Tsugio Okazaki

New Technique of Activating Palladium Surface for Absorption of Hydrogen or Deuterium

Activation is carried out by heating a Pd specimen at about 600 °C for several minutes in air. The activated surface is blue, and it is bleached when immersed hi hydrogen gas. The blue film is identified as PdO, and the bleached surface consists of nanocrystallites of metallic Pd, as proved by electron diffraction. An activated Pd plate 0.7 mm in thickness is capable of absorbing, in 1 h, about 70 at% of H or D, the saturation value, in hydrogen gas of 1 atm at room temperature. The atomic ratio of H absorbed in Pd has been estimated to be about 70% when Pd metal is in equilibrium with hydrogen gas of 1 atm at 25C. Since this value could not easily be attained in ordinary experimental studies, various activation procedures have been proposed. The present note proposes a new activation technique which is very simple and more efficient. It is useful also for D, although detailed data for H are given below.

OPTICAL EMISSION SPECTRA DURING CARBON NANOTUBE PRODUCTION BY ARC DISCHARGE IN H2, CH4 OR HE GAS

Optical emission spectra during carbon nanotube production by DC arc discharge in H2, CH4 or He gas were investigated. Emission spectra for C(I) (neutral carbon) atoms and C2 dimers were commonly observed in the three gases. The existence of H atoms and CH molecules was verified by in situ observation during the evaporation in H2 or CH4 gas, because strong H and CH spectra were identified. It was concluded that H atoms were conducive for production of high-quality multiwalled carbon nanotubes by means of forming hydrocarbon species, but were not conducive for production of C60 and C70.

Formation of Quasicrystalline Aluminium-Vanadium and Aluminium-Chromium Fine Particles by Gas-Evaporation Technique

Fine particles in icosahedral phase have been prepared by the gasevaporation method, and studied by electron microscopy. The particles are spherical ranging from 20 to 300 nm in diameter and show a characteristic contrast with an irregular striation. Edge lengths of the fundamental hexahedron in the Penrose tiling are 0.474±0.002 nm in the Al–V system and 0.473 ± 0.003 nm in the Al–Cr system. Though most of the quasicrystalline particles are in a single phase, composite particles of the icosahedral phase and the crystalline phase(β–Al6V) are also observed in the Al–V system. From the orientation relationship between the two phases, atomic sites of vanadium in the icosahedral phase are discussed.

Structures and Habits of Manganese Fine Particles Prepared by Gas-Evaporation Technique

Manganese fine particles were prepared by gas-evaporation technique and observed by transmission electron microscope (TEM). A new habit of β-Mn was found, which was a truncated rhombic dodecahedron bounded by twelve (110), twenty-four (210) and eight (111). α-Mn and β-Mn with rodlike habits were identified in addition to tetragonal structure. The tetragonal structure of rodlike particles found by Kimoto and Nishida (Jpn. J. Appl. Phys: 6 (1967) 1017) was revised to be a=1.191 nm and c=0.4585 nm. The tetragonal one transformed to α-Mn at nearly 330°C.

New optical absorption spectra of Cu2 molecules produced by the gas evaporation technique

A study was conducted on the optical absorption spectra ranging from 233 to 285 nm, which were taken in a region close to the source of evaporation of Cu, in low-pressure helium gas of 100 Torr. Eight band systems for Cu2 dimers designated as system 1 through 8 were identified. The spectroscopic constants for the band origins were derived as follows: ṽ ≈ 42 200 cm−1 for system 1, ṽ00 = 41 604.74cm−1 for system ṽ00 = 39 606.70cm−1 for system ṽ00 = 38 124.32cm−1 for system 4, ṽ00 = 38 048.65 cm−1 for system 5, 98, ṽ00 = 36 834.22cm−1 for system 6, ṽ00 = 36 341.55 cm−1 for system 7 and ṽ00 = 36 174.99cm−1 for system 8. For all cases in which vibrational constants of the lower state could be determined, it was found that the transition originated from the ground state of Cu2.

OPTICAL EMISSION SPECTRA OF AG3 MOLECULES IN THE GAS EVAPORATION TECHNIQUE

A study was conducted of optical emission spectra, taken at a region near the source of the evaporation of Ag in a low pressure helium gas (100 Torr). A new Ag3 emission band system was identified. Spectroscopic constants for an excited and a lower state (the ground state) in the gas phase were derived as follows: ν00=19 809.4±2.0 cm−1, ω′1=106.8±1.0 cm−1, x′11=−0.2±0.5 cm−1, ω″1=129.0±1.0 cm−1, and x″11=−0.1±0.5 cm−1 for the 107Ag2109Ag trimers. Spectroscopic constants for three other isotope species were also derived. The lower state was the 2B2 ground state.

Production and New Habits of TiN Ultrafine Particles Produced by DC Arc Discharge in N2 Gas

TiN ultrafine particles were prepared by DC arc discharge in N2 gas and observed by a scanning electron microscope (SEM) and transmission electron microscope (TEM). New habits of TiN were identified, which were a basic cubic shape bounded by six {100}, and its truncated forms bounded by {110} and/or {111}.

Fine particles of icosahedral quasicrystal formed by gas evaporation technique

Al-T (T=Mn, V, Cr) particles in the icosahedral phase have been prepared by evaporation and condensation of metals in an inactive gas. The particles were spherical in shape, with diameters ranging from 50 to 300 nm, and showed speckled contrast in bright and dark field images. Each particle consisted of fine grains of several nm with small misorientations (less than a few degrees). Patterson functions of the icosahedral Al-Mn were also calculated from electron diffraction data. Among several structure models examined in the present study, a model with an array of two-shell Mackay icosahedra gave the best fit with the Patterson functions.

Optical absorption spectra of Au2 using the gas evaporation technique: 211–229 nm

The optical absorption spectra of Au2 in the 211–229 nm range were studied in a region close to the source of Au evaporation in low pressure helium gas (100 Torr). Three new band systems (designated systems 1–3) of Au2 dimers in the gas phase were identified. The spectroscopic constants derived for system 1 are T e = 44 692.8 ± 3.7cm−1, ν00 = 44 672.6 ± 3.7 cm−1, ω′ e = 151.7 ± 0.5 cm−1, ω e x′ e = 0.15 ± 0.38 cm−1, ω″e = 192.3 ± 1.1 cm−1 and ω e x″e = 0.73 ± 0.36 cm−1. Only the lower progressions of the other two systems were observed.

Spectroscopic study on the crystal growth in gas evaporation: emission and absorption spectra from Cu smoke

Optical emission and absorption spectra from a growth zone in Cu smoke were measured by using a quartz prism spectrograph and a single-grating spectrophotometer. Atomic lines of Cu, band systems of Cu2 were observed. Two new band systems with 0–0 band heads at 252.88 and 238.79 nm were found. The continuous spectra due to Rayleigh scattering by fine particles were also observed. Variations of density of various species as a function of vertical position were revealed.