Single-phase filled skutterudite compounds, CeyFexCo4−xSb12 (x = 0 to 3.0, y = 0 to 0.74), were synthesized by a melting method. The effects of Fe content and Ce filling fraction on the thermoelectric properties of CeyFexCo4−xSb12 were investigated. The lattice thermal conductivity of Ce-saturated CeyFexCo4−xSb12, y being at the maximum corresponding to x, decreased with increasing Fe content (x) and reached its minimum at about x = 1.5. When x was 1.5, lattice thermal conductivity decreased with increasing Ce filling fraction till y = 0.3 and then began to increase after reaching the minimum at y = 0.3. Hole concentration and electrical conductivity of Cey Fe1.5Co2.5Sb12 decreased with increasing Ce filling fraction. The Seebeck coefficient increased with increasing Ce filling fraction. The greatest dimensionless thermoelectric figure of merit T value of 1.1 was obtained at 750 K for the composition of Ce0.28Fe1.52Co2.48Sb12.

A novel optical multilayer filter characterized by symmetrically stepwise graded refractive index profiles and high optical performance was designed. This 33-layer TiO2–SiO2 filter was fabricated by helicon plasma sputtering. The prepared filter exhibited a sharp cutoff reflection band around the central wavelength of 1340 nm and wide pass regions with high transmittance. These results correspond well with calculated estimations. Symmetrically stepwise graded refractive index profiles were demonstrated to effectively contribute to suppression of the sidelobes and to be potentially applicable in the design of other filters.

Various methods are used in functionally gradient materials technology to control the composition and structure of a composite.

The chemical vapor deposition (CVD) method yields a deposit with source gases by applying variou s forms of energy (heat, light, plasma, etc.) to the gases after they are introduced into a CVD reactor. Hydride, bromide, and chloride are generally used for source materials. By continually changing the mixture ratio of source gases or by controlling the CVD conditions such as deposition temperatures, gas pressure, and gas-flow rate, CVD permits relatively easy syntheses of various FGMs (to a maximum thickness on the order of a centimeter).

Epitaxially grown films of Bi4Ti3O12 (BIT) were prepared on the substrate of a sapphire single crystal heated at 650°C using a sintered Bi4Ti3O12 target by electron cyclotron resonance (ECR) plasma sputtering. The BIT film of the same composition with the target was obtained under the conditions of microwave power(Mp) higher than 500 W and RF power(Rp) between 300 to 700 W. Increasing Mp or Rp, the deposition rate of the film was increased and the surface of the film became rough. The film exhibiting flat surface, good crystalline orientation and stoichiometric composition was prepared at such the high rate as 3.5 Å/sec under the conditions of Mp=500W and Rp=500W. Dielectric constants(1KHz) of the films deposited on (1120), (1102) and (0001) of sapphire were 93, 121 and 90, respectively, and refractive indexes of each films for the wave length of 632 nm were 2.32, 2.38 and 2.37, respectively.

Thermal oxidation resistance, in a temperature range of 600 to 1100° C, of AIN-Al2O3 composite, AIN and θ-A12 O3 films has been studied. The films were prepared by microwave plasma CVD using an AlBr3 -H2 -N2 -Ar gas system at a substrate temperature of 430° C. AIN-Al2O3 composite film was found to have good surface stability below an oxidaton temperature of 1100°C and to have the best properties for insulation film.

Key words: microwave plasma CVD, AIN-Al2O3 composite, passivation film, oxidation resistance, AlBr3