Anisotropic growth rates, interface processes during growing and occurrence of an inversion twin of ZnO crystals have been studied under a hydrothermal condition as growth temperature 360°-380°C, temperature difference 10°-25°C, pressure 600-1000 bar, solvent 3.0mol KOH with 0-2.0mol LiOH.
The results showed:
(1) The growth rate was a function of growth temperature, concentration of LiOH added and temperature difference between dissolution and growth zones; under Li-free condition the activation energies in normal direction of basal and prismatic face, (0001) and (1010), were 20 and 80kcal/mol, respectively, whereas these energies almost reversed in 2.0mol LiOH.
(2) The concentration of Li adsorbed on -c (0001) or O-layer side was higher than that on c (0001) or Zn-layer side. This anisotropic adsorption of Li seems to be caused by the growth environment or reductive atmosphere.
(3) The growth mechanism on (0001) face distinctly changed from a rough pattern to a spiral step with the increase of adsorbed Li content.
(4) The rate functions of R_g∝t^m and R_g∝ΔTⁿ had the transition point which can be regarded as the alteration of processes at the interface, where R_g is the growth rate of linear extention of a particular face, t the growth time, ΔT the temperature difference between dissolution and growth zones, m and n constants. It is phenomenologically concievable that a interface of the initial crystal growth from the seed crystals, and the one of the following principal growth can be corresponded to the processes of the growth on the rough surface or kink face and on the smooth surface or spiral step face, respectively. From the results obtained m=1/2 and n=1 for the initial growth, and m=-1/2 and n=1.5-1.7 for the principal growth.
(5) A polar twin easily occurred from spontaneous nucleation. This twin was an inversion contact twin at the initial state of the growth. With progressing of the growth, the twinning shape which changed from the inversion contact to the inversion core twin was observed by chemical etch pattern on the cross section in parallel with the c-axis.
Thus the growth kinetics and morphology of ZnO single crystal are closely correlated with calculated activation energies, adsorbed Li content in the crystal, the rate functions and micro-growth mechanism of a particular surface.

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Mixture of milk of lime and silica powder was treated hydrothermally up to 191°C (12kg/cm²) and kept for 4hrs in such condition. Products at several steps were examined and the formation process of xonotlite grain was analyzed. Firstly calcium hydroxide and silica powder made fine aggregated lumps partly forming C-S-H (II) and then they changed to combined lumps partly forming C-S-H (I).
At 191°C, they formed spherical shape consisting of tobermorite partly changing to xonotlite. After 4hrs spherical grains consisting of tobermorite and xonotlite were completed. Further treating at 191°C made grains completely xonotlite. The higher treating temperature resulted the faster rate of xonotlite formation.

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[in Japanese]

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The shrinkage isotherms of the powder compacts of spherical soda-lime glasses were measured in the temperature range of 590° to 660°C in air. An analytical equation for the initial sintering of glass powders was developed from the viewpoint of non-Newtonian flow. The shrinkage data measured with a dilatometer consisting of a linear variable transformer were best correlated with the equation. The results indicated that the length of unit flow, δ, was 3-10Å and that the viscosity coefficients were in fairly good agreement with those obtained by other authors.

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The factors involved in the slip casting of dense ferrites have been investigated, particular attention being paid to the effect of calcination temperature, particle-size distribution, deflocculant and protective colloid. Suitable particle-size distribution for slip casting can be obtained from a mixture of calcine and raw batch. Effective additives for casting slip are triethylamine and NH₄-alginate.

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The rate of transition from the disordered lattice to the ordered lattice in the lithium ferrite has been found to depend strongly on the preparation conditions of the ferrite sample. The present study was done to investigate the governing factors of the transition rate. Various samples of ferrite were made by changing the preparation conditions variously and their long-range order parameter was measured by X-ray diffraction. The results obtained are as follows.
1) The order-disorder transition temperature of the lithium ferrite was found to be 725°C in a flowing atmosphere of nitrogen and to be 750°C in a flowing atmosphere of oxygen.
2) The disorder-to-order transition proceeds at an observable rate in a temperature range from 400°-450°C to the transition temperature. In a temperature below 400°-450°C the transition scarcely proceeds.
3) The experimental results show that the disorder-to-order transition rate is governed by the oxygen content in the ferrite sample. The transition rate becomes larger in proportion to the oxygen content.
4) It is considered that the concentration of cation vacancies on B-sites (octahedral sites) of the ferrite increases with the oxygen content, and through those vacancies the exchange of lattice position between Li⁺ and Fe³⁺ ions on B-sites will easily proceed to complete the transition.

