Thermal quenching limits further large-scale applications of Pr^(3+)-doped phosphors.Research shows that intervalence charge transfer(IVCT)can be used as both the quenching luminescence channel and the red-emitting co...Thermal quenching limits further large-scale applications of Pr^(3+)-doped phosphors.Research shows that intervalence charge transfer(IVCT)can be used as both the quenching luminescence channel and the red-emitting compensation channel for Pr^(3+)-doped phosphors due to its unique dual-function mechanism.The problem of how to reduce quenching and improve compensation effects through IVCT has become an important issue.In this contribution,a dual compensation mechanism is proposed by designing an excitation-driven strategy of charge transfer(CT)and IVCT,thus realizing anti-thermal quenching of red light.Under different excitation-driven strategies,YNbO_(4):x%Pr^(3+)phosphors exhibited both single compensation and dual compensation effects in red emission.In the case of excitation of the IVCT band alone,the 3P0 energy level electrons of Pr^(3+)were transferred to the^(1)D_(2)level through the IVCT state formed between Pr^(3+)and Nb^(5+),resulting in enhanced red emission from the^(1)D_(2)→^(3)H_(4)transition of Pr^(3+).In the case of simultaneously exciting the charge transfer band(CTB)and the IVCT band,there is a charge transfer from both the host matrix and the Pr^(3+)3P_(0)level to the^(1)D_(2)level,leading to higher red emission intensities in all samples within the temperature range of 303 K to 523 K compared to single compensation.Notably,the YNbO_(4):0.1%Pr^(3+)sample exhibited a maximum comprehensive intensity of red emission under dual compensation,reaching 2.18 times its intensity at 303 K,significantly higher than the 1.38 times its intensity under single compensation.Furthermore,this phosphor exhibits high optical temperature sensing sensitivity and excellent thermochromic properties,allowing for both quantitative and qualitative temperature measurements.This work provided a new avenue for the development of Pr^(3+)-doped niobate anti-thermal quenching luminescent materials.展开更多
A Pr^(3+)/Tb^(3+)co-doped LuNbO_(4) phosphor was synthesized as a self-calibrated optical thermometer using a high-temperature solid-state method,and its structure and luminescent property were elaborately investigate...A Pr^(3+)/Tb^(3+)co-doped LuNbO_(4) phosphor was synthesized as a self-calibrated optical thermometer using a high-temperature solid-state method,and its structure and luminescent property were elaborately investigated.Under intervalence charge transfer(IVCT)excitation at 305 nm,the sample LuNbO_(4):Pr^(3+)/Tb^(3+)exhibited several bands in the green and red regions,originating from characteristics transitions of Pr^(3+)and Tb^(3+)ions.Through monitoring thermo-responsive emission intensity ratios from the ^(1)D_(2)→^(3)H_(4)(Pr^(3+))and ^(5)D_(4)→^(7)F_(5)(Tb^(3+))transitions,sensitive thermometry with good signal discriminability was achieved in phosphor LuNbO_(4):Pr^(3+)/Tb^(3+)owing to a significant difference in thermal activation energy between Pr^(3+)and Tb^(3+)under IVCT excitation.Moreover,the maximum absolute sensitivity and relative sensitivity reached about 0.024 K^(-1) at 493 K and 1.26%K^(-1) at 463 K,respectively,for the LuNbO_(4):Pr^(3+)/Tb^(3+)sample,which implies that the present phosphor could be considered as a promising candidate for self-calibrated optical thermometers.展开更多
The synthesis,single-crystal structures and magnetic properties of three new cyano-bridged complexes[Fe_(4)^(III)M_(2)^(II)](M=Fe^(II),Co^(II),Ni^(II))are reported.Electronic absorption spectroscopy reveals the occurr...The synthesis,single-crystal structures and magnetic properties of three new cyano-bridged complexes[Fe_(4)^(III)M_(2)^(II)](M=Fe^(II),Co^(II),Ni^(II))are reported.Electronic absorption spectroscopy reveals the occurrence of intervalence charge transfer for[Fe_(4)^(III)Fe_(2)^(II)].Field-induced slow magnetic relaxation behavior is exhibited for[Fe_(4)^(III)Co^(II)2]and[Fe_(4)^(III)Ni^(II)2]which originates from the ferromagnetic interactions between Fe^(III)and M_(II)spin centers of the square.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.21401130)the Opening Research Fund of the State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences(RERU2014005).
