It is well known that Cu-oxygen plays a very important role in high T<sub>c</sub> superconductors YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7<sub>δ</sub></sub>. NQ...It is well known that Cu-oxygen plays a very important role in high T<sub>c</sub> superconductors YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7<sub>δ</sub></sub>. NQR can provide microscopic information about the electronic configuration around each Cu site, so it is a powerful method for revealing the structure of high T<sub>c</sub> superconductors.展开更多
A dream or interesting problem is to obtain more information based on one measurement,for example to obtain all the thermodynamic functions based on specific heat only. We call it"holographic"study.After mor...A dream or interesting problem is to obtain more information based on one measurement,for example to obtain all the thermodynamic functions based on specific heat only. We call it"holographic"study.After more than 10 year's efforts,we suggest one possibility(or only one)is to solve an inverse problem(specific heat-phonon spectrum inversion,SPI).In this talk we will review recent development of studies of a class of inverse problems,including Dai's exact solution and Chen's formula and their unification.T...展开更多
A unidirectional reaction for synthesis of the high T_c superconductor YBa_2Cu_3O_x has been proposed, Its T_c is 90-94.5 K and △T is 1 K. The phase relationships in the system Y_2BaCuO_5-Y_2Cu_2O_5-CuO-YBa_2Cu_3O_x ...A unidirectional reaction for synthesis of the high T_c superconductor YBa_2Cu_3O_x has been proposed, Its T_c is 90-94.5 K and △T is 1 K. The phase relationships in the system Y_2BaCuO_5-Y_2Cu_2O_5-CuO-YBa_2Cu_3O_x were studied and discussed.展开更多
We have developed an experimental setup that has been proven suitable for the study of photoresponse of high Tc superconductors. The distinguish feature of this experimental setup lies mainly in the data acquisition s...We have developed an experimental setup that has been proven suitable for the study of photoresponse of high Tc superconductors. The distinguish feature of this experimental setup lies mainly in the data acquisition system which is equipped with computer as well as the IEEE-488 interface bus. which ensures the accuracy to experimental results. Using the experimental setup, the optical response to laser radiation in high-Tc superconductors has been examined, both of bolometric effect and nonequilibrium optical response are revealed.展开更多
The phonon density of states of YBa2Cu3O6.92 is obtained with the method of Fourier decon-volution and Tikhonov-s regularization technique from the experimental specific heat data. The result is compared with that of ...The phonon density of states of YBa2Cu3O6.92 is obtained with the method of Fourier decon-volution and Tikhonov-s regularization technique from the experimental specific heat data. The result is compared with that of neutron inelastic scattering.展开更多
The synthesis kinetics of YBa_2Cu_30_x supercon- ductor was studied through comparing the calcina- tion (sintering) processes of different kinds of powders. It was shown that the temperature of synthesis of YBa_2Cu_30...The synthesis kinetics of YBa_2Cu_30_x supercon- ductor was studied through comparing the calcina- tion (sintering) processes of different kinds of powders. It was shown that the temperature of synthesis of YBa_2Cu_30_x phase can be lowered from 950℃ to 800℃ through direct calcination of multiphase powder with uniform chemical com- position. The stress which is caused by the volume change during synthetic reaction breaks the particles. It facilitates the formation of highly active superfines of superconductor.展开更多
The X-ray Ф-scan technique was applied to determine the in-plane orientation relationship of the high T_csuperconductins bi-epitaxial junction. The result shows that the in-plane orientation relation of the films in ...The X-ray Ф-scan technique was applied to determine the in-plane orientation relationship of the high T_csuperconductins bi-epitaxial junction. The result shows that the in-plane orientation relation of the films in thetwo sides of the grain boundary can be easily obtained with this method. By controlling the growth condition,a 45° YBCO grain boundary can be made on the SrTiO_3 substrate.展开更多
0 Introduction In recent years, the study of Y-Ba-Cu-O superconductor have made much progress. The superconducting applications are showing bright future. Generally, critical current is very lower (especially bulk sam...0 Introduction In recent years, the study of Y-Ba-Cu-O superconductor have made much progress. The superconducting applications are showing bright future. Generally, critical current is very lower (especially bulk sample ). The Largest J_c is only 10~3 A/cm^2. Ordinarilly, the typical critical current of Nb-Ti alloy is 10~6 A/cm^2 about 4.2 K. Hence, the level of current density have become a problem interested in by scientists. In this paper, microstrueture of Y_1 Ba_2 Cu_2 O_(7-8) superconductor is examined. The grade intersection-tunnel modal is put forward here. Some mecha-展开更多
用 EPMA 的背散射电子像和相的元素分析发现,在 Ag-EuBa_2Cu_(3-x)O_7高 T_c 陶瓷中存在富 Ag 贫Cu 和无 Eu 二种非超导相,在 Ag-YBa_2Cu_(3-x)O_7中存在富 Ag 贫 Cu,富 Y 贫 Cu 和无 Y 富 Cu 三种非超导相,减少非超导相和气孔的数量是...用 EPMA 的背散射电子像和相的元素分析发现,在 Ag-EuBa_2Cu_(3-x)O_7高 T_c 陶瓷中存在富 Ag 贫Cu 和无 Eu 二种非超导相,在 Ag-YBa_2Cu_(3-x)O_7中存在富 Ag 贫 Cu,富 Y 贫 Cu 和无 Y 富 Cu 三种非超导相,减少非超导相和气孔的数量是提高超导氧化物陶瓷临界电流密度的重要途径。对高 T_(?)陶瓷显微结构的观察度现,T_c 对显微结构因素不敏感,T_c 相同的超导陶瓷显微结构可有明显差异;断裂方式与烧结温度有关。展开更多
基金Project supported by the National Superconductivity Research and Developing Center.
