A thermodynamic study was carried out to check the possibility of direct production of the binary transition metal-rare earth alloys from the rare earth raw materials with various alkali or alkali earth metals, based on the evaluated thermodynamic data for the formation of alloys. Due to the large, negative free energy of mixing in the alloy formation, the direct production can take place more preferably on energy basis than getting pure rare earth metals and alloying them with transition metals.
Some thermodynamic data for the III-V metallic compounds, which are very important semi-conductor materials, are also summarized and discussed, intensively related to the production of these materials.

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Hydrogen reduction of acidic copper sulfate solution was studied to obtain fine copper powder suitable for conductive paste. Reaction rate of hydrogen reduction of cupric ion to cuprous (Cu²⁺+1/2H₂→Cu⁺+H⁺) was catalytically enhanced twice by addition of 0.1g/l Bi³⁺Coarse copper powder (>10μm) was obtained with further hydrogen reduction of cuprous ion to metallic copper (Cu⁺+1/2H2→Cu0 +H⁺), because of some heterogeneous nature of the reaction.
Fine copper powder (about 2μm) was obtained only by disproportionation of cuprous ion to metallic copper and cupric ion (2Cu→Cu⁰+Cu²⁺), which occurs by means of cooling the Cu⁺solution. The cooling rate and Cu⁺ion concentration determine size and shape of the powder. Experiments using a continuous autoclave resulted in oxidation resistant powder consisted of single crystals of about 5μm in size.

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In the current investigation, reduction behaviours of samarium, europium thulium and ytterbium oxides with each rare earth metal (La, Ce, Nd and Pr) have been examined under the conditions of high temperature and vacuum atmosphere. Compact samples were prepared by pressing mixtures of both oxide and reducing agent. The experimental results obtained are summarized as follows:
(1) Reduction reaction of each oxide with mischmetal rapidly proceeded with time at early stage andshowed slow progress at the middle and final stages. The reactivity for the reduction of each oxide was better in the order of europium oxide>ytterbium oxide>samarium oxide>thulium oxide. This result is in fair agreement with the thermodynamic evaluation.
(2) The reactivity of each oxide differed with the kind of rare earth metals used as the reducing agents.
(3) In the case of the reduction at low temperature region, the melting point of the reducing agent was considered to be one of important factors for accelerating the reduction reaction of rare earth oxides.
(4) In order to recover each rare earth metal having high purity, the reduction of oxides must be carried out at low temperature region because the vapour pressure of the reducing reagent affects the reduction reaction at high temperature region.
(5) For the reduction at low temperature region, metallic. cerium and lanthanum were more effective than metallic neodymium and praseodymium as the reducing agents.

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A new process was proposed for the recycling of Ta capacitor scrap containing about 4-7% of MnO₂as solid electrolyte. This paper describes the removal leaching of MnO₂with various reductive agents, and moreover, disscuses the dissolution reactions of MnO₂in FeSO₄-H₂SO₄aqueous solution from both thermodynamic and kinetic aspects. The results are summarized as follows:
1) In the leaching of block Ta anode scrap, H₂O₂and Na₂SO₃solution were the most effective leaching agents with more than 90% of Mn extraction at room temperature after 24 hours.
2) When the sample was ground to-200 mesh, MnO₂was almost completely removed in a short time by use of H₂O₂solution, cheap FeSO₄solution also showed satisfactory result.
3) In the dissolution reactions of MnO₂with FeSO₄-H₂SO₄solution, primary and secondary periods were observed. The reaction rate of primary was in proportion to [Fe²⁺] 0.65, and [H⁺] 0, while the reaction rate of secondary showed the dependency of [Fe²⁺] 0.45 and [H⁺] 0.25 The activation energies for primary and secondary were 4.6 kJ/mole and 5.1 kJ/mole respectively.
4) The overall reaction of primary was seemed to be controlled by a mass transfer of Fe²⁺ions through the boundary layer between the solution and the surface of MnO₂inside the capacitor, while dissolution of Fe (OH) 3 and other reaction products was the rate determining step in the secondary.
5) Hermetic seal type Ta capacitor scraps were graded up by applying the Fe³⁺/Fe²⁺oxidative-reductive consistent leaching method.

