Novel Method of Search for Transparent Optical Materials with Extremely High Melting Point

We propose a novel crystal growth method, "Core Heating (CH) Method", which is suitable for a search of novel materials with extremely high melting points above the melting (softening) point of an Ir crucible. As a feasibility test of the novel CH method, we fabricated the conventional material, (Y0.99Ce0.01)(3)Al5O12 (Ce:YAG), with a melting point of similar to 1970 degrees C, because this material can be grown by the conventional melt growth technique like the micropulling down (mu-PD) method for the comparison. We compared scintillation properties for Ce:YAG prepared by the CH and mu-PD methods in order to find if the CH method can be applied to the material search. The crystals grown by both methods showed the YAG single-phase, and almost all their optical and scintillation properties of them were comparable for both samples. Particularly, the light output of Ce:YAG crystal grown by the CH method (20,000 +/- 1,000 photons/MeV) was similar to that of the sample grown by the mu-PD method (23,000 +/- 1,000 photons/MeV). Therefore, we concluded that the CH method is a useful technique for the search of scintillation materials with extremely high melting points.