Method for controlling gallium content in gadolinium-gallium garnet scintillators
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A technology of scintillators and products, which is applied in the measurement of radiation, chemical instruments and methods, and uses directions such as seed crystals remaining in the melt during growth, which can solve the problem of difficult control of gallium evaporation loss, quality changes of GAGG crystals, and uncontrollable scintillation decay time and high levels of afterglow and other issues
Inactive Publication Date: 2017-07-25
SIEMENS MEDICAL SOLUTIONS USA INC
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[0009] However, this method also has its disadvantages
The quality of GAGG crystals can change significantly due to the fact that gallium evaporation losses are difficult to control
Loss of stoichiometry can cause considerable inhomogeneity in the scintillation characteristics of GAGG crystals, such as: deviations in light output, uncontrollable scintillation decay times, and high levels of afterglow, all of which are undesirable
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[0017] Disclosed herein is a method for producing polycrystalline or single crystal garnet (hereinafter referred to as "garnet") comprising gadolinium and gallium and using gallium oxide as a starting raw material. In garnet the composition contains one or more elements in addition to gadolinium and gallium. In other words, in its simplest form, garnet contains three or more elements.
[0018] In one embodiment, the garnet has the formula:
[0019] m 1 a m 2 b m 3 c m 4 d o 12 (1)
[0020] Among them, O represents oxygen, M 1 , M 2 , M 3 and M 4 Denotes first, second, third and fourth metals that are different from each other, where the sum of a+b+c+d is about 8, where "about" is defined as ±10% from the expected value, where, "a" has a value of about 2 to about 3.5, preferably about 2.4 to about 3.2, and more preferably about 3.0, "b" has a value of 0 to about 5, preferably about 2 to about 3, and more preferably about 2.1 to about 2.5 Value, wherein, "b" and ...
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Abstract
Disclosed herein is a method including manufacturing a powder having a composition of formula (1), M1aM2bM3cM4dO12 (1) where O represents oxygen, M1, M2, M3, and M4 represents a first, second, third, and fourth metal that are different from each other, where the sum of a + b + c+ d is about 8, where 'a' has a value of about 2 to about 3.5, 'b' has a value of 0 to about 5, 'c' has a value of 0 to about 5, 'd' has a value of 0 to about 1, where 'b' and 'c', 'b' and 'd', or 'c' and 'd' cannot both be equal to zero simultaneously, where M1 is a rare earth element comprising gadolinium, yttrium, lutetium, scandium, or a combination of thereof, M2 is aluminum or boron, M3 is gallium, and M4 is a codopant; and heating the powder to a temperature of 500 to 1700 degrees centigrade in an oxygen containing atmosphere to manufacture a crystalline scintillator.
Description
Background technique [0001] The present disclosure relates to methods for controlling the gallium content in garnet scintillators containing gadolinium and gallium during the manufacturing process. In particular, the present disclosure relates to methods for controlling the gallium content in gadolinium-aluminum-gallium garnet scintillators during the manufacturing process. [0002] Gadolinium aluminum gallium garnet (commonly known as GAGG) due to its high density of 6.63 grams per cubic centimeter (g / cc), high light output of greater than 65,000 photons / MeV (million electron volts or megaelectron volts), and 88 nanosecond The relatively short decay times of (ns) / 91% and 258 ns / 9% make them promising candidates for use as scintillators in time-of-flight (TOF) positron emission tomography (PET). [0003] GAGG can be prepared from oxides such as ceria (CeO 2 ), gadolinium oxide (Gd 2 o 3 ), gallium oxide (Ga 2 o 3 ) and alumina (Al 2 o 3 ) grow in the form of large crys...
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