International
Tables for
Crystallography
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk

International Tables for Crystallography (2018). Vol. H, ch. 3.10, pp. 382-383

Section 3.10.9. Increasing amorphous content series within an inorganic crystalline phase matrix

L. León-Reina,a A. Cuesta,b M. García-Maté,c,d G. Álvarez-Pinazo,c,d I. Santacruz,c O. Vallcorba,b A. G. De la Torrec and M. A. G. Arandab,c*

aServicios Centrales de Apoyo a la Investigación, Universidad de Málaga, 29071 Málaga, Spain,bALBA Synchrotron, Carrer de la Llum 2–26, Cerdanyola, 08290 Barcelona, Spain,cDepartamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga, Spain, and dX-Ray Data Services S.L., Edificio de institutos universitarios, c/ Severo Ochoa 4, Parque tecnológico de Andalucía, 29590 Málaga, Spain
Correspondence e-mail:  g_aranda@uma.es

3.10.9. Increasing amorphous content series within an inorganic crystalline phase matrix

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Fig. 3.10.8[link] shows Mo Kα1 (transmission), Cu Kα1 (reflection) and SXRPD (transmission) raw patterns for the mixtures with increasing amounts of glass. It is important to highlight that the increase in the background due to the glass is very modest even for ∼32 wt% of glass. Table 3.10.4[link] shows the RQPA of these mixtures, prepared with C, Z and an increasing amount of Gl, for the three radiations. The glass-free sample may contain amorphous material from the employed phases. Hence, we used the SXRPD data to calculate a correction factor for quartz to yield zero amorphous content for the glass-free sample (León-Reina et al., 2016[link]).

Table 3.10.4| top | pdf |
Rietveld quantitative phase analyses of the CQZ_xGl mixture, where quartz (Q) is the internal standard, to derive amorphous content (am), obtained from SXRPD, Mo Kα1 and Cu Kα1 patterns

Absolute values of the Kullback–Liebler distance (AKLD) for each mixture and the KLD value for the amorphous content are also included. Trm, transmission; rfl, reflection.

MixtureWeighedSynchrotron trm
C wt%Z wt%Gl wt%C wt%Z wt%Am wt%AKLD sumAm KLD
CZQ_0Gl 50.01 49.99 0.00 49.9 (1) 49.6 (1) 0.4 (1) 0.0050
CZQ_2Gl 48.98 48.96 2.05 49.7 (1) 49.0 (1) 1.3 (1) 0.0169 0.009
CZQ_4Gl 47.93 47.91 4.17 47.9 (1) 47.6 (1) 4.5 (1) 0.0066 −0.003
CZQ_8Gl 46.00 46.00 7.99 46.6 (1) 45.9 (1) 7.5 (1) 0.0120 0.005
CZQ_16Gl 41.99 41.99 16.01 42.0 (1) 41.6 (1) 16.4 (1) 0.0079 −0.004
CZQ_32Gl 34.00 34.00 31.99 34.0( 1) 33.7 (1) 32.3 (1) 0.0061 −0.003

MixtureMo Kα1 trmCu Kα1 rfl
C wt%Z wt%Am wt%AKLD sumAm KLDC wt%Z wt%Am wt%AKLD sumAm KLD
CZQ_0Gl 47.5 (1) 49.0 (1) 3.5 (1) 0.0358 47.2 (1) 40.8 (1) 12.0 (1) 0.1305
CZQ_2Gl 45.9 (1) 47.7 (1) 6.4 (1) 0.0679 −0.023 47.4 (1) 40.6 (1) 12.0 (1) 0.1440 −0.036
CZQ_4Gl 46.5 (1) 47.0 (1) 6.5 (1) 0.0422 −0.019 45.8 (1) 39.7 (1) 14.6 (1) 0.1641 −0.052
CZQ_8Gl 42.6 (1) 44.8 (1) 12.5 (1) 0.0832 −0.036 45.3 (1) 38.1 (1) 16.6 (1) 0.1522 −0.058
CZQ_16Gl 39.9 (1) 41.7 (1) 18.5 (1) 0.0475 −0.023 40.9 (1) 35.8 (1) 23.4 (1) 0.1388 −0.061
CZQ_32Gl 31.7 (1) 33.1 (1) 35.2 (1) 0.0635 −0.031 32.2 (1) 28.7 (1) 39.1 (1) 0.1403 −0.064
[Figure 3.10.8]

Figure 3.10.8 | top | pdf |

Raw powder patterns for the amorphous-material-containing series composed of a constant matrix of calcite and zincite, and increasing amounts of ground glass. Quartz was added as internal standard. (a) Mo Kα1, (b) Cu Kα1 and (c) SXRPD radiations. The intensities of the patterns have been rescaled to highlight the contributions of the glass to the background.

The linear fit to the amorphous content values obtained using SXRPD was very good, R2 = 0.998, with the slope being 1.00 within the errors (see Fig. 3.10.7[link]c). This plot also shows the quantified amorphous contents, in weight percentage, as a function of the amount of added ground glass, measured with Mo Kα1 and Cu Kα1 radiations. Open symbols indicate the derived amorphous contents obtained with the internal-standard method in the mixture without any added glass, CZQ_0Gl. Both R2 values are quite close to 1.00, showing the consistency of the internal-standard methodology. However, the slope values were 0.98 and 0.89 for Mo Kα1 and Cu Kα1 radiations, respectively. Furthermore, the y-intercept values were 3.7 and 10.0 for Mo Kα1 and Cu Kα1 radiations, respectively. Again, slope values close to 1.0 and y intercepts close to 0.0 mirror accurate analyses. It must also be pointed out that for the Mo Kα1 analyses the value from the measurement of the Gl-free sample, 3.5 wt%, matches the value from the y intercept of the plot, 3.7 wt%, very well. Meanwhile, there is a much larger discrepancy for the similar Cu-based analyses, 12.0 and 10.0 wt%, respectively, which is quite far from zero. Hence, it is concluded that the amorphous contents derived from Mo Kα1 data are more accurate than those derived from Cu Kα1 data. However, it is not possible to reliably quantify amorphous contents below ∼8–10 wt% from Mo Kα1 and Cu Kα1 diffraction data (see Table 3.10.4[link]) with the internal-standard method.

On the contrary, SXRPD reliably allows quantification of amorphous contents down to ∼2 wt% for this relatively simple mixture. In addition, the AKLD and the KLD values reported in Table 3.10.4[link] demonstrate that the synchrotron analyses are indeed much better than the laboratory analyses.

References

León-Reina, L., García-Maté, M., Álvarez-Pinazo, G., Santacruz, I., Vallcorba, O., De la Torre, A. G. & Aranda, M. A. G. (2016). Accuracy in Rietveld quantitative phase analysis: a comparative study of strictly monochromatic Mo and Cu radiations. J. Appl. Cryst. 49, 722–735.Google Scholar








































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