The Nernst glower is an obsolete device for providing a continuous source of (near) infrared radiation for use in spectroscopy. Typically it was in the form of a cylindrical rod or tube composed of a mixture of certain oxides such as  zirconium oxide (ZrO₂), yttrium oxide (Y₂O₃) and erbium oxide (Er₂O₃) at a ratio of 90:7:3 by weight. They operated by being electrically heated to about 2000 °C. Initially they required external heating because the material is an insulator at room temperature.