Journal of the Ceramic Association, Japan
Online ISSN : 1884-2127
Print ISSN : 0009-0255
ISSN-L : 0009-0255
Volume 83, Issue 963
Displaying 1-9 of 9 articles from this issue
  • Toshio TSUCHIYA, Taro MORIYA
    1975 Volume 83 Issue 963 Pages 519-527
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The electrical conductivities of glasses in the system Li2O-K2O-Fe2O3-P2O5 were observed in the temperature range 20° to 160°C. Whereas alkali ions, Li2O and K2O, give rise to ionic conduction, Fe2O3 to electronic conduction. In the series (40-x) Li2O-xK2O-60P2O5 the conductivity was found to have a minimum and the activation energy to have a maximum at the composition corresponding to x=20mol%. In the series (20-x) Li2O-xK2O-20Fe2O3-60P2O5 the curves of logσ versus the content of K2O were shown to have the minimum at about x=5mol%, however, the activation energy curves decreased with increasing K2O content without having any maximum. This can be considered from the fact that a part of Li2O combines with Fe2O3 in some ways, i.e. by way of producing a phase LiFeO2 or LiFe5O8. Li+ utilized for the ionic conduction may actually decrease.
    In complicated composition of glass, the simple additivity law does not hold. The experimental values of logσ100°C in the 20Li2O-20Fe2O3-60P2O5 glass was about one order of magnitude lower than those calculated from the formula of additive property,
    σ=K1ye-ΔHa/RT+K2⋅(1-y)2c(1-c)⋅e-ΔHe/RT
    where K1, K2 are constants, ΔHa the activation energy for the glass 40R2O-60P2O5, ΔHe the activation energy for the glass 40Fe2O3-60P2O5, y the concentration of R2O, (1-y) the concentration of Fe2O3, c the ratio of Fe2+/Fe2++Fe3+, R gas constant, and T absolute temperature.
    On the other hand the experimental values of the conductivity in xK2O-(40-x)Fe2O3-60P2O5 glasses were found to be approximately equal to the calculated values from the above formula of additivity law. In this experiment, therefore, the additivity law holds only for the glass containing K2O as alkali component. Accordingly the formula of the conductivity in the glasses containing both Li2O and Fe2O3 is considered to be supplemented by a correction term owing to the producing of the phase LiFeO2 and LiFe5O8 which hinder both ionic and electronic conduction; that is, we have a conduction formula,
    σ=K1ye-ΔHa/RT+K2⋅(1-y)2c(1-c)⋅e-ΔHe/RTc.
    σc is a correction term.
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  • Takeshi HOSHIKAWA, Saburo AKAGI
    1975 Volume 83 Issue 963 Pages 528-534
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The glasses of SiO2-Fe2O3-K2O system were heat-treated at 800°C-1100°C, and the inversion temperature and the lattice constants of Fe-leucite crystals precipitated in the glass were measured by using DTA apparatus and X-ray diffractometer.
    It was found that the change of inversion temperature was closely related with the atomic ratio δ=Si/(Si+Fe+K) of the mother glass composition. Each Fe-leucite crystal precipitated in the glasses with δ<0.5 showed a constant inversion temperature 552±8°C corresponding to the inversion temperature of the Fe-leucite with the ideal composition. Inversion temperature of Fe-leucite crystal precipitated in the glass with δ>0.5 lowered with the increase of δ. The lower crystallization temperature was, the more steep the degree of lowering was. It was also observed that there is a linear relationship between the inversion temperature and the lattice parameter c/a, when δ>0.5.
    It was considered that in the case of δ>0.5, Fe-leucite crystal having the composition of (KFe)1-xSi2+xO6(x>0) had a higher symmetrical lattice than the ideal one and the lattice defects which might be caused by the defficiencies of K+ increasing with δ.
    The influence of other phases such as residual glass, hexagonal KFeSiO4 crystals and hematite crystals on the inversion temperature was not observed.
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  • Jun FUKUSHIMA, Kohei KODAIRA, Atsumu TSUNASHIMA, Toru MATSUSHITA
    1975 Volume 83 Issue 963 Pages 535-540
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Polycrystalline zinc oxide film was prepared as follows. Zinc naphthenate was coated on a glass or fused silica substrate. The coated zinc naphthenate was decomposed thermally by calcining at 300°C in vacuum or air to form amorphous zinc oxide. On calcining zinc naphthenate at 400°C for 1h, the decomposition was completed and a transparent and uniform film was obtained. However, the amorphous zinc oxide produced by hydrolysis of zinc naphthenate in the presence of small amounts of water (17.5mmHg) crystallized rapidly at 200°C. Consequently, no uniform film was observed, and fine powder of zinc oxide deposited on the substrate. Thus, the uniformity of the film is closely related to the crystallization temperature of amorphous zinc oxide.
    The thickness attained to 2μ on repeating the coating and calcining procedures. Preferred orientation with c-axis perpendicular to the film surface developed with an increase in the thickness.
    The electrical resistivity of the film having the thickness of 1μ was 109Ω-cm at room temperature. The temperature dependence resistivity had a minimum at 280-290°C and a maximum at 420-430°C.
