Journal of the Ceramic Association, Japan
Online ISSN : 1884-2127
Print ISSN : 0009-0255
ISSN-L : 0009-0255
Volume 85, Issue 982
Displaying 1-13 of 13 articles from this issue
  • Shuzo KATO, Takeo IGA
    1977 Volume 85 Issue 982 Pages 253-257
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Effect of crystallinity of parent salt on the sinterability of α-alumina has been studied. Two series of NH4AlO(OH)HCO3 tentatively designated as I- and R-series, were prepared under the different conditions.
    It is shown that the sinterability of the α-alumina powders of I-series increased with decreasing crystallinity of the parent salt. Alpha-alumina powder of the R-series, on the other hand, exhibited the sinterability comparable to that of poor-crystallized I-series powders in spite of the good crystallinity. This is explained in terms of the well-dispersed nature of the primary particles of parent salt.
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  • Hiroo TAKASHIMA, Hajime SAITO
    1977 Volume 85 Issue 982 Pages 257-263
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The assignment of infra-red reflection spectra resulted from phase separation of silicate glass and borosilicate glass were studied.
    The results obtained were as follows:
    1) The main peak due to Si-O-Si bond shifted to higher wavenumber by the change of glass state from homogeneous phase to a separated state phase in indentical composition of silicate glass. Another peak of about 1200cm-1 wavenumber due to Si-O-Si bond also shifted to higher wavenumber and its peak sharpened.
    2) The shoulder height at lower wavenumber side of the main peak increased with phase separation in the particular glass composition. Its shoulder peak considered was due to Si-O-Si bond in one of the two phase separated glasses. It was considered that, that glass phase had higher network modifier cation content than that of the other glass phase.
    3) The peaks of about 1150cm-1 and 1220cm-1 wavenumber resulted from phase separation of borosilicate glasses. These peaks were assigned to _??_B-O-|Si| bond, and _??_B-O-B_??_ bond, respectively.
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  • Hiroshi TOYUKI
    1977 Volume 85 Issue 982 Pages 263-268
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The glass forming region in the system K2O-AlF3-B2O3 has been determined. The measurements of optical absorption spectra of VO2+ ions dissolved in the system glasses and AlKα X-ray emission spectra of 0.25K2O⋅0.15 AlF3⋅0.60B2O3 and 0.25K2O⋅0.20AlF3⋅0.55B2O3 glasses have been made. In the light of these spectral results obtained, the bonding mode of Al atoms in the glasses has been discussed. Two modes have been suggested to be considered. In a mode, the only K+[K+AlO3F3-]- group is formed and, in the other, K+[K+(O3B-O-AlF3)-]- or K+[K+(O3Al-O-BF3)-]- group is formed together with the K+[K+AlO3F3-]- in arbitrary ratios.
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  • Shigehide TAKAGI, Goro YAMAGUCHI
    1977 Volume 85 Issue 982 Pages 268-272
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    It is well known that the energy distribution, the spectrum profile of emission and absorption spectrum are affected by the electron orbit according to the binding state of atoms, and the analysis of those spectra in order to investigate the binding state of constituent atoms became widely applied.
    The present study was performed in order to confirm how those spectra would be observed according to the co-ordination state of atoms in solid solution phases of synthetic MgO⋅Al2O3-MgO⋅nAl2O3 system by means of electron microprobe spectroscopy.
    The X-ray emission spectrum energies were obtained from the mean value of 3/4 peak height position and analyses were carried out from a standpoint of the half width and the asymmetry index for the spectrum profile.
    In this experiment, the AlKα, β, MgKα and their satellite line profile remained unchanged, even though n was varied from 1 to 1.8. The OKα spectra, however, showed shift toward high energy side, and the half width and their asymmetry indices were increased.
    From these experimental results it was assumed that the distribution of Mg2+ and Al3+ ions did not change while n was varied from 1 to 1.8 for MgO⋅nAl2O3.
    Though the character change of OKα spectra is not so easily determined, it may be attributed to the existence of anisotropic O2- ions caused by cation vacancy formation.
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  • Tadashi NISHINO, Tadashi SAKURAI
    1977 Volume 85 Issue 982 Pages 273-277
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    In order to elucidate the phase relation of pseudo-ternary system BaO-TiO2-Cr2O3 in an oxydizing atmosphere, the reaction of BaO-TiO2 compounds with Cr2O3 was investigated by chemical, thermal and X-ray diffractometric analyses.
