Studies on crystal growth of 2Ca₂SiO₄⋅CaCl₂ which suggested a chlorine analogue to calcio-chondrodite (2Ca₂SiO₄⋅Ca(OH)₂) were attempted by slow cooling from CaCl₂ flux.
For crystal growth of 2Ca₂SiO₄⋅CaCl₂, CaCl₂ was found to be suitable as flux, and SiO₂ was used as starting material which was as suitable as calcium silicates. The mixtures of CaCl₂ of about 60g and SiO₂ of 1.0-5.0g in the Pt crucible were soaked for 3.0-9.0 hours at 995°-1180°C and then slowly cooled to about 500°C with a rate of 5°C per hour.
The largest crystal as large as 30mm in size weighed by 14.5g was grown, when mixture of CaCl₂ of 54.1g and SiO₂ of 4.0g was soaked at 1080°C. In this case, all the constituents of 2Ca₂SiO₄⋅CaCl₂ in flux resulted to crystallize into a single crystal, which should be most desirable at flux method.
The processes of reaction of CaCl₂ with SiO₂ and crystal growth of 2Ca₂SiO₄⋅CaCl₂ are inferred as follow:
CaCl₂ reacts with H₂O absorbed in itself and SiO₂ for heating process.
SiO₂+2CaCl₂+2H₂O→Ca₂SiO₄+4HCl………………………………………(1)
On slow cooling, Ca₂SiO₄ in equation (1) reacts with CaCl₂, and after that, crystal-nuclei formation and crystal growth take place.
2Ca₂SiO₄+CaCl₂→2Ca₂SiO₄⋅CaCl₂……………………………………………(2)
Combining equations (1) and (2),
2SiO₂+5CaCl₂+4H₂O→2Ca₂SiO₄⋅CaCl₂+8HCl
The unit monoclinic cell constants of the crystal are a₀=9.8₄Å; b₀=6.7₈Å; c₀=10.9Å; angle β=105°30′. The space group is C⁵_2h=P2₁/c.
The mean refractive index of the crystal is n=1.66.

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Here we consider a one-dimensional random walk diffusion of particles through a diffusion field which consists of particle sites, vacancy sites and dead sites. In general, numbers of those sites are independent one another. In our case, a step of diffusion is a movement of a particle from a particle site to a vacancy site and the Kirkendall effect is out of consideration.
Fig. 1 is a schematic diagram of a diffusion system. The notations are as follows: λ (distance between neighboring sites), n (number of particles in sites at a certain x position), p (concentration of vacancies at a certain x position), τ (mean transfer time when both sides of a particle became vacancy, mean transfer time of vacancy), j (particle flow to the positive direction per unit time), j (particle flow to the negative direction per unit time), J (net particle flow per unit time).
The probability of the transfer of a particle to each side is 1/2 when both sides of the particle became vacancy. So that following equations are obtained.
j=n(p+Δp)/2τ, j=(n+Δn)p/2(τ+Δτ), J=j=-pΔn/2τ+nΔp/2τ+npΔτ/2τ²
From the definitions of a particle concentration and a diffusion coefficient, following relations are obtained.
c=n/λ, Ddc/dx=pΔn/2τ=DΔn/λ², D=pλ²/2τ
Therefore, J=-Ddc/dx+Dc1/pdp/dx+Dc1/τdτ/dx (1st diffusion equation)
The 1st diffusion equation is a general form and consists of three terms generally independent one another, the concentration term, the vacancy (or probability) term and the kinetic term. If some conditions are fixed, however, derivatives are obtained as follows: (1) τ=coast. D=D₀p (D₀…extreme diffusion coefficient or vacancy diffusion coefficient). J=-Ddc/dx+D₀cdp/dx=-Ddc/dx+cdD/dx (2nd diffusion eq.) This equation is applied to the analysis of cation interdiffusion in a solid solution with different concentration of cation vacancy, (2) p=const. J=-Ddc/dx-cdD/dx (3rd diffusion eq.) This equation may have some way of application. (3) p=const. τ=const. J=-Ddc/dx (4th diffusion eq.) This is the simple diffusion equation and applied to the analysis of diffusion with a definite concentration of vacancy. (4) p=f(c), τ=g(c) J=-D_adc/dx=-D{1-c/f(c)df(c)/dc-c/g(c)dg(c)/dc}dc/dx (5th diffusion eq.) This equation explains the meaning of the apparent diffusion coefficient D_a. (5) p=1-c/c₀, τ=const. J=-D₀dc/dx (6th diffusion eq.) This equation is applied to the analysis of the diffusion with a gradient of a vacancy concentration and shows that the apparent diffusion coefficient of such a diffusion is the extreme diffusion coefficient.
C. Wagner obtained an interdiffusion coefficient of cations in a solid solution with different concentration of cation vacancies using the simple diffusion equation but in such a case the 2nd diffusion equation must be applied.
J₁=-D₁dc₁/dx+c₁dD₁/dx-z₁c₁D₁Kdφ/dx

