Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- ...Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- x Cu 3O 7- δ before and after the heat treatment was investigated by XRD. In order to know the effects of heat treatment, the T c and J c of samples with and without the heat treatment in Ar were comparatively studied. The results show that the substitution of Nd for Ba decreases, whereas T c and J c increase after the treatment. The Nd 1+ x Ba 2- x Cu 3O 7- δ samples were oxygenated in pure oxygen at 300 ℃ . Based on the XRD spectra it was found that the samples with x <0.4 can transform from tetragonal phase into orthorhombic phase after the oxygenation, whereas in the sample with x >0.4 no phase transition occurs even after a long time oxygenation.展开更多
Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu...Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu_3O_(7-δ)(YBCO) and half of HoBa_2Cu_3O_(7-δ)(HBCO) superconducting materials. As the distance between HBCO targetmaterial and substrate is varied , the Ho content in material is changed respectively. When the content of Ho is0. 7 (atom ratio) , the T_c>83K.展开更多
Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temper...Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temperature T_s and the distance of the target to subetrate. Thin films deposited under the optimum conditions (Po_2/P_(Ar)= 1:2 ; T_s=730℃) show a critical temlierature clase to 87K and a transition width less than 1K. X-raydiffraction analysis shows that the films are highiy c-axis oriented. Auger electron spectroscopy depth profilingdemonstrates Ho diffusion into the Zr(Y)O_2 subetrate owing to the Ho subetitution for Y.展开更多
High-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y_(0.7)+Dy_(0.2)+Gd_(0.2)+Sm_(0.2)+Eu_(0.2))(HE-REBCO) superconducting films doped with multiple rare earth elements were successfully fabricated with thickness up to 800 nm by a...High-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y_(0.7)+Dy_(0.2)+Gd_(0.2)+Sm_(0.2)+Eu_(0.2))(HE-REBCO) superconducting films doped with multiple rare earth elements were successfully fabricated with thickness up to 800 nm by a trifluoroacetate-metal organic deposition(TFA-MOD).The enhanced entropy change ΔS of the HEREBCO system promotes the c-axis growth of REBCO thin film in the competition with a/b-axis growth.The microstructure and element distribution were investigated by the transmission electron microscopy(TEM) and energy dispersive spectroscopy(EDS).The results show that HE-REBCO films have a great amount of stacking defects,lattice distortions and various rare earth oxides.Furthermore,the microstrain of HE-REBCO films increases significantly compared to the undoped YBCO and(Y,Dy)BCO films.Finally,the superco nducting critical temperature(T_c^(onset)) of HE-REBCO films is about 93 K,and the in-field properties are significantly improved,especially at the temperature of about 77 K.The maximum pinning force density(F_(p,max)) of the HE-REBCO samples at 77 K is 1.7 times higher than that of the undoped YBCO films.展开更多
文摘Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- x Cu 3O 7- δ before and after the heat treatment was investigated by XRD. In order to know the effects of heat treatment, the T c and J c of samples with and without the heat treatment in Ar were comparatively studied. The results show that the substitution of Nd for Ba decreases, whereas T c and J c increase after the treatment. The Nd 1+ x Ba 2- x Cu 3O 7- δ samples were oxygenated in pure oxygen at 300 ℃ . Based on the XRD spectra it was found that the samples with x <0.4 can transform from tetragonal phase into orthorhombic phase after the oxygenation, whereas in the sample with x >0.4 no phase transition occurs even after a long time oxygenation.
文摘Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu_3O_(7-δ)(YBCO) and half of HoBa_2Cu_3O_(7-δ)(HBCO) superconducting materials. As the distance between HBCO targetmaterial and substrate is varied , the Ho content in material is changed respectively. When the content of Ho is0. 7 (atom ratio) , the T_c>83K.
文摘Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temperature T_s and the distance of the target to subetrate. Thin films deposited under the optimum conditions (Po_2/P_(Ar)= 1:2 ; T_s=730℃) show a critical temlierature clase to 87K and a transition width less than 1K. X-raydiffraction analysis shows that the films are highiy c-axis oriented. Auger electron spectroscopy depth profilingdemonstrates Ho diffusion into the Zr(Y)O_2 subetrate owing to the Ho subetitution for Y.
基金Project supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB25000000)National Natural Science Foundation of China (52172271)。
文摘High-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y_(0.7)+Dy_(0.2)+Gd_(0.2)+Sm_(0.2)+Eu_(0.2))(HE-REBCO) superconducting films doped with multiple rare earth elements were successfully fabricated with thickness up to 800 nm by a trifluoroacetate-metal organic deposition(TFA-MOD).The enhanced entropy change ΔS of the HEREBCO system promotes the c-axis growth of REBCO thin film in the competition with a/b-axis growth.The microstructure and element distribution were investigated by the transmission electron microscopy(TEM) and energy dispersive spectroscopy(EDS).The results show that HE-REBCO films have a great amount of stacking defects,lattice distortions and various rare earth oxides.Furthermore,the microstrain of HE-REBCO films increases significantly compared to the undoped YBCO and(Y,Dy)BCO films.Finally,the superco nducting critical temperature(T_c^(onset)) of HE-REBCO films is about 93 K,and the in-field properties are significantly improved,especially at the temperature of about 77 K.The maximum pinning force density(F_(p,max)) of the HE-REBCO samples at 77 K is 1.7 times higher than that of the undoped YBCO films.
