The percentage crystallinity and amorphous content in a sample can be determined by Rietveld refinement on XRD data. The powdered specimen (preferably with mean particle size of less than 50 microns) is mixed with an internal standard and analyzed through XRD. The XRD dats is further processed through a Rietveld refinement software. TOPAS is a licensed software which is sold by Bruker. Else you can use GSAS-EXPGUI which is a freeware but not as efficient as TOPAS or any other licensed software. For further details, you may refer to any of my research articles on glass-ceramics published after 2009.

The percentage crystallinity and amorphous content in a sample can be determined by Rietveld refinement on XRD data. The powdered specimen (preferably with mean particle size of less than 50 microns) is mixed with an internal standard and analyzed through XRD. The XRD dats is further processed through a Rietveld refinement software. TOPAS is a licensed software which is sold by Bruker. Else you can use GSAS-EXPGUI which is a freeware but not as efficient as TOPAS or any other licensed software. For further details, you may refer to any of my research articles on glass-ceramics published after 2009.

Dear Dr. Morteza Tahmasebi Yamchelou ,

a common measurement of amorphous structure involves the analysis of the glass transition by DSC. It is important to examine both the size of the transition in heat flow or heat capacity units and the temperature (Tg) at which it occurs. The size of the transition provides quantitative information about the amount of amorphous structure in the sample, and the temperature identifies the point where there is a dramatic change in physical properties. Below the glass transition temperature there is limited molecular mobility; above Tg there is high mobility, which results in much lower viscosity and potentially much greater chemical interaction between components.

An alternative method for quantifying the amorphous content involves the measurement of crystallization. All compounds exhibit a known heat of crystallization (ΔHc) and the value can be calculated or sometimes directly measured. The ratio of a measured ΔHc to its literature value can be used to calculate the amorphous content of the sample.

A final technique to measure amorphous content involves solution calorimetry (SolCal), which is an alternative to heat flow microcalorimetry in the assessment of amorphicity. SolCal works by dissolving the solid material in a solvent and measuring the temperature rise or fall in the solvent as a result of dissolution. Since amorphous and crystalline materials will have a different heat of solution, SolCal can be used to quantify the amount of amorphous material in a mixture of the two.

For details, please see the source of these info at:

http://www.tainstruments.com/pdf/literature/TA340%20Amorphous%20Content%20in%20Pharmaceuticals%20by%20MDSC%20MC%20DVS.pdf

Also these links could be useful for answer to your question:

- http://www.stk-online.ch/zurich/giron.pdf

- http://www.icdd.com/assets/ppxrd/presentations/13/PPXRD-13-Dinnebier-WS.pdf

- https://link.springer.com/article/10.1007/s13346-018-0519-3

Best regards, Pierluigi Traverso

Morteza.... When we do not have a direct measure of a component, we refer to the measurement of the other components and find our component of interest by difference. I agree with Mathias in doing your own calibration plot for the standard additions of the 2 or 3 levels of the crystalline component to determine the crystalline content in the sample. The remaining will be the amorphous component content... Good luck

It is difficult to have a value of amorphous content of clay samples. It is generally made available by following the chemical method of Jackson (1979).

Jackson, M.L., 1979. Soil Chemical Analysis, Advanced Course, 2nd edn. University of Wisconsin, Madison, WI, USA, 11th Printing, Published by the author, pp. 895.

Ashutosh Goel Pierluigi Traverso Mathias H. Köster

Thank you all for your precious feedback. Highly appreciated

Clay turns into "amorphous" after losing crystalline (bonded) water, which has been well studied and reported in the literature. It is not unreasonable to consider nearly all converted into "amorphous" at some elevated temperature range. But if you heat the clay too high, SiO2 and mullite phases start to grow from the "amorphous" phase. If i remember correctly, it is termed silica liberation.... Hope it helps.

Dear Hong Li

Thanks for your comment. You are right, but mullite and spinel phases forms at temperatures above 850 C. I treat my samples below 600 C.

Best regards,

Morteza

I suggest that you check also this RG discussion: https://www.researchgate.net/post/Could_anyone_explain_how_the_amorphous_content_of_a_material_is_analyzed_using_the_internal_standard_method_by_XRD

Carlos Araújo Queiroz

Thanks for sharing the link

In materials science, normally, the sample amorphous content is determined from the XRD pattern by the amorphicity index, which is defined as:

Ia (%) = (Aa / At) * 100 = (Aa / Ac + Aa) * 100,

where Aa represents the area of ​​the amorphous phase, Ac is the area of ​​the crystalline phases and At = Aa + Ac the total area under the X-ray diffraction pattern. The crystallinity index is similarly defined:

Ic (%) = (Ac / At) * 100 = (Ac / Ac + Aa) * 100,

It is evident that Ia + Ic = 1, and that once one of the two indices is determined, the other is determined directly from this equation.

Obviously, it is inferred from the foregoing that it is required to make the X-ray diffraction test of the sample. For this purpose, as others colleages have suggested, there are different professional software that allow you to make the task, by estimating the area of amorphous phase and the area of crystalline phase. The MicrocalOrigin software has too the option of determining areas, so you can use it to determine the area under the peaks of the XRD pattern and the total area of ​​the pattern, from which you can calculate the crystallinity index and by the equation Ia + Ic = 1 determine the index of amorphicity, as well as determine the uncertainties in their measurements.

There is a formula to calculate crystallinity index with the help of XRD patterns. In this formula, we use the intensity of crystalline and amorphous character of the samples. I agree with mr. Jesús Eleuterio Hernández-Ruíz.