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The most important part in the tubing construction of the ultraclean gas delivery system is the automatic butt welding technology. The welding process, in which metal needs to be turned into a molten state to be welded, always causes the generation of metal fumes. Manganese (Mn) is easier to evaporate and redeposit in the vicinity of the weld bead during the welding process because the vapor pressure of Mn is higher than that of other metal elements composed of stainless steel. It is revealed that the redeposited Mn is a trigger for the corrosion for a corrosive gas delivery system. The postwelding ultrapure water rinse has a good effect on removing the redeposited metals on the stainless steel surface. In an attempt to further suppress metal fumes generated during the welding process, the high-speed single-path narrow bead welding process is newly established. Its technique is characterized by a welding speed of 30 rpm, single path, and a bead width of 1 mm. Moreover, in order to reduce the generation of Mn fumes, the high quality material which reduces the Mn content in the base metal from the conventional 0.65% down to 0.01% is introduced and evaluated. As a result, the quantity of redeposited Mn on the downstream location of the weld bead is reduced to less than 1/3300 as a compared to that of the conventional welding technique (7.5 rpm x 2 paths, bead width 2 mm). Therefore, the corrosion resistance around the weld bead is greatly enhanced in comparison with the conventional welding method.

Anisotropic thermoelectric characteristics of a sintered Bi2Te3 system have been evaluated on the basis of the orientation distribution of crystallites. Uniaxially anisotropic resistivities, Hall coefficients, and thermal conductivities of sintered Bi2Te3 were expressed by linear combinations of those of single crystal. The combination coefficients are specified by an anisotropy parameter that may be estimated by the anisotropy in the observed resistivities. Two types of x‐ray diffraction experiments were performed to confirm the validity of the estimate. The observed diffraction intensities were reasonably consistent with the orientation distribution predicted by the anisotropy parameter. Theoretical curves of resistivities, Hall coefficients, and thermal conductivities of the sintered material were calculated by using the orientation distribution which was specified by a parameter estimated by the observed resistivities. The theoretical curves were in reasonable agreement with the observed data.

A calculational model is proposed to analyze the anisotropic galvanomagnetism of sintered Bi2Te3 on the basis of the orientation distribution function method. The orientation distribution of crystallites in a specimen is expressed by a distribution function of the Eulerian angle that represents the rotation of the crystallites distributed in the specimen. The distribution can be specified by a single rotation parameter because of the uniaxial anisotropy of Bi2Te3. The rotation parameter can be expressed as the angular width of the distribution by introducing the approximation that the distribution function is a Gaussian function of the tilting angle of the c axis with respect to the pressing direction of the specimen. Resistivity and Hall tensors of sintered specimens are calculated by this method to evaluate the angular width of the distribution. Theoretical curves are calculated from the data of a corresponding single crystal by estimating the distribution parameters. The theoretical curves are in reasonable agreement with the observed data.

A single crystal of ${\mathrm{CrSi}}_{2}$ was grown by a modified floating-zone refining technique, and its magnetic susceptibilities and Hall coefficients in the directions of both the a and c axes were measured over a temperature range from room temperature to 1000 K. The susceptibilities were constantly negative over the temperature range and possessed a minimum value at 770 K. The temperature dependence of the hole concentration estimated from observed data of the Hall measurement suggested that above 770 K the susceptibility is primarily dominated by the contribution from charge carriers. The chemical composition of the crystal was estimated at ${\mathrm{CrSi}}_{1.985}$ by quantitative chemical analysis. A theoretical curve of susceptibility was calculated by assuming that the excess Cr atoms act as ${\mathrm{Cr}}^{3+}$ ions in the crystal. The observed susceptibilities were in good agreement with the theoretical curve. It was concluded that the Cr atoms constituting a stoichiometric ${\mathrm{CrSi}}_{2}$ lattice are quadrivalent by reason of their negligibly small contribution to the susceptibility.

X-ray diffraction photographic experiments and anisotropic magnetic susceptibility measurement were made to examine the crystal structure of a Ru/sub 2/Si/sub 3/ single crystal. The X-ray analysis revealed that the single crystal possesses a tetragonal symmetry. Some very weak X-ray diffraction spots suggest a superstructure with 4-times larger lattice constants than those of the conventional tetragonal lattice. It was found from the susceptibility measurement that the single crystal is diamagnetic at low temperatures ranging from 20 to 300 K, and that the susceptibilities are uni-axially anisotropic, which is consistent with the results of the X-ray diffraction experiments. It is concluded from the diamagnetic susceptibilities that coordinate bonding is established between Si and Ru atoms, which is consistent with the results of a previous magnetic susceptibility analysis of CrSi/sub 2/.

Anisotropic thermoelectricity of n-type Bi2Te2.85Se0.15 single crystal doped with HgBr2 is discussed on the basis of a multivalley model and an anisotropic scattering mechanism. Temperature dependence of the anisotropy parameters of the six-valley model are calculated from observed galvanomagnetic data. It is confirmed that below 200 K, a weakly anisotropic band (the first conduction band) is dominant, while above 200 K, a strongly anisotropic band (the second conduction band) also contributes the conduction. Anisotropic scattering parameters are determined from observed thermoelectric powers. It is concluded that conduction electrons are scattered by not only acoustic phonons but also optical phonons, and that the effect of optical phonons in the c-direction is greater than that in the a-direction.

The crystal growth of manganese silicide with a Si/Mn ratio near 1.73 was performed by the Bridgman method followed by chemical transport. The Bridgman as grown boule was observed to have a lamellar structure identified to be composed of a MnSi precipitate and a Mn 15 Si 26 matrix. The chemical transport was carried out by using crushed grains of the Bridgman boule as starting material and CuCl 2 as transport agent. Homogeneous single crystals of Mn 15 Si 26 having an average linear size of 0.5 mm were grown on the colder zone. The crystals were identified by X-ray technique as well as by electron probe micro analysis.