Schwingungsspektren und Kraftkonstanten der Elpasolithe Cs₂KMF₆ (M = Sc, Y, La, Gd, Yb)

Abstract

Die Schwingungsspektren der Elpasolithe Cs2KMF6 (M = Sc, Y, La, Gd, Yb) wurden aufgenommen und einschließlich der Gitterschwingungen zugeordnet. Die so erhaltenen Frequenzwerte wurden zur Berechnung von Kraftkonstanten nach einem modifizierten Valenzkraftfeld benutzt. Der Gang der Valenzkraftkonstanten wird diskutiert.

Raman Spectroscopic and Theoretical Study of Scandium Fluoride and Oxyfluoride Anions in Molten FLiNaK

“…It is well-known that group 3 fluorometallates such as ScF 6 3– can be readily synthesized via the reaction of corresponding metal fluorides in excess HF and NH 4 F solutions, and the coordination structures of solid-state fluorometallates are therefore well characterized using a series of spectroscopic methods. , In addition to the aqueous medium, molten fluoride such as FLiNaK is also a kind of appropriate medium that can be employed for the synthesis of group 3 fluorometallates due to the presence of free F – anions. , By varying the ratio of MF 3 and FLiNaK, it is possible to probe the coordination structures of binary fluorometallates that are not isolable in solid state, which not only provide a unique opportunity for a comprehensive understanding of the coordination chemistry of group 3 metal fluorides but also help solve the technical problems such as those involved in the manufacture of aluminum–scandium master alloy, , which is related to the speciation of metal fluoride in a molten salt environment.…”

Structural transformations in a single‐crystal Rb2NaYF6: Raman scattering study

“…Site symmetry of YF ions coincides with the free ion symmetry. Symmetry and frequencies of the free ion vibrations are ν 1 ( A 1 g ) – 476 cm − 1 , ν 2 ( E g ) – 382 cm − 1 , ν 3 ( F 1 u ) – 160 cm −1 , ν 4 ( F 1 u ) – 200 cm −1 , ν 5 ( F 2 g ) – 194 cm −1 , ν 6 ( F 2 u ) – wavenumber unknown . We might expect the splitting of the ν 2 ( E g ) and ν 5 ( F 2 g ) degenerate modes in the probable distorted phase and soft modes recovering below the transition from the cubic to this second phase.…”

“…Totally symmetrical mode is underlined. Table shows experimental band positions for Rb 2 NaYF 6 and Cs 2 KYF 6 cubic phase . Natural positions of these bands for these crystals are slightly different.…”

“…Symmetry and frequencies of the free ion vibrations are n 1 (A 1g ) -476 cm À 1 , n 2 (E g ) -382 cm À 1 , n 3 (F 1u ) -160 cm À1 , n 4 (F 1u ) -200 cm À1 , n 5 (F 2g ) -194 cm À1 , n 6 (F 2u )wavenumber unknown. [31,32] We might expect the splitting of the n 2 (E g ) and n 5 (F 2g ) degenerate modes in the probable distorted phase and soft modes recovering below the transition from the cubic to this second phase. Lines at 493, 385 and 209 cm À1 (at 295 K) correspond to internal YF 3À 6 modes: n 1 , n 2 and n 5 , respectively.…”

Gibt es „Wolframylgruppierungen”︁? Über Perowskitphasen im System Ba2Y0,67UO6Ba2CaWO6

“…Werden fur geordnete Perowskite vom Typ BaZB1'Mv1O6 (I) und B a z B~~~7 -Oo,33MV10, (11) -In den Priiparaten mit x = 0,25-0,05 wird keine temperaturabhangige, durch Fehlstellenordnimg liervorgerufene Polymorphie beobachtet. Die Gittersyinmetrie ist fur x = 0,25 rhombjsch mit der einfachen Elementarzelle.…”