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 2F5/2 and 2F7/2 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.