What Is Magnesium Fluoride?
Magnesium fluoride is an inorganic compound with the formula MgF2. It is known by its CAS number 7783-40-6. Occurring naturally in small quantities as the mineral serratite, magnesium fluoride is a rare mineral. It can irritate the skin and eyes and is harmful if ingested.
Uses of Magnesium Fluoride
As a material with a low refractive index, magnesium fluoride is extensively used for anti-reflective coatings. By depositing magnesium fluoride films on lenses and prisms, the reflection of light can be minimized. Its applications extend to antireflective coatings, multilayers, beamsplitters, polarizing films for LCDs, and glass coatings.
Magnesium fluoride’s single crystals, notable for their ease of processing and wide transmission wavelength range (0.11-7.5 μm), find use as materials for ultraviolet region deflecting elements, optical substrates, window plates, and lenses. They are also utilized in the manufacturing of optical fluoride lenses for digital SLR cameras and scintillators and as base materials for optical fibers.
Properties of Magnesium Fluoride
With a molecular weight of 62.30, magnesium fluoride is a white powdery solid at room temperature, melting at 1,248°C and boiling at 2,260°C. It has a density of 3.15 g/mL and is insoluble in water and ethanol, slightly soluble in nitric acid, but not in dilute hydrochloric acid. It efficiently transmits electromagnetic waves in the 0.11~7.5 μm range and is durable against heat and shock. While stable under typical storage conditions, it should be kept away from strong oxidizers, extreme heat, and direct sunlight to prevent decomposition into halides and metal oxides.
Types of Magnesium Fluoride
Available mainly for research and industrial applications, magnesium fluoride is sold in various sizes suitable for laboratory use (e.g., 5g, 25g, 100g, 500g) and is ideal for vacuum evaporation techniques. Industrially, it is used in optical thin films and as a material for transparent, low-refractive index coatings, classified under rare metals. It is supplied in larger quantities, such as 20 kg bags, for factory use, appearing in white to transparent, granular, or tablet forms.
Other Information on Magnesium Fluoride
1. Synthesis of Magnesium Fluoride
Magnesium fluoride can be synthesized by reacting magnesium oxide with a hydrogen fluoride source, such as ammonium hydrogen fluoride.
2. Crystal Structure of Magnesium Fluoride
Its crystal structure is rutile-type, belonging to the tetragonal crystal system, similar to TiO2. The structure features an octahedral coordination of six F atoms around each Mg atom and a triangular coordination of three Mg atoms around each F atom. In its gaseous form, MgF2 exhibits a linear molecular structure.