Synthesis and Characterization of Li 2 MgGeO 4 :Ho 3 .

In this work, the synthesis and characterization of Li 2 MgGeO 4 :Ho 3+ ceramics were reported. The X-ray diffraction measurements revealed that the studied ceramics belong to the monoclinic Li 2 MgGeO 4 . Luminescence properties were analyzed in the visible spectral range. Green and red emission bands correspondent to the 5 F 4 , 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 transitions of Ho 3+ were observed, and their intensities were significantly dependent on activator concentration. Luminescence spectra were also measured under direct excitation of holmium ions or ceramic matrix. Holmium ions were inserted in crystal lattice Li 2 MgGeO 4 , giving broad blue emission and characteristic 4f-4f luminescent transitions of rare earths under the selective excitation of the ceramic matrix. The presence of the energy transfer process between the host lattice and Ho 3+ ions was suggested.