Bi(Sb)_(2)Te(Se)_(3)alloys,as the only commercial thermoelectric materials,have been applied widely in cooling fields.While,the current energy conversion efficiency(dominated by the dimensionless ZT)of commercial prod...Bi(Sb)_(2)Te(Se)_(3)alloys,as the only commercial thermoelectric materials,have been applied widely in cooling fields.While,the current energy conversion efficiency(dominated by the dimensionless ZT)of commercial products is still lower and cannot meet the market demand.In this paper,high thermoelectric performance at room temperature in both zonemelted(ZM)Bi_(0.46)Sb_(1.54)Te_(3)ingots and powder-metallurgy(PM)Bi_(0.46)Sb_(1.54)Te_(3)blocks with a large size was realized successfully by optimizing their preparation process.The peak ZT values of ZM and PM p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys reached 1.26 and 1.45,respectively.They are higher than those of all the n-type or p-type Bi_(2)Te_(3)-based products in current commercial applications.In particular,their production process of large size p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys could be directly industrialized.展开更多
A series of highly Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses were investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and up-conversion s...A series of highly Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses were investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and up-conversion spectra were performed to examine the effect of concentration quenching on spectroscopic properties. In the glasses with Er^(3+) concentrations below 10% (mol fraction), concentration quenching is low and the Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses gave stronger fluorescence of 1.54 μm from the (()~4I_(13/2))→(()~4I_(15/2)) transition than those of Er^(3+) singly-doped glasses. In the glass with Er^(3+) concentrations above 10%, concentration quenching of 1.54 μm obviously occurs more than that of the Er^(3+) singly-doped samples because of the back energy-transfer from Er^(3+) to Yb^(3+). To obtain the highest emission efficiency at 1.54 μm, the optimum doping-concentration ratio of Er^(3+)/Yb^(3+) is found to be approximately 1∶1 in mol fraction when the Er^(3+) concentration is less than 10%.展开更多
The enhanced intensity and lengthened lifetime of 1.54 μm emission were observed for Er：LiNbO3 crystal codoped with Zn2＋ ions.The ZnO codoping led to the reduction of the green upconversion emission in Er：LiNbO3 c...The enhanced intensity and lengthened lifetime of 1.54 μm emission were observed for Er：LiNbO3 crystal codoped with Zn2＋ ions.The ZnO codoping led to the reduction of the green upconversion emission in Er：LiNbO3 crystals.The decay trace of the 4S3/2→4I15/2 was ob-viously nonexponential for Er：LiNbO3 codoped with 0 and 3 mol.% ZnO,but became exponential for one codoped with 6 mol.% ZnO.The OH-absorption spectra showed after codoping with Zn2＋ ions,the OH-absorption peaking position shifted from ~3495 to 3484 cm-1,and the absorption cross section decreased.These spectroscopic characteristics suggested that the improvement of 1.54 μm emission was attributed to the reduction of Er3＋ cluster sites.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2024YFE0105200)the China Postdoctoral Science Foundation(Grant No.2023M743151)the Natural Science Foundation of Henan Province,China(Grant No.242300420304)。
文摘Bi(Sb)_(2)Te(Se)_(3)alloys,as the only commercial thermoelectric materials,have been applied widely in cooling fields.While,the current energy conversion efficiency(dominated by the dimensionless ZT)of commercial products is still lower and cannot meet the market demand.In this paper,high thermoelectric performance at room temperature in both zonemelted(ZM)Bi_(0.46)Sb_(1.54)Te_(3)ingots and powder-metallurgy(PM)Bi_(0.46)Sb_(1.54)Te_(3)blocks with a large size was realized successfully by optimizing their preparation process.The peak ZT values of ZM and PM p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys reached 1.26 and 1.45,respectively.They are higher than those of all the n-type or p-type Bi_(2)Te_(3)-based products in current commercial applications.In particular,their production process of large size p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys could be directly industrialized.
文摘A series of highly Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses were investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and up-conversion spectra were performed to examine the effect of concentration quenching on spectroscopic properties. In the glasses with Er^(3+) concentrations below 10% (mol fraction), concentration quenching is low and the Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses gave stronger fluorescence of 1.54 μm from the (()~4I_(13/2))→(()~4I_(15/2)) transition than those of Er^(3+) singly-doped glasses. In the glass with Er^(3+) concentrations above 10%, concentration quenching of 1.54 μm obviously occurs more than that of the Er^(3+) singly-doped samples because of the back energy-transfer from Er^(3+) to Yb^(3+). To obtain the highest emission efficiency at 1.54 μm, the optimum doping-concentration ratio of Er^(3+)/Yb^(3+) is found to be approximately 1∶1 in mol fraction when the Er^(3+) concentration is less than 10%.
基金Project supported by the National Natural Science Foundation of China (10732100)National Science Foundation of Heilongjiang Province (B200903)
文摘The enhanced intensity and lengthened lifetime of 1.54 μm emission were observed for Er：LiNbO3 crystal codoped with Zn2＋ ions.The ZnO codoping led to the reduction of the green upconversion emission in Er：LiNbO3 crystals.The decay trace of the 4S3/2→4I15/2 was ob-viously nonexponential for Er：LiNbO3 codoped with 0 and 3 mol.% ZnO,but became exponential for one codoped with 6 mol.% ZnO.The OH-absorption spectra showed after codoping with Zn2＋ ions,the OH-absorption peaking position shifted from ~3495 to 3484 cm-1,and the absorption cross section decreased.These spectroscopic characteristics suggested that the improvement of 1.54 μm emission was attributed to the reduction of Er3＋ cluster sites.
