Cr^(3+)-activated phosphors have attracted significant attention for their tunable emission,spanning narrow-band red to broadband near-infrared(NIR)luminescence,depending on the crystal field environment.Here,we repor...Cr^(3+)-activated phosphors have attracted significant attention for their tunable emission,spanning narrow-band red to broadband near-infrared(NIR)luminescence,depending on the crystal field environment.Here,we report the realization of wideband NIR emission in Cr^(3+)-doped GaScO_(3)(GaScO_(3):Cr^(3+))phosphors with perovskite structure.The phosphors were synthesized by traditional solid-state reaction method.The first-principles calculations were conducted and the results demonstrate that the octahedral[GaO_(6)]sites exhibit relatively weak crystal field strength(Dq/B≈2.2),facilitating efficient spin-allowed transitions of Cr^(3+)from the^(4)T_(2)state to the^(4)A_(2)state.The photoluminescence spectroscopy revealed an exceptionally broad NIR emission band from a range of 700 nm-1200 nm with full width at half maximum(FWHM)of 145 nm under 465-nm excitation.Overall,these results highlight the viability of GaScO_(3):Cr^(3+)as a highly promising material for wideband NIR applications.展开更多
In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as...In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.展开更多
Under the excitation of a 980 nm laser,the visible upconversion(UC)luminescence of Er^(3+)ions doped Yb^(3+)ions selfactivated NaYb(MoO_(4))_(2)phosphor and crystal,as well as the Yb^(3+)/Er^(3+)ions codoped NaBi(MoO_...Under the excitation of a 980 nm laser,the visible upconversion(UC)luminescence of Er^(3+)ions doped Yb^(3+)ions selfactivated NaYb(MoO_(4))_(2)phosphor and crystal,as well as the Yb^(3+)/Er^(3+)ions codoped NaBi(MoO_(4))_(2)crystal were investigated comprehensively.The results indicate that all three samples exhibit two significant green emission bands and a weak red emission band in the visible band corresponding to the transitions of^(2)H_(11/2)/^(4)S_(3/2)→^(4)I_(15/2)and^(4)F_(9/2)→4 I_(15/2)of Er^(3+)ions,respectively.Through the variable power density spectra of three different samples,the relationship between the energy back transfer(EBT)process of Yb^(3+)-Er^(3+)ions and the power density point and Yb^(3+)ion concentration was investigated.The EBT process was observed in both the Er^(3+)ions doped Yb^(3+)ions self-activated NaYb(MoO_(4))_(2)phosphor and crystal,as confirmed by the luminescence image of the sample.At high power density,the Yb^(3+)ions self-activated sample exhibited yellow luminescence,with the crystal appearing later than the phosphor.In contrast,the NaBi(MoO_(4))_(2)crystal displayed bright green emission within the measured power density range.In addition,by monitoring the relative intensity change of Yb^(3+)emission in 5 at%Er^(3+):NaYb(MoO_(4))_(2)crystal,the generation of EBT process in self-activated samples at high power density is more directly explained.These experimental results provide a reliable basis for our comprehensive understanding of the EBT mechanism,and also provide a reliable direction for the final determination of the optimal excitation power density for optical temperature measurement.展开更多
Optical thermometry based on the upconversion(UC)luminescence intensity ratio(LIR)has attracted considerable attention because of its feasibility for achievement of accurate non-contact temperature measurement.Compare...Optical thermometry based on the upconversion(UC)luminescence intensity ratio(LIR)has attracted considerable attention because of its feasibility for achievement of accurate non-contact temperature measurement.Compared with traditional UC phosphors,optical thermometry based on UC single crystals can achieve faster response and higher sensitivity due to the stability and high