2018 Fiscal Year Annual Research Report
Development of bismuth-based persistent phosphors with wavelength tunability
| Project/Area Number |
17F17761
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
田部 勢津久 京都大学, 人間・環境学研究科, 教授 (20222119)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
BACK MICHELE 京都大学, 人間・環境学研究科(研究院), 外国人特別研究員
|
|---|
| Project Period (FY) |
2017-11-10 – 2020-03-31
|
| Keywords | ビスマス / 蛍光体 / クロム / ペロブスカイト / 長残光 / サーモメトリ |
|---|
| Outline of Annual Research Achievements |
[1] By considering the perovskite family of compounds CaMO3 (M=Ti, Sn, Zr) as a prototype, the optical properties of doped Bi3+ ions have been successfully investigated.
By combining VUV spectroscopy together with temperature dependence of photoluminescence (PL) spectra, the VRBE diagram was constructed to describe the thermal quenching mechanism of PL. The comparison of the temperature dependent PL spectral shift together with the shift of the exciton peaks allowed to disclose the origin of the emitting states; an unprecedented result after one century of studies on Bi-activated phosphors.
[2] By exploring the optical properties of Bi-based compounds, Cr3+-doped bismuth gallate and aluminates were unexpectedly discovered as effective optical thermometers.
Based on this discovery, different Cr3+-doped compounds were investigated demonstrating the superior sensitivity of the optical thermometers based on Cr3+ for biological applications respect to the standard Nd3+-doped thermometers.
The above results were submitted to Journal of Physical Chemistry C and now under revision stage after accepting a review of minor revision.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
[1] The deep investigation on the optical properties of the Bi3+-activated phosphors has allowed to develop an unprecedent strategy to discriminate the origin of the emitting states in Bi3+-activated phosphors. The discovery of this new strategy to experimentally demonstrate the MMCT nature of an emitting state and the discovery of a new parameter to theoretically predict the nature of the emitting state based on structural and chemical properties of the hosts will have a big impact on the development of the next generation of Bi-activated phosphors and persistent luminescent materials.
[2] Our first proposal of Cr3+-doped Bi2Ga4O9 as optical thermometer for biological applications has attracted the attention of the scientific community. In addition, we have demonstrated Cr3+-activated phosphors are characterized by an absolute sensitivity of two orders of magnitude higher than the standard Nd3+-doped thermometers, a key discovery from the application point of view.
|
| Strategy for Future Research Activity |
In view of the achieved results, the research will be mainly divided into two targets:
[1] Based on the strategy recently developed by our group to discriminate the origin of the emitting states in Bi-doped phosphors, the nature of the emitting state of famous Bi3+-activated phosphors will be disclosed analyzing the temperature dependence of both the Bi3+ PL emissions and the exciton peak of different families of compounds such as vanadates and phosphates. In addition, due to the promising properties for biological applications shown by CaSnO3:Bi,Cr, the persistent luminescence properties of this system will be investigated by means of thermoluminescence glow curves, 2D-plot and VRBE diagram. The performances will be compared with the standard ZnGa2O4:Cr3+.
[2] Based on the excellent results on the thermal sensitivity of Cr3+-doped materials as biological sensors and preliminary results, Cr3+-activated perovskite oxides will be employed to develop cryogenic thermometers. Finally, the systems developed will be tested as pressure sensors.
|
