Multi-component rare earth garnet scintillator

Abstract

A multi-component rare-earth garnet optical material containing at least three different rare-earth elements and optionally activator ions is described. The optical material includes a rare-earth garnet scintillator. A method for preparing powders, ceramics, and single crystals of the optical material is also described. Further, a radiation detector including a rare-earth garnet scintillator is described.

Description

Technical Field

[0001] Related Applications This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 343,885, filed May 19, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] Parties to a Joint Research Agreement The subject matter disclosed herein was made, at least in part, in lieu of and / or in connection with one or more of the following parties that have entered into a joint research agreement: Siemens Medical Solutions USA, Inc., and The University of Tennessee. The agreement was in effect prior to the effective filing date of the subject matter of this disclosure, and the subject matter of this disclosure was made as a result of activities performed within the scope of this agreement.

[0003] The subject matter of the present disclosure relates to rare earth garnet optical materials comprising a combination of ions of at least three rare earth elements. The subject matter of the present disclosure further relates to scintillators of the optical materials, radiation detectors comprising the scintillator materials, methods of detecting radiation using the scintillator materials, and methods of making the optical materials.

[0004] Abbreviations % = percentage °C = degrees Celsius Al = aluminum at% = atomic percentage a.u. = arbitrary unit CCD = charge-coupled device Ce = cerium cm = centimeter CT = computed tomography DI = deionized Dy = dysprosium Em = emission Er = erbium Eu = europium Exc = excitation g = gram Ga = gallium Gd = Gadolinium h = time Ho = Holmium keV = kilo - electron volt kVA = kilo - volt - ampere La = Lanthanum Lu = Lutetium LY = Light yield MeV = mega - electron volt min = minute ml = milliliter mm = millimeter mol = mole mPa = megapascal Nd = Neodymium nm = nanometer PEG = Polyethylene glycol PET = Positron emission tomography ph = photon PL = Photoluminescence Pm = Promethium PMT = Photomultiplier tube Pr = Praseodymium PTFE = Polytetrafluoroethylene PVA = Polyvinyl alcohol RE = Rare earth RF = Radio frequency RL = Radioluminescence Sc = Scandium Sm = Samarium Tb = Terbium Tm = Thulium XRD = X - ray diffraction Y = Yttrium Yb = Ytterbium

Background Art

[0005] Optical materials include phosphors and scintillators that can emit optical pulses in response to impinging radiation such as X-rays, gamma rays, and neutrons. Inorganic scintillators are widely used in radiation detectors having a wide range of applications in medical imaging, particle physics, geological surveys, homeland security, and other related fields because they are of high density and have a high atomic number compared to gas detectors and organic scintillators. These various applications use scintillators having appropriate luminescence characteristics when used in different areas. Considerations in selecting scintillators and other optical materials typically include, but are not limited to, luminosity, decay time, and emission wavelength.

[0006] Although various optical materials have been developed, there is a continuing need to develop additional optical materials having improved characteristics for specific applications.

Summary of the Invention

[0007] This summary lists some embodiments of the subject matter of this disclosure and often lists variations and substitutions of these embodiments. This summary is merely illustrative of a large number of various embodiments. References to one or more representative features of a given embodiment are similarly illustrative. Such embodiments can typically exist with or without the recited feature(s), and likewise, those features can apply to other embodiments of the subject matter of this disclosure whether or not they are listed in this summary. To avoid excessive repetition, this summary does not list or suggest all possible combinations of such features.

[0008] In some embodiments, the subject matter of this disclosure is of the formula: (RE 1-y X y )3(Al 1-z Ga z )5O 12 [where 0 ≤ y ≤ 0.1; 0 ≤ z ≤ 1; RE is a combination of ions of three or more rare earth elements selected from the group consisting of Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La; X is one or more activator ions selected from the group consisting of Ce ions, Tb ions, Dy ions, Eu ions, Yb ions, and Pr ions)] To provide an optical material containing the composition of . In some embodiments, z is 0.

[0009] In some embodiments, RE is a combination of ions of 3, 4, 5, or 6 elements selected from the group consisting of Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La. In some embodiments, RE is a combination of ions of at least 3 elements selected from the group consisting of Y, Lu, Tb, and Gd.

[0010] In some embodiments, y is 0. In some embodiments, 0.001 ≤ y ≤ 0.1. In some embodiments, 0.005 ≤ y ≤ 0.05; where y may be 0.005, 0.02, or 0.05. In some embodiments, X is Ce ions, Pr ions, or a mixture thereof, and X may be Ce 3+ as well.

[0011] In some embodiments, the optical material is (Y 0.2 Gd 0.2 Tb 0.2 Y 0.2 Lu 0.2 )3Al5O 12 ; (Y 0.25 Gd 0.25 Er 0.25 Lu 0.25 )3Al5O 12 ; (Y 0.25 Gd 0.25 Ho 0.25 Lu 0.25 )3Al5O 12 ; (Y0.2 Gd 0.2 Tb 0.2 Dy 0.2 Lu 0.2 )3Al5O 12 ; (Y 0.25 Gd 0.25 Tb 0.25 Lu 0.25 )3Al5O 12 ; (Y 0.2 Eu 0.2 Gd 0.2 Yb 0.2 Lu 0.2 )3Al5O 12 ; (Y 0.1667 Eu 0.1667 Gd 0.1667 Tb 0.1667 Yb 0.1667 Lu 0.1667 )3Al5O 12 ; (Y 0.25 Gd 0.25 Tb 0.25 Lu 0.25 )3Al5O 12 ; (Y 0.25 Nd 0.25 Gd 0.25 Lu 0.25 )3Al5O 12 ; (Y 0.25 Pr 0.25 Gd 0.25 Lu 0.25 )3Al5O 12 ; and (Y 0.25 La 0.25 Gd 0.25 Lu 0.25 )3Al5O 12 comprises a composition selected from the group comprising.

[0012] In some embodiments, the optical material is (Y 0.199 Gd 0.199 Tb 0.199 Yb 0.199 Lu 0.199 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Gd 0.24875 Er 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Gd 0.24875 Ho 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.199 Gd 0.199 Tb 0.199 Dy 0.199 Lu 0.199 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Gd 0.24875 Tb 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.199 Eu 0.199 Gd 0.199 Yb 0.199 Lu 0.199 Ce 0.005 )3Al5O 12 ; (Y 0.16583 Eu 0.16583 Gd 0.16583 Tb 0.16583 Yb 0.16583 Lu 0.16583 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Sm 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Nd 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Pr 0.24875 Gd 0.24875 Lu 0.24875 Ce0.005 )3Al5O 12 ; (Y 0.24875 La 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.245 Gd 0.245 Tb 0.245 Lu 0.245 Ce 0.02 )3Al5O 12 ; (Y 0.2375 Gd 0.2375 Tb 0.2375 Lu 0.2375 Ce 0.05 )3Al5O 12 ; (Y 0.2375 Gd 0.2375 Tb 0.2375 Lu 0.2375 Ce 0.05 )3Al5O 12 ; and (Y 0.294 Gd 0.294 Tb 0.098 Lu 0.294 Ce 0.02 )3Al5O 12 comprises a composition selected from the group consisting of.

[0013] In some embodiments, the optical material is (Y 0.33167 Tb 0.33167 Gd 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.33167 Y 0.33167 Gd 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.33167 Y 0.33167 Tb 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.24875 Y 0.24875 Tb 0.24875 Gd0.24875 Ce 0.005 )3Al5O 12 ; and (Lu 0.245 Y 0.245 Tb 0.245 Gd 0.245 Ce 0.02 )3Al5O 12 comprises a composition selected from the group consisting of.

