Molecular Level Control over the Surface and Interfacial Properties of High-T_c Superconductors

Abstract

The spontaneous adsorption of alkylamines and fluorinated alkylamines onto the surface of cuprate-based compounds is reported. These monolayer films allow for control of the wetting properties, corrosion resistance, and adhesion characteristics of these superconductors. The molecules form densely packed, highly oriented structures on the high-T c surfaces as evidenced by contact angle, X-ray photoelectron spectroscopy, X-ray reflectivity, and corrosion resistance measurements. Thus, molecular level control over important surface and interfacial properties of cuprate superconductors is demonstrated.

Substrate photoelectron enhancement of carbonaceous overlayer Auger emission: effect of the substrate on carbon overlayer thickness determination in XPS

“…The surface of the gold samples, which were also prepared in the ambient, was assumed to be pure metal; the glass sample was assumed to be SiO 2 . For an oxide sample, oxygen transitions must be included in the summation of Eqn (9) and each term in the summation must be weighted according to the stoichiometry of the oxide. For example, for a CuO surface, the copper transitions were weighted by a factor of 0.5 and the oxygen transitions were also weighted by a factor of 0.5.…”

“…Preparation of the dodecylamine (Aldrich) monolayer on copper followed the procedures described in the papers by Chen et al 8 and McDevitt et al 9 The C 10 hydroxamic acid was graciously supplied by the group of G. Whitesides, Harvard University, Cambridge, MA. Procedures for the preparation of hydroxamic acid layers on silver are described in a paper by this group.…”

“…Figure 2 shows that the Substrate Effect Model is very similar to the Ebel Model for low atomic number substrates but is appreciably different for higher atomic number substrates. Equation (9) shows that the enhancement in the C KVV signal predicted by the Substrate Effect Model depends linearly on n S i , the photoelectron emission from the substrate. Thus, the large number of photoelectrons from high-Z substrates increases the flux of carbon Auger electrons emitted from the carbonaceous layer.…”

“…Such a treatment would seem to presuppose the final composition of the substrate. However, it would be sufficient to use the approximate substrate composition extracted from the survey data in the evaluation of Eqn (9). With the Substrate Effect Model determination of the carbonaceous overlayer, the substrate composition can be refined to reflect the true composition.…”

Do Alkanethiols Adsorb onto the Surfaces of Tl−Ba−Ca−Cu−O-Based High-Temperature Superconductors? The Critical Role of H2O Content on the Adsorption Process

“…Indeed, McDevitt and Mirkin have shown in other work that the corrosion resistance and surface adhesion properties of the HTSC can be tailored rationally through choice of adsorbate molecules. 7 After this initial report, a critical question pertaining to the generality of the method for other cuprate-based HTSCs still remained unanswered, especially since preliminary reports from Murray suggested that alkanethiols do not adsorb stably onto the surfaces of certain cuprate-based HTSCs. 6 A major difference between the Murray work and the Mirkin and McDevitt work was that the latter was performed on YBa 2 Cu 3 O 7-δ , while the former was performed on a Tl-Ba-Ca-Cu-O-based HTSC consisting of a composite mixture of Tl 2 -Ba 2 CaCu 2 O 8 and Tl 2 Ba 2 Ca 2 Cu 3 O 10 .…”