle at which primary beam completely
enlightens sample
NUMBER OF REFINED PARAMETERS
Maxs: Number of refined parameters (one integer, one line)
REFINEMENT CONTROLS II (LINE 14, REFINABLE)
Zero:Zero point for T Sycos: Systematic shift with cosθ
dependence Sysin:Systematic 2 shift with sin2θ
dependence Lambda:Wavelength to be refined More: Flag to read micro-absorption
coefficients ≠ 0 Line 15 is read to define
microabsorption
JASON-HODGES FORMULATION FOR TOF DATA (LINE 16)
Zerot: Zero shift for thermal neutrons Dtt1t: Coeff. #1 for d-spacing calc Dtt2t: Coeff. #2 for d-spacing
calculation x-cross:Position of the center of the
crossover region Width:Width of crossover region
REFINEMENT PARAMETERS FOR EACH PHASE (LINE 19)
Nat: Number of atoms in asymmetric unit Dis: Number of distance constraints Mom:Number of angle constraints or number of magnetic
moment constraints Jbt: Structure factor model and refinement method = 0 Rietveld Method = 1 Rietveld Method but purely magnetic phases = -1 Like 1 but with extra parameters in spherical coordinates = 2 Profile matching mode with constant scale factor = -2 Like 2 but modulus instead of intensity given in .hkl file = 3 Profile matching with constant relative intensities = -3 Like 3 but modulus instead of intensity given in .hkl file = 4 Intensities of nuclear reflections are calculated from Rigid
body groups = 5 Intensities of magnetic reflections calculated from conical
magnetic structures in real space = 10 Phase can contain nuclear and magnetic contributions = 15 Phase is treated as commensurate modulated crystal
structure
Pr1, Pr2, Pr3: Preferred orientation in reciprocal
space for all three directions Irf: Method of reflection generation = 0 List of reflections for the phase
generated by space group = 1 h, k, l, mult read from .hkl file = 2 h, k, l, mult, intensity read from .hkl file = 3 h,k,l, mult, F_real, F_imag read
from .hkl file = 4 list of integrated intensities given as
observations
Isy: Symmetry operators reading control code = 0 Operators automatically generated from Space
Group = 1 Symmetry operators read below (use for
magnetism) = 2 Basis functions of irreducible representations of
propagation vector group instead of symmetry operators Str: Size-strain reading control = 0 Strain/size parameters correspond to selected
models = 1 Generalized formulation of strain used = 2 Generalized formulation of size used = -1 Options 1 and 2 simultaneously, size read before
strain = 3 Generalized formulation of size and strain
parameters Furth:Number of user defined parameters (only when
Jbt=4)
ATZ:Quantitative phase analysis coefficient ATZ = ZMwf2/t Z: Formula units per cell Mw: Molecular weight f: Site multiplicity t: Brindley coefficient for microabsorption Nvk: Number of propagation vectors Npr Specific profile function for the phase More: If not 0, then line 19-1 read
ATOMIC PARAMETERS (LINE 25) Atom:Atom name Typ:Atom type X, Y, Z:Coordinates Biso:Isotropic B factor Occ:Occupancy In/Fin:Ordinal number of first and last symmetry operator
applied to the atom (when users supply own list of reflections)
N_t: Atom type = 0 Isotropic atom = 2 Anisotropic atom = 4 Form-factor of atom is calculated Spc: Number of chemical species (For bond valence calcs.) betaij:6 numbers (i,j =1,2) for anisotropic factors (line
25b)
PROFILE SHAPE PARAMETERS Scale:Scale factor Shape 1:Profile shape parameter Bov:Overall isotropic B factor Str1, Str2, Str3:Strain parameters Strain Model: U,V,W:Half-width parameters X: Lorentzian isotropic strain param. Y: Lorentzian isotropic size param. GauSiz:Isotropic size parameter of Gaussian
character LorSiz:Anisotropic Lorentzian contribution of particle
size Size-Model:Size model selector
DATA RANGE PARAMETERS (LAST LINE)
2Th1/TOF1:First value for x-axis 2Th2/TOF2:Last value for x-axis