[0014] In some embodiments, the optical material, when stimulated with high-energy radiation, results in luminescence from optically active RE ions, and the optically active RE ions may be Tb ions.

[0015] In some embodiments, the subject matter of the present disclosure is a radiation detector comprising the optical material and a photon detector of the subject matter of the present disclosure, wherein the optical material is (Y 0.33167 Tb 0.33167 Gd 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.33167 Y 0.33167 Gd 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.33167 Y 0.33167 Tb 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.24875 Y 0.24875 Tb 0.24875 Gd 0.24875 Ce 0.005 )3Al5O 12 ; and (Lu 0.245 Y 0.245 Tb 0.245 Gd 0.245 Ce 0.02 )3Al5O 12 and may comprise a composition selected from the group consisting of, a radiation detector is provided.

[0016] In some embodiments, the subject matter of the present disclosure provides a method for detecting gamma rays, X-rays, cosmic rays, and / or particles having an energy of 1 keV or more, the method including using a radiation detector. In some embodiments, the subject matter of the present disclosure provides for the use of a radiation detector in medical imaging, homeland security, or high energy physics research.

[0017] In some embodiments, the subject matter of the present disclosure provides a method for preparing an optical material of the subject matter of the present disclosure, the method including preparing a single crystal of the optical material from a melt.

[0018] In some embodiments, the subject matter of the present disclosure provides a method for preparing an optical material of the subject matter of the present disclosure, including: (i) preparing a foam by heating an aqueous solution containing a mixture of a polymer, optionally polyvinyl alcohol (PVA) or polyethylene glycol (PEG), and a metal nitrate, wherein the metal nitrate contains ions of an element corresponding to an element of the optical material, and pulverizing the foam to provide a powder; or (ii) coprecipitating a powder by adding an aqueous solution containing a mixture of a metal nitrate and ammonium sulfate to an aqueous solution of ammonium carbonate, wherein the metal nitrate contains ions of an element corresponding to an element of the optical material, thereby preparing a powder of the optical material.

[0019] In some embodiments, the subject matter of the present disclosure provides a method for preparing an optical material of the subject matter of the present disclosure, the method including preparing a ceramic of the optical material by a technique selected from the following.

[0020] An object of the subject matter of the present disclosure is to provide a multi-component rare earth garnet optical material, such as a scintillator, a radiation detector including the optical material, a method of using the radiation detector, and a method of preparing the optical material.

[0021] The objectives of the subject matter of the present disclosure described above in this specification are achieved, in whole or in part, by the subject matter of the present disclosure, and other objectives will become apparent upon consideration of this specification and the description to follow in connection with the accompanying drawings and examples, as best described herein below.

Brief Description of the Drawings

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Best Mode for Carrying Out the Invention

[0023] Here, the subject matter of the present disclosure will be described more fully. However, the subject matter of the present disclosure can be embodied in different forms and should not be construed as limited to the embodiments described below and in the appended examples. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the embodiments to those skilled in the art.

[0024] All references listed in this specification, including but not limited to all patents, patent applications and their publications, and scientific journal articles, are incorporated herein by reference in their entirety to the extent that they supplement, explain, provide background for, or teach the methodologies, techniques and / or compositions used herein.

[0025] I. Definitions The following terms are believed to be well understood by those skilled in the art, but the following definitions are provided to facilitate the description of the subject matter of the present disclosure.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter of the present disclosure belongs.

[0027] In accordance with longstanding patent law convention, the terms "a", "an", and "the" when used in this application, including in the claims, refer to "one or more".

[0028] The term "and / or" when used to describe two or more items or conditions refers to situations where all of the specified items or conditions may be present or applicable, or where only one (or fewer than all) of the items or conditions may be present or applicable.

[0029] The use of the term "or" in the claims is used to mean "and / or" unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive, but the present disclosure supports definitions that refer to alternatives only as well as "and / or". As used herein, "another" can mean at least second and later.

[0030] The term "comprising" is synonymous with "including", "containing", or "characterized by", is inclusive or open-ended, and does not exclude additional unrecited elements or method steps. "Comprising" is a technical term used in the language of the claims to mean that the specified elements are essential, but other elements can be added to form a construct within the scope of the claim.

[0031] As used herein, the phrase "consisting of" excludes any element, step, or ingredient not specified in the claims. When the phrase "consists of" appears in a clause of the body of the claim rather than immediately following the preamble, it limits only the elements recited in that clause; other elements are not excluded from the claim as a whole.

[0032] As used herein, the phrase "consisting essentially of" limits the scope of a claim to those things that do not materially affect the basic and novel characteristics of the claimed subject matter in addition to the specified materials or steps.

[0033] Regarding the terms "comprising", "consisting of", and "consisting essentially of", when one of these three terms is used in this specification, the claimed subject matter of the present disclosure can include the use of either of the other two terms.

[0034] Unless otherwise indicated, all numbers representing quantities such as time, temperature, light output, atoms (at) or mole (mol) percentages (%) used in this specification and the claims should be understood to be modified in all cases by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and the appended claims are approximations that can vary depending on the desired properties sought to be obtained by the subject matter of the present disclosure.

[0035] As used herein, the term "about", when referring to a value, means including variations of, in one example, ±20% or ±10% from a particular amount, in another example ±5%, in another example ±1%, and in yet another example ±0.1%, such variations being appropriate to practice the disclosed method.

[0036] The term "scintillator" refers to a material that emits light (e.g., visible light) in response to stimulation by high-energy radiation (e.g., X, α, β, or γ radiation).

[0037] The term "phosphor", as used herein, refers to a material that emits light (e.g., visible light) in response to irradiation with electromagnetic radiation or particle radiation. Thus, a phosphor is a material that can emit light (e.g., of a particular wavelength or wavelength range) when exposed to ultraviolet or visible light (e.g., of a particular wavelength or wavelength range).

[0038] In some embodiments, the expression of the composition formula of an optical material (e.g., a scintillation material or a phosphor) can contain a colon ":" or a comma, and the composition of the main or base matrix material (e.g., the main rare earth garnet matrix, i.e., RE3Al5O 12 ) is shown on the left side of the colon or comma, and the activator (or dopant ion) is shown on the right side of the colon or comma. Alternatively, the expression of the composition formula may not contain a colon, and when an activator (or dopant) is present, it may be included with the element it replaces, e.g., (RE / activator)3Al5O 12 .

[0039] The term "high-energy radiation" can refer to electromagnetic radiation having an energy higher than that of ultraviolet light, including, but not limited to, X-rays (i.e., X-ray radiation), alpha (α) particles, gamma (γ) radiation, and beta (β) radiation. In some embodiments, high-energy radiation refers to gamma rays, cosmic rays, X-rays, and / or particles having an energy of 1 keV or more. The scintillator materials described herein can be used as components of radiation detectors in devices such as counters, image intensifier tubes, and computed tomography (CT) scanners.

[0040] "Optical coupling", as used herein, refers to the physical coupling between a scintillator and an optical sensor, for example, through the presence of an optical grease or another optical coupling compound (or refractive index matching compound) that bridges the gap between the scintillator and the optical sensor. In addition to optical grease, the optical coupling compound may include, for example, liquids, oils, and gels.

