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The relationship between substrate materials and the deposition of diamond or graphitic soot was studied in the low-pressure synthesis of diamond. Electrocatalytic metals such as Fe, Ni, Rh, Pd, Pt, and Ir result in soot deposition while insulating materials such as Al2O3and SiO2result in diamond deposition. There exists a strong correlation between the electrocatalytic substrate materials and soot deposition. The substrate dependence of the deposition behavior is approached by the theory of charged clusters. The substrate dependence is suggested to be related to the charge-transfer rate at the substrate surface for charged clusters, which had formed in the gas phase. The evolution of soot and diamond is explained in terms of the floccula-tion and deflocculation behavior of colloid particles, respectively.

The grain growth behavior of La-doped BaTiO3specimens was investigated at 1350 °C under DC external electric field. In air atmosphere, grain growth was enhanced at the positive-biased region for the 0.15 mol% La-doped and 0.3 mol% La-doped specimens, while it was enhanced at the negative-biased region for the 1.0 mol% La-doped specimen. For the 0.6 mol% La-doped specimen, on the other hand, both positive- and negative-biased regions showed the same grain size. The demarcation donor composition (0.6 mol% La) shifted to a higher donor concentration when the specimen was heat-treated in nitrogen. The results were explained in terms of the grain boundary potential and its variation with donor concentration, oxygen partial pressure, and defect polarization.

Spontaneous generation of charged atoms or clusters was investigated during thermal evaporation of silver. For this, the effect of the applied electric bias on the film growth rate was examined during evaporation of silver at 1373 K in a tungsten basket. Film growth rates on three silicon substrates biased + 300, 0 and –300 V with respect to the chamber were 300, 420 and 960 nm per hour, respectively. The number density of generated positively-charged atoms or clusters could be measured by the electric current on the Faraday cup in the chamber. From the temperature dependence of the positive current, the activation energy for charging was determined to be ~ 2.2 eV. This value could be best explained by the surface ionization of clusters of a few atoms on the oxidized tungsten surface.