    Both of 2BaO⋅TiO2 and BaO⋅TiO2 react with Cr2O3 to form BaCrO4 as a product, the maximum values of the fractional formation to BaCrO4 were 90 and 80% of theoretical, respectively, and the resulting TiO2 was not detected in the process of the reaction, both of which indicated a new compound with about 1/5 of the molar ratio BaO/TiO2 would be produced.
    As a result of an investigation by the disappearing-phase method, it could be concluded that the new compound may be represented as BaO⋅5TiO2⋅Cr2O3 (tetragonal, a0=7.11Å, c0=8.50Å) isomorphous with BaO⋅5TiO2⋅Fe2O3 (tetragonal, a0=7.14Å, c0=8.54Å).
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  • Takehiko TAKAHASHI, Katsumi KUWABARA
    1977 Volume 85 Issue 982 Pages 277-281
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Formation of β-Al2O3 was investigated in the composition range of 73.9-92.6 weight percent (w/0) Al2O3 by the use of thermal and X-ray analyses.
    Specimens fired at 1000°C for 3h in flowing N2 gas showed (1) mixed phases of β-Al2O3, NaF and Na3AlF6 at low Al2O3 region, (2) single phase of β-Al2O3 at 86.7w/0 Al2O3, and (3) mixed phases of β-Al2O3 and α-Al2O3 at high Al2O3 region.
    An exothermic peak point starting at 730-780°C in DTA curve ascended from 780 to 840°C and the weight loss due to the AlF3 sublimation descended with the increase of Al2O3 content. The exothermic peak temperature was made clear to correspond to the reaction of β-Al2O3 formation by X-ray diffraction.
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  • Kyung Hee LEE, Masaru SHIMURA, Masaki DAIMON, Renichi KONDO
    1977 Volume 85 Issue 982 Pages 281-286
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The chemical composition of solution was measured in hydrothermal reaction of lime-quartz-water system. In this reaction the effects of particle size of quartz and added kaolin were discussed. Quartz powder with 2-3μm and 5-10μm in particle radius were suspended with lime in pure water in molar ratio of 1:0.8, and autoclaved at 181°C for 3-8 days. Changes in the concentration of SiO2 and CaO in solution were analysed. Identification of products were performed by means of X-ray powder diffraction and scanning electron microscope (S. E. M.).
    It was found that
    1) The solubility of quartz at 181°C was 205mg/l.
    2) It took rather long time to reach equilibrium in Ca(OH)2 dissolution.
    3) CaO concentration was high at first, in lime-quartz-water reaction, and the products in this period was lime rich phase. The transformation of the products was represented by the following reaction. α-C2SH→C-S-H(I)→tobermorite C-S-H(II)→C-S-H(I)→tobermorite Concentration of SiO2 increased until all the quartz had reacted, suggesting that the dissolution of quartz was faster than the consumption by reaction.
    4) Added kaolin retarded the dissolution of quartz.
    5) The presence of kaolin retards the lime-quartz-water hydrothermal reaction. This effect was supposed to be originated by the retardation of quartz dissolution by aluminate.
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  • Atsushi OHTSUKA, Hiroshi NAKAMURA
    1977 Volume 85 Issue 982 Pages 286-294
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    This study was concerned with the formation and color development of the solid solution in CoO-MgO-ZnO system.
    Specimens were prepared by calcining the oxide mixture at 1200, 1300, 1400 and 1500°C for 1h respectively.
    Formation of solid solution was examined by X-ray analysis, and the lattice parameter were calculated. Furthermore, the color was discussed by measuring the spectral reflectance.
    The results obtained at 1400°C, were summarized as follows.
    1) Having electronic configuration 3 d7, Co2+ revealed appreciable tetrahedral preference in addition to the octahedral preference. Therefore, CoOCo2O3 (spinel) was observed with (Co, Mg, Zn)O solid solution (rock salt type structure) in CoO rich region.
    2) Solid solution limits of approximately 35mol% ZnO into MgO, and approximately 10mol% MgO into ZnO were obtained.
    3) ZnO was incorporated into CoO approximately 30mol%, and CoO was incorporated into ZnO approximately 20mol%.
    4) The formation range of (Co, Mg, Zn)O solid solution with rock salt type structure was fairly wide, whereas in the case of wurtzite type structure was narrow.
    5) Obedience to Vegard's law was observed in mutual replacement of Co2+ and Zn2+ in the solid solution with rock salt type structure, whereas in CoO-MgO system, the linearity of the lattice parameter was not revealed, owing to the change of bond character.
