Related Experiment Video
Updated: Aug 16, 2026

X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects
Published on: June 8, 2016
Powder diffraction crystal structure analysis using derivative difference minimization: example of the potassium salt
Leonid A Solovyov1, A M Astachov, M S Molokeev
1Institute of Chemistry and Chemical Technology, 660049 Krasnoyarsk, Russia. leosol@icct.ru
Abstract:
The crystal structure of the potassium salt of 1-(tetrazol-5-yl)-2-nitroguanidine [K(C2H3N8O2)] was solved and refined from X-ray powder diffraction data by applying the derivative difference minimization (DDM) method. The compound is of interest as an energetic substance. The structure model was found from a Patterson search. The reflection intensities for the Patterson synthesis were derived from the powder profile by applying a newly developed DDM-based profile decomposition procedure. The use of the DDM method allowed successful location and unconstrained refinement of all the atomic positions, including those of three independent H atoms. The advantages of DDM in terms of the precision and reproducibility of the structural parameters are discussed in comparison to Rietveld refinement results. The failure to refine the H-atom positions by the Rietveld method was attributed to systematic errors associated with the background modelling, which are avoided by DDM.
Related Concept Videos
Determination of Crystal Structures
X-ray Diffraction of Biological Samples
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
Imperfections in Crystal Structure: Stoichiometric Point Defects

