Luminescence and vibrational characteristics of the submicro crystals of lanthanum orthophosphates and metaphosphates codoped with Er3+ and Yb3+ ions

Er3+ and Yb3+ doped K3La(PO4)2 ortho- and KLa(PO3)4 metaphosphates were synthesised by the solid state reaction method. The obtained powders were characterised by XRD method, IR and Raman spectroscopy as well as optical absorption spectroscopy. The emission spectra were measured and fluorescence decay studies were carried out at room temperature. The energy transfer from Yb3+ to Er3+ and two-photon up-conversion processes were observed and discussed. The influence of the ortho- and metaphosphate host on efficiency of the luminescence was discussed.