Journal of the Society of Powder Technology, Japan
Online ISSN : 1883-7239
Print ISSN : 0386-6157
ISSN-L : 0386-6157
Search
Advanced search
OR
Browse
Search
Volume 52, Issue 9
Special Issue of 52nd Symposium on Powder Science and Technology
Displaying 1-5 of 5 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
Original Paper
  • Flame Synthesis of Substoichiometric Titanium Oxide under Reduction Atmosphere
    Kenji Iimura, Yuya Fujiwara, Atsushi Mineshige, Hiroshi Satone, Michi ...
    2015 Volume 52 Issue 9 Pages 500-507
    Published: September 10, 2015
    Released on J-STAGE: September 18, 2015
    DOIhttps://doi.org/10.4164/sptj.52.500
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Flame made gray titanium oxide particles which exhibit visible light absorption were successfully prepared via reduction atmospheric flame synthesis process. It was clarified that the particles have high specific surface area and are of nanometer size as a result of FE-SEM observation and specific surface area measurement. Particle properties could be varied by controlling equivalence ratio and introducing cooling gas, and the specific surface area increased as equivalence ratio increased. It was revealed that the particles are hollow for φ ＝ 1.54，1.68 and the constituent particles of shells are quite small in size. And the introducing of cooling gas affects the color of particles attributed to the oxidation degree and the specific surface increased as well. The result of XRD spectroscopy did not clearly show the generation of any magneli phases, however the peak intensity of anatase phase decreased which suggests the repression of oxidation. It was confirmed that carbon is rarely included in products and the change in color can be attributed not to carbon but to oxygen defect as a result of Raman spectrometry. Furthermore, the measurement of electric conductivity demonstrated the drastic improvement compared to stoichiometric titanium dioxide.
    View full abstract
    Download PDF (1982K)
  • Synthesis of Hollow Silica Nanoparticles Using Decomposition of Urea by Urease
    Masayoshi Fuji, Chika Takai, Masashi Yamashita
    2015 Volume 52 Issue 9 Pages 508-514
    Published: September 10, 2015
    Released on J-STAGE: September 18, 2015
    DOIhttps://doi.org/10.4164/sptj.52.508
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The ammonia-catalyzed system derived from the decomposition of urea by urease to synthesize hollow silica nanoparticles was proposed. The progress of silica from TEOS using the urea/urease-catalyzed system was first confirmed. Based on these results, the synthesis of hollow particles was then attempted as follows. Colloidal calcium carbonate as the template was suspended in ethanol/distilled water, then TEOS was added along with urea/urease. After a specific reaction time, a diluted HCl solution was added to the suspension to remove the template. A 6-hour reaction provided hollow structures using the proposed system. As a reference, the conventional ammonia-catalyzed system was also performed to prepare hollow particles. By analyzing the XRD, SEM, TEM and TG/DTA results, there were no significant differences in the physical properties of the hollow particles between the proposed system and the conventional system. In order to promote the TEOS reaction in the urea/urease system, an ultrasonic treatment of the urease suspension was applied to improve the urease dispersibility. As a result, the reaction time for the hollow structure formation could be reduced to 4 hours. This still long reaction time is caused by the induction time for the ammonia generation. It can be said that the ammonia uniformly generates after sufficient mixing of the suspension in order to inhibit heterogeneous nucleation.
    View full abstract
    Download PDF (1435K)
Review
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top