CN101054522B

CN101054522B - Cerium activated rare earth halide bromide scintillator and preparing method thereof

Info

Publication number: CN101054522B
Application number: CN200710105857XA
Authority: CN
Inventors: 张明荣; 张春生; 葛云程; 郭建军; 范宇红; 陆红; 丁小东; 张红梅
Original assignee: BEIJING GLASS RESEARCH INSTITUTE
Current assignee: BEIJING GLASS RESEARCH INSTITUTE
Priority date: 2007-06-01
Filing date: 2007-06-01
Publication date: 2010-10-13
Anticipated expiration: 2027-06-01
Also published as: CN101054522A

Abstract

A cerium-activated brominated rare earth scintillant and method for preparing same belongs to the scintillating materials field. The scintillant in the invention uses brominated rare earth compound or mixture thereof as the substrate and halogen cerium compound or mixture thereof except for bromine as the activating agent. The chemical formula of the scintillant is (1-a)ReBr3.aCeX3, wherein Re isone of or mixture of two to four of lanthanum, gadolinium, lutecium and yttrium, X is one or mixture of two to three of F, Cl and I and a is the moore percentage of CeX3, 0<a<=0.4. The scintillant single crystal in the invention is grown in a crucible descending method, especially in a vacuum encapsulated quartz crucible or a platinum crucible encapsulated in the quartz tube or a graphite crucible or glass carbon crucible encapsulated in the quartz tube, by using the descending method in the resistance heating growth furnace.

Description

A kind of cerium activated rare earth halide bromide scintillator and manufacture method thereof

Technical field

The present invention relates to cerium activated rare earth halide bromide scintillator and manufacture method thereof, belong to the scintillation material technical field.

Background technology

Scintillator is meant under the irradiation of high energy particle or ray (as gamma-rays, X ray, Millikan's rays and the energy particle greater than 1keV), can be with flashing mode luminous material.Scintillator has been widely used in various high-energy radiation field of detecting, be specifically related to fundamental research fields such as high energy physics, nuclear physics, earth physics, space physics, and Application Areas such as geological exploration, oil well logging, environmental monitoring, port security inspection, industrial nondestructive testing, medical imaging.

The parameter of passing judgment on scintillator performance quality mainly comprises: light output, energy resolution and time response.

Wherein, light is output as the ratio of scintillator emission total number of light photons that goes out and the incident radiation energy that is absorbed by this scintillator, is used for characterizing the luminous intensity of scintillator, the luminous efficiency of reflection scintillator, and unit is the every million-electron-volt of number of photons (photons/MeV).The photoelectric yield of the scintillator that light output detector commonly used records in the actual measurement represents that unit is the every million-electron-volt of photoelectron number (photo-electrons/MeV).

Energy resolution uses the half-width (FWHM) at the energy measurement peak of monoenergetic photon recently to represent with the percentage of peak energy usually, is used for characterizing the ability that scintillator is differentiated projectile energy.When the energy resolution of more different scintillators, generally adopt different scintillators caesium-137 ( ¹³⁷Cs) the monoenergetic photon in source (622KeV gamma-rays) acts on the following energy resolution data that record foundation as a comparison, and the value that records is more little, and the performance of scintillator is good more.

Time response comprises rise time of a pulse and luminescence decay time, and the former characterizes the speed degree of scintillator paired pulses source of radiation response, and the latter represents that radiation fails back scintillator luminous intensity in time and the speed degree of decay.The luminescence decay time of scintillator is short more, illustrates that its time resolving power is high more.

Different Application Areass has different requirements to the performance of scintillator, but all expects and pursue those both had output of higher light and energy resolution preferably, has the high-performance scintillator of short fall time again.For example: light output exists greater than 30000photons/MeV, energy resolution ¹³⁷Cs source effect down less than 7%, be shorter than the scintillator of 50ns fall time.

