Hybrid preparation of terbium(iii)-doped mesoporous silica particles with calcium phosphates

Abstract

The preparation of terbium(III) (Tb³⁺)-doped mesoporous silica (Tb:MPS) particles and subsequent hybrid formation with calcium phosphate (CP) were proposed in this study. The surfactant/Tb:MPS particles with an initial doping concentration of Tb³⁺ ions to (Si + Tb) of 2 mol% were synthesized by a sol–gel reaction based on the cooperative organization of tetraethoxysilane, terbium(III) chloride and cetyltrimethylammonium bromide. Subsequently, the Tb:MPS particles were hybridized with CP through precipitation to form CP/Tb:MPS, where the formation was demonstrated by XRF and EDS analyses. The Tb:MPS showed a mesoporous structure which is typically seen in silica-surfactant mesostructured materials and the mesopores were preserved after precipitating the CP with crystalline phases. PL spectra were measured before and after the precipitation and some spectral changes were recognized. The PL spectral shapes due to the transitions of Tb³⁺ ions indicated that the Tb³⁺ ions were located inside the silica framework to interact with the siliceous O atoms. After the CP precipitation, the hybrid particles demonstrated higher quantum efficiency as well as longer PL life time, indicating the improved PL properties based on the CP–Tb³⁺-silica hybrid states. The interfacial manipulation of the present CP–Tb³⁺-silica hybrid allowed for unique material design in terms of its morphology and properties. This finding will be utilized for the encapsulation techniques for porous silica including with lanthanide ions and can be applicable for optical devices.