[0041] "Light output" can refer to, for example, the number of photons generated per unit energy deposited by the absorbed gamma rays, typically photons / MeV.

[0042] As used herein, chemical ions can be represented simply by their chemical element symbols only (e.g., the europium ion (e.g., Eu 2+ ) by Eu or the samarium ion (e.g., Sm 2+ ) by Sm).

[0043] The term "rare earth element" as used herein refers to one or more elements selected from the lanthanides (e.g., lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu)), scandium (Sc), and yttrium (Y).

[0044] The term "transition metal element" as used herein refers to one or more elements selected from titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), rutherfordium (Rf), dubnium (Db), seaborgium (Sg), bohrium (Bh), hassium (Hs), meitnerium (Mt), darmstadtium (Ds), roentgenium (Rg), and copernicium (Cn).

[0045] II. Multicomponent rare earth garnet materials and related devices and methods The subject matter of this disclosure provides multi-component rare earth garnet optical materials. These optical materials can be phosphors and / or scintillators. In some embodiments, the optical material comprises or consists of a composition of the general formula (RE 1-y X y )3(Al 1-z Ga z )5O 12 , wherein RE represents ions of a combination of three or more rare earth elements (including Y and Sc). Thus, the rare earth elements can be selected from the group including Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La. X represents a luminescent activator, e.g., Ce ions, Tb ions, Dy ions, Eu ions, Yb ions, or Pr ions, while y is the relative activator concentration and is in the range of 0 ≦ y ≦ 0.1. Thus, 0% to 10% of the total amount of rare earth element ions (RE) can be replaced with one or more activator ions. A small amount of X ions (e.g., Ce, Tb, Dy, Eu, Yb, or Pr ions) can act as luminescent activators, but optically active matrix elements that are typically present in larger amounts than the activator, e.g., Yb, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, and Pr, can also contribute to luminescence. The relative concentration of Ga compared to Al in the garnet matrix represented by the variable z is in the range of 0 ≦ z ≦ 1. Further, in some embodiments, a portion of the Al or Ga content can be replaced with rare earth element ions, e.g., Sc ions.

[0046] The main matrix of the optical material (i.e., the optical material without activator or co-dopant ions) is (RE)3(Al 1-z Ga z )5O 12) The concentration of rare earth elements in [it] can be either equimolar or non-equimolar in the melt, or in the finished crystal or ceramic. In the case of compounds that melt stoichiometrically, in some embodiments, the concentration of rare earth elements is equimolar. For example, in a material having ions of four different rare earth elements, each ion can constitute 1 / 4 (i.e., 25%) of the total amount of RE ions. An exemplary formula having equimolar RE is, for example, (Lu 1 / 4 Y 1 / 4 Tb 1 / 4 Gd 1 / 4 )3Al5O 12 (which can also be represented as (Lu 0.25 Y 0.25 Tb 0.25 Gd 0.25 )3Al5O 12 , i.e., when the relative amounts of specific RE ions in the formula are expressed as percentages rather than ratios).

[0047] In the case of compounds that melt non-stoichiometrically, in some embodiments, the concentration of rare earth elements can vary from equimolar as needed to achieve consistency. An exemplary formula where the rare earth elements are not equimolar is, for example, (Y 3 / 8 Dy 1 / 8 Tb 1 / 4 Gd 1 / 4 )3Al5O 12 ((Y 0.375 Dy 0.125 Tb 0.25 Gd 0.25 )3Al5O 12 and can also be represented as). In some embodiments, the amount of activator ion X such as Ce or Pr (relative to the total amount of RE ions), if present, is in the above general formula, i.e., (RE 1-y X y )3(Al 1-z Ga z )5O 12 As an alternative representation of the formula of the optical material, i.e., (RE)3(Al 1-z Ga z )5O 12: It is provided as a percentage (i.e., atomic percentage) after the colon of (X y%), and the relative amount X of the activator ions is included as a ratio or percentage within the parentheses that also describes the combination of rare earth element ions RE.

[0048] When there is a large variation in the ionic radii of rare earth elements, considering segregation at the solid-liquid contact surface, the concentrations of rare earth elements with different ionic radii can be adjusted to stabilize the cubic garnet phase or achieve congruent melting. Examples of these include (Lu 1 / 4 Y 1 / 4 Tb 1 / 4 Gd 1 / 4 )3(Al 1 / 2 Ga 1 / 2 )5O 12 :Ce, (Y 3 / 8 Dy 1 / 8 Tb 1 / 4 Gd 1 / 4 )3Al5O 12 :Ce, and (Lu 1 / 9 Y 1 / 9 Tb 2 / 9 Gd 2 / 9 Sm 3 / 9 )3Al5O 12 :Ce is included, but not limited to these.

[0049] In some embodiments, for example, when doped with an activator such as trivalent Ce or Pr, the optical material of the present disclosure becomes a scintillator suitable for radiation detection applications including medical imaging, homeland security, and high-energy physics experiments.

[0050] Thus, in some embodiments, the subject matter of the present disclosure is of the formula: (RE 1-y X y )3(Al 1-z Ga z )5O 12 [wherein, 0 ≦ y ≦ 0.1; 0 ≦ z ≦ 1; RE is a combination of ions of three or more rare earth elements selected from the group including Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La; X is one or more activator ions selected from the group including Ce ions, Tb ions, Dy ions, Eu ions, Yb ions, and Pr ions] Provided is an optical material comprising or consisting of the composition of . As described above, the respective relative concentrations of the rare earth element ions in the optical material may be substantially the same (i.e., equimolar) or different.

[0051] In some embodiments, z is 0. Thus, in some embodiments, the optical material does not contain Ga, and the optical material comprises or consists of the formula (RE 1-y X y )3Al5O 12 .

[0052] In some embodiments, RE is a combination of ions of 3, 4, 5, or 6 elements selected from the group including Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La. In some embodiments, RE is a combination of ions of at least 3 elements selected from Y, Lu, Tb, and Gd. In some embodiments, RE contains Y ions. In some embodiments, RE contains Lu ions.

[0053] In some embodiments, y is 0 (and the optical material does not contain the activator ion X). For example, in some embodiments, the optical material is (Y 0.2 Gd 0.2 Tb 0.2 Y 0.2 Lu 0.2 )3Al5O 12 ; (Y 0.25 Gd 0.25 Er 0.25 Lu 0.25 )3Al5O 12 ; (Y 0.25 Gd 0.25 Ho0.25 Lu 0.25 )3Al5O 12 ;(Y 0.2 Gd 0.2 Tb 0.2 Dy 0.2 Lu 0.2 )3Al5O 12 ;(Y 0.25 Gd 0.25 Tb 0.25 Lu 0.25 )3Al5O 12 ;(Y 0.2 Eu 0.2 Gd 0.2 Yb 0.2 Lu 0.2 )3Al5O 12 ;(Y 0.1667 Eu 0.1667 Gd 0.1667 Tb 0.1667 Yb 0.1667 Lu 0.1667 )3Al5O 12 ;(Y 0.25 Gd 0.25 Tb 0.25 Lu 0.25 )3Al5O 12 ;(Y 0.25 Nd 0.25 Gd 0.25 Lu 0.25 )3Al5O 12 ; (Y 0.25 Pr 0.25 Gd 0.25 Lu 0.25 )3Al5O 12 ; and (Y 0.25 La 0.25 Gd 0.25 Lu 0.25 )3Al5O 12 comprises or consists of a composition selected from the group consisting of.

