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Results for “Cation interdiffusion”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1993

The Fe2(+)-Mg interdiffusion in orthopyroxene: Constraints from cation ordering and structural data and implications for cooling rates of meteorites

Orthopyroxene crystals in a number of meteorites exhibit compositional zoning of Fe and Mg, which provide important constraint on their cooling rates. However, attempts to model cooling rate of these crystals from Fe-Mg zoning profiles suffer from the lack of any measured or theoretically well constrained Fe-Mg interdiffusion data in OP(x) It has been assumed that Fe-Mg interdiffusion in OP(x) only slightly slower than that in olivine. The purpose of this paper is to (1) calculate the Fe-Mg fractionation, and (2) provide analytical formulation relating cooling rate to the length of the diffusion zone across the interface of the overgrowth of a mineral on itself with application to Mg diffusion profile across OP(x) growth on OP(x) in certain mesosiderites.

Ganguly, J.↗
NASA NTRS1991

High-T sub c fluorine-doped YBa2Cu3O(y) films on ceramic substrates by screen printing

Thick films of fluorine-doped YBa2Cu3O(y) were screen printed on highly polished alumina, magnesia spinel, strontium titanate, and yttria-stabilized zirconia (YSZ) substrates. They were annealed at 1000 C and soaked in oxygen at 450 C, followed by slow cooling to room temperature. The films were characterized by electrical resistivity measurements as a function of temperature and x-ray diffraction. The film on YSZ showed the best characteristics with a T sub c (onset) of 91 K, T sub c (R equals 0) of 88.2 K, and a transition width, delta T sub c (10-90 percent), of approximately 1.7 K. The film adhesion, probably controlled by interdiffusion of cations between the film and the substrate, was good in all cases except on strontium titanate where the film completely detached from the substrate.

Bansal, Narottam P.↗