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  • Hideo TAMURA, Tetsuro YOSHIDA
    1975 Volume 83 Issue 963 Pages 540-546
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    To elucidate the microstructure, sintering process and developement of second phase at the grain boundary, model grain boundary was prepared and observed, by contacting two polished surfaces of sintered spinel Cu0.75Fe2.25O4+x and annealing. Because the sintered specimen was grown its grains extremely (above several hundreds microns diameter), little grain growth and little boundary migration occurred during annealing for bonding. Therefore, the bonded part could be cleaved again along the new grain boundary, and the both sides of boundary surface were observable.
    The oxygen content of the specimen was controlled by previous annealing, and the bonding was carried out between 1100°C and 1180°C. The bonding was nearly complete at the conditions, in which specimen was oxidized and the bonding was little when it was reduced (Fig. 1, 4). It was confirmed that the new grain boundary was not different from the grain boundary of the inner part of sintered body (Fig. 2, 3).
    The crystallographic orientation of the grains at the bonded boundary was determined by measuring the orientation of α-Fe2O3 crystallites, which developed in the spinel crystals by oxidation. Various step configurations were observed at the cleaved boundary surfaces (Fig. 5, 6). The relation between step configuration and crystallographic orientation of the grains at the boundary was plotted in the stereographic projection diagram (Fig. 7). It is confirmed that the (111) plane is one constituent of the step, and it seems to be stable at the grain boundary (Fig. 8).
    The process of developing α-Fe2O3 or CuFeO2 crystallites at the grain boundary of spinel was observed, when specimen was oxidized or reduced. It was confirmed from the observation of the cleaved boundary surfaces that the both crystallites developed along the (111) plane of spinel. The various configurations of developed crystallites were related to the orientation of the spinel crystal grains at the boundary (Fig. 9, 10).
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  • Issei HAYAKAWA, Hiroaki YANAGIDA
    1975 Volume 83 Issue 963 Pages 546-552
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The effect of particle size and impurity on initial sintering of Bi2O3 was investigated in the range 550° to 700°. The isothermal shrinkage rate was analyzed by four different kinetic equations.
    The sintering of Bi2O3 with the grain size larger than 2μ was controlled by grain boundary diffusion mechanism and quick aggregation or adhesion of particles was observed for fine powder Bi2O3 (0.2μ). The activation energy for grain boundary diffusion was 140 to 150kcal/mol and it was presumed that the sintering rate determinant or slow diffusion species was O2- ion. Remarkable promotive effect on sintering was observed for CdO added Bi2O3 powder compact, while addition of CeO2 suppressed much the rate of sintering.
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  • Nobuo KAMIYA, Yoichi OYAMA, Osami KAMIGAITO
    1975 Volume 83 Issue 963 Pages 553-557
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    On the basis of the solid solution in the system, Si3N4-AlN-Al2O3, the presence of silicon nitride solid solution in the system, Si3N4-AlN-SiO2, is expected from the consideration of their composition. The range of the solid solution expected on this basis covers the compo sitional triangle made by connecting the three points, A (57mol% AIN-43mol% SiO2), B (67mol% AIN-33mol% SiO2), and C (100mol% Si3N4). An experimental study of the solid solution proved the expectation valid. In addition to this, the actual range of the solid solution was found to be wider than the triangle mentioned above. This excess range agrees rather well with the expected range on the basis of the vacancy concentration, with the exception of the range near Si2ON2.
    The points, A and B, lie on the binary system, AlN-SiO2. The triangle, ABC, is intercepted by the line connecting the two points, AlN and Si2ON2. In other words, the two binary systems, AlN-SiO2 and AlN-Si2ON2, contain the solid solution which is distinguished from the end members in the cystral structure. Thus the presence of two new compounds to represent the solid solution, SiAl2N2O2 and Si2AlN3O is exected for the systems, AlN-SiO2 and AlN-Si2ON2, respectively.
    Experimental examinations by X-ray diffraction method, however, failed to confirm the presence of the compounds, may be due to the order-disorder transformation in the compounds, as in some of spinel structure.
    The presence of silicon nitride solid solution in the system, Si3N4-AlN-SiO2, shows that the addition of AlN to silicon nitride would be effective to eliminate the glassy phase which is considered to reduce the high temperature strength.
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  • Shigeki OOBA, Seiichi UENO, Yasushi HASEGAWA
    1975 Volume 83 Issue 963 Pages 558-561
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    As2S3 glass rods were prepared by melting the raw materials in evacuated silica glass ampoules which had been placed horizontally in a rocking furnace, and cooled at vertical position.
    The effect of the melting temperature ranging 600-900°C on the uniformity of the chemical composition of the glass rod was studied. Maximum difference of the arsenic content at the each fraction of the glass rod, ΔAs, was employed as the evaluation of uniformity of the glass. To keep the ΔAs value less than 0.5wt%, melting time of 24h was required for melting at 600°C, 6h at 700°C, and 1h at 800°C. While only by heating up to 900°C, the ΔAs value went down to 0.3wt% and less.
    For the sample with poor uniformity, it was found that the arsenic contents in a lower half of glass rod (63-64wt%) was higher than the average arsenic content (60.9wt%).
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  • Makoto HATTORI
    1975 Volume 83 Issue 963 Pages 561-563
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • 1975 Volume 83 Issue 963 Pages A72-A78
    Published: November 01, 1975
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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