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  1. Overview of SIMS-Based Experimental Studies of Tracer Diffusion in Solids and Application to Mg Self-Diffusion

    Kulkarni, Nagraj S. ; Bruce Warmack, Robert J. ; Radhakrishnan, Bala ; ... - Journal of Phase Equilibria and Diffusion
    Tracer diffusivities provide the most fundamental information on diffusion in materials and are the foundation of robust diffusion databases. Compared to traditional radiotracer techniques that utilize radioactive isotopes, the secondary ion mass spectrometry (SIMS) based thin-film technique for tracer diffusion is based on the use of enriched stable isotopes that can be accurately profiled using SIMS. Experimental procedures & techniques that are utilized for the measurement of tracer diffusion coefficients are presented for pure magnesium, which presents some unique challenges due to the ease of oxidation. The development of a modified Shewmon-Rhines diffusion capsule for annealing Mg and an ultra-highmore » vacuum (UHV) system for sputter deposition of Mg isotopes are discussed. Optimized conditions for accurate SIMS depth profiling in polycrystalline Mg are provided. An automated procedure for the correction of heat-up and cool-down times during tracer diffusion annealing is discussed. The non-linear fitting of a SIMS depth profile data using the thin film Gaussian solution to obtain the tracer diffusivity along with the background tracer concentration and tracer film thickness is discussed. An Arrhenius fit of the Mg self-diffusion data obtained using the low-temperature SIMS measurements from this study and the high-temperature radiotracer measurements of Shewmon and Rhines (1954) was found to be a good representation of both types of diffusion data that cover a broad range of temperatures between 250 - 627° C (523 900 K).« less

  2. Studies on Coördination Compounds. XIV. The Determination of Enthalpy and Entropy Values for Several Bivalent Metal Ions and Cerium(III) with the Acetylacetonate Ion

    Izatt, Reed M. ; Fernelius, W. Conard ; Block, B. P. - Journal of Physical Chemistry
    Thermodynamic stepwise equilibrium formation constants are given for the reaction in aqueous solution of the acetylacetonate ion with Cu2+, Be2+, UO22+, Ni2+, Co2+, Zn2+, Mn2+, Cd2+, Mg2+ and Ce3+ at 10, 20 and 40°. Constants at 30° have been given in previous publications. Values of the thermodynamic quantities, ΔH, ΔS and ΔF are given over the temperature range 10 to 40° for the formation of the first complex, MCh(n-1)+, in each case (except UO22+), of MCh2(n-2)+ in each case (except Zn2+ and Cd2+), and of MCh3- in the case of Ni2+. Values for these thermodynamic quantities are also given formore » the dissociation of acetylacetone over the above temperature range. The significance of the values obtained is discussed in the light of the reactions involved. Comparisons are made with other thermodynamic values in the literature involving several of these same ions with other ligand types.« less

  3. Acoustic Wave Velocities, Elastic Constants, and Debye Characteristic Temperature for Polycrystalline MgCd

    Smith, Charles S. ; Wallace, W. E. - Journal of Chemical Physics
    The longitudinal and transverse acoustic wave velocities in a polycrystalline magnesium-cadmium alloy containing 50.6 atomic per cent cadmium were measured using the pulsed ultrasonic method. The alloy was prepared by fusing together spectroscopically pure magnesium and cadmium under a blanket of helium purified by evaporation. Experimental details concerning preparation and analysis of the alloy and the method employed in measuring the sound velocities are given elsewhere.

  4. The Synthesis of Heterocyclic Nitrogen-containing Ketones. I. Ketones Derived from 2-Picoline

    Goldberg, Newton N. ; Barkley, Lloyd B. ; Levine, Robert - Journal of the American Chemical Society
    2-Picolyllithium, prepared from 2-picoline and phenyllithium, has been acylated in good yields with methyl benzoate, 2-furoate, 2-thiophenate, acetate, propionate and isovalerate and ethyl benzoate and isobutyrate. Finally, in addition to the 2-picolyl ketones, alkyldi-2-picolylcarbinols were isolated in those experiments in which aliphatic esters were used as the acylating reagents.

  5. Magnesium-Cadmium Alloys. VI. Heat Capacities between 12 and 320°K. and the Entropies at 25° of Magnesium and Cadmium1,2

    Craig, R. S. ; Krier, C. A. ; Coffer, L. W. ; ... - Journal of the American Chemical Society
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