学术报告

Prof. Martin Nikl
Institute of Physics, Academy of Sciences of the Czech Republic, Prague

First seminar

2011-7-18，长宁园区，时间：上午9：30， 4号楼14楼第2会议室，

联系人：潘裕柏 2820，冯锡淇 5315

Garnet optical ceramics: luminescence and scintillation characteristics, defects and material performance.

The Ce and Pr-doped aluminum garnet optical ceramics became a hot topic in the R&D of fast scintillation materials. Though the creation of antisite defects, a well-known problem in single crystals of this kind, can be avoided in ceramics technology, the problem of trapping states at the grain surfaces and interfaces appears quite severe: these defects significantly decrease the scintillation performance. It is not clear, what kind of defects and traps is created in optical ceramics and how they are related to the manufacturing technology.We have recently demonstrated the positive role of Ga admixture in lutetium aluminum garnet to diminish trapping effects in single crystals. In this lecture, luminescence and scintillation mechanism in these materials will be surveyed, possible ways in composition engineering will be proposed to facilitate energy transport towards emission centers and to increase the light yield.

Second seminar

2011-7-19，嘉定园区，时间：上午9:30；地点：青年公寓二楼会议室，

联系人：任国浩 69987741

Invesitigation on the Luminescence mechanism of  Ce and Pr-doped Lu- containing scintillation  crystals

The survey of luminescence mechanism in Ce and Pr-doped ortho- and pyrosilicates of general formula (Lu-Y)₂SiO₅ and Lu₂Si₂O₇, respectively, will be given with special attention to the processes in the 5d₁ excited state of the emission centers and their dependence on the host composition. Usage of purely optical methods for the study of thermally induced excited state ionization will be demonstrated. Current understanding of the defects and traps and their participation in scintillation mechanism in these material will be discussed as well. Recently reported codoping by Ca²⁺ and other divalent cations will be mentioned as a tool for material optimization.