Study On Luminescent Properties Of Sn²⁺ And Mn²⁺ Ions Doped Rare Earth Aluminum-silicate Glasses

In recent years,with the rapid development of solid-state lighting in the luminescent field,fluorescent materials with broad emission characteristics have become the focus of research.At the same time,with the deepening of high-energy physics research,the application fields of scintillating materials are becoming wider,which also puts forward different requirements for scintillating materials.Rare earth luminescent centers have been the focus of previous studies due to their strong emission characteristics.The study of non-rare earth luminescent centers is necessary due to their rich spectral properties.Among them,the Sn²⁺centers in the ns²（n≥5）type luminescent center have attracted worldwide attention due to their broad emission,strong luminescent intensity and high quantum efficiency.The Mn²⁺centers in the transition metal are difficult to emit light directly due to the spin-forbidden transition.However,the Mn²⁺centers have strong red photoluminescence,which can replace some low-abundance rare-earth luminescent centers,and is highly sensitive to the coordination field,which has received extensive attention in recent years.Aluminum-silicate glass is of great significance in industrial applications due to its low cost,simple preparation process and continuously adjustable components.Therefore,a series of Sn²⁺,Mn²⁺and Sn²⁺-Mn²⁺doped Gd₂O₃-Al₂O₃-SiO₂（GAS）glasses were prepared by the conventional melt quenching method.The optical properties,energy transfer properties and scintillating properties of these glasses were investigated.The research content of the full text is as follows:（1）The photoluminescence and scintillation properties of Sn²⁺doped gadolinium aluminum-silicate Gd₂O₃-Al₂O₃-SiO₂（GAS）glass using Si₃N₄ as reducing agent were studied.Due to the transitions of S₁-S₀ and T₁-S₀ at the Sn²⁺luminescent center,the glasses show a broad emission band in the range of 360-730 nm.The luminescent intensity of Sn²⁺-doped GAS glass reaches the maximum at 0.3 mol% Sn²⁺.The lifetimes of the glasses vary from 6 to 12μs,which is related to the full width at half maximum（FWHM）of the emission spectra.Different oxides were added to explore the relationship between the optical basicity of the glasses and their luminescent properties.The maximum quantum yield of GAS glasses is about 35%.The addition of B₂O₃ improves the photoluminescence quantum yield（PL QY）of the glasses due to the increase of radiative transition opportunities in energy level transitions.The X-ray excited luminescence of the glasses was observed and studied,and the results showed that the scintillating intensity of the glasses was independent of change trend of its photoluminescence intensity.（2）Based on Gd₂O₃-Al₂O₃-SiO₂ matrix glasses,a series of Mn²⁺single-doped luminescent glasses excited by[SiO_4-x]defects in the glass were prepared.And the existence of[SiO_4-x]defects was determined from the absorption and excitation spectra of the glasses.X-ray photoelectron spectroscopy（XPS）and absorption spectra demonstrated that almost onlyMn²⁺ions were presented in the glasses.The photoluminescence,energy transfer and scintillation of GAS:xMn²⁺glasses were investigated.With the increase of Mn²⁺concentration,the blue emission intensity of the glasses(⁶A₁（S）→[⁴E（G）,⁴A₁（G）]transition belonging to the Mn²⁺center) gradually decreases,and the red broadband emission intensity（⁶A₁（S）→⁴T₁（G） transition）increases.When the Mn²⁺concentration reaches 6 mol%,the color coordinates of the glass are（0.264,0.226）,which is belong to white light emission.The quantum yield of the GAS:xMn²⁺glasses was tested,and it showed a trend of first increasing and then decreasing with the increase of Mn²⁺ions concentration.The decay times of the glasses near 440 nm are consisted of fast and slow components.The fast component is in the range of 17 and 85μs,and the slow component is in the range of 200 and 650μs.The decay times near 630 nm also consist of fast and slow components,and the fast component is in the range of 110 and 300μs,slow component between 680 and 1250μs.The decay time of glass decreases with the increase of Mn²⁺ions concentration.The energy transfer process from[SiO_4-x]defects in the glasses to Mn²⁺centers is revealed.The electron- phonon interaction in the radiative transition of the glasses is calculated by the thermal quenching behavior of the glasses.In addition,the X-ray excited scintillation luminescence of the glasses was also tested,and the different luminescence mechanisms of Mn²⁺in PL and XEL were investigated.（3）The Sn²⁺-Mn²⁺co-doped Gd₂O₃-Al₂O₃-SiO₂(GAS:0.5Sn²⁺,yMn²⁺)glasses were prepared by traditional high temperature melt-quenching technology.The photoluminescence properties of the glasses and the energy transfer process of Sn²⁺-Mn²⁺were studied.In the photoluminescence process,under 365 nm excitation wavelength,with the increase of Mn²⁺content,the emission intensity of the Sn²⁺center gradually decrease,and the emission intensity of the Mn²⁺center gradually increases.Moreover,the decay time of the Sn²⁺center decreases with the increase of Mn²⁺content,indicating that energy transfer from Sn²⁺to Mn²⁺ions occur in the glass.The maximum photoluminescence quantum yield（PL QY）of GAS:0.5Sn²⁺,yMn²⁺glasses is 25.48%,which decreases with the increase of Mn²⁺ content.When the Mn²⁺ions concentration reaches 4.0 mol%,the chromatic coordinate of the glass is（0.323,0.273）,which is belong to the standard white light emission.In addition,the thermal quenching behavior of Sn²⁺-Mn²⁺co-doped glass was also studied.The thermal activation energy required to overcome the electronic transition of the Sn²⁺emission center is approximately 0.23 eV.