Passivation of metal halide scintillators

Patent metadata

Field	Value
Publication number	US-10087367-B2
Application number	US-201614994181-A
Country	US
Kind code	B2
Filing date	Jan 13, 2016
Priority date	Jan 21, 2013
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

A halide material, such as scintillator crystals of LaBr 3 :Ce and SrI 2 :Eu, with a passivation surface layer is disclosed. The surface layer comprises one or more halides of lower water solubility than the scintillator crystal that the surface layer covers. A method for making such a material is also disclosed. In certain aspects of the disclosure, a passivation layer is formed on a surface of a halide material such as a scintillator crystal of LaBr 3 :Ce of SrI 2 :Eu by fluorinating the surface with a fluorinating agent, such as F 2 for LaBr 3 :Ce and HF for SrI 2 :Eu.

First claim

We claim:

1. A material, comprising:
a first metal halide that is operative to function as a scintillator, where the first metal halide excludes cesium iodide and cesium bromide; and
a layer comprising a second metal halide that is disposed on a surface of the first metal halide and where the halogen atom of the layer has a lower atomic number than a halogen of the scintillator; and
further comprising a surface layer disposed in a surface of the second metal halide; where the surface layer comprises a third metal halide that has a lower water solubility than the second metal halide.

2. The material of claim 1 , wherein the first metal halide has a composition that is described by formula (1):
M 1 X 1 a :Y b   (1)

where M 1 is a metal that is lithium, sodium, potassium, rubidium, cesium, thallium, copper, silver, lead, bismuth, indium, tin, antimony, tantalum, tungsten, strontium, barium, boron, magnesium, calcium, cerium, yttrium, scandium, gadolinium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium, or neodymium, X 1 is a halogen, where the halogen is chlorine, bromine, iodine, astanine, or a combination thereof and were Y is a codopant and comprises and comprises one or more of thallium, copper, silver, lead, bismuth, indium, tin, antimony, tantalum, tungsten, strontium, barium, boron, magnesium, gadolinium, calcium, potassium, cerium, yttrium, scandium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium or neodymium, where M 1 and Y are different elements, where a has a value of 1 to 4 and where b has a value of 0 to about 1 and where the second metal halide has a composition that is described by formula (5)
M 1 X 2 a :Y b   (5)

where M L , Y, a and bare detailed above in the Formula (1), where X 2 in the Formula (5) is a halogen that is fluorine, chlorine, bromine, iodine, or a combination thereof and that has at least one halogen atom having a lower atomic weight than X 1 in the Formula (1).

3. The material of claim 2 , where b has a value of about 0.001 to about 0.5 and where “a” has a value of 1, 2 or 3.

4. The material of claim 2 , where here when X 2 and X 1 both involve a combination of halogen atoms, the combined atomic weight of X 2 is less than X 1 or alternatively, when X 2 involves a combination of halogen atoms, but X 1 contains only a single halogen atom, then X 2 contains at least one halogen atom that has a lower atomic weight than the single halogen atom contained in X 1 .

5. The material of claim 1 , where the first metal halide has a composition that is described by Formula (2), Formula (3) or Formula (4):
M 1 l M 2 m X 1 a :Y b   (2)

