K2GeF6 compound crystalline structure analysis

• Main Author: Viktor Zavodyannyy
• Format: Article
• Language: English
• Published: PC Technology Center 2018-05-01
• Series: Tehnologìčnij Audit ta Rezervi Virobnictva
• Subjects: X-ray structural analysis; Bragg-Bertrand survey geometry; Rietveld method; crystal structure; K2GeF6 composition
• Online Access: http://journals.uran.ua/tarp/article/view/143747
• ISSN: 2226-3780; 2312-8372

The object of research is the crystal structure of the polymorphic modification of the K2GeF6 compound. One of the problem areas is the existence of a large number of diffraction spectra obtained with the Bragg-Bertrand survey geometry in the PDF-2 database for 2004. This paper proposes a structural model for the diffraction spectrum of the compound numbered 00-037-1154. The study used the PDF-2 database for 2004. As well as the program HiphScorePlus 3.0, which allows to refine the microstructural parameters of the structural model using the Rietveld method. As a result, it was obtained that this diffraction spectrum of the studied compound can correspond to the following structural model: • orthorhombic syngonies, Imma symmetry space group, lattice а=8.3327 А°, b=5.891212 A°, c=5.908473 A°; • the microstructural parameters of Ge 16j x/a=0.172086, y/b=0.353968, z/c=0.291034; • the fill factor of positions 0.25 K 16j x/a=0.316837, y/b=0.636701, z/c=0.134786; • fill factor of 0,5 F1 16j x/a=-0.087258, y/b=0.119218, z/c=0.783618; • fill factor of the positions 0.5 F2 16j x/a=0.406830, y/b=-0.603655, z/c=0.376365; • fill factor of positions 0.5 F3 8f x/a=0.581125, y/b=0, z/c=0; • fill factor of positions 1.0; • disagreement factor R = 8.65453 %.   Analyzing the obtained results, it is possible to assume that in addition to two known polymorphic modifications of the compound, namely, trigonal and hexagonal syngonies, there is a new polymorphic modification and has its own structural type. The correct system of points of 16j for atoms of germanium, potassium and fluorine is not completely filled. It is shown that the crystal structure of the compound is associated with its optical properties. In particular, crystals of trigonal and hexagonal systems have an absorption spectrum in the infrared region. The influence of the crystal structure on the scattering spectra of this compound has also been observed. There is also a splitting of radiation lines, which is closely related to the structure of the crystal lattice. Therefore, the study of this polymorphic modification of the K2GeF6 compound provides an opportunity to consider and study its optical properties in a new way, thanks to which it can be used as a phosphor for the commercial production of LEDs.