Strontium fluoride

Strontium Fluoride (SrF₂) is an inorganic compound composed of the strontium and fluoride ions. It is a colorless solid that finds use in various applications due to its optical and mechanical properties. Strontium fluoride is part of the alkaline earth metal fluorides, which are known for their high melting points and low solubility in water.

Properties

Strontium fluoride crystallizes in the fluorite structure, a common motif for compounds with the formula AB₂. In this structure, strontium ions are coordinated by eight fluoride ions in a cubic geometry. This compound has a melting point of approximately 1473 K and exhibits low water solubility, characteristics that are typical for alkaline earth metal fluorides.

Due to its optical clarity in the wide range of wavelengths, from vacuum ultraviolet (VUV) to the infrared (IR) region, SrF₂ is used as an optical material. It is particularly valued for its low refractive index and absence of birefringence, making it suitable for use in optical coatings and lenses.

Synthesis

Strontium fluoride can be synthesized by reacting strontium carbonate (SrCO₃) or strontium hydroxide (Sr(OH)₂) with hydrofluoric acid (HF):

SrCO₃ + 2 HF → SrF₂ + CO₂ + H₂O

Sr(OH)₂ + 2 HF → SrF₂ + 2 H₂O

It can also be produced by the action of fluorine gas on strontium chloride (SrCl₂):

SrCl₂ + F₂ → SrF₂ + Cl₂

Applications

Strontium fluoride is used in a variety of applications, including:

• Optical materials: Due to its wide transmission range and resistance to thermal shock, SrF₂ is used in optical components such as windows, lenses, and prisms, especially in deep UV and IR regions.
• Fluoride glass: It is a component in the production of fluoride glasses, which are known for their low optical dispersion and are used in optical fibers for telecommunications.
• Electronics: SrF₂ is utilized in the electronics industry for the production of thin films and coatings due to its insulating properties.

Safety

As with other fluoride compounds, strontium fluoride should be handled with care. Inhalation, ingestion, or skin contact can lead to fluoride poisoning, which can be fatal in severe cases. Appropriate safety measures, including the use of personal protective equipment, are essential when handling this compound.