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The cuprate superconductors are fascinating not only because of their technical promise, but also because of their structures, especially the anisotropy of the crystal lattice. There are some structural similarities among these compounds, but also significant differences. Measurements of the oxygen tracer diffusion coefficients have been carried out as a function of temperature, oxygen partial pressure, crystal orientation, and doping in the La-Sr-Cu-0, Y-Ba-Cu-0, and Bi-Sr-Ca-Cu-0 systems. These measurements have revealed a variety of defect mechanisms operating in these compounds; the exact nature of the mechanism depends on the details of the structure.

The government agencies responsible for Good Laboratory Practices (GLP) place accountability for assuring compliance of studies intended for submission on the sponsor. An initial step toward meeting these legal obligations includes a comprehensive assessment of the candidate testing facility. Literature review has substantiated that the initial evaluation may be best accomplished through both technical and compliance-focused inspections (O'Brien-Pomerleau, 1991; Schroeder, 1989). Combined technical and compliance inspections have also been reported as an effective auditing approach for long-term studies (Hoover and Baldwin, 1984). However, for the purposes of the initial qualifying assessment inspection, personal experiences and published literature indicate that these two equally important evaluations are commonly conducted independently of one another (Scozzie, 1995). A collaborative approach utilized by Dow Corning Corporation in the preliminary assessment of a contract testing facility builds upon those methods just mentioned. Coupling this evaluation with a program of actively monitoring the testing facility's performance in study conduct provides continued assessment and has proven to be beneficial to all stakeholders (sponsor, testing facility, and regulatory agency). Details of the process practiced by this sponsor to assure that studies conducted by a contract testing facility meet GLP requirements are presented.

Eutectoid mixtures of ZrO{sub 2}-ThO{sub 2} with 1 to 4 mol% Y{sub 2}O{sub 3} additions were prepared and their ionic conductivity measured by complex impedance technique. The conductivity was less than that of YSZ, as was that of mixtures lower in ThO{sub 2} concentration. The decomposition of the mixtures was studied by x-ray diffractometry.

The diffusion of 68Ge in single crystals of high-purity (over 99.99% pure) Ni has been measured using the sectioning technique. The plot of log D versus 1/T is straight from 939 to 1675K, over 61/2 orders of magnitude in D, with parameters D0=2.10+or-0.47 cm2 s-1, Q=2.74+or-0.03 eV (264+or-3 kJ mol-1). The data suggest a low Ge-vacancy binding enthalpy for Ni.

Diffusion of 18O in the superconductor La2−x Srx CuO4−y has been measured as a function of x (0 to 0.20) between 300 and 500°C at an oxygen partial pressure of ≍ 1 atm. Concentration profiles were obtained using a secondary ion mass spectrometer. The diffusion coefficient decreases with increasing Sr additions from 0.1 to 0.2, primarily because of an increase in activation energy. This result, which is contradictory to the expectation that the diffusion coefficient should increase with increasing vacancy concentration caused by the added Sr, can be explained if oxygen vacancies are bound to Sr clusters. Measurements on samples with x = 0 or 0.05 were unsuccessful, probably because of porosity.

NiO scales were formed on pure Ni and Ni-0.1 wt.% Y alloy by oxidation in pure O2 at 1200°C, and the grain boundary self-diffusion coefficients of Ni in the dense region of the scale were measured by the tracer-sectioning technique. The volume diffusion coefficient was also measured in the alloy scale. The grain boundary and volume diffusion coefficients and the grain boundary width were found to be the same for the two materials within the experimental uncertainty.

The radiation-enhanced self-diffusion coefficient D rad in silver under 270 keV proton bombardment has been measured over the temperature range from 240° to -60 °C. The flux dependence of D rad has also been studied at 106° and 179 °C with the flux varying from 2.5 × 10 12 to 6.3 × 10 13 protons/cm 2 sec. The experimental data are analyzed in the framework of the classical model involving single vacancies and interstitials as mobile defects.

The simultaneous lattice diffusion of 59Fe, 51Cr and 57Ni tracers has been measured in the alloys Fe-15Cr-20Ni, Fe-15Cr-45Ni, Fe-22Cr-45Ni and Fe-15Cr-20Ni-1.4Si between 960 and 1400 degrees C. In all four alloys at all temperatures, DCr>DFe>DNi, with DCr/DNi approximately=2.5 and DFe/DNi approximately=1.8. The activation enthalpies for diffusion of the major constituents in any one alloy are quite close to each other. No correlation is found between swelling under irradiation and the diffusion behaviour of the major constituents. The results are discussed on the basis of the random-alloy model. Grain-boundary diffusion is found in these alloys at surprisingly high temperatures.

Measurements of the diffusion of 64Cu in pure and impure α and γ iron show a large discontinuity in the Arrhenius plot of the lattice diffusion coefficient at the α‐γ transformation, contrary to the data of Anand and Agarwala [J. Appl. Phys. 37, 4248 (1965)]. Grain‐boundary diffusion predominates at T≤815°C in the α phase and at T≤1250°C in the γ phase. Trapping of the radioactive copper by inclusions or impurities in solution also appears to have a profound effect on the diffusion process.

Self-diffusion in silver single crystals was measured at temperatures between 270 and 500 °C. The diffusion coefficients were in the range of 3×10−18 to 2×10−13 cm2/s. The results indicate that the Arrhenius plot is curved owing to a large divacancy contribution and that the activation energy for diffusion by divacancies is temperature dependent due to a partial dissociation of the divacancies. The best values of the parameters for diffusion by monovacancies are Do= 0.041 cm2/s, Q = 1.76 eV.