Structural phase transition in elpasolite-like (NH4)2KWO3F3

Flerov, I. N.; Горев, М. В.; Fokina, V. D.; Bovina, A. F.; Мolokeev, Maxim S.; Boĭko, Yu. V.; Voronov, V. N.; Kocharova, A. G.

doi:10.1134/s1063783406010215

Cited by 12 publications

(14 citation statements)

References 13 publications

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“…Probably ordering of WO 3 F 3 3-ions provides a possibility to form W-O· · ·H-N hydrogen bonds. Structural data [5] provide N-H· · ·O bonds lengths equal to 2.28 to 2.88Å, that agrees with typical 2.88Å value [6]. Fig.…”

Section: Anionssupporting

confidence: 56%

“…X-ray analysis [4][5] confirmed its composition Powder of Cs 2 NH 4 WO 3 F 3 was obtained by spontaneous crystallization from water solution according to:…”

Section: Methodsmentioning

confidence: 99%

“…Phase transition in A2K crystal was found at 235 K according to calorimetry data [5]. This transition shows in the 750-1000 cm -1 range in a splitting of 917 cm -1 line into doublet, yet its components stay wide (Fig.…”

Section: Anionsmentioning

confidence: 99%

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Raman Spectra and Ordering Processes in Alcaline-Tungsten Oxyfluorides

et al. 2007

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Raman spectra of perovskite-like (NH 4 ) 3 WO 3 F 3 (assigned below as A3), (NH 4 ) 2 KWO 3 F 3 (A2K), Cs 2 (NH 4 )WO 3 F 3 (C2A) oxyfluorides are obtained in a wide temperature range including transition points for A3 and A2 K crystals. Transition anomalies are found and analyzed. Transformation in A3 crystal is shown to be bound with octahedron groups ordering and H-bond formation, that is accompanied by cell volume multiplication, hardening and formation of complex discrete low frequency lattice spectrum. Same cell doubling was found in A2 K crystal, but without lattice ordering. C2A lattice stays disordered down to 15 K.

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Section: Anionssupporting

confidence: 56%

“…X-ray analysis [4][5] confirmed its composition Powder of Cs 2 NH 4 WO 3 F 3 was obtained by spontaneous crystallization from water solution according to:…”

Section: Methodsmentioning

confidence: 99%

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Raman Spectra and Ordering Processes in Alcaline-Tungsten Oxyfluorides

et al. 2007

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“…As a rule such PT are displacive type. Relatively recent research of ammonium elpasolites (NH 4 ) 2 KGaF 6 [3] and (NH 4 ) 2 KWO 3 F 3 [4], solid solutions of ammonium cryolites (NH 4 ) 3 Ga 1−x Sc x F 6 [5][6][7], oxyfluorides (NH 4 ) 3 WO 3 F 3 , (NH 4 ) 3 TiOF 5 [8,9] showed that at PT the ordering of atoms and groups including octahedral groups occur, i.e. PT is order-disorder type.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental [3][4][5][6][7][8][9] and theoretical investigations [9][10][11] of A 2 BB ′ X 6 crystals prove that order parameters (OP) at PT, which are associated to ordering of X anions, are transformed by IR of center, point Γ, and boundary, point X, of Brillouin zone (Tab. 1) of space group F m3m (designation of IR are in accordance with reference books [15,16]).…”

Section: Introductionmentioning

confidence: 99%

Phases of Anionic Ordering in Elpasolite Structures (Ordered Perovskites

Sevryukov¹,

Misyul²,

Севрюков³

et al. 2016

J. Sib. Fed. Univ., Math. phys.

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Vibrational spectroscopy of alkaline tungsten oxyfluoride crystals: structure, lattice dynamics, ordering processes, and phase transitions

Vtyurin

Gerasimova

Крылов

et al. 2010

J Raman Spectroscopy

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Raman scattering (RS) and infrared absorption (IR) of ammonium oxyfluoride crystals (NH 4 ) 3 WO 3 F 3 , (NH 4 ) 2 KWO 3 F 3 , and Cs 2 (NH 4 )WO 3 F 3 are compared. Conformation of the WO 3 F 3 octahedral groups has been established; anomalies have been found close to the transition temperatures in the internal vibrational regions of ammonium and WO 3 F 3 groups. The phase transition in (NH 4 ) 3 WO 3 F 3 is associated mostly with the ordering of octahedral groups and formation of W-O· · ·H-N hydrogen bonds.In (NH 4 ) 2 KWO 3 F 3 crystal, the transition is not related to the ordering processes; Cs 2 (NH 4 )WO 3 F 3 retains its disordered structure down to 10 K.

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Structural phase transition in elpasolite-like (NH4)2KWO3F3

Cited by 12 publications

References 13 publications

Raman Spectra and Ordering Processes in Alcaline-Tungsten Oxyfluorides

Raman Spectra and Ordering Processes in Alcaline-Tungsten Oxyfluorides

Phases of Anionic Ordering in Elpasolite Structures (Ordered Perovskites

Vibrational spectroscopy of alkaline tungsten oxyfluoride crystals: structure, lattice dynamics, ordering processes, and phase transitions

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