Fabrication of Superconducting Bi-Sr-Ca-Cu-O Oxide Films Using the Metal Alkoxide Method
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FABRICATION OF SUPERCONDUCTING THE METAL ALKOXIDE METHOD
Bi-Sr-Ca-Cu-O
SHINGO KATAYAMA AND MASAHIRO SEKINE 350-1 Colloid Research Institute, Kitakyushu 805, Japan
Ogura,
OXIDE
FILMS
USING
Yahata-higashi-ku,
ABSTRACT system were Superconducting films in the Bi-Sr-Ca-Cu-O To make a mixed alkoxide fabricated using metal alkoxides. into a dip-coating solution, insoluble Cu alkoxide solution and insoluble Bi with 2-dimethylaminoethanol was modified of Ca and/or Sr dissolved in the presence alkoxide was alkoxides. The structures of these alkoxide derivatives were 1 The film with Tc(zero) H-NMR, and EXAFS. studied by FT-IR, =115K was fabricated using the alkoxide solution with a nominal composition of Bi:Sr:Ca:Cu=2:2:3:4. INTRODUCTION Bi-Sr-Ca-Cu-O films have been fabricated using the metal alkoxide method[l,2], because of advantages for obtaining shaped films, and fibers, as well as pure materials such as bulks, method for For applying this and homogeneous products. a homogeneous solution of Bi-Sr-Ca-Cu-O films, fabricating first prepared as the starting solution. However, alkoxides is to prepare this solution due to the insolubility it is difficult of Cu and Bi alkoxides in common organic solvents. In the case there are some reports that Cu alkoxide is of Cu alkoxides, organic can be dissolved in chemically modified so that it is known of the structure of modified solvents[3-51, but little In the case of Bi alkoxides and the effects of modifiers. the of an alkoxide solution in the preparation alkoxides, but without any system has been reported[l,2], Bi-Sr-Ca-Cu-O discussion on the solubility increase of Bi alkoxides. In this paper, a solution of Bi, Sr, Ca, and Cu alkoxides was prepared and the mechanism of solubility increase of Cu and Bi alkoxides is discussed. Furthermore, Bi-Sr-Ca-Cu-O films fabricated using alkoxide solutions with various compositions, and their superconductivities were characterized. EXPERIMENTAL 1 mol of Cu(OCH3)2 was modified using 2 mol of 2-dimethylThe structure of the to dissolve in ethanol. aminoethanol 1 H-NMR and EXAFS. modified Cu alkoxide was investigated using solution of dissolved into an ethanol Bi(O-iC3 H7 ) 3 was clear homogeneous alkoxide or Sr(OC2Hs)2. The Ca(OC2 H5 ) 2 solution obtained at a (Ca or Sr)/Bi molar ratio of 0.5 was the solvent under reduced pressure isolated by evaporating were These alkoxide derivatives to give a solid product. analyzed by FT-IR. of for the fabrication Fig.l shows the process Bi-Sr-Ca-Cu-O films. The fired films were examined using XRD The resistivity of the films was measured by the and SEM. conventional four-probe method. Mat. Res. Soc. Symp. Proc. Vol. 180. @1990 Materials Research Society
874
C(OCMHs)2. Sr(OC2H,)2/C HOH
Cu(OCH,)
Cu(OCH3)2
CHOH/
Cu(O3l-42
HOC2NaN(CH2)2 Bi(O-iC3H7)3
a
-1C
Mixin 0.5-0.7moW-akoxidef Mooing
dre-up spCeed:3rn
1 sec
z
n=15 Heatingat 200*C for 5min in air iin8
.1or48h
Fig.1 Process for the fabrication of Bi-Sr-Ca-Cu-0 films.
2
4
6
8
A
Fig.2 Fourier transform of EXAFS spectra of Cu(OCH 3 )
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