The thermal conductivity of polycrystalline magnesium oxide has been measured over the temperature range from 400 K to 1300 K using a modified guarded-hot-plate design. Three different thicknesses of specimens having 93 % of theoretical density were tested to verify the operation, accuracy, and reproducibility of our apparatus. The measured thermal conductivity ranges from 30 W · m−1 · K−1 down to 8 W · m−1 · K−1 and has an inverse-temperature functionality. The results agree well with literature values for this material.
The conductivity of a thermal-barrier coating composed of atmospheric plasma sprayed 8 mass percent yttria partially stabilized zirconia has been measured. This coating was sprayed on a substrate of 410 stainless steel. An absolute, steady-state measurement method was used to measure thermal conductivity from 400 to 800 K. The thermal conductivity of the coating is 0.62 W/(m⋅K). This measurement has shown to be temperature independent.
Thin multilayer samples of Si/Ge, with individual layer thicknesses of 4-33 om, have been analyzed by secondary ion mass spectrometry (SIMS) using AT' , 0,' and Cs' primary ion beams. Bombardment with both Ar' and 0,' produced positive secondary ion depth profiles in which pronounced distortions were observed. Similar effects were found in negative secondary ion depth profiles with Cs* bombardment. In each case, the SIMS depth profiles were characterized by abrupt interfacial secondary ion signal variations and a shift in the secondary ion signal maxima indicating that the layers were superposed, a condition that was not consistent with sample preparation, as verified by Auger electron spectroscopy. Auger electron spectroscopy depth profiling was also used to quantify the level of oxygen in the films. From these data it was concluded that the distortions in the positive secondary ion depth profiles under Ar' bombardment were the result of secondary ion yield variations induced by enhanced incorporation of ambient oxygen, during sample preparation, into the stronger oxide-forming silicon layers. Under 0,' and Cs' bombardment, the profile distortions were introduced by differential incorporation of the implanted primary species into the lower-sputter-yield silicon layers.
Numerical simulations based on the exact Fresnel equations are used to show that it is possible to determine uniquely the relative permittivity and thickness of a thin lossless dielectric film adsorbed on a gold or silver layer. The calculations, which include the effects of up to 1% random noise on the experimental data, show clearly that there is no degeneracy in the solutions of the Fresnel equations even for films as thin as 2 nm. It is shown that gold is preferable to silver as a substrate when the overlayer properties need to be determined accurately. It is further shown that, if the overlayer is bounded by water rather than air, then the experimental constraints would preclude the use of silver as a substrate but measurements would still be possible with gold.
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