Method of X-Ray Diffraction Data Processing for Multiphase Materials with Low Phase Contents
Amorphous, glass, and glass-ceramic materials practically always include a significant number (more than eight) of crystalline phases, with the contents of the latter ranging from a few wt.% to several hundredths or tenths of wt.%. The study of such materials using the method of X-ray phase analysis faces difficulties, when determining the phase structure. In this work, we will develop a method for the analysis of the diffraction patterns of such materials, when diffraction patterns include X-ray lines, whose intensities are at the noise level. The identification of lines is based on the search for correlations between the experimental and test lines and the verification of the coincidence making use of statistical methods (computer statistics). The method is tested on the specimens of a-quartz, which are often used as standard ones, and applied to analyze lava-like fuel-containing materials from the destroyed Chornobyl NPP Unit 4. It is shown that the developed technique allows X-ray lines to be identified, if the contents of separate phases is not less than 0.1 wt.%. The method also significantly enhances a capability to determine the phase contents quantitatively on the basis of lines with low intensities.
R.V. Arutyunyan, L.A. Bolshov, A.A. Borovoi, E.P. Velikhov, A.A. Klyuchnikov. Nuclear Fuel in the "Shelter" Facility of the Chernobyl NPP (Nauka, 2010) (in Russian).
S.V. Gabielkov, A.V. Nosovskii, V.N. Shcherbin. Degradation model of lava-like fuel-containing materials in the "Shelter" facility. Probl. Bezpek. At. Elektrost. Chornobyl. 26, 75 (2016) (in Russian).
S.V. Gabielkov, I.V. Zhyganiuk, V.G. Kudlai, P.E. Parkhomchuk, S.A. Chikolovets. Crystallization of lava-like fuel-containing materials NBK-OU. Probl. Bezpek. At. Elektrost. Chornobyl. 32, 44 (2019) (in Ukrainian). https://doi.org/10.31717/1813-35184.108.40.206
Phase Identification from Powder Diffraction "Match!". Version 220.127.116.11, Crystal Impact, Bonn, Germany [http://www.crystalimpact.com].
S. Graˇzsulis, A. Merkys, A. Vaitkus, M. Okuliˇc-Kazarinas. Computing stoichiometric molecular composition from crystal structures. J. Appl. Crystallogr. 48, 85 (2015). https://doi.org/10.1107/S1600576714025904
A.D. Scorbun, M.I. Panasyuk. Resolution of low-intensity lines in gamma spectra. Probl. Bezpek. At. Elektrost. Chornobyl. 9, 125 (2008) (in Ukrainian).
D.S. Moore, G.P. McCabe, B.A. Craig. Introduction to the Practice of Statistics (Freeman, 2014) [ISBN: 1464158932].
F. Machatschki. Die kristallstruktur von tiefquarz SiO2 und aluminiumorthoarsenat AlAsO4. Z. Kristallogr. Krist. 94, 222 (1936). https://doi.org/10.1524/zkri.1918.104.22.168
P. Kroll, M. Milko. Theoretical investigation of the solid state reaction of silicon nitride and silicon dioxide forming silicon oxynitride (Si2N2O) under pressure. Z. Anorg. Allg. Chem. 629, 1737 (2003). https://doi.org/10.1002/zaac.200300122
D.J. Hudson. Statistics. Lectures on Elementary Statistics and Probability (CERN, 1964).
H. Tanizaki. On small sample properties of permutation tests: Independence test between two samples. Int. J. Pure Appl. Math. 13, 235 (2004) [ISSN: 1311-8080].