Tc, Jc and Rs properties of large area double sided YBCO thin films deposited on LaAlO3 substrates by direct current sputtering were reported.Film thickness of the obtained thin films is over 300 nm, Tc > 90 K; Rs ...Tc, Jc and Rs properties of large area double sided YBCO thin films deposited on LaAlO3 substrates by direct current sputtering were reported.Film thickness of the obtained thin films is over 300 nm, Tc > 90 K; Rs can be as low as less than 1.0 mΩ(77 K, 10 GHz).Homogenousity of the properties around the plane was studied.Under the measnous distributions.Influences of substrate temperature and Ar and O2 pressures on properties of the double-sided thin films were discussed.展开更多
A study of the phase transitions in superconducting thin films of the Thallium-Barium-Calcium-Copper (TBCCO) system is carried out. In particular, it was got the Tl-1223 phase. For this purpose, and using the ultrason...A study of the phase transitions in superconducting thin films of the Thallium-Barium-Calcium-Copper (TBCCO) system is carried out. In particular, it was got the Tl-1223 phase. For this purpose, and using the ultrasonic spray pyrolysis technique, Barium-Calcium-Copper precursor films were first obtained. Upon deposition of the precursor films, and as a second step, they were thallium (Tl) diffused in the one-zone furnace at 860°C. This methodology resulted in superconducting films that showed a phase transition as follows: Tl-2223 → Tl-2223 + Tl-2212 → Tl-2212 → Tl-1223, achieved between 2 and 7 hours of thallium diffusion. The evidence of the phase transitions was corroborated by the experimental results of X-ray diffraction, energy dispersive spectroscopy and resistance-temperature measurements.展开更多
The growth character and microstructure of high-T_c supereonducting YBCO thin films deposited on vari- ous substrates have been studied by X-ray diffraction, TEM and SEM.The results show that when the substrate temper...The growth character and microstructure of high-T_c supereonducting YBCO thin films deposited on vari- ous substrates have been studied by X-ray diffraction, TEM and SEM.The results show that when the substrate temperaturc is around 700～800℃ the films have a highly oriented texture with c-axis pependicular to the substrate. The structure of the single crystalline YBCO films grown epitaxially at optimal substrate tem- perature of 800℃ has been established by X-ray diffraction using Seemann-Bohlin geometry (SB). Brentano-Bragg geometry(BB),transmission Laue method and TEM. The lattice matching required for epitaxial growth is achievcd by azimuthal adjustment of the film plane with respect to the substrate plane. The sperior growth is demonstrated by film properties such as critical current density(2.4×10~6 A /cm^2,3.4× 10~6 A/cm^2 and 4.7×l0~6 A/cm^2) for films deposited on YSZ[(Zr(Y)O_2],SrTiO_3 and LaAIO_3 respectively at 77 K and zero fie1d.展开更多
A novel double buffer of Eu2CuO4 (ECO)/YSZ (yttrium-stabilized zirconia) was developed for growing YBa2Cu3Oy (YBCO) thin films on Si substrates. In these films, the severe reaction between Si and YBCO is blocked by th...A novel double buffer of Eu2CuO4 (ECO)/YSZ (yttrium-stabilized zirconia) was developed for growing YBa2Cu3Oy (YBCO) thin films on Si substrates. In these films, the severe reaction between Si and YBCO is blocked by the first YSZ layer, whereas, the degradation of crystallinity and superconductivity in the grown YBCO is greatly improved by the second ECO layer. Such an ECO material possesses a very stable 214-T’ structure and excellent compatibilities with YBCO and YSZ. The result shows that the epitaxy and crystallinity of YBCO deposited on Si could be considerably enhanced by using the ECO/YSZ double buffer. The grown films are characterized by high-resolution X-ray diffraction, grazing incidence X-ray reflection, and transmission electron microscopy (TEM), respectively. It is found that well defined interfaces are formed at YBCO/ECO/YSZ boundaries. No immediate layer could be seen. The defect density in all grown layers is kept at a lower level. The YBCO film surface turns out to be very smooth. These films have full superconducting transitions above 88 K and high current carrying capacity at 77 K. The successful growth of highly epitaxial YBCO thin films on silicon with ECO/YSZ buffer, demonstrate the advantages of such a double buffer structure.展开更多
Expermental results of the preparation of YBaCuO superconductor thin film on Si(100) substrate by the method of ion beam sputtering deposition is presented.A ZrO_2 buffer layer was applied to Si(100)substrate,and was ...Expermental results of the preparation of YBaCuO superconductor thin film on Si(100) substrate by the method of ion beam sputtering deposition is presented.A ZrO_2 buffer layer was applied to Si(100)substrate,and was found to play an important role in resisting the diffusion of Si toward the film.The thin film is mainly a 123 phase with strong c-axis prefer- red orientation.The onset transition temperature of the film is 100 K and the final transition temperature 78 K.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
