The moisture and water absorption and thermal behavior of potassium tetratitanates (K₂Ti₄O₉) are studied by means of TG, DTA, IR spectra and high temperature X-ray diffraction.
The moisture absorption under normal atmospheric conditions of as-prepared crystalline powder of K₂Ti₄O₉ exhibited an arrest with increase up to 3.5wt% or to the composition K₂Ti₄O₉⋅0.8H₂O for 100h, and furthermore, it was saturated with 9wt% or at the composition of K₂Ti₄O₉⋅2H₂O after 700h. This absorbed moisture was contained as interlayer water, and was dehydrated by heating at 120°C. The melting point of K₂Ti₄O₉ was determined to be 1114°C±10°C by DTA.
The powder treated with distilled water at room temperature for 48h absorbed water up to 12.1wt% or to the composition K_2-xTi₄O₉⋅2.8H₂O (x≤0.7). The water occupied two kinds of site which corresponded to interlayer water and bound water, respectively. The water-treated powder changed into K₂Ti₆O₁₃ phase by heating at above 750°C. This showed that about one third of K⁺ in K₂Ti₄O₉ were easily eliminated in hydrolysis process.
The K₂Ti₄O₉ powder treated with 1N acetic acid solution at room temperature for 40h absorbed water up to 16.4wt% or to the composition K_2-xTi₄O₉⋅3.8H₂O (x≤2). The water occupied three kinds of site which corresponded to interlayer water and two kinds of bound water, respectively. The hydrated phase obtained by acetic acid treatment changed into TiO₂ of anatase structure by heating at above 700°C with accompanying small amount of K₂Ti₄O₉.
Infrared spectra of K₂Ti₄O₉ by KBr pellet method revealed absorption on bands at wave-numbers of 510cm^-1, 460cm^-1, 420cm^-1 (shoulder) and 300cm^-1, respectively. These bands shifted with the change in moisture and water absorption behavior caused by acid treatment.
EDTA titration method showed cation exchange of K⁺↔Ca²⁺ for well crystallized K₂Ti₄O₉⋅nH₂O powder with the ion exchange capacity of 0.25meq/g.

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Vanadium oxide films were prepared by drying and then calcining the vanadium naphthenate coated on a glass substrate in air or nitrogen atmosphere.
The formation processes of the films were examined by thermogravimetric analysis, infrared spectrometry and electron and X-ray diffraction techniques.
The amorphous vanadium oxide precipitated in the film through the hydrolysis of vanadium naphthenate by the moisture in air. The film mainly consisted of V₂O₅ or VO₂ was obtained by the calcination at the temperature 500 to 600°C for 20min in air or nitrogen atmosphere, respectively.
The VO₂ films showing the transition of nonmetallic-metallic conduction at about 60°C were obtained by the repitition of coating, drying and heating. The transitions were more sharply with an increase of the number of the repitition.
The VO₂ films formed on the c-plane of synthetic fluorophlogopite substrate showed more sharp transitions than those formed on the slide and silica glass substrate.

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Crazing is one of the most serious defects in tableware. Stress in glaze due to an unfitness of the thermal expansion of body and that of glaze is the main cause for crazing. A rapid method of determining the stress in porcelain glaze was developed, in which birefringence caused by the stress in the glaze was measured using a quartz optical wedge and a gypsum test plate under a polarizing microscope. Test pieces were cut from sample wares by using a cutting tool driven by an ultrasonic vibrator.
The dimensions of the test pieces were pre-determined, so that stresses in the glaze would not be released by the cutting operation. The variation of stresses in each item was measured using test pieces cut from various positions of the same item and it was confirmed that the measurement of stress in one test piece per sample ware was sufficient for quality and production controls.
Through the measurements of stresses in the glaze of a large number of crazed and non-crazed porcelain wares, it was found that stresses in the glaze of crazed wares were always tensile and were in the range of +10 to +500kg/cm², while those in non-crazed wares were in the range of +200 (tensile) to -1100kg/cm² (compressive). Most of the compressive stresses in the non-crazed wares were in the range of -500 to -800kg/cm². When stresses in the glaze of commercial wares, both domestic and imported, were measured, most of them were found to be compressive, but a few of them, especially those of vitreous china were found to be more or less tensile.

