| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat treatment method for a single crystal capable of sufficiently suppressing the increase of a back ground of a fluorescence output, sufficiently preventing the variation of the fluorescence output and sufficiently improving fluorescence output characteristics even in the case of a specific cerium-activated silicate compound, particularly even in the case of a single crystal using at least one element selected from a groupe consisting of Dy, Ho, Er, Tm, Yb, Lu, Y and Sc and having a smaller ion radius than that of Tb as Ln. SOLUTION: The heat treatment method for the above single crystal has a step of heating the single crystal of the specific activated silicate compound in the atmosphere having a small amount of oxygen and at a temperature T<SB>1</SB>(unit:°C) satisfying a condition expressed by formula (3). The formula (3) is 800≤T<SB>1</SB><(T<SB>m1</SB>-550) (3) and T<SB>m1</SB>(unit:°C) in formula (3) expresses a melting point of the single crystal. COPYRIGHT: (C)2007,JPO&INPIT
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