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The analytical relationship among the total pressure P (or the volume per total mol of all species, V*), the composition, and partial pressures of species is discussed for the equilibrium gas mixture of A-B-C...-N system at a constant temperature, ideal behaviour of each species being assumed.
The n components are chosen so that
1) they are necessary and sufficient to define the composition of the gas under the study,
2) there are n “component species”, defined as the species having the same formula with corresponding components, and
3) any species other than “component species”, are compound or associated molecules of several “component species”, or dissociated molecules from a single “component species”.
As long as the components are chosen as above, the partial pressures of “component species” are defined as P_A, P_B..., and P_N, and mole fractions of components are defined as X_A, X_B, ..., and X_N, it follows that 1) X_H/X_A increases monotonously with P_H if T, P (or V*), P_B (or X_B/X_A), P_c (or X_c/X_A), ..., P_G (or X_G/X_A), P_I (or X_I/X_A) and P_N (or X_N/X_A) are kept constant, 2) P (or 1/V) increases monotonously with P_A if T, P_B, P_C and P_N are kept constant, 3) condition:[T;P (or 1/V*);P_B (or X_B/X_A), P_c (or X_c/X_A), ..., P_N (or X_N/X_A)] is in one-to-one correspondence with condition:[T;PA, P_B, P_C, ..., P_N], and is necessary and sufficient to describe the state.
To compute gas equilibria a new technique, which is 1) initial estimates-free, 2) convergence-guaranteed, and 3) iteration parameter-free, is developed by combining the “monotone rule” derived above with the method of nested iterations.

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Using the SOLGAS-MIX computer program and the JANAF thermochemical data, the equilibrium phase diagrams of Si-N-Cl-H, Si-C-Cl-H and Al-N-Cl-H systems at 1473K and 1 atmosphere have been costructed for synthesis of Si₃N₄, SiC and AIN.Based on these phase diagrams selection and combination of gaseous reactant chemicals have been discussed with respect to the synthesis yields and total free energy change in these synthesis formation reactions. Desirable conditions for these compound synthesis could be shown under equilibrium conditions by the computer calculation using these phase diagram and thermochemical data

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Pressureless sintered hexagonal boron nitride (h-BN) were fabricated using turbostratic BN and amorphous B as starting powders. Further, the effects of additives on bending strength and corrosion resistance of the sintered BN were studied.
Bulk density and bending strength of the sintered BN with additives were significantly increased compared to the case of using pure h-BN as a starting powder. Especially in the sintered BN with 5 wt%SiC, high bending strength, -9kg/mm2, were constantly obtained in the range room temperature to 1200C°C. On the other hand, the sintered BN with 30 wt%AlN had revealed superior corrosion resistance. These materials could be applicable to the protective tube for the continuous temperature measurement of molten steel in the range 1500 to 1560C°C.

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A diamond thin film was formed on the SiC substrate in hydrogen and methane mixed atmosphere by means of thermal CVD process. The structure of the deposits was analyzed by Raman spectroscopy and X-ray diffraction and reflective electron diffraction. The morphology was estimated by the SEM observation. It was confirmed that the deposits were diamond and i-carbon (amorphous carbon). Optimum condition for the formation of the diamond thin film in this experiment were as follows; substrate temperature of 700°C, filament temperature of 1900°C, the distance between filament and substrate; 5mm, CH₄/(CH₄+H₂) =1 vol%, gas flow rate 20SCCM and gas pressure 4000Pa. The i-carbon in the deposites tended to increase with the increase of methane concentration at the temperature above 800°C and below 600°C, and the addition of cathodic voltage on the substrate. It was considered that these condition was concerned with the formation of methyl radical and hydrogen radical near the substrate and the hydrogen played a very important role for the diamond synthesis.

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Ag and Pd sub-micron powders and three different types of Ag-Pd ultrafine powders (MIX, COPPT and ALLOY) were prepared. MIX was named for the mechanical mixing powder of Ag and Pd powders obtained by precipitation from each aqueous solution. COPPT powder was made by co-precipitation in the alloy composition. ALLOY was prepared by heat treatment of COPPT powder in a vacuum. Ag3d_5/2 and Pd3d_5/2 photoelectron spectra and valence band spectra of those fine powders were measured to characterize the surface of the powders.
Since the surface of the Pd fine powder was partly oxidized and not completely covered with a dense oxide layer, it showed sufficient electroconductivity. No significant change of Pd valence band spectra was observed in the Pd powders of which average particle size ranged from 20 nm to 500nm. Intensity ratios of Ag3d_5/2 to Pd3d_5/2 2 spectra of Ag-Pd fine powders were measured with Ar sputtering. It was suggested that Ag was enriched at the surface of the ALLOY type powder when compared with the other powders such as MIX and COPPT even at the same chemical composition.

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