Abstract--Expansion properties of ten homoionic smectites that differed in amount and location of layer charge were examined by X-ray powder diffraction analysis at various relative humidities, or after glycerol or ethylene glycol solvations. Except for K-samples with glycerol solvation, and Na-and Ca-samples with ethylene glycol, differences in the basal spacings are observed in samples having similar layer charge. These results show that the basal spacings are larger when the layer charge is located in octahedral sites than when it is in tetrahedral sites. This suggests that expansion is due to the combined effects of the charge location and amount.The effects of layer charge magnitude and location on expansion were represented by an energy change (expansion energy: AEr) during the hydration and solvation processes. Plots of basal spacings versus AEr show a reasonable relationship; the spacings generally decrease stepwise as the value of AEr increases. The basal spacings of K-samples with glycerol solvation, Na-saturated and K-saturated samples at 100% RH are apt to contract stepwise with increasing value of AEr. For these samples, the figures showing the relationship between each expanded phase and the charge characteristics are obtained from the isoquants of AEr, given the boundary of the expanded phases. A behavior test using these figures may be combined with the Greene-Kelly test to estimate the amount and the location of the layer charge of common smectites.

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The emissivity of silicon was observed in the spectral region from 0.4 to 15 µ at various temperatures from 340°K to 1070°K by using two n-type specimens with the resistivity of 15 ohm-cm and 7×10-3 ohm-cm at 300°K, respectively. The thermal radiation of silicon consists of three types due to band-to-band transition, free carriers and lattice vibration. It was made clear from the emissivity measurement that, in a pure specimen, the radiation due to lattice vibration is conspicuous at low temperatures, while that due to free carriers is predominant at higher temperatures, and that, in a doped specimen, the radiation due to free carriers is predominant even at low temperatures. The observed emissivity is close to the theoretical formula represented by the refractive index n and the extinction coefficient k. The temperature dependence of n and k is shown and a brief discussion is also added.

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The structure of nanocrystalline calcium silicates hydrates (C–S–H) having Ca/Si ratios ranging between 0.57 ± 0.05 and 1.47 ± 0.04 was studied. All samples are nanocrystalline and defective tobermorite. An increase of the Ca/Si ratio resulting from omission of bridging Si in the Si chains and incorporation of interlayer Ca was observed.