Study On Luminescence And Thermal Stability Of Rare-earth Complexes And Hybrid Materials

In our study, a series of ternary complexes of rare earth (Eu³⁺,Tb³⁺) with Phthalic acids and 1,10-Phenanthroline were synthesized. The composition and structure of the resulting ternary lanthanide complex was established based on the elemental analysis results and further confirmed by IR spectra and DTA-TG., respectively. The photoluminesent of the products were examined by the PL spectum. Then we could get the conclusions as following:â‘´We study the effection of the doping sequence of the three different components to the fluorescence of the complexes. Through the experiments, we got the fitting synthesis methods, and we could conclude that the rare-earth (Eu³⁺,Tb³⁺) coordinate with the nitrogen atom of 1,10-Phenanthroline (Phen) firstly, then coordinate with carboxyl-oxygen of Phthalic acids.⑵Analysis the fluorescence intensity of different replace dicarboxylic on benzene, it was shown that the ternary complexes with p-phthalate acid had the maximal fluorescence intensity. That due to the symmetry of p-phthalate acid which was advantaged for the energy transfer in the complex molecule, and it could cooperate with 1,10-Phenanthroline commendably, this function was good for the rare-earth ion.⑶The ternary complexes of Eu³⁺ with Phthalic acids and Phen emitted red-light, while the homologous of Tb³⁺ emitted green-light. When the ternary complexes with the same organic ligants, the ternary complexes of Tb³⁺ exhibited higher relative emission intensity, the causation is the matching effection between the ternary energy of Phthalic acids and 5D4 of Tb³⁺ advantaged than that of Eu³⁺. In this article we also synthesized MCM-41 and MCM-48 molecular sieve, which had high surface area and big pore volume and fitting pore diameter. A series of high luminescent and thermal stability dopant concentrations hybrid materials of Eu(Phen)₂Cl₃/MCM-41(48) have been synthesized by ultrasound technology. The characterization of XRD,N2-adsorption-desorption,FTIR and luminescence spectrum showed that the rare earth compound had doped into the holes of mesoporous material MCM-41 and MCM-48. At the same time, we also discussed the properities of the hybrid materials through a series of characterization and analyzed their potential uses in the filed of solid luminescent laser materials, biosensor, photoelectricity switch, flat display, etc. The as-prepared products had such charactorities as follows:â‘´We synthesized the MCM-41 and MCM-48 using the proper methods, which had high surface area and big pore volume, then we steeped it into different concentrations of Eu(Phen)₂Cl₃ methyl alcohol solution, under the help of ultrasonic. The doping masses of Eu(Phen)₂Cl₃ were measured by ICP. The doping mass of the hybrid materials are improving with the increase of the concentrations of Eu(Phen)₂Cl₃ methyl alcohol solution. The maximal doping intensity of hybrid material Eu(Phen)₂Cl₃/MCM-41(48) are 7.17 % and 8.6 % respectively.⑵The luminescence intensities of Eu(Phen)₂Cl₃/MCM-41(48) increased with the increasing of the doping mass of Eu(Phen)₂Cl₃. The luminescence intensity of hybrid materials Eu(Phen)₂Cl₃/MCM-41(7.17%)and Eu(Phen)₂Cl₃/MCM-48(8.6 %) are 42.6 % and 50 % as high as the pure rare-earth compound, respectively. The luminescence intensities of hybrid materials are much improved, because of the interaction between the silica-bases composites and the rare-earth compound.⑶Compared to the pure rare-earth compound, the thermal stability of the hybrid materials Eu(Phen)₂Cl₃/MCM-41(48) enhances by about 100 oC and 200 oC, respectively. The hole-path of the molecular sieve protected the rare-earth compound from decompounding when it was heated, and the structure of MCM-48 molecular sieve was three-dimensional which was more available for the protection of Eu(Phen)₂Cl₃ than one-dimensional straight hole of MCM-41, so the hybrid materials of Eu(Phen)₂Cl₃/MCM-48 had very high thermal stability.