Present widely used scintillator mainly is an alkaline metal iodide class scintillator, comprise the sodium iodide (NaI:Tl) of mixing thallium, the cesium iodide (CsI:Tl) of mixing thallium and the cesium iodide (CsI:Na) of mixing sodium, its dominate in the scintillator Application Areas has reached more than 50 year.This type of scintillator have the output of higher light (30000～52000photons/MeV), and ¹³⁷Have 6%～7% energy resolution under the effect in Cs source, but their twinkling light is all long fall time, wherein the fastest NaI:Tl crystal of decay also reaches 230ns.

A lot of fast decay scintillators have been found and have obtained practical application, comprising being shorter than 30ns many fall times, even are shorter than the scintillator of 10ns, for example plumbous tungstate (PbWO ₄, note by abridging be PWO), mix the yttrium aluminate (YAlO of cerium ₃: Ce, note by abridging be YAP:Ce), mix the oxygen silicic acid lutetium (Lu of cerium ₂SiO ₅: Ce, note by abridging be LSO:Ce).But these fast decay scintillators fail to have concurrently the energy resolution that high light output is become reconciled.For example: only be 200photons/MeV though PWO is shorter than the output of 10ns light fall time; Though YAP:Ce has flicker decay faster (25ns) and higher energy resolution (4.3%), light output individual difference is very big, and self-absorption is serious; LSO:Ce is the good comprehensive properties scintillator of just having found soon, have the light output of about 27500photons/MeV, the fall time of 40ns, but its energy resolution has only 8%, and radiation background is arranged.

A kind of acquisition has the approach of the high-performance scintillator of expectation in the art methods, is from cerium activated rare earth or contains the compound of rare earth and seek.In recent years, several appearances that have cerium activated rare earth (or containing rare earth) halide scintillator of the output of high light, good energy resolution and fast attenuation characteristic concurrently, encouraging.

To should be mentioned that two kinds of non-fluorine halogenation lanthanum crystal of mixing cerium that the people such as P.Dorenbos of Holland find especially.At first a kind of of discovery is with Lanthanum trichloride (LaCl ₃) be matrix, Cerium II Chloride (CeBr ₃) be Lanthanum trichloride (the cerium) (LaCl of activator ₃: Ce) crystal (European patent WO01/60944, Chinese patent CN1404523A); What find after a while is with lanthanum bromide (LaBr ₃) be matrix, comprise cerium bromide (CeBr ₃) be lanthanum bromide (the cerium) (LaBr of activator ₃: Ce) crystal (European patent WO01/60945, Chinese patent CN1404522A).These two kinds of scintillators have identical hexagonal structure, and spacer is P6 ₃/ m.

After above-mentioned two kinds of scintillation crystals, with the in-phase CeBr of its class matter ₃Crystal also is found have good scintillation properties (K.S.Shah, et al., CeBr ₃Scintillators for Gamma-RaySpectroscopy, IEEE Transactions on Nuclear Science., 52 (6), 2005:pp.3157～3159.).The in-phase CeCl of another kind matter ₃Crystal also has good scintillation properties (E.V.D.van Loef, et al., Scintillation properties of LaCl ₃: Ce ³⁺Crystals:Fast, Efficient, and High-Energy Resolution Scintillators, IEEE Trans.Nucl.Sci.，48(3)，2001，pp.341～345.)

Recently, the people such as A.M.Srivastava of the U.S. declare to have found a kind of Ce ³⁺Activated mixing halogenation lanthanum scintillator (U.S. Pat 2005/0104001A1).Different with people's such as P.Dorenbos contrivance is that its substrate material is not to be made of single Lanthanum trichloride or lanthanum bromide compound, but is made of two kinds in three kinds of non-fluorine halogenation lanthanums (being Lanthanum trichloride, lanthanum bromide, the lanthanum iodide) mixtures of forming at least.Along with LaCl ₃And LaBr ₃The variation of mol ratio, obvious variation has appearred in the luminescent spectrum of this material.

