Soluble and Volatile Precursors for the Preparation of Superconducting Films
ABSTRACTAttempts to identify intermediates in an alkoxide-based solution route to films of the high temperature superconductor YBa2Cu3O7 reported by Fahrenholtz et al.[1] have led to the isolation of the first molecular barium-copper cluster, Ba2Cu2(OR)4(acac)4·2 HOR, R = CH2CH2OCH3. The extension of this route to the preparation of the bismuth superconductors has necessitated the investigation of bismuth alkoxide chemistry. Two separate routes to bismuth alkoxides have been examined: the metathesis of the metal halides with NaOR, (R = t-butyl, and diisopropylphenoxide) and the alcoholysis of bismuth amides, Bi(NR2)3, [R = N(SiMe3)2] The alcoholysis preparation gives high yields of several alkoxides suitable as precursors to the high Tc materials. A monomeric bismuth phenoxide, which is targeted as a volatile precursor, and a bismuth t-butoxide cluster have been isolated and stucturally characterized. Solubility and volatility studies have also been undertaken.
Persistent-current switch for pancake coils of rare earth-barium-copper-oxide high-temperature superconductor: Design and test results of a double-pancake coil operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K)