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Sintering process of the heat treated product of the synthesized magnesite at temperatures between 450° and 1500°C with the intervals 100°C in air and the resulting materials were studied by the X-ray powder diffraction and scanning electron microscopy.
It was found that the product at 600°C was identified as periclase and these small magnesia particles began to sinter each other with increasing rapidity at about 1100°C. The pseudorhombohedral shape of the magnesite was almost retained after it was heated at 1500°C.
The particles of the magnesia increased in size and the lattice dimension decreased with increasing temperatures. High preferred orientation of the magnesia crystallite with respect to the original magnesite was revealed from electron diffraction and X-ray oscillation photograph.

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Phase relations in the system ZrSiO₄-TiO₂ was investigated by a quenching method. Mixtures of ZrSiO₄ and TiO₂ were heated from 1500° to 1700°C in air with silicon carbide heating element furnace. Phases in the quenched specimens were identified by a X-ray diffraction method and also under a reflecting microscope. TiO₂ and ZrTiO₄ were presented as solid solutions and these solubility were determined from the variation of the lattice constant and the unit cell volume. The results obtained were as follows;
(1) The decomposition of ZrSiO₄ was accelerated by the addition of TiO₂. Dissociated SiO₂ existed as cristobalite below 1540°C and changed into liquid with TiO₂ above 1550°C. Dissociated ZrO₂ reacted with TiO₂ to ZrTiO₄ solid solution or TiO₂ solid solution, ZrO₂ however, existed at low TiO₂ compositions above 1550°C and it increased with TiO₂ contents at high temperatures.
(2) Limits of solubility of ZrO₂ and TiO₂ into ZrTiO₄ solid solution were 65wt% ZrSiO₄, 35wt% TiO₂ and 62wt% ZrSiO₄, 38wt% TiO₂ at 1500°C; 70wt% ZrSiO₄, 30wt% TiO₂ and 61wt% ZrSiO₄, 39wt% TiO₂ at 1550°C; 74wt% ZrSiO₄, 26wt% TiO₂ and 61wt% ZrSiO₄, 39wt% TiO₂ at 1600°C; and 75wt% ZrSiO₄, 25wt% TiO₂ and 61wt% ZrSiO₄, 39wt% TiO₂ at 1700°C.
(3) Limits of solubility of ZrO₂ into TiO₂ solid solution were 25wt% ZrSiO₄, 75wt% TiO₂ at 1500°C; 26wt% ZrSiO₄, 74wt% TiO₂ at 1600°C; and 29wt% ZrSiO₄, 71wt% TiO₂ at 1700°C.

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Recently, big increase of ceramic product has brought the great consumption of its materials. The author has tried to obtain the ceramic clay from the weathered granitic rocks. At first the forming process and containing situation of clay minerals were surveyed on various rocks at each step of weathering, and then the selection of suitable raw material and extracting method of ceramic clay were investigated.
The results of this study are summarized as follows:
(1) Among the constituent minerals of granitic rocks, plagioclase and biotite are altered most easily by weathering and kaoline, gibbsite, vermiculite etc. are formed and contained in the weathered rocks.
(2) Kaoline is contained in all kinds of weathered and decomposed granitic rocks, even in the rather coarse size range of about 100-150micron.
(3) The clay from so called “masatsuchi” can be used as a material of ceramics. Especially, the extremely weathered but not contaminated one provides the clay of higher grade in good yield.
(4) In order to get the clay of high quality from the weathered granitic rocks, raw material should be scrubbed softly in water, and the cut size of clay should be as fine as possible. And clay can be made higher grade through magnetic separation.

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