Fluoride

Fluoride compounds are a group of chemical compounds that contain the element fluorine. These compounds have various applications, including their use as optical coatings by sputtering technique. Sputtering is a process in which atoms or molecules are ejected from a solid sputter target material and deposited onto a substrate to form a thin film.

When it comes to optical coatings, fluoride compounds are chosen for their unique properties, such as high transparency in the ultraviolet (UV), visible, and infrared (IR) regions of the electromagnetic spectrum. They also exhibit low refractive index, high chemical stability, and good resistance to environmental factors like moisture and temperature.

During the sputtering process, a sputter target made of the desired fluoride compound is bombarded with high-energy ions to dislodge atoms or molecules. These ejected particles then deposit onto the substrate to form a thin and uniform coating.

Some fluoride compounds commonly used as optical coatings by sputtering technique include:

1. Magnesium fluoride (MgF2): MgF2 is a widely used optical coating material, and it serves as a popular sputter target due to its excellent transparency and low refractive index in the UV and visible regions. It is commonly used as an antireflection coating on lenses and other optical components.

2. Aluminum fluoride (AlF3): AlF3 is known for its high refractive index in the UV and visible regions. As a sputter target, it is often used as a reflective coating or in combination with other materials to adjust the refractive index of multilayer coatings.

3. Lithium fluoride (LiF): LiF is transparent in the UV and visible regions and has a relatively high refractive index. It serves as an effective sputter target for antireflection coatings, enhancing the durability and performance of optical components.

4. Calcium fluoride (CaF2): CaF2 is highly transparent in the UV, visible, and IR regions and has a low refractive index. As a sputter target, it is commonly used as a protective coating for sensitive optical elements and as a substrate for other thin films.

5. Barium fluoride (BaF2): BaF2 is transparent in the UV, visible, and IR regions and has a low refractive index. It serves as a versatile sputter target in various optical applications, including antireflection coatings, beam splitters, and windows.

These fluoride compounds can be made into a sputter target and deposited as thin films onto optical substrates using the sputtering technique. By bombarding the sputter target made of the desired fluoride compound with high-energy ions, atoms or molecules are dislodged and then deposited onto the substrate, resulting in a thin and uniform coating.