文摘It is well known that Cu-oxygen plays a very important role in high T<sub>c</sub> superconductors YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7<sub>δ</sub></sub>. NQR can provide microscopic information about the electronic configuration around each Cu site, so it is a powerful method for revealing the structure of high T<sub>c</sub> superconductors.
文摘A dream or interesting problem is to obtain more information based on one measurement,for example to obtain all the thermodynamic functions based on specific heat only. We call it"holographic"study.After more than 10 year's efforts,we suggest one possibility(or only one)is to solve an inverse problem(specific heat-phonon spectrum inversion,SPI).In this talk we will review recent development of studies of a class of inverse problems,including Dai's exact solution and Chen's formula and their unification.T...
文摘A unidirectional reaction for synthesis of the high T_c superconductor YBa_2Cu_3O_x has been proposed, Its T_c is 90-94.5 K and △T is 1 K. The phase relationships in the system Y_2BaCuO_5-Y_2Cu_2O_5-CuO-YBa_2Cu_3O_x were studied and discussed.
文摘We have developed an experimental setup that has been proven suitable for the study of photoresponse of high Tc superconductors. The distinguish feature of this experimental setup lies mainly in the data acquisition system which is equipped with computer as well as the IEEE-488 interface bus. which ensures the accuracy to experimental results. Using the experimental setup, the optical response to laser radiation in high-Tc superconductors has been examined, both of bolometric effect and nonequilibrium optical response are revealed.
文摘The phonon density of states of YBa2Cu3O6.92 is obtained with the method of Fourier decon-volution and Tikhonov-s regularization technique from the experimental specific heat data. The result is compared with that of neutron inelastic scattering.
文摘The synthesis kinetics of YBa_2Cu_30_x supercon- ductor was studied through comparing the calcina- tion (sintering) processes of different kinds of powders. It was shown that the temperature of synthesis of YBa_2Cu_30_x phase can be lowered from 950℃ to 800℃ through direct calcination of multiphase powder with uniform chemical com- position. The stress which is caused by the volume change during synthetic reaction breaks the particles. It facilitates the formation of highly active superfines of superconductor.
文摘The X-ray Ф-scan technique was applied to determine the in-plane orientation relationship of the high T_csuperconductins bi-epitaxial junction. The result shows that the in-plane orientation relation of the films in thetwo sides of the grain boundary can be easily obtained with this method. By controlling the growth condition,a 45° YBCO grain boundary can be made on the SrTiO_3 substrate.
文摘0 Introduction In recent years, the study of Y-Ba-Cu-O superconductor have made much progress. The superconducting applications are showing bright future. Generally, critical current is very lower (especially bulk sample ). The Largest J_c is only 10~3 A/cm^2. Ordinarilly, the typical critical current of Nb-Ti alloy is 10~6 A/cm^2 about 4.2 K. Hence, the level of current density have become a problem interested in by scientists. In this paper, microstrueture of Y_1 Ba_2 Cu_2 O_(7-8) superconductor is examined. The grade intersection-tunnel modal is put forward here. Some mecha-
文摘用 EPMA 的背散射电子像和相的元素分析发现,在 Ag-EuBa_2Cu_(3-x)O_7高 T_c 陶瓷中存在富 Ag 贫Cu 和无 Eu 二种非超导相,在 Ag-YBa_2Cu_(3-x)O_7中存在富 Ag 贫 Cu,富 Y 贫 Cu 和无 Y 富 Cu 三种非超导相,减少非超导相和气孔的数量是提高超导氧化物陶瓷临界电流密度的重要途径。对高 T_(?)陶瓷显微结构的观察度现,T_c 对显微结构因素不敏感,T_c 相同的超导陶瓷显微结构可有明显差异;断裂方式与烧结温度有关。
