Packing behavior of the dry ramming mixes by method with stick penetration were in good agreement with calculations of author's previous report. Also, attempts at removal tendency of intermediate component were not so effective for obtaining a closer packing.
It was shown that the q value of closest packing (=q_ρm) might shift to a lower value when the stick penetration times becames larger, and the q_ρm could be expressed as hyperbolic function of stick penetration times.
Another intensified packing experiment of the dry mixes was shown that the q_ρm was inversely proportioned to the maximum particle-size, and that a closer packing was obtained as the particle were more spherical in shape.
In packing experiment of the wet ramming mixes, the behavior by light ramming was similar to that of dry mixes, however, the packing intensity dependence and the maximum particle-size dependence on the q_ρm was not so much as that of dry mixes, and the shift of the q_ρm was lower than that of dry mixes.
A different tendency about packing behavior by heavy ramming and press moulding of wet mixes was observed, that the q_ρm might shift to a higher value as the intensity of packing operation got higher, probably as a result of the crushing and defacement of grains.
From these results, it might be concluded that the factors of the degree of packing for magnesia ramming mixes was moisture and binder, particle-shape, mechanical properties of magnesia clinker grain, maximum particle-size or extension of distribution, grading of particle-size, and intensity of packing operation.

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Partially stabilized zirconia (PSZ)-kovar sealing glass or practical soda lime glass composites sintered at 750° and 1050°C were studied by means of X-ray diffractometer, tensile testing machine, XMA, dilatometer and differential thermal analysis apparatus.
The results obtained were as follows:
(1) In PSZ-kovar sealing glass composites sintered at 1050°C, ZrO₂⋅SiO₂ (zircon) was formed at 800°-1000°C in great quantity. Modulus of rupture was minimum at PSZ 10 vol%. Thermal expansion coefficients of the composites sintered at 1050°C were smaller than those of the composites sintered at 750°C.
(2) In PSZ-practical soda lime glass composites sintered at 1050°C, β-cristobalite, CaO and ZrO₂⋅SiO₂ (trace) were formed at 950°-1050°C.
Modulus of rupture was maximum at PSZ 40 vol%. Thermal expansion coefficients were smaller than those of the composites sintered at 750°C.
(3) It was attributed that the original structures of the glasses were varied with exolution of the CaO from the PSZ to kovar sealing glass and practical soda lime glass.
It seems that in PSZ-kovar sealing glass composite, active SiO₂ of phase-separated glass reacts with ZrO₂, (monoclinic) to form ZrO₂⋅SiO₂. And that after in PSZ-practical soda lime glass composites the content of CaO in glass becomes too much to form stable glass, the glass is partly decomposed to form β-cristobalite and CaO.

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To elucidate the redox equilibrium of high concentration transition metal ions in a highly viscous oxide melts with gas phase, the effect of iron concentration on the redox equilibriums in the oxide melts of FeO-Fe₂O₃-RP₂O₆ system (R=Mg, Ca, Ba) at 1200°C with CO₂ atmosphere, which oxygen partial pressure is about 10^-3.6 atm, was studied in this report.
The [Fe²⁺]/[Fe³⁺] ratios decreased at low iron oxide concentration and then increased after reaching their minimum values, as iron oxide concentration increased. These ratios also decreased at low iron oxide level and increased at high iron oxide level, as R was exchanged by Mg, Ca, Ba. The minimum values of [Fe²⁺]/[Fe³⁺] ratios shifted to the low iron oxide concentration by these exchange.
It is discussed from these experimental results that the reaction between free ferrous ion and ferric oxiacid ion such as
Fe²⁺+1/4 O₂+(x-1/2)O^2-=FeO_x^(2x-3)-
contributes mainly to the redox equilibrium at the low iron oxide concentration, and that the reaction between oxiacid ions of ferrous and ferric ions such as
FeO_y^(2y-2)-+1/4 O₂=FeO_x^(2x-3)-+{1/2-(x-y)}O^2-
contributes mainly at the high iron oxide concentration.
The relation between [Fe²⁺]/[Fe³⁺] and [O^2-], oxygen ion concentration, given by the combination of the above two redox reactions, agrees with the experimental results about the relation between iron oxide concentration and [Fe²⁺]/[Fe³⁺] ratios in various melts, if the oxygen ion concentration increases with the increase of iron oxide concentration.
The increase of oxygen ion concentration was recognized from the infra-red spectrums of glasses, obtained by quenching the melts in the redox equilibrium. Comparing the I. R. spectrums of FeO-Fe₂O₃-RP₂O₆ glasses with RP₂O₆ glasses, it was observed that the increase of iron oxide concentration corresponded to the exchanging R by Mg, Ca, Ba in RP₂O₆ glasses, the increase of basicity in the melts. This increase seemed to accompany with the change of the form (for example, chain length) of the phosphorus oxiacid ions in the melts. The formation of ferrous oxiacid ion in the melt was found to be possible from the shift of absorption peak by ferrous ion in the optical absorption spectrum in the above glass.
Discussion about activities of various ions was not successful in this paper.

