Strontium bromide explained

Strontium bromide is a chemical compound with a formula . At room temperature it is a white, odourless, crystalline powder. Strontium bromide imparts a bright red colour in a flame test, showing the presence of strontium ions. It is used in flares and also has some pharmaceutical uses.

Preparation

can be prepared from strontium hydroxide and hydrobromic acid.

Alternatively strontium carbonate can also be used as strontium source.

These reactions give hexahydrate of strontium bromide, which decomposes to dihydrate at 89 °C. At 180 °C anhydrous is obtained.[1]

Structure

At room temperature, strontium bromide adopts a crystal structure with a tetragonal unit cell and space group P4/n. This structure is referred to as α- and is isostructural with and . The compound's structure was initially erroneously interpreted as being of the type,[2] but this was later corrected.[3]

Around 920 K (650 °C), α- undergoes a first-order solid-solid phase transition to a much less ordered phase, β-, which adopts the cubic fluorite structure. The beta phase of strontium bromide has a much higher ionic conductivity of about 1 S/cm, comparable to that of molten, due to extensive disorder in the bromide sublattice.[4] Strontium bromide melts at 930 K (657 °C).

See also

References

Notes and References

  1. Dale L. Perry, Sidney L. Phillips: Handbook of Inorganic Compounds. CRC Press, 1995,, .
  2. Kamermans . M. A. . The Crystal Structure of SrBr2. . Zeitschrift für Kristallographie - Crystalline Materials . Walter de Gruyter GmbH . 101 . 1–6 . 1939-12-01 . 2196-7105 . 10.1524/zkri.1939.101.1.406 . 406–411. 102183214.
  3. The crystal structure of strontium bromide. R. L. Sass. J. Phys. Chem. . 1963 . 67 . 2862. 10.1021/j100806a516. 12. etal.
  4. Stephen . Hull . Stefan T. . Norberg . Istaq . Ahmed . Sten G. . Eriksson . Chris E. . Mohn . High temperature crystal structures and superionic properties of SrCl2, SrBr2, BaCl2 and BaBr2 . . 184 . 11 . 2011 . 2925–2935 . 10.1016/j.jssc.2011.09.004 . 2011JSSCh.184.2925H.