Utilization of the high temperature superconductor, YBa2Cu3O7-delta, in commercial applications is becoming increasingly feasible. Before full advantage of this material can be taken, however, the lifetime, oxygen stability and processability of this ambient reactive superconductor must be improved. Corrosion resistance of YBa2Cu3O7-delta and a cation substituted compound, Y0.6Ca0.4Ba1.6La0.4Cu3O7-delta, were studied and their lifetimes in aqueous environments were determined. Results indicate a dramatic enhancement in the stability against environmental degradation for the cation substituted phase. Important mechanistic factors responsible for the enhanced corrosion resistance of the substituted phase over the parent compound are discussed.

Utilization of the high temperature superconductor, YBa2Cu3O7−δ, in commercial applications is becoming increasingly feasible. Before full advantage of this material can be taken, however, the lifetime, oxygen stability and processability of this ambient reactive superconductor must be improved. Corrosion resistance of YBa2Cu3O7−δ and a cation substituted compound, Y0.6Ca0.4Ba1.6La0.4Cu3O7−δ, were studied and their lifetimes in aqueous environments were determined. Results indicate a dramatic enhancement in the stability against environmental degradation for the cation substituted phase. Important mechanistic factors responsible for the enhanced corrosion resistance of the substituted phase over the parent compound are discussed.

A cosubstitution of Ca2+ for Y3+and La3+ for Ba2+ in YBa2Cu3O7−δ is found to improve the corrosion resistance of this high- Tc superconductor. The reactivity characteristics of bulk and thin film samples of Y1−zCazBa2−yLayCu3O7−δ indicate that the corrosion resistance in water environments increases with increasing degree of cation substitution up to z=y=0.4. The composition of Y0.6Ca0.4Ba1.6La0.4Cu3O6.96 with a Tc of 80 K is found to be at least 100 times more stable than YBa2Cu3O6.94. Possible contributing factors that could be responsible for the marked improvement in the corrosion resistance of this high-Tc phase are discussed.

Effects of NH3 nitridation on the chemical and electrical properties of N2O oxides have been studied. Compared with NH3-nitrided SiO2, NH3 nitridation does not degrade the electrical properties of N2O oxides, thus resulting in superior impurity diffusion barrier properties, while preserving excellent interface immunity to hot-carrier injection and much lower charge trapping. Correlation studies between the chemical and electrical properties of NH3-nitrided N2O and NH3-nitrided SiO2 have been done to explain these results.

The chemical structure and composition of ultrathin N2O oxides have been investigated using angle resolved x-ray photoelectron spectroscopy and compared to those of reoxidized NH3-nitrided SiO2. It is found that N2O oxide shows a second nitrogen-related bond (N-O bonds) in close proximity to the SiO2/Si interface in addition to the typically observed Si-N bonds in reoxidized NH3-nitrided SiO2. In addition, the change of the difference between Si 2p and O 1s binding energies in the N2O oxide and reoxidized NH3-nitrided SiO2 with the take-off angle is negligible due to the interfacial nitrogen incorporation.

Although it is known that some of the high-Tc phases react rapidly with water, CO2, CO, and acids, no systematic comparison of the relative reactivities of the various cuprate superconductors is available. In this letter, x-ray powder diffraction, scanning electron microscopy, x-ray photoemission spectroscopy, and electrochemical measurements are utilized to establish a comprehensive comparison of the intrinsic reactivity characteristics of the common copper-oxide superconductors. Consequently, the following reactivity scale has been determined: YBa2Cu3O7≳Tl2Ba2Ca2Cu3O10≳Bi2Sr2CaCu2O8 ≥La1.85Sr0.15CuO4 ≳Nd1.85Ce0.15CuO4≳Nd1.85Th0.15CuO4.