Synthesis, simulation and luminescence performances of macroporous terbium-doped Ca12Al14O32Cl2 monoliths for Ag+ fluorescence sensor

Abstract

Macroporous terbium-doped Ca12Al14O32Cl2 (C12A7:Tb3+) monoliths were synthesized via a sol-gel route accompanied by phase separation, and the luminescence performances and detection of Ag+ in water of the C12A7:Tb3+ monoliths were investigated in detail. The simulation of the hydrolysis and dimerization reactions of C12A7:Tb3+shows that the hydrolysis and dimerization of Tb3+ are prior to Al3+, and the doped Tb3+ will affect the sol-gel transition of the system. The addition of Tb element changes the macrostructure derived from phase separation and sol-gel transition, and decreases the macropore size of C12A7 monolith. Heat treatment allows the formation of a single mayenite phase C12A7:Tb3+ without spoiling the macrostructure, and the Tb3+ ions replace the position of the Ca2+ ions of the “cage” structure without destroying the lattice structure of C12A7. The luminescence intensity of C12A7:3%Tb3+ monolith reaches the maximum, and the corresponding macropore size and porosity are 0.3 μm and 79% respectively. High luminescence intensity of C12A7:Tb3+ monolith is attributed to higher scattering light and wonderful high temperature stability derived from the macrostructure. The obtained macroporous C12A7:Tb3+ material has a sensitive response to Ag+ ions, and can become a promising fluorescence sensor for the detection of Ag+ ions.