M 1 l M 2 m M 3 n X 1 a :Y b   (3) and

M 1 l M 2 m M 3 n M 4 o X 1 a : Y b   (4),

where in the Formulas (2), (3) and (4), where applicable, M 1 is lithium, sodium, potassium, rubidium, gadolinium, cesium, thallium, copper, silver, lead, bismuth, indium, tin, antimony, tantalum, tungsten, strontium, barium, boron, magnesium, calcium, cerium, yttrium, scandium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium, or neodymium, M 2 is selected from the group consisting of boron, aluminum, gallium, indium, sodium, potassium, calcium, gadolinium, rubidium, cesium, thallium, cerium, yttrium, scandium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium, or neodymium, M 3 and M 1 are different from one another and are one of strontium, calcium, barium, gadolinum, yttrium, scandium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium, or neodymium, X 1 is a halogen selected from chlorine, bromine, iodine, astinine, or a combination thereof; Y is a codopant and comprises and comprises one or more of thallium, copper, silver, lead, bismuth, indium, tin, antimony, tantalum, tungsten, strontium, barium, boron, magnesium, gadolinium, calcium, potassium, cerium, yttrium, scandium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium or neodymium, where 1 is 0 to 3, m is 0 to 3, n is 0 to 3, and o is 0 to 3, and where the sum of 1+m in Formula (2) is not equal to 0, where the sum of 1+m, m+n, 1+n and 1+m+n is not equal to 0 in Formula (3) and where the sum of l+m, m+n, 1+n, 1+o, m+o, n+o and 1+m+n+o is not equal to 0 in the Formula (4); where in the Formulas (2), (3) and (4), “a” is 1 to 8, and “b” is 0 to about 1; where in the Formula (2), M 1 , M 2 and Y are different from each other and only one of M 1 or M 2 is a rare earth metal; where in the Formula (3), M L , M 2 , M 3 and Y are different from each other and at least one of M L , M 2 and M 3 is a rare earth metal and where embodiment in the Formula (3), M, M 3 and Y are different from each other and may or may not be rare earth metals and where in the Formula (4), M L , M 2 , M 3 and M 1 and Y are each different from each other and at least one of M, M 2 , M 3 and M 4 and Y are rare earth metals.

6. The material of claim 5 , where the second metal halide has a composition that is described by formula (5)
M 1 X 2 a :Y b   (5)

where M 1 is a metal that is lithium, sodium, potassium, rubidium, cesium, thallium, copper, silver, lead, bismuth, indium, tin, antimony, tantalum, tungsten, strontium, barium, boron, magnesium, calcium, cerium, yttrium, scandium, gadolinium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium, or neodymium, X 1 is a halogen, where the halogen is chlorine, bromine, iodine, astanine, or a combination thereof and were Y is a codopant and comprises and comprises one or more of thallium, copper, silver, lead, bismuth, indium, tin, antimony, tantalum, tungsten, strontium, barium, boron, magnesium, gadolinium, calcium, potassium, cerium, yttrium, scandium, lanthanum, lutetium, praseodymium, terbium, ytterbium, samarium, europium, holmium, dysprosium, erbium, thulium or neodymium, where M 1 and Y are different elements, where a has a value of 1 to 4 and where b has a value 0 to about 1 and where X 2 in the Formula (5) is a halogen that is fluorine, chlorine, bromine, iodine, or a combination thereof and that has at least one halogen atom having a lower atomic weight than X 1 in the Formulas (2), (3) and (4).

7. The material of claim 5 , where the second metal halide has a composition that is described by formulas (6) through (8)
M 1 l M 2 m X 2 a :Y b   (6)

M 1 l M 2 m M 3 n X 2 a :Y b   (7) and

M 1 l M 2 m M 3 n M 4 o X 2 a : Y b   (8),

where M 1 , M 2 , M 3 , M 4 , X, Y, l, m, n, o, a and b from the Formulas (6), (7) and (8) are defined above in Formulas (2) (3) and (4) and where X 2 from the Formulas (6), (7) and (8) has a lower atomic weight than X 1 in Formulas (2), (3) and (4).

8. The material of claim 6 , where when X 2 and X 1 both involve a combination of halogen atoms, the combined atomic weight of X 2 is less than X 1 or alternatively, when X 2 involves a combination of halogen atoms, but X 1 contains only a single halogen atom, then X 2 contains at least one halogen atom that has a lower atomic weight than the single halogen atom contained in X 1 .

9. The material of claim 6 , where b has a value of about 0.001 to about 0.5 and where “a” has a value of 2 to 3.

10. The material of claim 1 , where the first metal halide comprises NaI:Tl, KI:Tl, CsI:Tl, LaCl 3 :Ce, LaBr 3 :Ce, LuCl 3 :Ce, LuBr 3 :Ce, SrI 2 :Eu, or a combinatio

Assignees

• Siemens Medical Solutions Usa Inc

Inventors

• Carey Alexander Andrew
• Cohen Peter Carl
• Andreaco Mark S

Classifications

• C09K11/77

  containing rare earth metals · CPC title

• C09K11/7728

  containing europium · CPC title

• C09K11/7733

  with alkali or alkaline earth metals · CPC title

• C09K11/7783 Primary

  containing two or more rare earth metals one of which being europium · CPC title

• C09K11/7715

  containing cerium · CPC title