Co-luminescence properties of terbium ions-benzoic acid-phen complexes doped with europium ions

Series of complexes Eu _x Tb_1-x (BA)₃phen (0.01 ≤ x ≤ 0.50) were synthesized by co-precipitation method, BA was used as the carboxylic acid ligand and 1, 10-phenanthroline was used as the electrically neutral ligand. The samples were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analyses and differential scanning calorimetry (TG-DSC), ultraviolet and visible spectrophotometer absorption spectra, and photoluminescence spectra to study the structure, the energy absorption, the thermal, and luminescent properties of the rare earth complexes. The results show that the series rare earth organic complexes are well crystallized and show high thermal stability. The luminescent intensity of europium ion in the complexes increases as terbium ion transfers the absorbed energy to europium ion in the complexes. The emission of terbium ion at 545 nm is not quenched by europium ion but increases with the content of europium ion decreasing. When the x value is 0.01, the fluorescence intensity reaches the maximum as well as the emission intensity of terbium ions at 545 nm and europium ions at 614 nm are almost equal. It realizes the co-luminescence phenomenon of terbium ion and europium ion. The series rare earth organic complexes with different colors can be obtained by adjusting the ratio of terbium ion and europium ion.