Holmium(III)-Oxide 99,99% – Ho2O3 –
Holmium(III) with the formula Ho2O3. Together with Dysprosium(III)-oxide (Dy2O3) it is one of the most powerfully paramagnetic substances known. The oxide, also called holmia, occurs as a component of the related erbium oxide mineral called erbia. Typically the oxides of the trivalent lanthanides coexist in nature and separation of these components requires specialized methods. Holmium oxide is used in making specialty colored glasses. Glass containing holmium oxide and holmium oxide solutions have a series of sharp optical absorption peaks in the visible spectral range. They are therefore traditionally used as a convenient calibration standard for optical spectrophotometers. Holmium oxide has some fairly dramatic color changes depending on the lighting conditions. In daylight, it is a tannish yellow color. Under trichromatic light, it is a fiery orange red, almost indistinguishable from the way erbium oxide looks under this same lighting. This is related to the sharp emission bands of the phosphors. Holmium oxide has a wide band gap of 5.3 eV and thus should appear colorless. The yellow color originates from abundant lattice defects (such as oxygen vacancies) and is related to internal transitions at the Ho3+ ions.