Method of forming a scintillation crystal including a rare earth halide

• US 9,796,922 B2
• Filed: 12/11/2015
• Issued: 10/24/2017
• Est. Priority Date: 06/06/2011
• Status: Active Grant

• Current Assignee: Luxium Solutions LLC
• Original Assignee: Saint-Gobain Ceramics & Plastics Incorporated (Compagnie De Saint-Gobain)
• Inventors: Menge, Peter R., Ouspenski, Vladimir
• Primary Examiner(s): Taningco, Marcus
• Assistant Examiner(s): Malevic, Djura
• Application Number:
  US14/966,610
• Publication Number:
  US 20160122639A1
• Time in Patent Office: 683 Days
• Field of Search: 25037011, 250361 R, 2523014 H, 25230117
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3227 Lanthanum oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/9646 Optical properties
• CPC Class Codes: C04B 35/5152 based on halogenides other than fluorides
• CPC Class Codes: C04B 35/553 based on fluorides
• CPC Class Codes: C09K 11/7772 Halogenides C09K11/7767 takes precedence
• CPC Class Codes: C09K 11/7773 with alkali or alkaline earth metal
• CPC Class Codes: C30B 11/04 adding crystallising materials or reactants forming it in situ to the melt
• CPC Class Codes: C30B 15/04 adding doping materials, e.g. for n-p-junction
• CPC Class Codes: C30B 29/12 Halides
• CPC Class Codes: G01T 1/202 the detector being a crystal
• CPC Class Codes: G21K 4/00 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

Abstract

A scintillation crystal can include Ln_(1-y)RE_yX₃, wherein Ln represents a rare earth element, RE represents a different rare earth element, y has a value in a range of 0 to 1, and X represents a halogen. In an embodiment, RE is Ce, and the scintillation crystal is doped with Sr, Ba, or a mixture thereof at a concentration of at least approximately 0.0002 wt. %. In another embodiment, the scintillation crystal can have unexpectedly improved linearity and unexpectedly improved energy resolution properties. In a further embodiment, a radiation detection system can include the scintillation crystal, a photosensor, and an electronics device. Such a radiation detection system can be useful in a variety of radiation imaging applications.

Claims

1. A method, comprising:

placing into a crucible precursors including;

a rare earth halide precursor; and

a dopant precursor that includes a strontium halide, a barium halide, or any combination thereof;

melting the precursors to form a melt;

contacting the melt with a seed crystal;

using the seed crystal to form a scintillation crystal from the melt, wherein the scintillation crystal comprises La_(1-y)RE_yX₃;

Me²⁺, wherein;

RE represents a rare earth element other than La;

y has a value in a range of 0 to 0.5;

X represents a halogen; and

Me²⁺ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %; and

roughening a surface of the scintillation crystal.

2. A method, comprising:

placing into a crucible precursors including;

a rare earth halide precursor; and

a dopant precursor that includes a strontium halide, a barium halide, or any combination thereof;

melting the precursors to form a melt;

contacting the melt with a seed crystal; and

using the seed crystal to form a scintillation crystal from the melt, wherein the scintillation crystal comprises La_(1-y)RE_yX₃;

Me²⁺, wherein;

RE represents a rare earth element other than La;

y has a value in a range of 0 to 0.5;

X represents a halogen; and

Me²⁺ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %.

3. The method of claim 2, wherein the scintillation crystal has a property including:

for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an average value for a departure from perfect linearity of no less than −

0.35%;

for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an average value for a departure from perfect linearity of no greater than 0.07%;

for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an absolute value for a furthest departure from perfect linearity of no greater than 0.7%;

or

any combination thereof.

4. The method of claim 3, wherein the average value for the departure from perfect linearity (DFPL_average) is determined by:

5. The method of claim 2, wherein the concentrations of Me²⁺ is no greater than 0.03 wt. %.

6. The method of claim 5, wherein y has a value in a range of 0.0001 to 0.2.

7. The method of claim 2, wherein RE is Ce.

8. The method of claim 7, wherein y has a value in a range of 0.0001 to 0.2.

9. The method of claim 2, wherein Me²⁺ represents Sr.

10. The method of claim 2, wherein Me²⁺ represents Ba.

11. The method of claim 2, wherein Me²⁺ does not include any divalent metal element other than Sr, Ba, or any combination thereof.

12. The method of claim 2, wherein the concentration of Me²⁺ is in a range of 0.005 wt. % to 0.02 wt. %.

13. The method of claim 2, further comprising placing the scintillation crystal within casing.

14. The method of claim 13, placing an optical interface adjacent to a surface of the scintillation crystal.

15. The method of claim 14, further comprising placing a photosensor adjacent to the optical interface, wherein the optical interface is disposed between and optically couples the scintillation crystal and the photosensor to each other.

16. A method, comprising:

placing into a crucible precursors including;

LaBr₃;

CeBr₃; and

a dopant precursor that includes SrBr₂, BaBr₂, or any combination thereof;

melting the precursors to form a melt;

contacting the melt with a seed crystal; and

pulling a scintillation crystal from the melt, wherein the scintillation crystal comprises wherein the scintillation crystal comprises La_(1-y)Ce_yBr₃;

Me²⁺,

wherein;

y has a value in a range of approximately 0.001 to 0.2; and

Me²⁺ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %.

17. The method of claim 16, wherein the scintillation crystal has a property including:

for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an average value for a departure from perfect linearity of no less than −

0.35%;

for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an average value for a departure from perfect linearity of no greater than 0.07%;

for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an absolute value for a furthest departure from perfect linearity of no greater than 0.7%;

or

any combination thereof.

18. The method of claim 17, wherein the average value for the departure from perfect linearity (DFPL_average) is determined by:

19. The method of claim 16, wherein the concentration of Me²⁺ is in a range of 0.005 wt. % to 0.009 wt. %.

20. The method of claim 16, further comprising roughening a surface of the scintillation crystal.