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As is well known, chromium oxide Cr₂O₃ will be readily oxidized to form the corresponding chromate by reacting with a compound of basic property such as Na₂CO₃ or CaCO₃ under elevated temperature and oxygen atmosphere.
The present investigation was attempted to estimate the value of the fractional conversion to chromate (α) for some double oxides containing alkaline earth cation in the presence of Cr₂O₃, the result of which might provide an information about the solid basicity of the double oxide used. The following 13 kinds of double oxide were synthesized by heat treatment and were subjected to the reaction with Cr₂O₃ in an oxidizing atmosphere; CaTiO₃, CaZrO₃, SrTiO₃, SrZrO₃, BaTiO₃, BaZrO₃, SrSiO₃, Ba₂SiO₄, BaSiO₃, Ba₂Si₃O₈, BaSi₂O₅, BaAl₂O₄ and BaAl₁₂O₁₉.
The results obtained are summarized as follows;
(1) The maximum values of the fractional reaction completed (α_max) are 0% for CaTiO₃ and SrTiO₃, and 100% for SrZrO₃ and BaZrO₃, indicating the both groups would be classified as acidic and basic oxides, respectively, but the values of α_max for CaZrO₃ and BaTiO₃ are close to 80% because of the formation of an intermediate phase during reaction.
(2) SrSiO₃ is foreign to the oxidation as same as CaTiO₃ and SrTiO₃.
(3) In the binary compounds of the system BaO-SiO₂, it shows a tendency that α value increases with increasing Ba content in the double oxide. In general, α_max value is depended on the oxygen partial pressure and the oxidation is interrupted by the consecutive reaction BaCrO₄ and SiO₂ under the atmospheric pressure.
(4) In the presence of Cr₂O₃, BaAl₂O₄ is converted to BaCrO₄ and Al₂O₃ completely in flowing oxygen gas but BaAl₁₂O₁₉ is found unreacted under an elevated temperature and in stream of oxygen gas.

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A congruently melting Li₂O⋅2SiO₂ (mol ratio) melt was unidirectionally solidified in a clay crucible from its bottom at a constant rate of 3.3mm/h, and effects of surface condition of the inner bottom surface of the crucible, from which crystallization started, on orientation of crystals grown in the melt was investigated: Four cases were examined in which the inner bottom surface was covered with a platinum sheet, sintered Li₂O⋅2SiO₂ polycrystalline plate, Li₂O⋅2SiO₂ glass-ceramic layer formed from its glass by crystallization or without any material, i.e., as-produced clay surface. In all cases the temperature gradient in the melt was set at 80°C/cm. When the bottom surface was covered with the glass-ceramic layer, Li₂O⋅2SiO₂ crystals grew from the surface of the glass-ceramic layer, being highly oriented with their c-axis parallel to their growth direction. The ingot thus obtained consisted of highly oriented Li₂O⋅2SiO₂ columnar crystals of ca. 460μm in diameter.
The further experiment in which the solidification rate was varied showed that the average diameter (D) of the columnar crystals decreased from 580 to 340μm as the solidification rate (R) was increased from 0.7 to 13mm/h, which yielded the relation, D∝R^-1/6.

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Shear wave velocity and its temperature dependency of lead silicate glasses containing fluorine ions were measured as a function of chemical composition, and the following results were obtained.
(1) Shear wave velocities of glass systems, K₂O-PbO-PbF₂-SiO₂, KF-PbO-SiO₂, and ZnO-PbF2-SiO₂ were treated by multiple correlation analysis and the following equations were derived in relation to chemical composition. For the glass system K₂O-PbO-PbF₂-SiO₂ v=38.22-8.34[Si]+2.89[K]-32.48[Pb]+47.39[O]-27.28[F] For the glass system KF-PbO-SiO₂ v=3240.16-0.69[Si]+360.96[K]-70.75[Pb]-2.28[O]-405.98[F] Differences between measured and calculated values were within ±0.01%.
(2) Introduction of fluorine ions into lead silicate glasses was effective on the decrease in shear wave velocity.
(3) Temperature coefficient of delay time of the glass K₂O-PbO-PbF₂-SiO₂ varied negatively by introduction of fluorine ions, and further introduction of fluorine ions varied positively. It was assumed to be due to the formation of inhomogeneous phase in the glass.
(4) Temperature dependency of delay time of the glass RO-PbF₂-SiO₂ increased positively in proportion to the ionic radius of divalent cations.
(5) Temperature coefficient of delay time were also treated by multiple correlation analysis, but the agreement was not so good compared to those of shear wave velocity.

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Ferrous hydroxide gel was found to be very efficient for removing various divalent metal ions in solution by coprecipitation. The coprecipitates were ferrimagnetic themselves or can easily be oxidized into ferrimagnetic oxides or hydroxides. The coprecipitation was proposed to be caused by (1) the formation of solid solution (Mg²⁺, Zn²⁺, Cd²⁺, Mn²⁺, Co²⁺ and Ni²⁺), and (2) the redox reaction with the results of the formation of insoluble solids (Hg²⁺ and Cu²⁺). The mechanism of the coprecipitation accompanied by the redox reaction is discussed in connection with ionic processes at the ferrous hydroxide crystal-solution interface.

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