A novel layered perovskite tantalate phosphor Sr_(3)LaTa_(3)O_(12):Sm^(3+)(SLTO:Sm^(3+)) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphol...A novel layered perovskite tantalate phosphor Sr_(3)LaTa_(3)O_(12):Sm^(3+)(SLTO:Sm^(3+)) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphology,element distribution and luminescent properties of the SLTO:xSm^(3+)(x= 0.01 mol%-0.30 mol%) phosphors were investigated. Under 408 nm excitation, the optimum doped SLTO:0.10Sm^(3+) phosphor emits orangered light at 598 nm with the highest emission peak(4G_(5/2)→6H_(7/2)). The critical energy transfer distance is 1.687 nm. The prepared SLTO:0.10Sm^(3+)phosphor has excellent thermal stability with temperature quenching temperature(T_(0.5)> 500 K) and high activation energy(E_(a)= 0.25 e V). Through calculation, the chromaticity coordinates of all samples are concentrated in the orange-red area, and the color purity reaches 99%. The fabricated white light-emitting diode(w-LED) has a good correlated color temperature(5132 K), a high R_(a)(89), and the CIE chromaticity coordinates(0.340, 0.327). Consequently, the superiority of orange-red-emitting tantalate SLTO:Sm^(3+) phosphors for w-LEDs is demonstrated.展开更多
Fabricating a high-performing thermoset using bio-based flame retardant is critical for the sustain-able development of engineering materials with superior fire safety and robust mechanical properties.Herein,the epoxy...Fabricating a high-performing thermoset using bio-based flame retardant is critical for the sustain-able development of engineering materials with superior fire safety and robust mechanical properties.Herein,the epoxy(EP)composites with the industrial requirements are manufactured with a novel high-efficient,lignin-based flame retardant named DAL-x,which is fabricated by grafting 9,10-dihydro-9-oxa-10-phosphaze-10-oxide(DOPO)onto lignin.The resulting DAL-x/EP composite exhibits excellent flame retardancy with a desirable UL-94 V-0 rating and a satisfactory limiting oxygen index(LOI)of 29.8%due to the appropriate phosphorus content of DAL-x with adjustable molecular chain structure.More-over,the DAL-x/EP composite shows an unexpected improvement in the elastic modulus(∼36%)and well-preserved strength and ductility compared with those of pure EP.This work offers a feasible strat-egy for creating efficient bio-based flame retardants utilizing industrial waste lignin and preparing high-performance EP composites that meet the demanding requirement of fire retardancy in industries,con-tributing to the circular economy and sustainability.展开更多
Understanding the damage behavior and cracking mechanism of brittle shale is crucial for hydraulic fracturing design.In this research,uniaxial compression tests are conducted on shale samples with different bedding pl...Understanding the damage behavior and cracking mechanism of brittle shale is crucial for hydraulic fracturing design.In this research,uniaxial compression tests are conducted on shale samples with different bedding plane orientations,and acoustic emission monitoring is implemented synchronously.The results indicate that the apparent elastic modulus increases with increasing bedding orientation.For the bedding orienta-tions of 45°and 90°,the lateral deformation is anisotropic due to the bedding structure,revealing the anisotropic Poisson effect.A shear failure surface and tensile failure surfaces form parallel to the bedding plane for bedding orientations of 45°and 90°,respectively.For the bedding orientation of 0°,shear failure mainly occurs through the bedding planes.Additionally,the damage mechanism of shale is investigated by crack classification based on AE parameters.It is found that crack initiation is induced by the generation of shear cracks for the bedding orientation of 45°,whereas by the generation of tensile cracks for other bedding orientations.According to damage attributable to different type cracks,shear cracks dominate the damage behavior for bedding orientations of 0°and 45°,whereas tensile cracks dominate the damage behavior for bedding orientation of 90°.Finally,the information entropy is calculated by AE energy.A low value of information entropy,approximately 0.36,predicts failure with a low degree of instability for the bedding orientation of 0°,whereas a high value of information entropy,more than 1.5,predicts failure with a high degree of instability for other bedding orientations.This finding indicates that the failure behavior is gradual progressive damage for bedding orientation of 0°,whereas sudden damage dominates failure behavior for other bedding orientations.展开更多
