Evaluation of degree of mixing in particulate mixtures for alumina ceramics has been made by XMA technique. Starting materials for alumina ceramics were prepared as shown in Table 1, and subjected to ball-mill mixing under the dry and wet conditions using nonaqueous medium. The slip was cast by a doctor blade method and dried.
The X-ray intensity of a cation of minority materials was measured from the cross section of the cast sheet (green sheet). XMA can analyze a minimum area of 2μ in diameter for a specified cation concentration in oxide. From the concentration of each samples, the variance σ_a² was calculated statistically, and the degree of mixing (M) was determined as follows:
M=1-σ_a²/(σ_a²)₀,
where (σ_a²)₀ is the variance when the respective powder materials are perfectly separated.
The following conclusions have been drawn concerning the degree of mixing of these materials:
(1) In dry mixing, M is expressed as follows:
1-M=t^-k,
where t is the mixing duration and k is the rate constant, and k=0.21-0.35 in this case. This equation is different from the generally known equation,
1-M=exp(-ct),
but the wet mixing applies to the above equation.
(2) In dry mixing, increase in the mixing duration decreases the agglomeration size of the elements of minority materials (Fig. 11). It is found that M is strongly affected by the dry mixing duration when the sample size is a few microns.
(3) Increase in M increases the bulk green density. It seems that the compaction of the materials results from deagglomeration.
(4) Increase in M increases the fired bulk density. It seems that the sintering is accelerated by deagglomeration.

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Many glasses were prepared by melting or remelting magnesium phosphate, monobasic, in a Pt-crucible at 1300°C for various duration times, from which two samples with the largest and the smallest water content were taken up.
The rate of crystal growth and the degree of crystallization of magnesium tetrametaphosphate were measured by high temperature microscopy and high temperature X-ray diffraction method, respectively. Some physical properties of the glasses were measured.
1) Spherulite of magnesium tetrametaphosphate grown in blown film glass sample showed periodic extinction rings when viwed under a polarization microscope. It was deduced that the lamellas have screwlike orientations with a common axis along the spherulite radius, and the period of the twisting is 12-14μ for the sample treated at 725°C.
2) The spherulitic growth rate and the activation energy (ca. 110kcal/mol) were almost independent of OH content of the glasses.
3) The athermal nucleation in the process of preparation of glass from its melt was inhibited by OH in the glass.
4) Avrami exponent m ranged from 1 to 1.5. The value had a tendency to be increased by OH in the glass, which was explained by the change of mechanism from athermal to thermal nucleation.

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Using titanium and zirconium fluorides of potassium and lead oxide as starting materials, the authors grew lead titanozirconate single crystals by the flux slow-cooling method. The results were as follows:
(1) With composition of more than 50mol% of PbO, the range of growth of Pb (Zr_xTi_1-x)O₃ single crystals was determined.
(2) Within the maximum temperature range from 920°C to 1100°C, single crystals of lead titanate of 7.3×4.7×4.0mm in size, lead titanozirconate of 2.4×2.0×1.5mm and lead zirconate of 3.1×2.3×2.0mm were obtained. Their crystallinity was high so that it was more easy to obtain an individual single crystal than a granular mass produced from the oxide materials.
(3) Assuming a reaction formula of the K₂(Zr_xTi_1-x)F₆-PbO system; the yield of lead titanate could be increased to 80% from 40% by adding 0.2mol of KOH according to the formula.
(4) In the case of lead titanate, (a) there was a tendency that tabular and acicular crystals grew from oxide materials, whereas (b) square crystals were obtaind from fluoride materials.
In addition, when the slow cooling rate changed from 8°C to 2°C/h, the obtained maximum individual single crystals were increased in size linearly from 0.05 to 0.55g.
(5) The solid solution condition of zirconium in lead titanozirconate was good and crystals of just the same composition as the raw material were obtained.
Owing to the use of a vessel of type (ii) for crystal growth, the flux evaporation was decreased to 15% from 40% of that by oxide materials.
(6) In the case of lead zirconate, the yield was increased to 80% from 25% of that by oxide materials.
Further more, a crystal of 4.3×4.1×2.2mm was obtained by adding ZrO₂.