[0054] In some embodiments, the optical material contains at least a certain amount of one or more activator ions. In some embodiments, 0.001 ≦ y ≦ 0.1 (i.e., the optical material contains from 0.1% activator (i.e., 0.1 at% activator ions relative to the total amount of RE ions) to 10% activator. In some embodiments, 0.005 ≦ y ≦ 0.05 (e.g., 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, or 0.050). In some embodiments, y is 0.005, 0.02 or 0.05. In some embodiments, X is a Ce ion, a Pr ion or a Tb ion. In some embodiments, X is a Ce ion, a Pr ion, or a mixture thereof. In some embodiments, X is Ce 3+ is.

[0055] In some embodiments, the optical material is (Y 0.199 Gd 0.199 Tb 0.199 Yb 0.199 Lu 0.199 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Gd 0.24875 Er 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Gd 0.24875 Ho 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.199 Gd 0.199 Tb 0.199 Dy 0.199 Lu 0.199 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Gd 0.24875 Tb 0.24875 Lu 0.24875 Ce0.005 )3Al5O 12 ; (Y 0.199 Eu 0.199 Gd 0.199 Yb 0.199 Lu 0.199 Ce 0.005 )3Al5O 12 ; (Y 0.16583 Eu 0.16583 Gd 0.16583 Tb 0.16583 Yb 0.16583 Lu 0.16583 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Sm 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Nd 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 Pr 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.24875 La 0.24875 Gd 0.24875 Lu 0.24875 Ce 0.005 )3Al5O 12 ; (Y 0.245 Gd 0.245 Tb 0.245 Lu 0.245 Ce 0.02 )3Al5O 12 ; (Y 0.2375 Gd 0.2375 Tb 0.2375 Lu 0.2375 Ce 0.05 )3Al5O 12 ; (Y 0.2375 Gd 0.2375 Tb 0.2375 Lu0.2375 Ce 0.05 )3Al5O 12 ; and (Y 0.294 Gd 0.294 Tb 0.098 Lu 0.294 Ce 0.02 )3Al5O 12 comprises or consists of a composition selected from the group comprising

[0056] In some embodiments, the optical material is (Y 0.33167 Tb 0.33167 Gd 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.33167 Y 0.33167 Gd 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.33167 Y 0.33167 Tb 0.33167 Ce 0.005 )3Al5O 12 ; (Lu 0.24875 Y 0.24875 Tb 0.24875 Gd 0.24875 Ce 0.005 )3Al5O 12 ; and (Lu 0.245 Y 0.245 Tb 0.245 Gd 0.245 Ce 0.02 )3Al5O 12 comprises or consists of a composition selected from the group comprising

[0057] In some embodiments, the optical material, when stimulated by high-energy radiation, results in luminescence from optically active RE ions. In some embodiments, the optically active RE ions are Dy ions, Er ions, Sm ions, Eu ions, Yb ions, Tb ions, or Pr ions, or any combination of any of the foregoing. In some embodiments, the optically active RE ions are Tb ions or Pr ions. In some embodiments, the optically active RE ions are Tb ions. In some embodiments, the optical material includes an optically active RE ion such as a Tb ion as one of the RE ions, and further includes another ion as an activator ion such as a Ce ion, Dy ion, Eu ion, Yb ion, or Pr ion. Alternatively, in some embodiments, Tb is used as an activator ion (e.g., in relative at% compared to other RE ions of 10 atomic% or less), and the optical material includes ions of at least three other RE elements.

[0058] The optical material can be provided as a single crystal, a polycrystalline material, a powder (e.g., a green powder), or a ceramic.

[0059] III. Radiation Detectors, Related Devices, and Methods In some embodiments, the subject matter of the present disclosure provides a radiation detector that includes the optical material described above or a mixture of such materials. For example, the radiation detector may include an optical material having the ability to act as a scintillator (absorbing radiation and emitting light) and a photodetector (detecting the emitted light). The photodetector may be any suitable one or more detectors and may or may not be optically coupled to the optical material to generate an electrical signal in response to the emission of light from the optical material. Thus, the photodetector may be configured to convert photons into an electrical signal. For example, a signal amplifier can be provided to convert the output signal from a photodiode into a voltage signal. The signal amplifier may be designed to amplify the voltage signal. Electronic equipment associated with the photodetector can be used to shape and digitize the electronic signal.

[0060] Referring now to FIG. 8, in some embodiments, the subject matter of the present disclosure provides an apparatus 10 for detecting radiation, the apparatus including a photon detector 12 and a scintillator material 14 (e.g., a rare earth garnet optical material acting as a scintillator). The scintillator material 14 can convert radiation into light that can be efficiently and rapidly collected by a charge-coupled device (CCD), or a photomultiplier tube (PMT), or other photon detector 12.

[0061] Referring again to FIG. 8, the photon detector 12 can be any suitable one or more detectors and can be optically coupled to the scintillator to generate an electrical signal in response to the emission of light from the scintillator (e.g., via an optical grease or another optical coupling compound, such as an optical coupling oil or an optical coupling fluid). Thus, the photon detector 12 can be configured to convert photons into an electrical signal. Electronics associated with the photon detector 12 can be used to shape and digitize the electrical signal. Suitable photon detectors 12 include, but are not limited to, photomultiplier tubes, photodiodes, CCD sensors, and image intensifier tubes. The apparatus 10 may also include electronics 16 for recording and / or displaying the electrical signal.

[0062] In some embodiments, the radiation detector is configured to be used as part of a medical or veterinary diagnostic device, a device for oil or other geological exploration (e.g., a well logging probe), or a device for security and / or military-related purposes (e.g., as a device for scanning containers, vehicles, or luggage, or for scanning humans or other animals). In some embodiments, the medical or veterinary diagnostic device is selected from, but not limited to, a positron emission tomography (PET) device, an X-ray computed tomography (CT) device, a radiography device, a single photon emission computed tomography (SPECT) device, or a planar nuclear medicine imaging device. For example, the radiation detector can be configured to move over and / or around a sample, such as a human or animal subject, (e.g., via mechanical and / or electronic control) so as to be able to detect radiation emitted from any one or more desired sites on the sample. In some embodiments, the detector can be set or attached to a rotator to rotate the detector around the sample. In some embodiments, the radiation detector is configured for use in CT, radiography, or high energy physics research.

[0063] In some embodiments, the device may also include a radiation source. For example, an X-ray CT device of the subject matter of the present disclosure may include an X-ray source for emitting X-rays and a detector for detecting the X-rays. In some embodiments, the device may include a plurality of radiation detectors. The plurality of radiation detectors can be arranged in a cylindrical or other desired shape, for example, to detect radiation emitted from various positions on the surface of the sample.

[0064] In some embodiments, the subject matter of the present disclosure provides a method of detecting radiation (or the absence of radiation) using a radiation detector that includes the above-described rare earth garnet optical material (i.e., a scintillator material including a rare earth garnet optical material). Thus, in some embodiments, the subject matter of the present disclosure provides a method of detecting gamma rays, X-rays, cosmic rays, and particles having an energy of 1 keV or greater, the method including using a radiation detector that includes a rare earth garnet optical material disclosed herein or a mixture of such materials. In some embodiments, the method includes using a radiation detector in computed tomography, radiography, or high energy physics research.

