서지주요정보
Study on the fabrication and the characteristics of $Sm_1Ba_2Cu_3O_{7-δ}$ high Tc superconducting films = $Sm_1Ba_2Cu_3O_{7-δ}$ 고온초전도박막 제작과 특성에 관한 연구
서명 / 저자 Study on the fabrication and the characteristics of $Sm_1Ba_2Cu_3O_{7-δ}$ high Tc superconducting films = $Sm_1Ba_2Cu_3O_{7-δ}$ 고온초전도박막 제작과 특성에 관한 연구 / Kook-Chae Chung.
저자명 Chung, Kook-Chae ; 정국채
발행사항 [대전 : 한국과학기술원, 2004].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8015398

소장위치/청구기호

학술문화관(문화관) 보존서고

DPH 04002

SMS전송

도서상태

이용가능

대출가능

반납예정일

초록정보

The growth properties and field dependent critical current densities of $Sm_{1+x}Ba{2-x}Cu_3O{7-\delta}$(SBCO) films on biaxially textured Ni tapes with $CeO_2/YSZ/CeO_2$ buffer layers were investigated.The window of substrate temperature($T_s$) for c-axis normal growth in 5mTorr of oxygen pressure were wider than $150^\circ C$. The upper limit of $T_s$-window was much higher than that of $Y_1Ba_2Cu_3O_{7-\delta}$(YBCO) films. Around the low limit of $T_s$, SBCO films grew in [103] normal textures. The zero field critical currents ($J_c$) were slightly smaller than those of YBCO films, while in high field regions critical current densities are much higher and the estimated pinning energies were less dependent on external fields than that of YBCO. We observed that a $Sm_1Ba_2Cu_3O_{7-\delta}(SBCO) film grown on a YSZ substrate with arbitrarily oriented crystal was textured in a single crystalline orientation, while there seems to be no noticeable relation between the crystalline orientations of the film and the substrate. The SBCO[103] axis was close to the surface normal axis. On the other hand, we could not grow an YBCO film on the same substrate, which implies the growth of SBCO film is more stable than YBCO film on that substrate. The qualities of SBCO films grown at substrate temperatures across a wide range of $680^\circ C$ ~ $750^\circ C$ were similar. The critical current density of this SBCO film was smaller than that of SBCO film on a RABiTS-Ni tape, which is several times smaller than that of the YBCO film of coated conductor. The transport properties of $Sm_1BA_2Cu_3O_{7-\delta}$ films, which were grown on the bi-crystalline $SrTiO_3$ substrates of $24^\circ$, $30^\circ$, $36.8^\circ$ and $45^\circ$ misorientation angles, were investigated by the measurements of the Ⅰ-Ⅴ curves at 77K under various magnetic fields. When the voltages were high enough, the Ⅰ-Ⅴ curves became straight. The resistances estimated from the slopes were almost independent of the applied fields mostly for the high quality films. For the slightly low quality films, the zero field resistances were smaller than those for other fields. When the voltages were low enough, the relations between voltages and currents approximately satisfied the power law. The exponents increased by one order of magnitude as the field was changed from zero to 1T. The field dependences of the critical current densities varied according to the voltage of the criterion. The misorientation angle dependence of the critical current density was weaker than that of the YBCO-GB's. We measured the critical current densities($J_{cb}$) in a bicrystalline $Sm_1Ba_2Cu_3O_{7-\delta}(YBCO) film of $24^\circ$, $30^\circ$, $36.8^\circ$, and $45^\circ$-misorientation angle. We obtained hysteretic curves of $J_{cb}$ as functions of applied fields for various temperatures. The main features of the data were qualitatively consistent with the calculation results, where $J_{cb}$'s were expressed as functions of the densities of Josephson vortices ($N_J$) using the modified Kim's model. $N_J$'s were estimated from the field distributions around the grain boundary. The field distributions were calculated using the Brandt's formula.

서지기타정보

서지기타정보
청구기호 {DPH 04002
형태사항 v, 63 p. : 삽도 ; 26 cm.
언어 영어
일반주기 저자명의 한글표기 : 정국채
지도교수의 영문표기 : Do-Jun Youm
지도교수의 한글표기 : 염도준
학위논문 학위논문(박사)- 한국과학기술원 : 물리학과,
서지주기 Includes references
주제 SBCO
SUPERCONDUCTING FILMS
CRITICAL CURRENT DENSITY
HYSTERESIS
고온초전도박막
임계전류밀도
히스테리시스
QR CODE qr code