Temperature Sensing And Scintillating Performances Of Rare Earth Doped Oxyfluoride Glass Ceramics

Oxyfluoride glass ceramics(GCs)are often formed by controlling the crystallization process of oxyfluoride glasses with specially designed chemical compositions,which are novel composite materials that containing fluoride nanocrystals phase and oxide glass phase.So they combine the advantages of good stability of oxide glass and low phonon energy environment of fluoride nanocrystals.Rare earth doped oxyfluoride GCs present potential applications in the fields of lighting,color displays,lasers,optical fiber amplifiers and so on because of their highly efficient optical and stable structural performances.Recently,many researchers have focused on rare earth doped oxyfluoride GCs to explore their performances and applications in all aspects.While,the temperature sensing and scintillating performances of GCs unable meet the normal procduction and living needs,which need to be greatly improved.In order to further enhance these two aspects of performance,this paper mianly researched the temperature sensing and scintillating performances of rare earth doped oxyfluoride GCs.The main contents are listed as follows:1.Temperature sensing properties of Tm3+Yb3+ co-doped Sr2YF7 GC:Tm3+/Yb3+co-doped transparent GC containing Sr2YF7 nanocrystals were successfully manufactured by traditional melt-quenching technique.Their structural and up-conversion luminescent properties were systemically investigated through X-ray diffraction(XRD),transmission electron microscope(TEM)and a series of spectroscopy methods.Enhanced up-conversion emissions with obvious Stark splitting and prolonged luminescence lifetime were observed after crystallization.These optical spectroscopy results manifest that Tm3+ions have incorporated into the Sr2YF7 crystalline lattice with lower phonon energy after heat-treatment.The 3F2,3 and 3H4 levels of Tm3+ can be explored as thermally coupled energy levels(TCEL)for temperature sensing because of their befitting energy gap(?2000 cm-1).At the same time,the population of 1G4 state of Tm3+ is indirectly originated from 3H4 one.Therefore the temperature sensing performances of Tm3+ doped Sr2YF7 GC were investigated by fluorescence intensity ratio(FIR)between 3F2,3?3H6 and 1G4?3F4 up-conversion emissions of Tm3+.Results show that the theoretical maximum value of relative sensitivity SR-max.is 1.16%K-1.And the absolute sensitivity SA keeps increasing with increasing temperature.Such Tm3+/Yb3+ co-doped Sr2YF7 GC may be excellent candidate for optical temperature sensors.2.Temperature sensing properties of Tm3+/Yb3+ co-doped Sr2GdF7 GC:Tm3+/Yb3+co-doped Sr2GdF7 GC was synthesized by traditional melt-quenching method with further crystallization process.Its structural and optical properties were systematically investigated by a series of characterization methods.The enrichment of Tm3+ into Sr2GdF7 lattice is confirmed by tremendously enhanced emission intensities,obvious Stark splitting and prolonged lifetimes of Tm3+ after crystallization.Based on fluorescence intensity ratio of 3F3 ? 3H6 and 1G4 ? 3F4 transitions of Tm3+,the temperature thermometric properties of Sr2GdF7:Tm3+ GC were explored.In this system,maximum relative sensitivity SR-max reaches 1.97%K-1 at 353 K,which further improved the temperature sensing properties of GCs.Our investigation demonstrates that Sr2GdF7:Tm3+/Yb3+ GC may act as promising candidate for optical temperature sensor.3.Scintillating properties of Tb3+ doped Na5Gd9F32 GC:Here,bulk Tb3+-doped Na5Gd9F32 GC scintillators with relatively high transparence were successfully manufactured via melt-quenching method with further thermal treatment.Their structural and luminescent properties were systemically investigated by a series of characterization techniques including XRD,TEM,absorption spectra,photoluminescence(PL)excitation and emission spectra,lifetime measurements and X-ray excited luminescence(XEL).Luminescent spectroscopy results show that optimum doping concentration of Tb3+ in precursor glass(PG)and GC systems are both 4 mol%.The XEL intensity of PG is about 64%of that of commercial Bi4Ge3O14(BGO)scintillator with the same thickness.Due to the incorporation of Tb3+ ions into Na5Gd9F32 nanocrystals,enhanced PL and XEL of Tb3+ion are realized after crystallization.The internal PL quantum yield of GC is 43.0%and the XEL intensity of GC reaches 130%of that of BGO scintillator.These results demonstrate that Na5Gd9F32 GC may be acted as efficient scintillator with large-volume and low-cost.4.Scintillating properties of Tb3+ doped Sr2GdF7 GC:this work obtained the GC scintillator with improved transmittance and luminescence by optimizing the composition and elaboration procedure.Tb3+ doped Sr2GdF7 GCs were successfully manufactured via melt-quenching method with further thermal treatment.Their structural and luminescent properties were systemically investigated by a series of characterization techniques.GC4 sample with 3 mm thickness keeps a high transmittance(64%at 550 nm)in VIS light region.The PL and XEL intensities of GC4 are enhanced by 3.5 and 1.6 times compared to that of PG4 after crystallization,respectively,which may be caused by the incorporation of Tb3+ ions into crystallized Sr2GdF7 nanocrystals.And the luminescent IQY and EQY of GC4 sample are about 59.1 and 26.4%,respectively.More interestingly,the XEL intensities of PG4(high transparency)and GC4(semitransparency)can reach 124%and 197%of that of commercial BGO scintillator,respectively.Sr2GdF7:Tb3+ GC,with low-cost elaboration,highly luminescent QY and intense XEL,can be applied as X-ray scintillator for slow event detection.