    6) Color obtained in (Co, Mg, Zn)O solid solution with rock salt type structure was pink, and the absorption of octahedral Co2+ was observed. Brilliant hue, so-called cobalt green, resulted from the absorption of tetrahedral Co2+, developed in (Co, Zn)O and (Co, Mg, Zn)O solid solution with wurtzite type structure.
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  • Ryohei TERAI, Eiji OHKAWA
    1977 Volume 85 Issue 982 Pages 294-299
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The self-diffusion coefficients of calcium ions in 16Na2O⋅12CaO⋅72SiO2(wt%) glass and 40CaO⋅20Al2O3⋅40SiO2(wt%) slag glass at temperatures near and below transition point have been measured employing radio-isotope 45Ca. The concentration gradient of radio-activity in surface layer of glass samples after diffusion annealing was determined by counting the residual activity with a GM-tube counter on the surface by progressively chemical etching away the material in steps of about 1 micron meter.
    It was found that the self-diffusion coefficients of calcium ions in both glasses below the transition point were of the order of 10-14-10-16cm2/s, suggesting that the mobility of calcium ions was extremely small in the solid glasses. The activation energy for diffusion of calcium ions in solid glasses was about 60kcal/mol, which seemed to be reasonable in comparison with the electrostatic binding energy between cation and oxygen ion.
    The self-diffusion coefficients of calcium ions in the slag glass agrees closely with those of oxygen ions below the transition point, while the self-diffusion coefficients of calcium ions in the soda-lime glass are greater by one order of magnitude than those of oxygen ions in the same glass. The difference of diffusion behavior of calcium ions in the slag and the soda-lime glasses may be attributed to action of alkali ions on the mobility of calcium ions.
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  • Sumio SAKKA
    1977 Volume 85 Issue 982 Pages 299-305
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The chemical shifts of AlKα1, 2 X-ray fluorescence lines of germanate, borate and phosphate glasses have been determined in order to investigate the coordination number of Al3+ ions in glasses.
    In Na2O-Al2O3-GeO2 glasses with 60 and 70mol% GeO2 and the Al2O3/Na2O ratios ranging from 0.5 to 1.5, the chemical shifts were nearly equal with each other and with that for orthoclase crystal, indicating that the Al3+ ions are fourfold-coordinated in the glasses.
    The chemical shifts for CaO-Al2O3-B2O3 glasses largely depended on the B2O3 content of glass and not on the Al2O3/CaO ratio. The chemical shift increased from the value nearly equaling that for the orthoclase towards that for α-Al2O3 as the B2O3 content increased, indicating that the average coordination number of the Al3+ ions increases with increasing B2O3 content.
    A wide variety of phosphate glasses with varying P/O ratio were melted from the batches containing various constituents besides Al2O3 and P2O5, and subjected to measurement of the AlKα1, 2 spectra, assuming that the P/O ratio of 0.333 would correspond to the metaphosphate and the ratio of 0.25 to the orthophosphate. It was found from the chemical shifts that glasses with the ratio near 0.333 contain a considerable fraction of six-coordinated Al3+ ions, while those with the ratio near or below 0.25 contain almost all Al3+ ions in four-coordination.
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  • Toshihisa MARUTA, Keiichi MINEGISHI, Takemitu KOYATA
    1977 Volume 85 Issue 982 Pages 305-307
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    In the Japanese Industrial Standard method (JIS R 5202) for the determination of iron in cements, it is recommended to use tin (II) chloride as reducing reagent of iron (III) and mercury (II) chloride for the oxidation of the excess tin (II) chloride. The zinc reduction-potassium dichromate titrimetry has been developed in order not to cause enviromental pollution by mercury chloride which is contained in the waste water.
    After 1g of cement sample was dissolved in excess hydrochloric acid, 1.0g of zinc powder, which could be found most suitable reducing reagent, was added into the solution. By heating the solution, the zinc powder could be dissolved immediately in excess hydrochloric acid and reduced iron (III) in the solution to iron (II) easily.
    Eight kinds of diverse ions such as sodium, potassium, magnesium, calcium, aluminum, silicon, titanium and sulfate, which present in cements, did not show interference.
    Analytical results of iron in cements obtained by the proposed method agreed well with those by the JIS method (JIS R 5202). The time of determination was about 30 minutes.
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  • Kanichi KAMIYA, Sumio SAKKA
    1977 Volume 85 Issue 982 Pages 308-309
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • 1977 Volume 85 Issue 982 Pages A34-A36
    Published: June 01, 1977
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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