The non-fluorine halide of above-mentioned cerium activated rare earth (or containing rare earth) (mainly being the compound of chlorine and bromine) generally has almost all-round excellent scintillation properties in alkaline metal iodide: light output is higher than 40000photons/MeV (LaBr ₃: Ce in addition can reach more than the 60000photons/MeV), energy resolution is less than 6%, even less than 4% (LaBr ₃: Ce in addition can be less than 3%), be shorter than 30ns fall time.Wherein, working as of scintillation properties the best, push away LaBr ₃: Ce.But, because LaBr ₃, CeBr ₃Compare LaCl ₃, CeCl ₃The easier moisture absorption, LaBr ₃: it is bigger that the Ce crystalline prepares difficulty, and manufacturing cost is higher.In addition, LaBr ₃: although Ce crystal scintillation properties is optimum in the known scintillator, the composition (CeBr of its highest light output and optimum capacity resolving power ₃Incorporation less than 1%) with the composition (CeBr of the shortest fall time ₃Incorporation be about 5%) and inconsistent, in material preparation (comprising crystal growth), can't take into account.

Ce ³⁺Activated scintillator luminous is Ce in essence ³⁺Ionic base configuration ([Xe] 4f ¹) electronics is the electronics on the 4f track, induced transition is to first excited configuration ([Xe] 5d ¹) be that de excitation is dealt into the 4f track again subsequently on the outer field 5d track, the result of optical radiation takes place simultaneously.

Because this transition of electron (5d → 4f transition) from the 5d track to the 4f track belongs to the transition that eelctric dipole allows, thereby luminous intensity height, decay are fast.Simultaneously, again because Ce ³⁺The 5d track on electronics be in naked state, be subject to the influence of ionic enclosed pasture effect on every side.Substrate composed variation and Ce ³⁺Neighbour's anion species and Ce ³⁺The symmetry of case of living in etc. all can influence Ce ³⁺The residing energy state of 5d orbital electron, and then have influence on Ce ³⁺Luminous behavior.

The crystallisation process of melt directional freeze is actually the atom of melt or the process that ion (group) moves and piles up in order to solid-liquid interface gradually from melt one side.With the yin, yang ion in a kind of raw material, the probability that becomes (maintenance) neighbour under molten state is bigger, the yin, yang ion that especially Coulomb attraction power is stronger, thereby when crystallization, tend to occupy next-door neighbour's lattice site.Single with regard to four kinds of cerium halide, by Coulomb attraction power by to weak ordering being cerium fluoride (CeF by force successively ₃) in cerium ion (Ce ³⁺) and fluorion (F ^-), Cerium II Chloride (CeCl ₃) in Ce ³⁺And Cl ^-(chlorion), CeBr ₃In Ce ³⁺And Br ^-(chlorion), CeI ₃In Ce ³⁺And I ^-(iodide ion).

From above-mentioned relevant Ce ³⁺The luminous mechanism and the process of melt crystallization can be known by inference, as the Ce of the special luminescent material of a class ³⁺The activated scintillator material, its scintillation properties not only depends on substrate material and composition thereof, but also can regulate by the introducing mode that changes activator.For example we can by mix different sorts and (or) cerium halide of different concns, the performance of cerium activated rare earth (or containing rare earth) halide scintillator is regulated and is optimized.

Summary of the invention

An object of the present invention is detection for high-energy radiation and provide a kind of with high light output, good energy resolution and fast attenuation characteristic, and, but high-performance scintillator that manufacturing cost may lower suitable even more excellent with existing optimum scintillator scintillation properties.

Another object of the present invention provides a kind of preparation method with scintillator of above-mentioned characteristic.

For achieving the above object, based on to Ce ³⁺Luminescence mechanism understanding and to the understanding of melt crystallization process, the invention provides a kind of new cerium activated rare earth halide bromide scintillator.

Scintillator of the present invention be a kind of be substrate material with Brominated rare earth compound or mixture, be the scintillator of activator material with the cerium halide compound or the mixture of non-bromine.Wherein, the total amount of the total amount of Ce elements and the halogens of non-bromine such as is at a mole number, and the halogens of non-bromine comprises chlorine, fluorine, iodine; The cerium halide of non-bromine comprises Cerium II Chloride, cerium fluoride, cerous iodide.The chemical constitution general formula of this scintillator is (1-a) ReBr ₃ACeX ₃, wherein, Re be in lanthanum (La), gadolinium (Gd), lutetium (Lu), the yttrium (Y) one or both to four kinds mixing, X be in fluorine (F), chlorine (Cl), the iodine (I) one or both to three kinds mixing, a (0＜a≤0.4) is CeX ₃Molar fraction.

