Potassium Heptafluorotantalate

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Crystal structure
Crystal structure of potassium heptafluorotantalate
__ K +      __ Ta 5+      __ F -
General
Surname Potassium Heptafluorotantalate
other names
  • Dipotassium heptafluorotantalate
  • Potassium Heptafluorotantalate (V)
  • Potassium Heptafluoridotantalate (V)
Ratio formula K 2 [TaF 7 ]
Brief description

white solid

External identifiers / databases
CAS number 16924-00-8
EC number 240-986-1
ECHA InfoCard 100.037.245
PubChem 28146
Wikidata Q7234706
properties
Molar mass 392.13 g mol −1
Physical state

firmly

density

4.11 g cm −3

Melting point

720 ° C

solubility

sparingly soluble in water (5 g l −1 at 15 ° C)

safety instructions
GHS labeling of hazardous substances
06 - Toxic or very toxic

danger

H and P phrases H: 301-331
P: 261-301 + 310-311
Toxicological data

110 mg kg −1 ( LD 50ratoral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Potassium heptafluorotantalate , according to IUPAC more precisely potassium heptafluoridotantalate (V), is an inorganic chemical compound of potassium from the group of fluoridotantalates.

Extraction and presentation

Potassium heptafluorotantalate can be obtained by reacting tantalum (V) oxide with hydrofluoric acid and potassium hydrogen difluoride .

properties

Potassium heptafluorotantalate is a white solid that is in the form of shiny, thin, short needles. It can easily be recrystallized from hydrofluoric acid. The compound has an orthorhombic crystal structure above 200 ° C with the space group Pmma (space group no. 51) . Otherwise a monoclinic crystal structure with the space group P 2 1 / c (No. 14) . Template: room group / 51Template: room group / 14

use

Potassium heptafluorotantalate is used for the electrochemical synthesis of tantalum diboride TaB 2 . It is also used to produce tantalum by reducing it with sodium . In a similar way, Jöns Jakob Berzelius first produced tantalum in 1825 , using potassium instead of sodium. K 2 [TaF 7 ] doped with Mn 4+ has been proposed as a luminescent material for warm white LEDs , since it exhibits intense narrow-band red luminescence under UV or blue excitation .

Individual evidence

  1. a b c d e f g Data sheet Potassium heptafluorotantalate (V), 99% from Sigma-Aldrich , accessed on October 15, 2013 ( PDF ).
  2. a b c Anatoly Agulyansky: Chemistry of Tantalum and Niobium Fluoride Compounds . Elsevier, 2004, ISBN 0-08-052902-X , pp. 7, 64 ( limited preview in Google Book search).
  3. a b c Georg Brauer , with the assistance of Marianne Baudler a . a. (Ed.): Handbook of Preparative Inorganic Chemistry . 3rd, revised edition. tape I . Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , pp. 263 .
  4. Roger Blachnik (Ed.): Paperback for chemists and physicists . Volume III: Elements, Inorganic Compounds and Materials, Minerals . founded by Jean d'Ans, Ellen Lax. 4th, revised and revised edition. Springer, Berlin 1998, ISBN 3-540-60035-3 , pp. 524 ( limited preview in Google Book search).
  5. CC Torardi, LH Brixner, G. Blasse: Structure and luminescence of K 2 TaF 7 and K 2 NbF 7 . In: Journal of Solid State Chemistry . 67, 1987, pp. 21-25, doi : 10.1016 / 0022-4596 (87) 90333-1 .
  6. Erwin Riedel, Christoph Janiak: Inorganic Chemistry . Walter de Gruyter, 2011, ISBN 3-11-022567-0 , p. 798 ( limited preview in Google Book search).
  7. Thomas Jansen, Florian Baur, Thomas Jüstel: Red emitting K2NbF7: Mn4 + and K2TaF7: Mn4 + for warm-white LED applications . In: Journal of Luminescence . tape 192 , p. 644–652 , doi : 10.1016 / j.jlumin.2017.07.061 ( elsevier.com [accessed October 12, 2017]).