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Electrical resistivities were measured through the nearly entire range of vitrification in the ternary system As-Se-Te. Ohmic contact was achieved when aluminium was evaporated onto sample surfaces, which were ultrasonically cleaned in trichloroethylene prior to the evaporation. Repeated annealing gave scarcely any effect on both resistivity and activation energy for conduction of the present glasses. The resistivity at room temperature and activation energy decreased monotonically from 10¹⁴ to 10⁶ ohm·cm and from 2.0 to 1.0 eV with increasing tellurium content, respectively. At a given tellurium content, little change in these values was observed when the content of arsenic and selenium varied. These results are discussed from the viewpoint of the ionization energy of the constituent elements. In contrast to the case of As-S glasses, the minimum was found near 40 atom. % As in the composition dependence of As-Se glasses. A linear correlation between the activation energy and log resistivity with the slope of 2.303×2kT holds for glasses in the present system As-Se-Te as well as in the previously reported system As-S-Te: The formula, E_th=0.1109log ρ₂₅+0.381, was obtained, the value 0.1109 being nearly equal to 2.303×2kT at 25°C (=0.11830, where E_th is the activation energy and ρ₂₅ the resistivity at 25°C. Applying the idea of the “steric factor” by Myuller to glasses in the present system, the glasses do not contain ring or cyclic chemical structures, but consist of chain and/or network structures.

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Hot-pressing of ZrO₂-CeO₂ powder mixtures was carried out at the temperature ranging from 1400° to 1700°C in graphite molds. Pressure of 210kg/cm² was applied throughout the hot-pressing process. Shrinkage of the compact during hot-pressing was measured by a dilatometric method. Bulk density of the hot-pressed body was measured and density change of the compact during hot-pressing was calculated. Densification data for ZrO₂ compacts without additives were processed with Murray's equation based on plastic flow mechanism. It was observed that plots of log (1-ρ) vs. t were divided into three parts, that is initial stage characterized by very rapid densification, intermediate stage in which fairly good linearities were obtained, and final stage characterized by very slow densification. The densification data were also processed with Fryer's equation based on stress enhanced diffusion mechanism. Densification of ZrO₂ was strongly accelerated by addition of up to 20mol% CeO₂. The maximum relative density was attained at ZrO₂ containing 5mol% CeO₂.
X-ray powder diffraction analysis showed that a pyrochlore-type Ce₂Zr₂O₇ was formed by hot-pressing of ZrO₂-CeO₂ mixtures in reducing atmosphere, and it was changed easily into tetragonal ZrO₂ solid solution by oxidizing at 1500°C in air.
The electrical conductivity of the oxidized specimen was measured in air with Kelvin's double bridge in the temperature range from 500° to 1500°C. The conductivity at elevated temperatures was strongly dependent on the temperature. It was observed from the electrical conductivity data that transformation temperatures from monoclinic form to tetragonal form were lowered by increasing the CeO₂ content. The maximum in conductivity isotherms was attained when ZrO₂ contained 80mol% of CeO₂. The conductivity in this composotion was 5.50×10^-5 ohm^-1cm^-1 at 600°C, 3.55×10^-2 at 1000°C and 1.15 at 1500°C.

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The stresses built up by ultra-violet irradiation in glasses containing rare earth (Pm and Lu were not examined.) oxides were measured. The effects of the additives were classified as follows: a-group; The stresses were large when added in amounts about 0.5g oxide per 100g of the base glass, b-group; The effects of the amount added were the intermediate ones between a- and c-group, and c-group; The stresses were only slightly dependent on the amounts added. It was noted that the ions belonging to the a-group corresponded to those which show f→d or charge transfer bands in optical absorption and change valencies by light or ionizing radiation. The enhancement effect of the stress by these ions was discussed. The ions belonging to the c-group behaved similarly with the rare gas type ions (such as alkali and alkaline earth ions). They seemed to be simple fillers of the glass network.

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