YBa2Cu3O7-x(YBCO) thin film has been epitaxially deposited on (1120) sapphire with Y2O3-stabilized ZrO2 (YSZ) buffer layer and shown a high critical current density Jc of 1. 6×106A/cm2 at 77 K in zero magnetic fi...YBa2Cu3O7-x(YBCO) thin film has been epitaxially deposited on (1120) sapphire with Y2O3-stabilized ZrO2 (YSZ) buffer layer and shown a high critical current density Jc of 1. 6×106A/cm2 at 77 K in zero magnetic field. The orientation relationship of the multilayer film superconductor has been determined. The(001) plane of the YBCO film is parallel to the(100) surface of the YSZ intermediate layer. YSZ buffer layer with(100) preferred orientation is about 20 nm thick and contains element Ba, due to out-diffusion of Ba from YBCO layer. The(100) preferred orientation of YSZ buffer permits the growth of high quality YBCO thin film. Y2BaCuO5 precipitates with small size distribute uniformly in the YBCO thin film and it is favourable to raise critical current density Jc.展开更多
The growth of epitaxial Ag nanoparticles doped (Bi, Pb)-2223 thin films on Si (111) substrates by pulsed laser deposition (PLD) and post-deposition oxygen annealing have been achieved. The phase identification and gro...The growth of epitaxial Ag nanoparticles doped (Bi, Pb)-2223 thin films on Si (111) substrates by pulsed laser deposition (PLD) and post-deposition oxygen annealing have been achieved. The phase identification and gross structural characteristics of synthesized films explored through X-ray diffractometer reveal that all the samples crystallize in orthorhombic structure. DC electrical resistivity measurements were done by the standard four-probe method and the results showed improvement in T<sub>c</sub> by increasing Ag nanoparticles to 1.0 wt% which had a maximum enhancement in T<sub>c</sub> for all investigated films. The surface morphology investigated through scanning electron microscope (SEM) and atomic force microscopy (AFM) results showed that an increase in T<sub>c</sub> with the appropriate Ag nanoparticles addition in the samples is associated with the enhancement of Bi (Pb)-2223 phase formation.展开更多
Textures in different layers of superconductors based on YBCO system are analyzed using the methods of pole figure and con-ventional φ scans. It is shown that the φ scanning technology has only 1-dimensional descrip...Textures in different layers of superconductors based on YBCO system are analyzed using the methods of pole figure and con-ventional φ scans. It is shown that the φ scanning technology has only 1-dimensional description and could omit some information of3-dimensional orientaion distribution, which will influence the superconductor quality The pole figure method, in contrast, demonstra-tes the orientation distribution 2-dimensionally and gives a comprehensive view of thin filIn textUr, which is a much bettCr method fortexture analysis in superconducting films, in which there is commonly an unique high sharpness textur component.展开更多
Micrcostructures of bulk and thin film YBa_2Cu_3O_(7-δ) superconductors were studied by using scanning elec-tron microscopy (SEM). It was confirmed that viscous technique processed bulk YBa_2Cu_3O_(7-δ) has a homoge...Micrcostructures of bulk and thin film YBa_2Cu_3O_(7-δ) superconductors were studied by using scanning elec-tron microscopy (SEM). It was confirmed that viscous technique processed bulk YBa_2Cu_3O_(7-δ) has a homoge-neous microstructure across the pellet diameter. Concerning the thin film, it was found that 2 ￣H￣+ ion implanta-tion with a dose of 1× 10￣(12)cm￣(-2) at 50 keV does not cause microstructural change of the film at a micrometrelevel. Combined with previous studies by using high resolution transmission electron microscopy, it appearsthat the structural modification is at an atomic scale.展开更多
文摘Tc, Jc and Rs properties of large area double sided YBCO thin films deposited on LaAlO3 substrates by direct current sputtering were reported.Film thickness of the obtained thin films is over 300 nm, Tc > 90 K; Rs can be as low as less than 1.0 mΩ(77 K, 10 GHz).Homogenousity of the properties around the plane was studied.Under the measnous distributions.Influences of substrate temperature and Ar and O2 pressures on properties of the double-sided thin films were discussed.
文摘A study of the phase transitions in superconducting thin films of the Thallium-Barium-Calcium-Copper (TBCCO) system is carried out. In particular, it was got the Tl-1223 phase. For this purpose, and using the ultrasonic spray pyrolysis technique, Barium-Calcium-Copper precursor films were first obtained. Upon deposition of the precursor films, and as a second step, they were thallium (Tl) diffused in the one-zone furnace at 860°C. This methodology resulted in superconducting films that showed a phase transition as follows: Tl-2223 → Tl-2223 + Tl-2212 → Tl-2212 → Tl-1223, achieved between 2 and 7 hours of thallium diffusion. The evidence of the phase transitions was corroborated by the experimental results of X-ray diffraction, energy dispersive spectroscopy and resistance-temperature measurements.