[0065] In some embodiments, the method includes providing a photodetector of the subject matter of the present disclosure and a radiation detector that includes a rare earth garnet optical material; positioning the detector, including disposing the detector at a position where the optical material is within the path of a radiation beam (or a suspected path of a radiation beam); and detecting (or detecting the absence of) light emitted by the optical material with the photodetector. Detecting the light emitted by the optical material can include converting photons into an electrical signal. Detecting can also include processing the electrical signal to shape, digitize, or amplify the signal. The method may further include displaying the electrical signal or the processed electrical signal.

[0066] In some embodiments, the subject matter of the present disclosure provides for the use of a radiation detector that includes a photon detector and a scintillator material including the above-described rare earth garnet optical material. In some embodiments, the use is for medical or veterinary diagnosis (e.g., the radiation detector is configured for use in medical or veterinary diagnosis). In some embodiments, the use is in computed tomography, radiography, or high energy physics research.

[0067] IV. Method for Preparing Optical Material The materials of the present disclosure can be prepared by any suitable route, including but not limited to, a crystal synthesis route, a powder synthesis route, or a ceramic synthesis route. Representative non-limiting examples of such routes are disclosed in the following examples, and other examples of such routes and other synthesis routes that will be apparent to those skilled in the art upon consideration of the present disclosure are also within the scope of the subject matter of the present disclosure.

[0068] For example, in some embodiments, suitable reactants (e.g., metal nitrates or metal oxides such as Lu2O3, CeO2, Pr6O3, α-Al2O3, Ga2O3, Gd2O3, etc.) are melted at a temperature sufficient to form a consistent melt composition. The melting temperature can depend on the identity of the reactants themselves (e.g., the melting points of the individual reactants), but typically is in the range of about 300 °C to about 1350 °C. Exemplary techniques for preparing the materials include, but are not limited to, the Bridgman or Bridgman-Stockbarger method, the Czochralski method, the zone melting method (or "floating zone" method), the vertical gradient freeze (VGF) method, and the temperature gradient method.

[0069] For example, in some embodiments, high-purity reactants can be mixed and melted to synthesize a compound of a desired composition. Single-crystalline or polycrystalline materials can be grown from the compound synthesized by the Bridgman method, in which a sealed ampoule containing the synthesized compound is transported from a hot zone to a cold zone through a controlled temperature gradient at a controlled rate (i.e., "pull rate"). In some embodiments, high-purity reactants can be mixed in stoichiometric ratios according to the desired composition of the optical material, filled into an ampoule, and then sealed. After sealing, the ampoule is heated and then cooled at a controlled rate. In some embodiments, the optical materials (e.g., scintillator materials) of the subject matter of the present disclosure are prepared by the vertical Bridgman technique. In some embodiments, the pull (or translation) rate used in preparing a scintillator crystal by the Bridgman technique is from about 0.1 millimeter per hour (mm / h) to about 5 mm / h (e.g., about 0.1 mm / h; about 0.5 mm / h, about 1 mm / h, about 2 mm / h, about 3 mm / h, about 4 mm / h, or about 5 mm / h). In some embodiments, the method includes using a pull rate of about 3 mm / h.

[0070] In some embodiments, the subject matter of the present disclosure is a rare earth garnet (RE)3(AlGa)5O 12A method for preparing an optical material comprising, wherein RE is a mixture of ions of at least three rare earth elements, and up to about 10 atomic % of the RE ions may be replaced by one or more activator ions of an element selected from Ce, Tb, Dy, Eu, Yb, and Pr. In some embodiments, the method includes heating a mixture of raw materials (e.g., a mixture of metal oxides in stoichiometric ratios according to the formula of the desired optical material) to a temperature higher than their respective melting temperatures (i.e., a temperature higher than the melting temperature of the raw material having the highest melting temperature). In some embodiments, the raw materials are dried before, during, or after mixing. In some embodiments, the raw materials are mixed under low humidity and / or low oxygen conditions. In some embodiments, the raw materials are mixed in a dry box and / or under conditions of less than about 0.1 parts per million (ppm) of moisture and / or oxygen (e.g., less than about 0.1 ppm, less than about 0.09 ppm, less than about 0.08 ppm, less than about 0.07 ppm, less than about 0.06 ppm, less than about 0.05 ppm, less than about 0.04 ppm, less than about 0.03 ppm, less than about 0.02 ppm, or less than about 0.01 ppm of moisture and / or oxygen).

[0071] The mixture of raw materials can withstand subsequent heating of the mixture and can be sealed in a container (e.g., a quartz ampoule) that is chemically inert to the mixture of raw materials. The mixture can be heated at a predetermined rate to a temperature higher than the melting temperature of the individual raw materials. In some embodiments, the mixture can be heated to a temperature about 10 °C to about 50 °C (e.g., about 10 °C, about 12 °C, about 14 °C, about 16 °C, about 18 °C, about 20 °C, about 22 °C, about 24 °C, about 26 °C, about 28 °C, about 30 °C, about 32 °C, about 34 °C, about 36 °C, about 38 °C, about 40 °C, about 42 °C, about 44 °C, about 46 °C, about 48 °C, or about 50 °C) higher than the melting temperature of the raw material having the highest melting temperature. In some embodiments, the mixture is heated about 50 °C higher than the melting temperature of the raw material having the highest melting temperature. This temperature can be maintained for a period of time, e.g., about 2 to about 36 hours (e.g., about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 14, about 16, about 18, about 20, about 22, about 24, about 26, about 28, about 30, about 32, about 34, or about 36 hours). In some embodiments, the temperature is maintained for about 24 hours. The mixture may then be cooled at a predetermined rate until the mixture reaches approximately room temperature (e.g., about 20 °C to about 25 °C). Optionally, the sealed container may be rotated or inverted. In some embodiments, for example, heating and cooling may be repeated to effect further mixing of all components in the mixture. The rotation or inversion and heating / cooling steps may be repeated one or more times further, as needed.

[0072] In some embodiments, the method further includes a post-growth annealing step. Thus, in some embodiments, the method further includes annealing an optical material (e.g., a crystalline optical material). The annealing may be carried out, for example, in air, in nitrogen, or in a mixture of nitrogen and hydrogen. The annealing can be carried out at any suitable temperature below the melting point of the optical material, for example, from about 100 °C to about 1600 °C (e.g., about 100 °C, about 200 °C, about 300 °C, about 400 °C, about 500 °C, about 600 °C, about 700 °C, about 800 °C, about 900 °C, about 1000 °C, about 1100 °C, about 1200 °C, about 1300 °C, about 1400 °C, about 1500 °C, and about 1600 °C).

[0073] In some embodiments, the optical (e.g., scintillation) material can be provided as a single crystal, as a polycrystalline material, and / or as a ceramic material. In some embodiments, the material is provided as a polycrystalline material. The polycrystalline material can have physical, optical, and scintillation properties similar to those of a single crystal having the same chemical composition otherwise.

