Fluorescence Regulation Of Rare Earth Ions Based On Nanoporous Silica Glass

Rare earth ions are rich in energy level structure and broad in luminous range.The rare earth ions doped fluorescent glasses have incomparable advantages in luminescent materials,communication as well as fiber laser.The silica glass with stable physical and chemical properties is extensively used in the market.However,the solubility of rare earth ions is limited in silica glass and easy to be clustered,which restricts its application greatly.In this paper,the nano-porous silica glass prepared by phase-separation technology is utilized as the glass matrix,and the fluorescence of rare earth ions is regulated by the method of ions doping and composite structure with metal nanoparticles.In respect of the preparation of nanoporous silica glass,through optimizing the composition of the glass precursor,adjusting the phase separation temperature,improving the acid leaching procedure and the subsequent sintering as well as the hydroxyl removal treatment,the nanoporous silica glass with uniformly distributed pore size is prepared successfully.The specific surface area of the fabricated porous silica glass is 176m²/g,which is beneficial to the preparation of the luminescent glass with high doping concentration of rare earth ions and the co-doping with different ions.On the aspect of fluorescence of Er³⁺doped nanoporous silica glass,Er³⁺,Yb³⁺,Al³⁺and P⁵⁺were introduced into glass host by solution doping method.The fluorescence spectra of the samples were compared and the effects of different ions on the fluorescence properties of Er³⁺were analyzed.The results showed that the introduction of Yb³⁺and Al³⁺could enhance the luminescence of Er³⁺by energy transfer process and increasing the quenching concentration.Meanwhile,the fluorescence bandwidth of Er³⁺in Er³⁺/Yb³⁺/Al³⁺tri-doped porous silica glass was 62 nm compared with Er³⁺singly doped sample.The introduction of P⁵⁺could change the coordination environment of Er³⁺.The back-energy transfer process from Er³⁺to Yb³⁺could be restrained and the fluorescence bandwidth could be expanded to70 nm,which providing a new orientation for realizing the broadband luminescence of Er³⁺in glass matrix.As for the regulation of rare earth ions fluorescence with metal nanoparticles,the composite system with rare earth ions and gold nanoparticles was fabricated in the reducing atmosphere.By adjusting the doping concentration and heat-treated temperature,the luminous of Eu²⁺and Yb²⁺could by controlled by the gold nanoparticles.The fluorescence intensity could be enhanced by 10.52 times and 14.33 times respectively.The higher heat-treated temperature limits the size and distribution of gold nanoparticles,which helps to enhance the fluorescence intensity of rare earth ions.The experimental results give a new orientation for the regulation of fluorescence of rare earth ions by metal nanoparticles.