thermal conductivity of the single crystals.In this study,a high-quality 5 at%Yb^(3+)and 1 at%Ho^(3+)co-doped Gd_(0.74)Y_(0.2)TaO_(4)single crystal was grown by the Czochralski(Cz)method,and the structure of the as-grown crystal was characterized.Importantly,the UC luminescent properties and optical thermometry behaviors of this crystal were revealed.Under 980 nm wavelength excitation,green and red UC luminescence lines at 550 and 650 nm and corresponding to the^(5)F_(4)/^(5)S_(2)→^(5)I_(8)and^(5)F_(5)→^(5)I_(8)transitions of Ho^(3+),respectively,were observed.The green and red UC emissions involved a two-photon mechanism,as evidenced by the analysis of power-dependent UC emission spectra.The temperature-dependent UC emission spectra were measured in the temperature range of 330–660 K to assess the optical temperature sensing behavior.At 660 K,the maximum relative sensing sensitivity(S_(r))was determined to be 0.0037 K^(−1).These results highlight the signifcant potential of Yb,Ho:GYTO single crystal for optical temperature sensors.展开更多
A Nd-doped GdNbO4 single crystals have been grown successfully using the Czochralski technique. The chemical etching method was employed to study the defects in the structural morphology of Nd：GdNbO4 crystal with pho...A Nd-doped GdNbO4 single crystals have been grown successfully using the Czochralski technique. The chemical etching method was employed to study the defects in the structural morphology of Nd：GdNbO4 crystal with phosphoric acid etchant. Mechanical proper- ties （such as hardness, yield strength, fracture toughness, and brittle index） of the as-grown crystal were system- atically estimated on the basis of the Vickers hardness test for the first time. The transmission spectrum of Nd： GdNbO4 was measured in the wavelength range of 320- 2400 nm at room temperature, and the absorption peaks were assigned. Results hold great significance for further research on Nd：GdNbO4.展开更多
基金supported by the Natural Science Research Project of Anhui Provincial Education Department for Excellent Young Scholars(Grant No.2024AH030007)the National Natural Science Foundation of China(Grant No.52202001).
文摘Cr^(3+)-activated phosphors have attracted significant attention for their tunable emission,spanning narrow-band red to broadband near-infrared(NIR)luminescence,depending on the crystal field environment.Here,we report the realization of wideband NIR emission in Cr^(3+)-doped GaScO_(3)(GaScO_(3):Cr^(3+))phosphors with perovskite structure.The phosphors were synthesized by traditional solid-state reaction method.The first-principles calculations were conducted and the results demonstrate that the octahedral[GaO_(6)]sites exhibit relatively weak crystal field strength(Dq/B≈2.2),facilitating efficient spin-allowed transitions of Cr^(3+)from the^(4)T_(2)state to the^(4)A_(2)state.The photoluminescence spectroscopy revealed an exceptionally broad NIR emission band from a range of 700 nm-1200 nm with full width at half maximum(FWHM)of 145 nm under 465-nm excitation.Overall,these results highlight the viability of GaScO_(3):Cr^(3+)as a highly promising material for wideband NIR applications.
基金supported by the National Natural Science Foundation of China (52202001)Open Project of Advanced Laser Technology Laboratory of Anhui Province (AHL2021KF07)+1 种基金Major Science and Technology of Anhui Province(202203a05020002)University Natural Science Research Project of Anhui Province (KJ2021A0388)。
文摘In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.
基金Foundation of China(Grant No.52202001)Special Project of the National Natural Science Foundation of China(Grant No.62241501)+1 种基金Major Science and Technology of Anhui Province(No.202203a05020002)University Natural Science Research Project of Anhui Province(No.KJ2021 A0388)supported this study.
