From the infrared to the visible range: Spectroscopic studies of ytterbium doped oxyborates

The spectroscopic study of yttrium oxyborates doped with trivalent ytterbium is conducted in the UV-Visible and infrared range. The multiplicity of the ytterbium environments in the studied compounds leads to complex emission spectra in the infrared and excitation spectra in the ultraviolet. Different ²F_5/2 and ²F_7/2 transitions have been pointed out. The emission extends up to 1090 nm for one compound. A correlation was evidenced between position and de-excitation mode of a charge transfer band and ytterbium environment for both oxyborates. Decay time dependence as a function of ytterbium concentration is also reported. For the highest concentration, a blue-green luminescence can be observed under strong IR excitation. Its study revealed two possible mechanisms: erbium ion emission at 550 nm after up-conversion and cooperative luminescence of ytterbium ions.