TY - JOUR
T1 - Alkali metals impurities influence on the magnetic and electrical properties of YBCO
AU - Nedkov, I.
AU - Veneva, A.
PY - 1994/12/1
Y1 - 1994/12/1
N2 - The samples were prepared using the primary batch formula Y 1-0.2xBa2-0.2xCu3+0.3x(Me)0.4xO y, where x=0-1.20 and Me denotes alkali metals (Na, K, Rb) introduced as carbonates. The presence of alkali carbonates during the process allows one to influence the YBCO grain size and improve the homogeneity of the structure. Despite the large concentration range of additives in the initial batch after the second treatment at temperatures higher than 900°C, only traces of the alkali metals were revealed. The influence of Na, K, and Rb impurities in concentrations for Na about 5×10-1 wt %; for K to 4×10-2 wt %, and Rb to 2×10-2 wt % in polycrystalline YBCO was investigated. For Rb and K, the R(T) transitions were comparable to that of pure YBCO. The microwave surface resistance Rs was least influenced by the impurities, but strongly depended on the polycrystalline microstructure. Each impurity had a specific effect on χ(T) and Jc which are related to the grain-boundary structure.
AB - The samples were prepared using the primary batch formula Y 1-0.2xBa2-0.2xCu3+0.3x(Me)0.4xO y, where x=0-1.20 and Me denotes alkali metals (Na, K, Rb) introduced as carbonates. The presence of alkali carbonates during the process allows one to influence the YBCO grain size and improve the homogeneity of the structure. Despite the large concentration range of additives in the initial batch after the second treatment at temperatures higher than 900°C, only traces of the alkali metals were revealed. The influence of Na, K, and Rb impurities in concentrations for Na about 5×10-1 wt %; for K to 4×10-2 wt %, and Rb to 2×10-2 wt % in polycrystalline YBCO was investigated. For Rb and K, the R(T) transitions were comparable to that of pure YBCO. The microwave surface resistance Rs was least influenced by the impurities, but strongly depended on the polycrystalline microstructure. Each impurity had a specific effect on χ(T) and Jc which are related to the grain-boundary structure.
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U2 - 10.1063/1.356850
DO - 10.1063/1.356850
M3 - Article
AN - SCOPUS:0000351672
VL - 75
SP - 6726
EP - 6728
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 10
ER -