文摘Under the excitation of a 980 nm laser,the visible upconversion(UC)luminescence of Er^(3+)ions doped Yb^(3+)ions selfactivated NaYb(MoO_(4))_(2)phosphor and crystal,as well as the Yb^(3+)/Er^(3+)ions codoped NaBi(MoO_(4))_(2)crystal were investigated comprehensively.The results indicate that all three samples exhibit two significant green emission bands and a weak red emission band in the visible band corresponding to the transitions of^(2)H_(11/2)/^(4)S_(3/2)→^(4)I_(15/2)and^(4)F_(9/2)→4 I_(15/2)of Er^(3+)ions,respectively.Through the variable power density spectra of three different samples,the relationship between the energy back transfer(EBT)process of Yb^(3+)-Er^(3+)ions and the power density point and Yb^(3+)ion concentration was investigated.The EBT process was observed in both the Er^(3+)ions doped Yb^(3+)ions self-activated NaYb(MoO_(4))_(2)phosphor and crystal,as confirmed by the luminescence image of the sample.At high power density,the Yb^(3+)ions self-activated sample exhibited yellow luminescence,with the crystal appearing later than the phosphor.In contrast,the NaBi(MoO_(4))_(2)crystal displayed bright green emission within the measured power density range.In addition,by monitoring the relative intensity change of Yb^(3+)emission in 5 at%Er^(3+):NaYb(MoO_(4))_(2)crystal,the generation of EBT process in self-activated samples at high power density is more directly explained.These experimental results provide a reliable basis for our comprehensive understanding of the EBT mechanism,and also provide a reliable direction for the final determination of the optimal excitation power density for optical temperature measurement.
基金The National Natural Science Foundation of China(Grant No.52202001)Open Project of Advanced Laser Technology Laboratory of Anhui Province(No.AHL2021KF07)+3 种基金Major Science and Technology of Anhui Province(No.202203a05020002)University Natural Science Research Project of Anhui Province(No.KJ2021A0388)Natural Science Foundation of Tianjin(No.20JCYBJC00390)Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energy(No.JJNY202001)supported this study.
文摘Optical thermometry based on the upconversion(UC)luminescence intensity ratio(LIR)has attracted considerable attention because of its feasibility for achievement of accurate non-contact temperature measurement.Compared with traditional UC phosphors,optical thermometry based on UC single crystals can achieve faster response and higher sensitivity due to the stability and high thermal conductivity of the single crystals.In this study,a high-quality 5 at%Yb^(3+)and 1 at%Ho^(3+)co-doped Gd_(0.74)Y_(0.2)TaO_(4)single crystal was grown by the Czochralski(Cz)method,and the structure of the as-grown crystal was characterized.Importantly,the UC luminescent properties and optical thermometry behaviors of this crystal were revealed.Under 980 nm wavelength excitation,green and red UC luminescence lines at 550 and 650 nm and corresponding to the^(5)F_(4)/^(5)S_(2)→^(5)I_(8)and^(5)F_(5)→^(5)I_(8)transitions of Ho^(3+),respectively,were observed.The green and red UC emissions involved a two-photon mechanism,as evidenced by the analysis of power-dependent UC emission spectra.The temperature-dependent UC emission spectra were measured in the temperature range of 330–660 K to assess the optical temperature sensing behavior.At 660 K,the maximum relative sensing sensitivity(S_(r))was determined to be 0.0037 K^(−1).These results highlight the signifcant potential of Yb,Ho:GYTO single crystal for optical temperature sensors.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61205173, 51272254, 51502292, and 61405206） and the Knowledge Innovation Program of the Chinese Academy of Sciences （No. CXJJ- 15M055）.
文摘A Nd-doped GdNbO4 single crystals have been grown successfully using the Czochralski technique. The chemical etching method was employed to study the defects in the structural morphology of Nd：GdNbO4 crystal with phosphoric acid etchant. Mechanical proper- ties （such as hardness, yield strength, fracture toughness, and brittle index） of the as-grown crystal were system- atically estimated on the basis of the Vickers hardness test for the first time. The transmission spectrum of Nd： GdNbO4 was measured in the wavelength range of 320- 2400 nm at room temperature, and the absorption peaks were assigned. Results hold great significance for further research on Nd：GdNbO4.