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Studies were made on the sintered Si₃N₄ with an addition of MgO, hot-pressed at the temperature of 1730°C.
The following results were obtained. At low concentration of MgO, only β-Si₃N₄ phase was observed. When MgO concentration was increased, the formation of MgSiN₂ was found. Further increase of MgO concentration gave rise to the formation of MgSiN₂ and 2 MgO⋅SiO₂. The X-ray diffraction angles or the lattice constants of β-Si₃N₄ were unchanged by the addition of MgO. The linear coefficient of the thermal expansion was increased with MgO concentration. MgO was inferred to dissolve into β-Si₃N₄. The solubility limit of MgO at 1730°C was estimated to be about 30mol%. In the solid solution, oxygen atoms are substituted for nitrogen atoms, a half of the dissolved magnesium atoms for silicon atoms and the rest magnesium atoms are located in the interstitial spaces, which are situated in some of the “tunnels” intrinsically present in the β-Si₃N₄ structure. The dissolution of four MgO molecules introduces one vacancy at the site of silicon. This interpretation for the solid solution was supported by the good agreement between calculated and observed values of both specific gravity and relative X-ray intensity. From the inferred structure of the solid solution and the agreement between the activation energy of sintering for Si₃N₄ containing MgO and that for Si₃N₄ containing Al₂O₃, enhanced sintering of β-Si₃N₄ added with MgO may be attributed to the diffusion of the silicon site vacancies introduced in the solid solution.

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The glass having the chemical composition of fluor-aluminum-richterite (Na⋅NaCa⋅Mg_5-xAl_xSi_8-xO₂₂F₂, x=1.5) was heat-treated at various temperatures. Glassy phase separation and crystallization of the glass were studied by X-ray powder diffraction method and electron microscopy. The results were summarized as follows;
1) The quenched glass had a slightly phase separated microstructure.
2) The glassy phase separation developed evidently at the temperature range of 600°-650°C.
3) Fluor-phlogopite and fluor-aluminum-richterite precipitated at the temperature ranges of 635°-1200°C and 1000°-1100°C in the glass, respectively.
4) At the crystallization temperature, the number of nuclei of phlogopite precipitated in the phase separated glass were larger than those precipitated in the quenched glass. It was considered that the nucleation was promoted by the phase separation.
5) The rates of nucleation and growth of phlogopite were largest at about 700°C and 1000°C, respectively.
6) Precipitation of richterite seemed to be in connection with decomposition of phlogopite.
7) The activation energies of nucleation and growth of phlogopite were determined as 60 kcal/mol and 128-140 kcal/mol, respectively.

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The electrical conductivity (σ) and dielectric relaxation of glasses in the system Fe₂O₃-MnO-P₂O₅ were studied over the temperature range 20°-180°C. The glasses were prepared by melting under various conditions i.e., melting in the air and in a reducing atmosphere and by an annealing condition. The ratio (Fe³⁺/Fe³⁺+Fe²⁺) in the system was analyzed by chemical method and the effects of the ratio on the electrical properties were also determined in connection with the composition of the glasses.
In the measurement of d.c. conductivity (σ) on glasses in the system xFe₂O₃-(40-x) MnO-60P₂O₅, the values increased by replacing MnO with Fe₂O₃ as shown in Fig. 4. The activation energy ΔH_dc of the glass 40MnO-60P₂O₅ was about twice that of the glass 40Fe₂O₃-60P₂O₅.
In the glass containing MnO, the conductivity decreases with the amount of MnO. The glass reduced by carbon during melting was found to decrease the conductivity (Fig. 5). In the glass containing Fe₂O₃, the conductivity increased with increasing FeO, the ratio (Fe³⁺/Fe_total) and the total amount of iron content in some limit (Fig. 6). In the system Fe₂O₃-MnO-P₂O₅, however, the conductivity was found to be unaltered with the ratio (Fe³⁺/Fe_total) and by heat treatment (Fig. 8).
It is suggested that in this system the multi-valency of manganese and iron may be affected with each other by oxidation and reduction, but its final state may practically be uneffected on the electronic conductivity. The conductivity in this system was observed to vary greatly with the glass composition.
The dielectric relaxation was observed by changing frequency and temperature. The frequency f_max at which the dielectric absorption shows the maximum was seen to a higher frequency with the amount of Fe₂O₃ and with the measuring temperature. The relation between logarithmic values of the f_max and 1/T showed a straight line, from which the activation energy ΔH_ac was calculated (Eq. 5 and Fig. 8). From the correlation between d.c. conductivity and dielectric absorption, the following formula has been presented by T. Nakajima & H. Namikawa.
σ≅ε₀⋅Δε⋅2πf_max
The relationship was determined to hold in the system Fe₂O₃-MnO-P₂O₅ as shown in Fig. 12.

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Thermal expansion of benitoite (BaTiSi₃O₉) was measured at the temperature range between 25° and 865°C by using a high temperature X-ray diffractometer, and the result was discussed in relation to its crystal structure. The results obtained were as follows.
1) Benitoite shows a linear expansion along the a axis and a parabolic contraction along the c axis.
2) The thermal expansion behaviour of henitoite is markedly similar to those of other ring silicates, namely heryl and cordierite; that is, it expands along the direction parallel to the rings (a axis) and contracts along the direction normal to them (c axis).

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