Strontium fluoride
Cubic
- Strontium (II ) fluoride
- Strontiumdifluorid
Colorless solid
Fixed
4.24 g · cm -3
1473 ° C
2489 ° C
Very poor in water ( 0.12 g · l-1 at 25 ° C)
1.4380
Attention
10600 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search is not possible
Strontium fluoride ( strontium (II ) fluoride ), the fluoride of the alkaline earth metal is strontium. It is a white, crystalline, brittle solid which is liquid at 1473 ° C and 2489 ° C finally evaporated.
Occurrence
The only known naturally occurring compound is the 2009 recognized as a mineral Strontiofluorit, which so far only at its type locality Koashva in the Russian Chibinen ( Kola Peninsula ) was found.
Representation
Strontium fluoride can be prepared by the reaction of strontium chloride ( SrCl 2 ) with fluorine.
Alternatively, the extraction is carried out by reaction of hydrofluoric acid with strontium carbonate ( SrCO 3 ).
Properties
The solid crystallizes in the cubic crystal system in the fluorite structure. The lattice parameter of a = 579.96 pm, the refractive index of the crystals is 1.439 at 580 nm in the vapor phase of the bond angles between the F- Sr -F is about 120 °, which is an exception to VSEPR model which predict a linear structure would. It calculations were used, who want to show that influences of the shell, which is located directly below the valence shell cause this effect. Another guess is that the polarization of the electron core of the strontium atom caused an approximately tetrahedral charge distribution, which leads interacts with the Sr -F bond and so to adjust this angle.
Strontium fluoride is almost insoluble with 0.12 g / l in water. It is irritating to both skin and eyes and is harmful if inhaled or swallowed.
Strontium fluoride at elevated temperatures to function as an ion conductor, that can transport electrical charges on ions and thus exhibits electrical conductivity.
The compound is in the light spectrum, that is the visible portion of the electromagnetic spectrum, and a little beyond translucent. Its optical properties are thus intermediate between those of calcium fluoride and barium fluoride. This makes it interesting for applications in the optical range (see use ).
Use
Strontium fluoride is used as a coating for lenses in order to reduce reflections and increase transmission. It is also used as a crystal in thermoluminescence. Furthermore, it is used as a support for the isotope, 90Sr, which is used in radionuclide.