基金Project supported by the Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)the Construction Program of the Key Discipline of the Education Department in Hunan Province(18A465)+1 种基金the Natural Science Foundation of Hunan Province(2023JJ31000)the Natural Science Foundation of Shaanxi Province(2022NY-224)。
文摘A novel layered perovskite tantalate phosphor Sr_(3)LaTa_(3)O_(12):Sm^(3+)(SLTO:Sm^(3+)) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphology,element distribution and luminescent properties of the SLTO:xSm^(3+)(x= 0.01 mol%-0.30 mol%) phosphors were investigated. Under 408 nm excitation, the optimum doped SLTO:0.10Sm^(3+) phosphor emits orangered light at 598 nm with the highest emission peak(4G_(5/2)→6H_(7/2)). The critical energy transfer distance is 1.687 nm. The prepared SLTO:0.10Sm^(3+)phosphor has excellent thermal stability with temperature quenching temperature(T_(0.5)> 500 K) and high activation energy(E_(a)= 0.25 e V). Through calculation, the chromaticity coordinates of all samples are concentrated in the orange-red area, and the color purity reaches 99%. The fabricated white light-emitting diode(w-LED) has a good correlated color temperature(5132 K), a high R_(a)(89), and the CIE chromaticity coordinates(0.340, 0.327). Consequently, the superiority of orange-red-emitting tantalate SLTO:Sm^(3+) phosphors for w-LEDs is demonstrated.
基金financially supported by the National Natural Science Foundation of China(Nos.51873196 and 51903222)the Australian Research Council(Nos.LP220100278,DP190102992 and FT190100188)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY21E030001)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2022C03128).
文摘Fabricating a high-performing thermoset using bio-based flame retardant is critical for the sustain-able development of engineering materials with superior fire safety and robust mechanical properties.Herein,the epoxy(EP)composites with the industrial requirements are manufactured with a novel high-efficient,lignin-based flame retardant named DAL-x,which is fabricated by grafting 9,10-dihydro-9-oxa-10-phosphaze-10-oxide(DOPO)onto lignin.The resulting DAL-x/EP composite exhibits excellent flame retardancy with a desirable UL-94 V-0 rating and a satisfactory limiting oxygen index(LOI)of 29.8%due to the appropriate phosphorus content of DAL-x with adjustable molecular chain structure.More-over,the DAL-x/EP composite shows an unexpected improvement in the elastic modulus(∼36%)and well-preserved strength and ductility compared with those of pure EP.This work offers a feasible strat-egy for creating efficient bio-based flame retardants utilizing industrial waste lignin and preparing high-performance EP composites that meet the demanding requirement of fire retardancy in industries,con-tributing to the circular economy and sustainability.
基金supported by the National Natural Science Foundation of China(Grant No.51704198)the Department of Science and Technology of Sichuan Province(No.2021YFH0030).
文摘Understanding the damage behavior and cracking mechanism of brittle shale is crucial for hydraulic fracturing design.In this research,uniaxial compression tests are conducted on shale samples with different bedding plane orientations,and acoustic emission monitoring is implemented synchronously.The results indicate that the apparent elastic modulus increases with increasing bedding orientation.For the bedding orienta-tions of 45°and 90°,the lateral deformation is anisotropic due to the bedding structure,revealing the anisotropic Poisson effect.A shear failure surface and tensile failure surfaces form parallel to the bedding plane for bedding orientations of 45°and 90°,respectively.For the bedding orientation of 0°,shear failure mainly occurs through the bedding planes.Additionally,the damage mechanism of shale is investigated by crack classification based on AE parameters.It is found that crack initiation is induced by the generation of shear cracks for the bedding orientation of 45°,whereas by the generation of tensile cracks for other bedding orientations.According to damage attributable to different type cracks,shear cracks dominate the damage behavior for bedding orientations of 0°and 45°,whereas tensile cracks dominate the damage behavior for bedding orientation of 90°.Finally,the information entropy is calculated by AE energy.A low value of information entropy,approximately 0.36,predicts failure with a low degree of instability for the bedding orientation of 0°,whereas a high value of information entropy,more than 1.5,predicts failure with a high degree of instability for other bedding orientations.This finding indicates that the failure behavior is gradual progressive damage for bedding orientation of 0°,whereas sudden damage dominates failure behavior for other bedding orientations.