A kind of comparatively concrete example of scintillator of the present invention is, Re is La, or is La and the mixing of Gd, La and Lu, La and Y, or be La with Gd, La, Y in two kinds to three kinds mix; X is F or Cl or I, or is two kinds to three kinds mixing among F, Cl, the I; And 0＜a≤0.4.

A kind of special case of scintillator of the present invention is that Re=La, X=Cl, chemical formula are (1-a) LaBr ₃ACeCl ₃, wherein 0＜a≤0.4, especially 0＜a≤0.1, even 0＜a≤0.01.

The another kind of special case of scintillator of the present invention is that Re=La, X=F, chemical formula are (1-a) LaBr ₃ACeF ₃, 0＜a≤0.2, especially 0＜a≤0.1 wherein.

Another special case of scintillator of the present invention is that Re=La, X=I, chemical formula are (1-a) LaBr ₃ACeI ₃, 0＜a≤0.3, especially 0＜a≤0.1 wherein.

Scintillator of the present invention with other contain rare earth halide (the comprising cerium halide) scintillator of cerium different be:

(1) scintillator of the present invention is to be substrate material with the Brominated rare earth, and with cerium fluoride or Cerium II Chloride or cerous iodide, or the mixture of these three kinds non-bromine cerium halide suitable proportions is the activator material.Wherein, the total amount of the amount of Ce elements and non-bromine halogen element such as is at a mole number.

(2) as (1-a) LaBr of comparatively special example of the present invention ₃ACeCl ₃, (1-a) LaBr ₃ACeF ₃(1-a) LaBr ₃ACeI ₃, be characterized in that with single lanthanum bromide be substrate material, with single CeCl ₃Or CeF ₃Or CeI is the activator material.

(3) scintillator of the present invention has unique scintillation properties, is better than mixing the Lanthanum trichloride (LaCl of Cerium II Chloride ₃: Ce), even be better than mixing the lanthanum bromide (LaBr of comprise cerium bromide ₃: Ce), and other rare earth halide of cerium activated.

(4) because the activator material adopts is not the expensive comprise cerium bromide of price, but the more cheap non-bromine cerium halide of price, for example Cerium II Chloride and cerium fluoride are so scintillator manufacturing cost of the present invention is relatively low.

Scintillator of the present invention with regard to form, both can be opaque polycrystal powder, can be transparent single crystal also, was made into what form, was decided by the needs of reality.The former making method is fairly simple, is easy to realize; The latter's making method is then more complex, realizes that difficulty is bigger.But, most application needs all be the scintillator of monocrystalline form, i.e. the scintillation crystal of saying usually, and generally be that form is greater than 50 millimeters ³, even greater than 1 centimetre ³The transparent single crystal body.

Scintillator of the present invention inevitably contains impurity element, as alkali metal, alkali earth metal and rare earth element.Impurity element specifically comprises sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), barium (Ba), lanthanum (La), gadolinium (Gd) etc., mainly comes from employed raw material, and its content is generally less than 0.1%, even less than 0.01%.

The raw material of making scintillator of the present invention is anhydrous Brominated rare earth and non-bromine cerium halide.Wherein, non-bromine cerium halide is meant cerium fluoride (CeF ₃), Cerium II Chloride (CeCl ₃) and cerous iodide (CeI ₃).These raw materials can be bought as commodity and obtain.

Scintillation crystal of the present invention can utilize melt directional freeze crystalline technology to realize, for example falling crucible method, crystal pulling and zone melting method etc.A kind of preferred falling crucible method can be used for the growth of scintillation crystal of the present invention, it is characterized in that used crucible is vacuum-packed quartz crucible, or be sealed in platinum crucible in the silica tube, or being sealed in plumbago crucible or vitreous carbon crucible in the silica tube, used crystal growing furnace is the resistive heating growth furnace.