[0074] In some embodiments, the subject matter of the present disclosure is an optical material of the subject matter of the present disclosure, i.e., the formula: (RE 1-y X y )3(Al 1-z Ga z )5O 12 、 [where 0 ≦ y ≦ 0.1; 0 ≦ z ≦ 1; RE is a combination of ions of three or more rare earth elements selected from the group consisting of Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La; X is one or more activator ions selected from the group consisting of Ce ions, Tb ions, Dy ions, Eu ions, Yb ions, and Pr ions] A method for preparing an optical material comprising or consisting of a composition of (a) preparing a single crystal of the optical material from a melt (e.g., as described above); (b)(i) Preparing a foam by heating an aqueous solution containing a mixture of a polymer (e.g., polyvinyl alcohol (PVA) or polyethylene glycol (PEG)) and a metal nitrate, wherein the metal nitrate contains ions of an element corresponding to an element of the optical material, and pulverizing the foam to provide a powder; or (ii) coprecipitating a powder by adding an aqueous solution containing a mixture of a metal nitrate and ammonium sulfate to an aqueous solution of ammonium carbonate, wherein the metal nitrate contains ions of an element corresponding to an element of the optical material, thereby preparing a powder of the optical material; or (c) Providing a method comprising preparing a ceramic of the optical material by a technique selected from the group consisting of sintering, hot pressing, hot isostatic pressing, and spark plasma synthesis (e.g., using a binary oxide as a starting material).

[0075] Thus, in some embodiments, the optical material is provided as a powder (e.g., a shaped body powder). In some embodiments, the powder can be prepared by preparing a foam and then grinding the foam (e.g., a dehydrated foam) to provide the powder. For example, in some embodiments, the foam can be prepared by heating an aqueous solution containing a polymer and metal nitrates containing ions of elements corresponding to the elements in the desired optical material. In some embodiments, the polymer is PVA or PEG. In some embodiments, the polymer is PVA. In some embodiments, preparing the foam further includes heating the aqueous solution to evaporate water from the aqueous solution. In some embodiments, the foam may be further dehydrated in an oven for a certain period of time to remove residual moisture. In some embodiments, the foam may be placed in an oven at about 180 °C for about 2 hours. In some embodiments, the method further includes firing the powder in air (e.g., at about 650 °C for about 2.5 hours) to remove nitrates and polymers (e.g., PVA). In some embodiments, the powder may be crystallized. Crystallization can be carried out in air at a temperature of about 900 °C to about 1300 °C for a certain period of time (e.g., about 1 hour).

[0076] Alternatively, the powder can be prepared by a coprecipitation method. For example, in some embodiments, the method includes coprecipitating the powder by adding an aqueous solution containing a mixture of metal nitrates and ammonium sulfate to an aqueous solution of ammonium carbonate, where the metal nitrates contain ions of elements corresponding to the elements of the optical material. The precipitate settling out of the solution can be collected by filtration. Similar to the powder prepared via the foam, in some embodiments, the initially precipitated powder may be fired. In some embodiments, the powder may be crystallized (e.g., in air at a temperature of about 900 °C to about 1300 °C).

[0077] In some embodiments, a mixture of metal oxides containing metal elements corresponding to the desired rare earth garnet may be mixed, ground in a mortar, and then pressed into pellets.

[0078] In some embodiments, the subject matter of the present disclosure is a method of preparing a ceramic of the optical material described herein, the method comprising performing a technique selected from the group consisting of hot pressing, hot isostatic pressing, and discharge plasma synthesis. In some embodiments, the method includes the use of binary oxides as starting materials for the ceramic. For example, in some embodiments, annealing may include grinding a stoichiometric mixture of binary oxides, pressing the mixture to form a pellet, and annealing the pellet at a temperature of about 1500 °C for a certain period of time (e.g., about 10 hours). In some embodiments, a stoichiometric mixture of binary oxide powder or rare earth garnet powder may be hot pressed at a temperature of about 1000 °C to about 2000 °C and a pressure of about 5 MPa to about 100 MPa for a certain period of time (e.g., about 2 hours).

Examples

[0079] The following examples are included to further illustrate various embodiments of the subject matter of the present disclosure. However, one skilled in the art should understand that, in light of the present disclosure, many changes can be made to the disclosed specific embodiments without departing from the spirit and scope of the subject matter of the present disclosure and still obtain similar or analogous results.

[0080] Example 1 Powder Synthesis Polymer Synthesis Route: The metal nitrates were dissolved in a beaker of deionized (DI) water, and polyvinyl alcohol (PVA, 9k - 10k g / mol, 80% hydrolyzed) was dissolved in another beaker of DI water. Once both solutions were dissolved, they were mixed and heated on a hot plate to evaporate the water to form a foam. The foam was placed in an oven at 180 °C for 2 hours to remove residual moisture. The powder produced by grinding the dehydrated foam was calcined in air at 650 °C for 2.5 hours to remove the nitrates and PVA. The resulting powder was crystallized in air for 1 hour at a temperature varying between 900 - 1300 °C. The result is the multi-component rare earth garnet powder.

[0081] Coprecipitation route: The metal nitrates and ammonium sulfate were dissolved in a beaker of DI water, and ammonium carbonate was dissolved in another beaker of DI water. The nitrate solution was dropped into the carbonate solution to form a precipitate. The precipitate was filtered off from the combined solution and calcined in air at 650 °C for 2.5 hours. The resulting powder was crystallized in air for 1 hour at a temperature varying between 900 - 1300 °C. The result is the multi-component rare earth garnet powder.

[0082] Example 2 Synthesis of ceramics The ceramics can be prepared from the multi-component rare earth garnet powder prepared in Example 1 or from a binary oxide powder having a purity of at least 99.99% dried in air at 800 °C for 5 hours.

[0083] Annealing: A stoichiometric mixture of the dry powder was ground in an agate mortar and pressed into pellets with a diameter of 13 mm. The pellets were sintered in air at 1500 °C for 10 hours.

[0084] Hot pressing: The stoichiometric binary oxide powder or multi-component rare earth garnet powder was pressed into pellets with a diameter of 13 mm. The resulting formed pellets were hot pressed at a temperature of 1400 - 1500 °C at 5 - 10 MPa for 2 hours.

[0085] Example 3 Synthesis of Single Crystal A stoichiometric mixture of dry powders was mixed manually in a 4 ml glass vial. Cylindrical single crystals with a diameter of 3 mm were grown using a KDN Dai-Ichi Kiden micro-pull-down furnace (Dai-Ichi Kiden Co., Ltd., Tokyo, Japan) equipped with a radio frequency (RF) generator model TR-02001 operating at 26 kilovolt amperes (kVA). A 16 mm diameter iridium crucible with a φ3 mm die and a φ0.5 mm capillary channel was used as the melt reservoir. Growth was initiated by contacting the exit of the capillary channel with a Czochralski grown Lu3Al5O 12 seed crystal. The RF generator power was increased over 2 hours to reach the melting point, which was visually determined by probing the capillary with the seed and observing the presence of the molten material. A charge-coupled device (CCD) camera was focused on the bottom of the crucible die to enable real-time visualization of seeding and monitoring of the melt zone. The pulling rate used was in the range of 0.05 - 0.20 mm / min. After growth was completed, the power ramp-down of the RF generator was carried out over 4 hours. The obtained single crystals had good optical quality. Disks with a thickness of 1 mm were cut and polished for optical and scintillation characterization.

[0086] Example 4 Characteristic Evaluation of Rare Earth Garnet Optical Materials Photographs of the crystals, ceramics, and shaped bodies of the subject matter of the present disclosure are shown in FIGS. 1 and 2.

[0087] Specific examples of single crystals include, but are not limited to, the crystals reported in Table 1 below.

[0088] TIFF2025518532000002.tif50170

[0089] Structural Characteristics Despite the complexity of the multi-component composition, powder X-ray diffraction (XRD) reveals a single cubic garnet structure with the space group Ia-3d. (RE 1-x Ce x )3Al5O 12 An example of the powder XRD pattern of the crystal is shown in Figure 3. Without being bound by any theory, since these single crystals grew from the melt, the compounds are thought to melt congruently. Furthermore, there are no signs of a phase transition from the crystallization temperature to room temperature.

