Temperature Dependence of the index of refraction of Rare-Earth Metal Oxides*

The index of refraction (n) of rare-earth metal oxides provides a wide range of applications spanning from communications to photovoltaics to optics. Given the oxide’s ability to withstand extreme temperatures, this utility spans much further, especially in refractory fields which require high temperatures. This work explores the temperature dependence of varying concentrations of neodymium and yttrium thin film oxides. We perform spectroscopic scans before and after the temperature experiment at a wavelength range of 290nm-3200nm. Pre-temperature treatment measurements yield indexes of refraction of about 1.8 for all samples. Post temperature treatment, the index of refraction of all samples returns to within 10% of pre-temperature treatment values. In-situ ellipsometry is conducted at temperature values of 25°C to 600°C in an oxygen-free environment. As the temperature rises, the index of refraction tends to drop to about 80% of pre-temperature treatment values. The goal of future experiments is to determine the dependence of rare-earth metal oxides in an oxygen-rich environment, with the hopes of further expanding practical application such as being a component in high-temperature alloys.