Scintillator powder of the present invention can adopt multiple manufacture method such as sintering process, method of fusion to obtain.Wherein, the way of vacuum melting a kind of effective means of can yet be regarded as can be selected crucible that materials such as silica glass, platinum, graphite, vitreous carbon the make utensil as the raw material fusing.

The invention has the beneficial effects as follows: scintillator of the present invention, to compare with general scintillator, its advantage is that it is a kind of scintillator that has the output of high light, good energy resolution and fast time response concurrently, and its manufacturing cost compares LaBr ₃: the Ce scintillator is low slightly.

Scintillation crystal in the embodiment of the invention all is water white, and the light of most scintillation crystals output is higher than 10000 photoelectrons/MeV, and energy resolution is less than 4%, even less than 3%, is shorter than 30ns fall time, even is shorter than 20ns.

Description of drawings

Fig. 1 is the structural representation of crystal growing furnace.

Fig. 2 is the excitation of X-rays emmission spectrum figure of part chlorine comprise cerium bromide scintillation crystal.

Fig. 3 is the excitation of X-rays emmission spectrum figure of part fluorine comprise cerium bromide scintillator powder.

Fig. 4 is 99.1%LaBr ₃0.9%CeCl ₃The energy spectrogram of scintillation crystal.

Fig. 5 is 99.1%LaBr ₃0.9%CeCl ₃Spectrogram time response of scintillation crystal.

Fig. 6 is 96%LaBr ₃4%CeCl ₃The energy spectrogram of scintillation crystal.

Fig. 7 is 96%LaBr ₃4%CeCl ₃Spectrogram time response of scintillation crystal.

Specific embodiment

Further specify the present invention below in conjunction with drawings and Examples, but not as a limitation of the invention.

Resistive heating growth furnace of the present invention as shown in Figure 1.This crystal growing furnace is made by fire-resistant and lagging material, comprises furnace shell 1 and body of heater.Described body of heater is made up of lagging material 12, refractory brick 9, boiler tube 4, stove silk 5.The center of body of heater bottom surface has the hole, and upper of furnace body is stamped fire door plug 3; The intravital burner hearth of stove is divided into three warm areas by thermal baffle 9: high-temperature zone A, crystallizing field B and cold zone C; Temperature-control heat couple 2 lateral penetration also are embedded in the body of heater, the inwall of the through burner hearth high-temperature zone A of front end; Crucible tray 11 is positioned at the centre of body of heater internal furnace, the hole of passing body of heater bottom surface center by support is connected with following descending mechanism 13, and quartz crucible or the silica tube 5 that has encapsulated other material crucible (as platinum crucible, plumbago crucible or vitreous carbon crucible) are positioned at crucible tray 11.

The temperature and the thermograde of three warm areas of growth furnace are not quite similar, and adjustable within the specific limits.The temperature of high-temperature zone is higher than crystalline melting point more than 20 ℃ at least, sometimes even exceed 100 ℃; The temperature of cold zone then generally is lower than crystalline melting point below 20 ℃, and the temperature of the crystallizing field at middle part is then in the scope of crystalline melting point ± 30 ℃.The longitudinal temperature gradient of whole burner hearth is between 0～50 ℃/centimetre, and wherein the longitudinal temperature gradient of high-temperature zone, crystallizing field and cold zone is respectively 0～30 ℃/centimetre, 5～30 ℃/centimetre and 0～20 ℃/centimetre.

The growth of all scintillation crystals in the embodiments of the invention all is to make crucible be similar to the way realization that from top to down is moved to cold zone gradually by the high-temperature zone of growth furnace in the atmospheric environment in above-mentioned resistance heading furnace.

Making the used raw material of scintillator of the present invention is anhydrous Brominated rare earth (ReBr ₃, Re=La, Gd, Y, Lu), and anhydrous non-bromine cerium halide (CeX ₃, X=F, Cl, I).The form of raw material can be Powdered, pearl, even block.

