Herein,we reported novel Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors elaborated via conventional solid-state reaction.and we further explored their properties as optical thermometer by using fluorescence intensity ratio(FIR...Herein,we reported novel Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors elaborated via conventional solid-state reaction.and we further explored their properties as optical thermometer by using fluorescence intensity ratio(FIR)method complemented by detailed analysis on crystal structure,up-conversion luminescence and energy transfer from Yb^(3+)to Er^(3+).Upon 980 nm laser excitation,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors present525,547 and 659 nm emission bands assigned to the characteristic transitions of Er^(3+).Furthermore,Y_(4)GeO_(8):Er^(3+),Yb^(3+)samples show outstanding temperature sensing performances.To be specific,the minimal temperature resolution is 0.03 K(303 K),and the relative sensitivity of FIR can be up to 1.152%/K(303 K).Hence,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors can be possible candidates for thermometry devices.展开更多
YBCO films doped with different contents of gadolinium(Gd) were prepared by the low-fluorine(low-F)trifluoroacetate metal-organic deposition(MOD) method.The effects of flow rate and holding time of the firing(crystall...YBCO films doped with different contents of gadolinium(Gd) were prepared by the low-fluorine(low-F)trifluoroacetate metal-organic deposition(MOD) method.The effects of flow rate and holding time of the firing(crystallization) stage on the superconducting properties of YxGd1-xBa2 Cu3 O7-δ(YGdBCO) films were investigated.The phase formation and texture were characterized by the X-ray diffraction(XRD),which indicate that severe degradation of the microstructure will be induced with the inappropriate flow rate.The surface morphology and element distribution were investigated by the scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS).The results show that increasing the holding time of the firing stage is effective for the further decomposition of residual impurity phase on the surface.The mechanisms of the phase and surface evolution are also discussed.Finally,a high critical current density(Jc) value of 5.4 MA/cm2 was achieved in the Y0.9Gd0.1BCO film fabricated by the cooperative control of the flow rate and holding time of the firing stage,which are contributed to the formation of excellent texture,homogeneous microstructure and dense surface of the YGdBCO films.展开更多
基金Project supported by National Natural Science Foundation of China(11974315)Guangdong Science and Technology Innovation Strategy Foundation of China(20190310)。
文摘Herein,we reported novel Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors elaborated via conventional solid-state reaction.and we further explored their properties as optical thermometer by using fluorescence intensity ratio(FIR)method complemented by detailed analysis on crystal structure,up-conversion luminescence and energy transfer from Yb^(3+)to Er^(3+).Upon 980 nm laser excitation,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors present525,547 and 659 nm emission bands assigned to the characteristic transitions of Er^(3+).Furthermore,Y_(4)GeO_(8):Er^(3+),Yb^(3+)samples show outstanding temperature sensing performances.To be specific,the minimal temperature resolution is 0.03 K(303 K),and the relative sensitivity of FIR can be up to 1.152%/K(303 K).Hence,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors can be possible candidates for thermometry devices.
基金Project supported by the National Natural Science Foundation of China (51577180,U1832131,51721005,51477168)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2016128)。
文摘YBCO films doped with different contents of gadolinium(Gd) were prepared by the low-fluorine(low-F)trifluoroacetate metal-organic deposition(MOD) method.The effects of flow rate and holding time of the firing(crystallization) stage on the superconducting properties of YxGd1-xBa2 Cu3 O7-δ(YGdBCO) films were investigated.The phase formation and texture were characterized by the X-ray diffraction(XRD),which indicate that severe degradation of the microstructure will be induced with the inappropriate flow rate.The surface morphology and element distribution were investigated by the scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS).The results show that increasing the holding time of the firing stage is effective for the further decomposition of residual impurity phase on the surface.The mechanisms of the phase and surface evolution are also discussed.Finally,a high critical current density(Jc) value of 5.4 MA/cm2 was achieved in the Y0.9Gd0.1BCO film fabricated by the cooperative control of the flow rate and holding time of the firing stage,which are contributed to the formation of excellent texture,homogeneous microstructure and dense surface of the YGdBCO films.