Aplicacoes Do Metodo de Rietveld-07

Roberto R. de Avillez 2004 1

Mtodo de Rietveld-Quantitativo

tempoVMZ

mS

ppp

pp ..

pkpkpi*kpkp

kkp

ppbici A.P)22(F.F.Lsyy +=

Intensidade Calculada de um material contendo muitas fases:Howard e Hill, Howard e Bish.

Fator de Escala proporcional massa

de cada fase e ao tempo


CeO2 + ZrO2

Sonia Letichevsky, Marco A. Fraga, Lucia G. Appel e M. Isabel Pais da Silva

Coprecipitation of mixed oxides and solid solutions from Ce(NO3)3 e (NH4)2Ce(NO3)6

XDR: CuK, 40kV, 30mA, graphite monochromator, Bragg-Brentano geometry.


CeO2+ZrO2+MgO* (internal standard)


CeO2*+ZrO2+MgO*


CeO2*(cs)+ZrO2+MgO*


CeO2*(cs)+ZrO2*(cs)+MgO*


CeO2*(cs)+ZrO2*(cs)+MgO*


Results: CeO2+ZrO2

Rwp= 31,30

25,5

74,5

%Mass

GOF= 1,10Rexp= 28,46Absorption= 499,9

6,15,259ZrO2

15,15,412CeO2

Crystallite size (nm)

Lattice Parameter (Angstron)

Phase


(Ce,Zr)O2 + MgO


Resultados do Ajuste: (Ce,Zr)O2

GOF= 1,10Rwp= 30,49Rexp= 27,59Absoro= 498,7

-0-ZrO2

6,81005,349(Ce,Zr)O2

Tamanho do Cristalito

(nm)

%MassaParmetro da rede

cristalina (Angstron)

Fase

Ce sublattice occupation: 0,74 Ce + 0,26 Zr


Quantitative analysis of amorphous phase

Rafael Cardoso, Maria Cecilia de S. Nobrega

Porcelains for dental prostheses

XDR: CuK, 40 kV, 30 mA, graphite monochromator


Rietveld Method-Internal standard

mmm ps =+

1=+ ca ww

( )( )pp

cc

s

pc ZMVS

ZMVSmm

w =

Sample with amorphous + crystalline materials

Initial mass of the sample: ms

Internal standard mass, mp


Dental porcelain


Quantitative analysis of leucite and amorphous

(73,7)0,1445Original sample

(amorphous)

26,340,95LeuciteK2O.Al2O3.4SiO2

59,050,0263Al2O3

%mass, in the original sample

%mass, determined

by XDR

Mass, gPhase


Lattice parameter changes of Zeolites

Bojan Marinkovic, Paula M. Jardim, Fernando C. Rizzo Assuno, Alvaro Saavedra, Lam Y. Lau, Michael Knapp e Carsten Bhtz.

The influence of the temperature on the crystal lattice of ZSM-5 zeolite.

DRX: Luz Sincrotron, HAZYLAB, = 0.9088 A, Debye-Scherrer.


Zeolite Structure


c

a

b

Estrutura cristalina da ZSM-5

ZSM-5 Crystalline Structure


ZSM-5 Results


4.4 4.6 4.8 5.0 5.2 5.4 5.610000

20000

30000

40000

50000

Cou

nts

2

ZSM-5

40oC 80oC 120oC 160oC 320oC

13.0 13.2 13.4 13.6 13.8 14.0 14.2 14.4 14.6 14.8 15.010000

20000

Cou

nts

2

ZSM-5

40oC 80oC 120oC 160oC 320oC

1 23

45

6

ZSM-5: XRD as a function of the temperature


Negative thermal expansion

0 200 400 600 800 10005260

5280

5300

5320

5340

5360

5380

5400

aps o resfriamento

volu

me

da c

lul

a un

itria

(A3 )

Temperatura (oC)

Unit cell volume as a function of temperature


Crystallite size distribution

Bojan Marinkovic, Alvaro Saavedra, Fernando C. Rizzo Assuno

Crystallite size distribution in a mixture of Bohemite, prepared by CENPES-PETROBRAS.

Materials Research-Revista Ibero Americana de Materiais, So Carlos, 4, 1-6 (2001).

XDR: CuK, graphite monochromator, Bragg-Brentano geometry


Warren-Averbach method

Advantages Separation of the contributions from the

crystallite size and deformation (distortion) Determination of the crystallite size

distribution Difficulties

Decomposition of the peak in Fourier series Requires the deconvolution of the equipment

and sample effects Requires a standard sample


Results for the Crystallite Size Distributions

Warren-Averbach Balzar Enzo et al.Sample Dv Ds 1/2 Dv Ds 1/2 Dv Ds 1/2 80 53 43 0.0011 61 63 0.0165 61 51 0.0018 200 143 103 0.0005 242 125 0.0017 245 125 0.0002Mixture 106 64 0.0008 129 64 0.0035 128 78 0.0005

Mixture is a 50 w% of each nominal sample.Crystalite sizes are in ngstrons.

1/2 is calculated at Dv/2.


Geometria associada ao feixe de Raios-X

Colimador de Raios-X

Aplicacoes Do Metodo de Rietveld-07

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