The growth technique process of scintillation crystal of the present invention is as follows:

At first, according to composition---(1-a) ReBr of the scintillation crystal that will grow ₃ACeX ₃, in the clean environment of drying (as glove box), take by weighing corresponding raw material, pack into through cleaning and the quartz crucible (or platinum crucible) of drying treatment in, and insert in the vacuum system rapidly again in the silica tube of the access promptly or the end closure of packing into earlier and vacuumize.When vacuum tightness reaches 10 ^-3When pa is above, the other end scorification of quartz crucible top or silica tube is sealed.

Used crucible in the embodiments of the invention depends in the scintillation crystal of growth whether contain fluorine element.If do not contain fluorine element, can adopt the quartz crucible that is made by fused quartz tube; Otherwise must use can the erosive of anti-fluorine crucible, as is encapsulated in platinum crucible, plumbago crucible or vitreous carbon crucible in the silica tube.The shape of crucible is generally axisymmetricly, and the bottom is cone-shaped and the top is cylindric opening.The angle of pointed cone needs to control especially, is generally less than 120 degree, preferably between 20～60 degree.The diameter of crucible, length and wall thickness are decided on the crystallographic dimension of growth.Wherein, quartz crucible system adopts commercially available purity at the transparent quartz tube more than 99.95%, fires with thermal-flame to form.

Then, with vacuum-packed quartz crucible or sealed in the crucible tray that silica tube is placed on central upright stanchion links to each other of platinum crucible (also can be plumbago crucible or vitreous carbon crucible), the position of regulating crucible is positioned at above zone, crystallizing field middle part at the bottom of making the awl of crucible.After intensification was all melted raw material, starting down, descending mechanism fell crucible from top to bottom with certain speed.The speed that descends generally is controlled in 0.1～2.0 millimeter/hour, especially in 0.5～1.5 millimeter/hour scope.By in the process of crystallizing field, the melt in the crucible progressively condenses into monocrystalline and grows up at crucible.After treating the whole crystallizations of melt, or after xln all is in cold zone, stop the decline of crucible, make the whole cooling of stove with 10～30 ℃/hour speed then, until room temperature.So crystal growth finishes.

Comparative Examples 1

LaBr ₃The growth of single crystal

Processing step:

(1) is that 20mm, wall thickness are that 2mm, length are the quartz crucible that the transparent quartz tube of 15-20cm is fired into about 60 degree of cone angle with internal diameter, and annealing, cleans and dry.

(2) getting purity is 99.99% anhydrous LaBr ₃50.0 gram is contained in through in the quartz crucible of drying treatment, inserts vacuum system then rapidly and vacuumizes, and is not less than 10 when quartz crucible is evacuated to vacuum tightness ^-3During Pa with thermal-flame with the complete sealing by fusing of the opening end of crucible.

(3) vacuum-packed band work stone English crucible is put into crucible tray after, put into the growth furnace burner hearth, make the crucible awl be positioned at the thermal baffle circular hole in the end, and make after the temperature to 830 ℃ of high-temperature zone constant temperature with 30～50 ℃/hour temperature rise rate at least 2 hours, all melt to guarantee raw material.

(4) start descending mechanism down, crucible steadily descended with 1mm/ hour speed, treat that melt all solidifies (crystallization) after, or after xln all is in cold zone, make the whole cooling of stove with 20 ℃/hour speed, until room temperature.

(5) whole process approximately needs 6 to 7 days, and gained crystal blank is a clear, colorless, and length reaches about 4 centimetres.

Comparative Examples 2

64%LaBr ₃32%LaCl ₃4%CeCl ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 29.45 gram; LaCl ₃(99.99%) 10.36 gram; CeBr ₃(99.99%) 1.30 gram.

Processing step: basic identical with Comparative Examples 1, repeat no more here.Different is, the temperature of high-temperature zone is 880 ℃ when step (3), and constant temperature at least 3 hours.

Comparative Examples 3

99.1%LaBr ₃0.9%CeBr ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 49.55 gram; CeBr ₃(99.99%) 0.56 gram.

