ZrO2 | Optical characterization of thin films

ZrO2(Zirconium Oxide) has refractive index near 2.1 at 550 nm, and a transmittance range from below 340 nm to 12 μm.

ZrO2 appears in a variety of naturally occurring crystalline phases. At ambient temperatures, the monoclinic phases exist with indices of 2.1-2.2 in the bulk form. A cubic phase can be observed at higher temperatures. Moreover, there is some inclusion of hafnium in almost all zirconia. The deposition of ZrO2 films was quite difficult prior to the development of the electron beam, but film inhomogeneity is still the classic problem with this material. Even so, this material is commonly used for fabricating AR coatings in combination with SiO2.

Mixture of ZrO2 and TiO2

ZrO2 tends to have inhomogeneous properties; these must be explicitly considered or minimized in your optical thin film design; the addition of TiO2 achieves the latter. The refractive index of the mixture is approximately 2.1-2.2 at 550 nm, and the transmittance range is similar to that of ZrO2. Many research have been conducted to overcome ZrO2's inhomogeneous properties by mixing other materials like TiO2.