Near infrared and charge transfer luminescence of trivalent ytterbium in KLa(PO3)4 powders

The polycrystalline powders of condensed polyphosphates KLa(1 − x)Ybx(PO3)4 (x = 5, 10, 15, 20%) with linear chain were prepared by solid-state reaction. These samples were characterized by X-ray diffraction, FTIR and Raman scattering spectroscopies. The obtained powders are formed by single monoclinic phase of type III of condensed polyphosphate KLa(PO3)4 (KLP) crystallized with P21 space group. Lattice parameters varied as a function of the ytterbium concentration. As the Yb3+ concentration increased, the crystal lattice parameters were decreased. For the first time, near infrared (NIR) and UV–Visible spectroscopy of Yb3+ in KLa(PO3)4 powders, at room temperature, are carried out. In the IR range, a broad band relative to the fundamental 2F5/2 → 2F7/2 emission was registered. In the UV–Visible spectra, two bands typical of the Yb3+ charge transfer band (CTB) luminescence are observed. The registered decay times of these two emission types showed low sensibility to the Yb3+ concentration in KLa(PO3)4.