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Keynote Lecture

WEB Blue photoluminescence from flash sintered oxide ceramics

Friday (25.09.2020)
09:00 - 09:30 P: Processing and Synthesis 1
Part of:


Flash sintering is one of very unique sintering techniques to realize lower sintering temperature and shorter sintering time by high electric fields, which was developed by Raj et al. So far, the effectiveness of flash sintering has been confirmed for various kinds of oxide ceramic. Various techniques to apply electric fields to green compacts have been also improved.

Recently, it was found that Y2O3-doped ZrO2 (YSZ) polycrystals sintered by flash sintering emits visibly blue photoluminescence (PL) at room temperature under ultraviolet light. The interesting point of this phenomenon is that visible PL emits under a weak excitation such as a handheld ultra violet light. Similar phenomenon of PL emission was also confirmed in Y2O3 polycrystals sintered by flash sintering. These PL emissions are not observed from conventionally sintered polycrystals using the same raw powders. Thus, PL emission observed in flash-sintered polycrystals can be considered to result from the loading of the electric field during sintering.

PL bands observed in flash-sintered YSZ polycrystals exhibit blue shift by increasing Y2O3 content. The blue shift ranged from 450 to 420 nm with Y2O3 content from 2 to 8mol%. The PL bands were related to the PL excitation at 320 nm, which appears owing to the loading of the electric field during flash sintering. The detail diagram for PL/PLE has not been clarified yet, however, it can be considered not to result from simple F+ center related to oxygen vacancies. In the presentation, the effects of electric fields, electric waveform, flash temperature etc on PL properties will be shown.

 

Speaker:
Prof. Takahisa Yamamoto
Nagoya University
Additional Authors:
  • Prof. Hidehiro Yoshida
    The University of Tokyo