[0090] Optical and scintillation properties The photoluminescence (PL) spectra were acquired at room temperature using a Hitachi Fluorescence Spectrophotometer (Hitachi, Tokyo, Japan) equipped with a xenon lamp. The spectra shown in Figures 4A - 4E have features characteristic of the luminescence of trivalent Ce including the 4f-5d transitions observed even in 1-component and 2-component (RE 1-x Ce x )3Al5O 12 [2 - 9]. These PL spectra have a Ce 3 + emission band with a maximum in the range of 542 - 552 nm and excitation bands with maxima in the ranges of 448 - 457 nm and 335 - 341 nm respectively for the Ce 3+ 4f-5d1 and 4f-5d2 transitions. Furthermore, the compound containing Tb has absorption bands at about 375 nm and below 300 nm corresponding to Tb 3+ 4f-4f transitions. In the 3-component composition containing Tb (see Figures 4B and 4C), the Ce 3+ 4f-5d2 and Tb 3+ 4f-4f excitation bands overlap with a maximum at about 320 nm. The emission spectra monitored at these excitation maxima have characteristic Ce 3+ emission bands that overlap with sharp Tb 3+ 4f-4f emission peaks.

[0091] The radiation luminescence (RL) spectrum was measured at room temperature under continuous irradiation from an X-ray generator model CMX003 (32 kV and 0.1 mA). The spectrum was recorded using a monochromator sold under the trade name PI Acton SPECTRAPRO® SP-2155 (Telecyne Digital Imaging U.S. Inc., Thousand Oaks, California, United States of America). The strongest emission band of the radiation luminescence spectrum shown in FIGS. 5A - 5F has a maximum value in the range of 535 - 563 nm and is a Ce 3+ emission band. Compounds containing Tb (see FIGS. 5A and 5C - 5E) also have Tb 3+ emission characteristics at approximately 495, 582, 625, and 652 nm.

[0092] The absolute light output of the crystal sample was obtained by measuring the pulse height spectrum shown in FIG. 6. A Hamamatsu 3177 - 50 photomultiplier tube (PMT) (Hamamatsu Photonics K.K., Shizuoka, Japan) was used. The sample was directly coupled to the PMT using optical grease and covered with multiple layers of polytetrafluoroethylene (PTFE) tape sold under the trade name TEFLON® (The Chemours Company, Wilmington, Delaware, United States of America). A reflection dome prepared from a polymer sold under the trade name SPECTRALON (Labsphere, Inc., North Sutton, New Hampshire, United States of America) was placed on top of the tape. The gamma-ray energy spectrum was 137 recorded using a Cs excitation source. Using the integrated quantum efficiency of the PMT according to the emission spectrum of the crystal, the light output per photon per unit of gamma-ray energy was estimated and is shown in Table 1.

[0093] Additional compositions The data in Table 2 were collected from additional exemplary rare earth garnet compact pellets. The RL spectra determined for both the Ce-doped and undoped compositions exhibit scintillation emission. See FIGS. 7A - 7Z. The garnet phase formation was identified using the presented powder XRD data. The lattice parameters were extracted using Rietveld refinement of the powder XRD data and then used to calculate the density of the garnet phase. The density was calculated assuming a composition formula, which was an appropriate assumption for a pure phase sample. However, it should be noted that for samples with a secondary phase, this composition formula may not be able to constitute the garnet phase, and errors may occur in the density calculation. Table 2 below summarizes the RL and XRD plots of additional exemplary rare earth garnets.

[0094] TIFF2025518532000003.tif185170

[0095] References All references listed in this specification, including but not limited to all patents, patent applications and their publications, scientific journal articles, and database entries, are hereby incorporated by reference in their entirety to the extent that they supplement, explain, provide background for, or teach the methodologies, techniques, and / or compositions used herein. [1] Euler,F.; Bruce,J.A., Oxygen Coordinates of Compounds with Garnet Structure.Acta Crystallogr 1965,19,971 - 978. [2] Nikl,M.; Yoshikawa,A.; Kamada,K.; Nejezchleb,K.; Stanek,C.R.; Mares,J.A.; Blazek,K., Development of LuAG - based scintillator crystals - A review.Prog Cryst Growth Ch 2013,59(2),47 - 72. [3] Su, X.; Zhang, K.; Liu, K.; Zhong, H.; Shi, Y.; Pan, Y., Combinatorial Optimization of (Lu1-xGdx)3Al5O12:Ce3y Yellow Phosphors as Precursors for Ceramic Scintillators. ACS Comb. Sci. 2011, 13, 79 - 83. [4] Li, J.; Li, J.G.; Liu, S.; Li, X.; Sun, X.; Sakka, Y., The development of Ce3+-activated (Gd,Lu)3Al5O12 garnet solid solutions as efficient yellow-emitting phosphors. Sci. Technol. Adv. Mater. 2013 14 054201 99pp. [5] Hu, S.; Qin, X.; Zhou, G.; Lu, C.; Guanghui, L.; Xu, Z.; Wang, Z., Luminescence characteristics of the Ce3+-doped garnets: the case of Gd-admixed Y3Al5O12 transparent ceramics. Opt. Mater. Express 2015 5 12. [6] Shao, C.; Zhang, L.; Zhou, T.; Gu, L.; Sun, B.; Jiang, Z.; Yao, Q.; Bu, W.; Wang, K.; Chen, H., Gd2O3 assisted densification of high quantity (Y,Gd)AG:Ce ceramic solid solutions and their luminescence characteristics. Ceram. Int. 2018 44 8672 - 8678. [7] Boukerika,A.; Guerbous,L.; Belamri,M., Effect of Y3+ substitution on structural and photoluminescence properties of solid solutions [(Lu1xYx)1z Cez]3Al5O12 phosphors. Mater. Chem. Phys. 2016 171 394-399. [8] Yadav,S.K.; Uberuaga,B.P.; Nikl,M.; Jianng,C.; Stanek,C.R., Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles. Phys. Rev. Applied. 2015 4 054012. [9] Dorenbos,P., Electronic structure and optical properties of the lanthanide activated RE3(Al1-xGax)5O12(RE=Gd,Y,Lu) garnet compounds. Journal of Luminescence. 2013 134 310-318.

[0096] It will be understood that various details of the subject matter of the present disclosure may be changed without departing from the scope of the subject matter of the present disclosure. Further, the foregoing description is for purposes of illustration only and not for purposes of limitation.

Claims

1. formula: (RE １－ｙ X ｙ ) ３ (Al １－ｚ Ga ｚ ) ５ O １２ [In the formula, 0 ≤ y ≤ 0.1; 0 ≤ z ≤ 1; RE is a combination of ions of three or more rare earth elements selected from the group consisting of Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La; X is one or more activating ions selected from the group consisting of Ce ions, Tb ions, Dy ions, Eu ions, Yb ions, and Pr ions. An optical material comprising the composition of the following.

2. The optical material according to claim 1, wherein z is 0.

3. The optical material according to claim 1, wherein RE is a combination of ions of 3, 4, 5, or 6 elements selected from the group consisting of Y, Sc, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, and La.

4. The optical material according to claim 1, wherein RE is a combination of ions of at least three elements selected from the group consisting of Y, Lu, Tb, and Gd.

