Metal fluoride crystal, light emitting element, scintillator, method of detecting neutron, and method of producing metal fluoride crystal

Patent metadata

Field	Value
Publication number	US-9388337-B2
Application number	US-201314396584-A
Country	US
Kind code	B2
Filing date	Apr 18, 2013
Priority date	Apr 26, 2012
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

A light emitting element according to one embodiment of the present invention is configured of a metal fluoride crystal which is represented by chemical formula LiM1M2F6 (wherein Li includes 6Li; M1 represents at least one alkaline earth metal element selected from among Mg, Ca, Sr and Ba; and M2 represents at least one metal element selected from among Al, Ga and Sc), said metal fluoride crystal containing 0.02% by mole or more of Eu and having an Eu2+ concentration of less than 0.01% by mole.

First claim

The invention claimed is:

1. A neutron scintillator, comprising a metal fluoride crystal including a crystal represented by a chemical formula LiM 1 M 2 F 6 wherein Li includes 6 Li, M 1 represents at least one alkaline earth metal element selected from the group consisting of Mg, Ca, Sr, and Ba, and M 2 represents at least one metal element selected from the group consisting of Al, Ga, and Sc, the crystal containing not less than 0.02 mol % of Eu, and the crystal having a concentration of Eu 2+ of less than 0.01 mol %.

2. The neutron scintillator according to claim 1 , wherein the Eu contained in the crystal includes Eu 3+ having a concentration higher than that of the Eu 2+ .

3. The neutron scintillator according to claim 1 , wherein a content of a 6 Li isotope is not less than 50% of Li.

4. The neutron scintillator according to claim 1 , further comprising at least one alkali metal element selected from the group consisting of Na, K, Rb, and Cs.

5. The neutron scintillator according to claim 4 , wherein a content of the alkali metal element is not less than 0.001 mol % and not more than 10 mol % with the LiM 1 M 2 F 6 as a reference.

6. A method of producing a neutron scintillator, comprising:
melting a mixed raw material including an Li-source raw material containing 6 Li, an alkaline earth metal-source raw material, a metal element-source material, and an Eu-source raw material; and
growing a metal fluoride crystal including a crystal represented by a chemical formula LiM 1 M 2 F 6 (wherein Li includes 6 Li, M 1 represents at least one alkaline earth metal element selected from the group consisting of Mg, Ca, Sr, and Ba, and M 2 represents at least one metal element selected from the group consisting of Al, Ga, and Sc) from the melted mixed raw material in an atmosphere containing a fluorine-source gas broken in a growth atmosphere, the crystal containing not less than 0.02 mol % of Eu, and the crystal having a concentration of Eu 2+ of less than 0.01 mol %.

7. The method of producing a neutron scintillator according to claim 6 , wherein the fluorine-source gas contains a carbonyl fluoride.

8. A method of producing a neutron scintillator, comprising:
melting a mixed raw material including a Li-source raw material containing 6 Li, an alkaline earth metal-source raw material, a metal element-source material, an Eu-source raw material, and at least one alkali metal-source raw material selected from the group consisting of a sodium fluoride, a potassium fluoride, a rubidium fluoride, and a cesium fluoride; and
growing a metal fluoride crystal including a crystal represented by a chemical formula LiM 1 M 2 F 6 (wherein Li includes 6 Li, M 1 represents at least one alkaline earth metal element selected from the group consisting of Mg, Ca, Sr, and Ba, and M 2 represents at least one metal element selected from the group consisting of Al, Ga, and Sc) from the melted mixed raw material in an atmosphere containing a fluorine-source gas broken in a growth atmosphere, the crystal containing not less than 0.02 mol % of Eu, the crystal having a concentration of Eu 2+ of less than 0.01 mol %.

9. The method of producing a neutron scintillator according to claim 8 , wherein a content of the alkali metal raw material is not less than 0.001 mol % and not more than 10 mol % with the LiM 1 M 2 F 6 as a reference.

Assignees

• Univ Tohoku
• Tokuyama Corp

Inventors

• Ishizu Sumito
• Fukuda Kentaro
• Kawaguchi Noriaki
• Yoshikawa Akira
• Yanagida Takayuki
• Yokota Yui
• Fujimoto Yutaka

Classifications

• C30B29/12

  Halides · CPC title

• C09K11/7733 Primary

  with alkali or alkaline earth metals · CPC title

• G21K4/00

  Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens (photographic processes using X-ray intensifiers G03C5/17; discharge tubes comprising luminescent screens H01J1/62; cathode ray tubes for X-ray conversion with optical output H01J31/50) · CPC title

• C30B15/08

  Downward pulling · CPC title

• G01T3/06

  with scintillation detectors · CPC title