文摘Thermal quenching limits further large-scale applications of Pr^(3+)-doped phosphors.Research shows that intervalence charge transfer(IVCT)can be used as both the quenching luminescence channel and the red-emitting compensation channel for Pr^(3+)-doped phosphors due to its unique dual-function mechanism.The problem of how to reduce quenching and improve compensation effects through IVCT has become an important issue.In this contribution,a dual compensation mechanism is proposed by designing an excitation-driven strategy of charge transfer(CT)and IVCT,thus realizing anti-thermal quenching of red light.Under different excitation-driven strategies,YNbO_(4):x%Pr^(3+)phosphors exhibited both single compensation and dual compensation effects in red emission.In the case of excitation of the IVCT band alone,the 3P0 energy level electrons of Pr^(3+)were transferred to the^(1)D_(2)level through the IVCT state formed between Pr^(3+)and Nb^(5+),resulting in enhanced red emission from the^(1)D_(2)→^(3)H_(4)transition of Pr^(3+).In the case of simultaneously exciting the charge transfer band(CTB)and the IVCT band,there is a charge transfer from both the host matrix and the Pr^(3+)3P_(0)level to the^(1)D_(2)level,leading to higher red emission intensities in all samples within the temperature range of 303 K to 523 K compared to single compensation.Notably,the YNbO_(4):0.1%Pr^(3+)sample exhibited a maximum comprehensive intensity of red emission under dual compensation,reaching 2.18 times its intensity at 303 K,significantly higher than the 1.38 times its intensity under single compensation.Furthermore,this phosphor exhibits high optical temperature sensing sensitivity and excellent thermochromic properties,allowing for both quantitative and qualitative temperature measurements.This work provided a new avenue for the development of Pr^(3+)-doped niobate anti-thermal quenching luminescent materials.
基金supported by National Natural Science Foundation of China(No.51672215,11274251)Research Fund for the Doctoral Program of Higher Education of China(RFDP)(No.20136101110017).
文摘A Pr^(3+)/Tb^(3+)co-doped LuNbO_(4) phosphor was synthesized as a self-calibrated optical thermometer using a high-temperature solid-state method,and its structure and luminescent property were elaborately investigated.Under intervalence charge transfer(IVCT)excitation at 305 nm,the sample LuNbO_(4):Pr^(3+)/Tb^(3+)exhibited several bands in the green and red regions,originating from characteristics transitions of Pr^(3+)and Tb^(3+)ions.Through monitoring thermo-responsive emission intensity ratios from the ^(1)D_(2)→^(3)H_(4)(Pr^(3+))and ^(5)D_(4)→^(7)F_(5)(Tb^(3+))transitions,sensitive thermometry with good signal discriminability was achieved in phosphor LuNbO_(4):Pr^(3+)/Tb^(3+)owing to a significant difference in thermal activation energy between Pr^(3+)and Tb^(3+)under IVCT excitation.Moreover,the maximum absolute sensitivity and relative sensitivity reached about 0.024 K^(-1) at 493 K and 1.26%K^(-1) at 463 K,respectively,for the LuNbO_(4):Pr^(3+)/Tb^(3+)sample,which implies that the present phosphor could be considered as a promising candidate for self-calibrated optical thermometers.
基金supported by the National Natural Science Foundation of China(NSFC,21701088)the Natural Science Foundation of Tianjin City(17JCYBJC41000)+1 种基金KRD gratefully acknowledges the National Science Foundation(CHE-1808779)the Robert A.Welch Foundation(A-1449)for support of this work.
文摘The synthesis,single-crystal structures and magnetic properties of three new cyano-bridged complexes[Fe_(4)^(III)M_(2)^(II)](M=Fe^(II),Co^(II),Ni^(II))are reported.Electronic absorption spectroscopy reveals the occurrence of intervalence charge transfer for[Fe_(4)^(III)Fe_(2)^(II)].Field-induced slow magnetic relaxation behavior is exhibited for[Fe_(4)^(III)Co^(II)2]and[Fe_(4)^(III)Ni^(II)2]which originates from the ferromagnetic interactions between Fe^(III)and M_(II)spin centers of the square.
