Ab‐initio Structure Determination of the New Ion Conductor K₂Al₂O₃F₂ from Powder Diffraction Data

Abstract

The crystal structure of K 2 Al 2 O 3 F 2, prepared at 800°C by ceramic methods, was determined from conventional laboratory X-ray powder diffraction data. The compound crystallizes in the monoclinic space group C2/m (No. 12) with a = 11.21675(8), b = 8.16351 (6), c = 6.12301(5) Å β = 88.8108(6)°and Z = 4. Unit cell and space group suggestions were found by using the TOPAS program. Starting positional parameters for potassium and aluminum atoms were obtained from 548 reflections by the methods implemented in the FOX program. Oxygen and fluorine atom positions were determined by structural con-* Univ. Prof. Dr. F. Kubel Fax: +43-1-58801-17199 E-Mail: Frank.Kubel@tuwien.ac.at [a]

Oxo- and Oxofluoroaluminates in the RbF–Al2O3 System: Synthesis and Structural Characterization

“…Both the Dicvol 41 A subsequent ICSD database research using similar cell parameters and chemistry requirements (only alkali metals, aluminum, and fluorine) enabled us to find a compound with a similar indexation: K 2 Al 2 O 3 F 2 (ICSD 421736). 10 This compound crystallizes in the C2/m space group. On the basis of this starting model, a Rietveld refinement of X-ray diffraction powder data was performed by replacing the potassium with rubidium atoms on the 4i sites and using the cell parameters previously defined.…”

“…A subsequent ICSD database research using similar cell parameters and chemistry requirements (only alkali metals, aluminum, and fluorine) enabled us to find a compound with a similar indexation: K 2 Al 2 O 3 F 2 (ICSD 421736) . This compound crystallizes in the C 2/ m space group.…”

“…A new potassium oxofluoroaluminate, K 2 Al 2 O 3 F 2 , was confirmed in the solid state, and a crystal structure of its powder has been reported. 10,11 This type of structure consist of oxygen-connected tetrahedra, where three oxygens and one fluorine are bound to aluminum. To the best of our knowledge only one oxofluoroaluminate structure has been reported, but without an alkali metal.…”

Effect of the Alkaline Metal Cations on the Electrical Conductivity of the Molten Cryolites (K3AlF6, Rb3AlF6, and Cs3AlF6)

“…The situation is different when we substitute sodium in cryolite for potassium or rubidium. Kubel et al 19 and S ̌imko et al 20 recently confirmed the existence of the potassium and rubidium oxyfluoroaluminate compounds in the solid state, M 2 Al 2 O 3 F 2 , (M = K, Rb, and Cs), and the crystal structure of both compounds has been reported. Both compounds consist of individual layers of oxygen-connected (AlO 3 F) tetrahedral groups with the fluorine atoms separating the layers.…”

An unprecedented planar π-conjugated [B2P5]5− group with ultra-large birefringence and nonlinearity: an ab initio study

“…Secondly, removing the A-site cations from crystal structures has become a viable proposition, Be 2 BO 3 F is derived from the notable KBe 2 BO 3 F 2 obtained through experiment, and Be 2 BO 3 F owns smaller interlayer space. 26 Besides, there are typical models which can be used for theoretical design, BaBPO 5 BPO 4 , [27][28] SrB 4 O 7 B 2 O 3 , 29-30 K 2 Al 2 O 3 F 2 AlOF, 19,31 etc. In the fluorooxoborate system, many new quaternary materials only with [BO x F 4x ] anionic units were synthesized, NaBOF 2 , 13 KB 2 O 3 F, 32 RbBOF 2 , 33 BaBOF 3 , 15 SnB 2 O 3 F 2 9 , PbB 2 O 3 F 2 , 9 with simple component ratio.…”