5. The optical material according to claim 1, wherein y is 0.

6. The optical material according to claim 1, wherein 0.001 ≤ y ≤ 0.

1.

7. The optical material according to claim 6, wherein 0.005 ≤ y ≤ 0.05; y may be 0.005, 0.02, or 0.

05.

8. X is a Ce ion, a Pr ion, or a mixture thereof, and X is Ce ３＋ The optical material according to claim 6, which may also be used.

9. (Y) ０．２ Gd ０．２ Tb ０．２ Y ０．２ Lu ０．２ ( ３ Al ５ O １２ ; (Y) ０．２５ Gd ０．２５ Er ０．２５ Lu ０．２５ ) ３ Al ５ O １２ ; (Y ０．２５ Gd ０．２５ Ho ０．２５ Lu ０．２５ ) ３ Al ５ O １２ ; (Y) ０．２ Gd ０．２ Tb ０．２ Dy ０．２ Lu ０．２ ( ３ Al ５ O １２ ; (Y) ０．２５ Gd ０．２５ Tb ０．２５ Lu ０．２５ ( ３ Al ５ O １２ ; (Y) ０．２ Eu ０．２ Gd ０．２ Yb ０．２ Lu ０．２ ) ３ Al ５ O １２ ; (9) ０．１６６７ E ０．１６６７ Z ０．１６６７ Tb ０．１６６７ Yb ０．１６６７ Lu ０．１６６７ ) ３ A ５ O １２ ; (Y) ０．２５ Gd ０．２５ Tb ０．２５ Lu ０．２５ ( ３ Al ５ O １２ ; (Y) ０．２５ Nd ０．２５ Gd ０．２５ Marriage ０．２５ ) ３ Al ５ Oh １２ ; (Y ０．２５ Pr ０．２５ Gd ０．２５ Lu ０．２５ ) ３ Al ５ O １２ ; and (Y) ０．２５ The ０．２５ Gd ０．２５ Lu ０．２５ ( ３ Al ５ O １２ The optical material according to claim 1, comprising a composition selected from the group consisting of the following.

10. (Y ０．１９９ Gd ０．１９９ Tb ０．１９９ Ya ０．１９９ Lu ０．１９９ Ce ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４８７５ Gd ０．２４８７５ Er ０．２４８７５ Lu ０．２４８７５ Ce ０．００５ ) ３ Al ５ O １２ ; (Y ０．２４８７５ Gd ０．２４８７５ Ho ０．２４８７５ Lu ０．２４８７５ Ce ０．００５ ) ３ Al ５ O １２ ; (Y) ０．１９９ Gd ０．１９９ Tb ０．１９９ Dy ０．１９９ Lu ０．１９９ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４８７５ Gd ０．２４８７５ Tb ０．２４８７５ Lu ０．２４８７５ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．１９９ Eu ０．１９９ Gd ０．１９９ Yb ０．１９９ Lu ０．１９９ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．１６５８３ Eu ０．１６５８３ Gd ０．１６５８３ Tb ０．１６５８３ Yb ０．１６５８３ Lu ０．１６５８３ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４８７５ Sm ０．２４８７５ Gd ０．２４８７５ Lu ０．２４８７５ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４８７５ Nd ０．２４８７５ Gd ０．２４８７５ Lu ０．２４８７５ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４８７５ Pr ０．２４８７５ Gd ０．２４８７５ Lu ０．２４８７５ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４８７５ L ０．２４８７５ Gd ０．２４８７５ Lu ０．２４８７５ Yes ０．００５ ) ３ Al ５ O １２ ; (Y) ０．２４５ Gd ０．２４５ Tb ０．２４５ Lu ０．２４５ Yes ０．０２ ) ３ Al ５ O １２ ; (Y) ０．２３７５ Gd ０．２３７５ Tb ０．２３７５ Lu ０．２３７５ Yes ０．０５ ) ３ Al ５ O １２ ; (Y ０．２３７５ Gd ０．２３７５ Tb ０．２３７５ Lu ０．２３７５ Ce ０．０５ ) ３ Al ５ O １２ ; and (Y) ０．２９４ Gd ０．２９４ Tb ０．０９８ Lu ０．２９４ Yes ０．０２ ) ３ Al ５ O １２ The optical material according to claim 1, comprising a composition selected from the group consisting of the following.

11. (Y) ０．３３１６７ Tb ０．３３１６７ Gd ０．３３１６７ Yes ０．００５ ) ３ Al ５ O １２ ; (Lu) ０．３３１６７ Y ０．３３１６７ Gd ０．３３１６７ Yes ０．００５ ) ３ Al ５ O １２ ; (Lu ０．３３１６７ 9 ０．３３１６７ Tb ０．３３１６７ Ce ０．００５ ) ３ A ５ O １２ ; (Lu ０．２４８７５ Y ０．２４８７５ Tb ０．２４８７５ Gd ０．２４８７５ Ce ０．００５ ) ３ Al ５ O １２ ; and (Lu) ０．２４５ Y ０．２４５ Tb ０．２４５ Gd ０．２４５ Yes ０．０２ ) ３ Al ５ O １２ The optical material according to claim 1, comprising a composition selected from the group consisting of the following.

12. The optical material according to claim 1, wherein when the optical material is stimulated with high-energy radiation, it produces light emission from optically active RE ions, and the optically active RE ions may be Tb ions.

13. Optical materials, (Y) ０．３３１６７ Tb ０．３３１６７ Gd ０．３３１６７ Yes ０．００５ ) ３ Al ５ O １２ ; (Lu) ０．３３１６７ Y ０．３３１６７ Gd ０．３３１６７ Yes ０．００５ ) ３ Al ５ O １２ ; (Lu ０．３３１６７ 9 ０．３３１６７ Tb ０．３３１６７ Ce ０．００５ ) ３ A ５ O １２ ; (Lu ０．２４８７５ Y ０．２４８７５ Tb ０．２４８７５ Gd ０．２４８７５ Ce ０．００５ ) ３ Al ５ O １２ ; and (Lu) ０．２４５ Y ０．２４５ Tb ０．２４５ Gd ０．２４５ Yes ０．０２ ) ３ Al ５ O １２ A radiation detector comprising the optical material and photon detector according to claim 1, which may be an optical material selected from the group consisting of the optical material and photon detector.

14. A method for detecting gamma rays, X-rays, cosmic rays, and / or particles having an energy of 1 keV or more, comprising using the radiation detector described in claim 13.

15. Use of the radiation detector according to claim 13 in medical imaging, homeland security, or high-energy physics research.

16. A method for preparing an optical material according to claim 1, comprising preparing a single crystal of the optical material from a molten material.

17. A method for preparing the optical material described in claim 1, (i) preparing a foam by heating an aqueous solution containing a polymer, optionally polyvinyl alcohol (PVA) or polyethylene glycol (PEG), and a metal nitrate, wherein the metal nitrate contains ions of elements corresponding to elements of the optical material, and grinding the foam to provide a powder; or (ii) Coprecipitation of a powder by adding an aqueous solution containing a mixture of a metal nitrate and ammonium sulfate to an aqueous solution of ammonium carbonate, wherein the metal nitrate contains ions of the element corresponding to the element of the optical material. A method comprising preparing powder for an optical material.

18. A method for preparing an optical material according to claim 1, comprising preparing a ceramic optical material using a binary oxide as a starting material optionally by a technique selected from the group consisting of sintering, hot pressing, hot isotactic pressing, and discharge plasma synthesis.

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