文摘The growth character and microstructure of high-T_c supereonducting YBCO thin films deposited on vari- ous substrates have been studied by X-ray diffraction, TEM and SEM.The results show that when the substrate temperaturc is around 700～800℃ the films have a highly oriented texture with c-axis pependicular to the substrate. The structure of the single crystalline YBCO films grown epitaxially at optimal substrate tem- perature of 800℃ has been established by X-ray diffraction using Seemann-Bohlin geometry (SB). Brentano-Bragg geometry(BB),transmission Laue method and TEM. The lattice matching required for epitaxial growth is achievcd by azimuthal adjustment of the film plane with respect to the substrate plane. The sperior growth is demonstrated by film properties such as critical current density(2.4×10~6 A /cm^2,3.4× 10~6 A/cm^2 and 4.7×l0~6 A/cm^2) for films deposited on YSZ[(Zr(Y)O_2],SrTiO_3 and LaAIO_3 respectively at 77 K and zero fie1d.
基金Project (HKU7104/02P) supported by Research Grants Council (RGC) of Hong Kong
文摘A novel double buffer of Eu2CuO4 (ECO)/YSZ (yttrium-stabilized zirconia) was developed for growing YBa2Cu3Oy (YBCO) thin films on Si substrates. In these films, the severe reaction between Si and YBCO is blocked by the first YSZ layer, whereas, the degradation of crystallinity and superconductivity in the grown YBCO is greatly improved by the second ECO layer. Such an ECO material possesses a very stable 214-T’ structure and excellent compatibilities with YBCO and YSZ. The result shows that the epitaxy and crystallinity of YBCO deposited on Si could be considerably enhanced by using the ECO/YSZ double buffer. The grown films are characterized by high-resolution X-ray diffraction, grazing incidence X-ray reflection, and transmission electron microscopy (TEM), respectively. It is found that well defined interfaces are formed at YBCO/ECO/YSZ boundaries. No immediate layer could be seen. The defect density in all grown layers is kept at a lower level. The YBCO film surface turns out to be very smooth. These films have full superconducting transitions above 88 K and high current carrying capacity at 77 K. The successful growth of highly epitaxial YBCO thin films on silicon with ECO/YSZ buffer, demonstrate the advantages of such a double buffer structure.
文摘Expermental results of the preparation of YBaCuO superconductor thin film on Si(100) substrate by the method of ion beam sputtering deposition is presented.A ZrO_2 buffer layer was applied to Si(100)substrate,and was found to play an important role in resisting the diffusion of Si toward the film.The thin film is mainly a 123 phase with strong c-axis prefer- red orientation.The onset transition temperature of the film is 100 K and the final transition temperature 78 K.
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YBa2Cu3O7-x(YBCO) thin film has been epitaxially deposited on (1120) sapphire with Y2O3-stabilized ZrO2 (YSZ) buffer layer and shown a high critical current density Jc of 1. 6×106A/cm2 at 77 K in zero magnetic field. The orientation relationship of the multilayer film superconductor has been determined. The(001) plane of the YBCO film is parallel to the(100) surface of the YSZ intermediate layer. YSZ buffer layer with(100) preferred orientation is about 20 nm thick and contains element Ba, due to out-diffusion of Ba from YBCO layer. The(100) preferred orientation of YSZ buffer permits the growth of high quality YBCO thin film. Y2BaCuO5 precipitates with small size distribute uniformly in the YBCO thin film and it is favourable to raise critical current density Jc.
文摘The growth of epitaxial Ag nanoparticles doped (Bi, Pb)-2223 thin films on Si (111) substrates by pulsed laser deposition (PLD) and post-deposition oxygen annealing have been achieved. The phase identification and gross structural characteristics of synthesized films explored through X-ray diffractometer reveal that all the samples crystallize in orthorhombic structure. DC electrical resistivity measurements were done by the standard four-probe method and the results showed improvement in T<sub>c</sub> by increasing Ag nanoparticles to 1.0 wt% which had a maximum enhancement in T<sub>c</sub> for all investigated films. The surface morphology investigated through scanning electron microscope (SEM) and atomic force microscopy (AFM) results showed that an increase in T<sub>c</sub> with the appropriate Ag nanoparticles addition in the samples is associated with the enhancement of Bi (Pb)-2223 phase formation.
文摘Textures in different layers of superconductors based on YBCO system are analyzed using the methods of pole figure and con-ventional φ scans. It is shown that the φ scanning technology has only 1-dimensional description and could omit some information of3-dimensional orientaion distribution, which will influence the superconductor quality The pole figure method, in contrast, demonstra-tes the orientation distribution 2-dimensionally and gives a comprehensive view of thin filIn textUr, which is a much bettCr method fortexture analysis in superconducting films, in which there is commonly an unique high sharpness textur component.
文摘Micrcostructures of bulk and thin film YBa_2Cu_3O_(7-δ) superconductors were studied by using scanning elec-tron microscopy (SEM). It was confirmed that viscous technique processed bulk YBa_2Cu_3O_(7-δ) has a homoge-neous microstructure across the pellet diameter. Concerning the thin film, it was found that 2 ￣H￣+ ion implanta-tion with a dose of 1× 10￣(12)cm￣(-2) at 50 keV does not cause microstructural change of the film at a micrometrelevel. Combined with previous studies by using high resolution transmission electron microscopy, it appearsthat the structural modification is at an atomic scale.
