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Volume 30, Issue 11
Displaying 1-5 of 5 articles from this issue
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Haruhisa SHIOMI, Touko FUKUZAKI, Masahiko NAKAMURA1993 Volume 30 Issue 11 Pages 768-776
Published: November 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSSemiconductive SnO2 fine powder, doped with Sb, was prepared by a mechano-chemical reaction during dry ball milling. The effects of the crystallinity of the SnO2 starting powder and the revolution rate of the pot mill were discussed in relationship to the doping reaction of Sb in SnO2 during ball milling by taking the milling mechanism into consideration.
The results obtained are the following:
(1) Ball milling at a high revolution rate was effective for the doping reaction of Sb in SnO2, so that the electrical conductivity of the powder mixture ball-milled at such a speed became higher compared with that of the powder mixture ball-milled at a low speed.
(2) When the ball milling was carried out at a high revolution rate using well crystallized SnO2, the doping reaction of Sb was facilitated. However, at the same time, since particle size reduction was significant, the increase in the electrical conductivity was prevented. Thus, when the SnO2 starting powder was used, with a medium degree of crystallinity, the increase in the electrical conductivity was greatest due to competition between the particle size reduction and Sb doping reaction in SnO2.View full abstractDownload PDF (5831K) -
Masahiro HASEGAWA, Tateaki OGATA, Masatake SATO, Yoshiteru KANDA1993 Volume 30 Issue 11 Pages 777-781
Published: November 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSMechanoradicals of quartz produced by grinding were studied by use of an electron spin resonance (ESR) measurement. Quartz was ground by a vibrating ball mill in a nitrogen atmosphere, and the specific surface area was measured by the BET adsorption method. The ESR measurements were carried out on an X-band apparatus at room temperature. As a result of grinding, the shape of the observed ESR spectra became complicated with the passage of grinding time, and the ESR signal intensity likewise increased. From the obtained g-values of the ESR spectra the mechanoradicals of quartz produced by grinding were estimated to be E' center, non-bridging oxygen hole center and peroxy radical. It was found that the mechanoradical concentration was approximately proportional to the produced specific surface area.View full abstractDownload PDF (586K) -
Hideto YOSHIDA, Toshiyuki FUJIOKA, Hisao MAKINO1993 Volume 30 Issue 11 Pages 782-789
Published: November 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSNumerical studies of the data reduction by a cascade impactor are conducted for specific conditions. It is clearly shown that the Twomey's method is superior to the conventional method which uses a 50% cut size, when nearly monodispersed particles are measured. It is impossible to estimate the true particle size distribution by the conventional method when the geometric standard deviation of the particle size is smaller than the geometric standard deviation of partial separation efficiency.
It is possible to estimate the true particle size distribution by use of a Twomey's method, which uses a virtual stage and increases the division of the particle size, even if the geometric standard deviation of particle size distribution is less than 1.1.View full abstractDownload PDF (724K) -
Functionally Gradient Materials and Unique Synthetic Processing Methods from Next Generation of Powder TechnologyMasao TOKITA1993 Volume 30 Issue 11 Pages 790-804
Published: November 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (20901K) -
Masaharu YAMADA1993 Volume 30 Issue 11 Pages 815-818
Published: November 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (1794K)
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