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Effects the addition of TiO₂-SiO₂ and TiO₂-Al₂O₃ on sintering of ZrSiO₄ were investigated at 1500°C and 1600°C for 1 to 24 h in air. Shrinkage, bulk density, apparent density, and apparent porosity of sintered bodies were measured in relation with sintering time, temperature and content of additives. Mineral constitutions of the sintered samples were identified with an X-ray diffractometer and a reflected microscope. Microstructures of the sintered bodies and chemical compositions of liquid phase were examined by means of an EPMA.
The results obtained were as follows:
(1) Sintering of ZrSiO₄ at 1600°C was promoted by the addition of TiO₂ and SiO₂ prepared for the eutectic composition in the system SiO₂-TiO₂; 10.5% TiO₂, 89.5% SiO₂. The decomposition of ZrSiO₄ was inhibited in the presence of SiO₂. Liquid phase was recognized in sintered ZrSiO₄ bodies and it consisted of TiO₂ and SiO₂. Promotion of sintering of ZrSiO₄ was due to the formation of liquid phase, and the space in ZrSiO₄ bodies was filled with liquid. But a great deal of liquid prevented ZrSiO₄ grains coming into contact. The optimum amount of the additives of TiO₂ and SiO₂ was between 10% and 20% at 1600°C.
(2) Promotion of sintering of ZrSiO₄ by the addition of TiO₂ and Al₂O₃ was due to the formation of ZrTiO₄ and very little 3Al₂O₃⋅2SiO₂ at 1500°C and a proper quantity of liquid at 1600°C. The optimum amount of the additives of TiO₂ and Al₂O₃ was about 15% at 1500°C and between 2.5% and 5% at 1600°C.
(3) Liquid phase, which existed in the TiO₂ and Al₂O₃ bearing ZrSiO₄ bodies heated at 1600°C, consisted of TiO₂, SiO₂, and Al₂O₃. The composition of Al₂O₃ in liquid increased with Al₂O₃ content in additives.

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The method of the determination of trace amount of chromium in television tube glass was investigated by diphenylcarbazide method.
The effect of diverse elements containing ordinarily in television tube glass was investigated, and almost all elements except iron did not interfere the determination of chromium.
Iron decreased the absorbance of the solution containing chromium, but up to the definite content of iron the absorbance was kept constant. The iron content in television tube glass is 0.5 per cent or less as Fe₂O₃, it was proved that the effect of iron was compensated by the addition of certain amount of iron to both sample and standard solution.
Considering the results of diverse elements and measuring conditions, the method of the determination of chromium in television tube glass was decided as follows:
1g of powdered sample is taken to the platinum dish and decomposed with hydrofluoric acid and sulfuric acid. The residue is resolved by about 0.5N sulfuric acid solution and then the precipitates of sulfates are filtered out. A certain amount of ferric sulfate and phosphoric acid are added to the filtrate and oxydation of Cr (III) to Cr (VI) by potassium permanganate is done and excess of potassium permanganate is destroyed by urea and sodium nitrite.
An aliquot containing less than 30μg Cr₂O₃ is transferred to a beaker and 1ml of diphenylcarbazide alcohol solution is added. The absorbance of the solution is measured at 540nm in 3cm cell, and the content of chromium is obtained comparing against a calibration curve.
Blank is run through the whole procedure. The calibration curve is similarly established using blank glass which is free from chromium.
By this method 1 to 30 ppm Cr₂O₃ in television tube glass is determined with relative error of ±5%.
The detection limit is 1μg of Cr₂O₃. The chromium in borosilicate, soda-lime and lead-barium glasses are determined similarly.

