Absorption spectra of molybdenum doped YAG crystals

Absorption spectra of molybdenum doped YAG crystals annealed in hydrogen, vacuum, oxygen and argon and exposed to an UV irradiation are given. Yellow or brown colour of the crystals is attributed to the O⁻ centre formation connected with the reduction of molybdenum ions to a lower valency state. Most intensive yellow colour was shown by crystals, the argon annealing of which was followed by a treatment in oxygen at rather low temperature (∼1000 °C) and by UV irradiation. Two types of O⁻ centres are suggested Blue colour of the samples annealed in argon is attributed to e⁻ centres.