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Y₂O₃ is chemically stable and one of the hopeful refractory materials. It is, however, difficult to obtain the dense Y₂O₃ pieces using an ordinary sintering method without any additives. A few kinds of powders were sintered by the ordinary method. The effect of sintering conditions such as sintering temperature, sintering time and atmosphere on sinterability of Y₂O₃ were investigated.
Total impurity of every Y₂O₃ was less than 0.1% and the average grain size of the powder was 4-6μm. The compacting pressure was 0.17-17t/cm². The green compacts were heated at 1, 700-2, 120°C for 30-100 min in a H₂ (d. p. -36 or 20°C) atmosphere or an Ar atmosphere. When the density of green compacts was 2.0-2.7g/cm³, the density of sintered pieces in a H₂(d. p. -36°C) atmosphere increased with that of green compacts. The sintered pieces became black from the inside. In-line transmittance of the sintered pieces in a H₂(d. p. 20°C) atmosphere increased with the grain size. Grain size was observed and described by D=(1.33-3.15)×10⁹t^1/2 exp (-9×10⁴/RT). Activation energy for the grain growth was approximately 90kcal/mol. The pieces sintered in an Ar atmosphere had the brown or dark surface layer where Mo was detected.
A translucent Y₂O₃ piece was obtained, which has in-line transmittance of 70% at 0.76mm thickness in the visible range.

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The SnO₂ crystals were grown by the following procedure: SnO₂ powder mixed with Sn powder of 20-50mol% was placed in a mullite porcelain boat and this boat was placed in a mullite reaction tube heated at a temperature of 1050°C-1350°C in a horizontal tubular electric furnace, and N₂ containing 1-20vol% O₂ was flowed through the reaction tube continuously with a rate of 50ml/min during the growth run.
The growth rate of the SnO₂ crystals was measured by means of telephotography through the viewing window laid at the end of the reaction tube.
The suitable Sn powder content, heating temperature and O₂ content for the growth of the SnO₂ crystals were 40mol%, 1200°C and 6-8vol%, respectively. The SnO₂ crystals which were colorless and transparent, grew up to about 4.7cm in length and 80μ in width. The long axis and the a-axis of the crystal were the same. In the case of O₂ content above 10vol%, SnO₂ ribbon crystals also grew. The direction of thickness of the ribbon agreed with the c-axis of the crystal.
In the case of 40mol% Sn powder and 6 or 10vol% O₂, the growth rate of the SnO₂ crystals at 1200°C was 8.4-6.0 or 5.4-4.2mm/min, respectively.

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The effect of grain boundaries on the fracture behaviour has been examined in magnesium oxide bicrystals under compression at room temperature.
Magnesium oxide bicrystals having small misorientation (i.e. simple tilt 2-3°) between two grains has shown that the slip bands formed by stress propagated across the boundary without formation of cracks. However, in the case above 10° (twist+tilt), the cracks nucleated at the grain boundary by the pile-up of a single band of edge dislocations.
These observations suggest that the twist angles between two grains are very important parameter for the crack nucleation.
And the angles between the direction of slip band and the grain boundaries exert strong influence on the fracture behaviour.
In all cases, the stress birefringence patterns around the indenter by the concentrated stress were formed in the ‹110› direction, and the propagated stress was blocked the grain boundary.

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Dense and nonporous films of semiconducting barium titanate showing the large positive temperature coefficient of resistivity (PTCR) effect were obtained by a modified doctor-blade method. The mixture of 100mol of BaTiO(C₂O₄)₂⋅4H₂O, 0.15mol of Sb(OH)₃, 0.87mol of TiO₂ and 2.62mol of SiO₂ was calcined at 1130°C for 3 hours. The powders were dispersed into polystyrene tetrahydrofuran fluid. Pasty sheets of about 80μ thick were made on a glass plate by an applicator. The sheets were heated on an alumina plate at 600°C for 1 hour in order to decompose and evaporate organic vehicle. Poorly coagulated powders left on the plate were pressed at about 700kg/cm² onto the polystyrene film. The film was heated on a platinum plate at 800°C for 1 hour first and subsequently at 1240, 1280, 1320 or 1360°C for 1 hour. Thus, dense and nonporous films were obtained. Observing the cross section of the film obtained at 1280, 1320 or 1360°C, the grain size was 19-23μ and the film thickness was 26-30μ.
Without pressure pretreatment cracks were found in the films obtained above 1260°C. On the contrary, the present method with pressure pretreatment made possible supply of dense and nonporous films. The semiconducting barium titanate films had resistivity at 30°C by 10²-10³ ohm⋅cm (two probe method with electroless nickel electrodes) and the PTCR effect was three or more orders of magnitude for the films sintered at 1280°C or 1320°C, while without pressure pretreatment the PTCR effect was negligible small and the resistivity was in the order of 10⁶-10⁷ohm⋅cm because of cracks.

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