Processing step: with Comparative Examples 1.

Embodiment 1-3

99.7%LaBr ₃0.3%CeCl ₃(embodiment 1), 99.4%LaBr ₃0.6%CeCl ₃(embodiment 2), 99.1%LaBr ₃0.9%CeCl ₃The growth of (embodiment 3) single crystal

Raw materials used:

	LaBr ₃(99.99％)	CeCl ₃(99.99％)
	LaBr ₃(99.99％)	CeCl ₃(99.99％)	Embodiment 1	49.85 gram	0.10 gram
Embodiment 2	49.70 gram	0.20 gram	Embodiment 1	49.85 gram	0.10 gram
Embodiment 2	49.70 gram	0.20 gram	Embodiment 3	49.55 gram	0.29 gram

Processing step: with Comparative Examples 1.

Embodiment 4

96%LaBr ₃4%CeCl ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 48.00 gram; CeCl ₃(99.99%) 1.30 gram.

Processing step: basic identical with Comparative Examples 1.Different is that the temperature of high-temperature zone is 850 ℃ when step (3).

Embodiment 5

90%LaBr ₃10%CeCl ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 45.00 gram CeCl ₃(99.99%) 3.25 gram.

Processing step: basic identical with Comparative Examples 1.Different is that the temperature of high-temperature zone is 860 ℃ when step (3).Whole process approximately needs 7 to 8 days.Gained crystal blank is a clear, colorless, the about 3-4 of length centimetre.

Embodiment 6

99.4%LaBr ₃0.6%CeF ₃The growth of single crystal

Processing step:

(1) prepares crucible.It is that 0.18-0.20mm, external diameter are that 19mm, length are the platinum crucible of the band circular cone (cone angle is about 45 degree) of 8-10cm that platinum is processed into thickness.Simultaneously, preparing an internal diameter is that 20mm, wall thickness are that 2mm, length are the silica tube that the band circular cone (tapering also is about 45 degree) of 15-20cm seals.Platinum crucible and silica tube are cleaned up and dry.

(2) getting purity in the exsiccant glove box is 99.99% anhydrous LaBr ₃49.70 gram, CeF ₃0.16 gram is in the platinum crucible of packing into.To be enclosed in the silica tube that step (1) seals with the band circular cone of getting ready with the material platinum crucible then, and insert vacuum system then rapidly and vacuumize, and in silica tube, be evacuated to vacuum tightness and be not less than 10 ^-3During Pa with thermal-flame with the complete sealing by fusing of the opening end of silica tube.

(3) silica tube of dress platinum crucible in vacuum-packed is put into crucible tray vertically after, put into the growth furnace burner hearth, make platinum crucible bore the end and be positioned at the thermal baffle circular hole.Make after the temperature to 840 ℃ of high-temperature zone constant temperature with 30～50 ℃/hour temperature rise rates at least 2 hours, all melt to guarantee raw material.

(4) start descending mechanism down, crucible is steadily descended with 1mm/ hour speed.After treating that melt all solidifies (crystallization), or xln all is in cold zone, makes the whole cooling of stove with 20 ℃/hour speed, until room temperature.

(5) whole process approximately needs 6 to 7 days.Gained crystal blank is a clear, colorless.

Embodiment 7

95%LaBr ₃5%CeF ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 47.50 gram; CeF ₃(99.99%) 1.3 gram.

Processing step: with basic identical to implementing 6.Different is that the temperature of high-temperature zone is 860 ℃ when step (3).

Embodiment 8

96%LaBr ₃1%CeCl ₃3%CeF ₃(a=4%) the growth of single crystal here,

Raw materials used: LaBr ₃(99.99%) 48.00 gram; CeCl ₃(99.99%) 0.33 gram; CeF ₃(99.99%) 0.78 gram.

Processing step: substantially the same manner as Example 6.Different is, the temperature of high-temperature zone is 860 ℃ when step (3), and constant temperature at least 3 hours.

Embodiment 9

96%LaBr ₃4%CeI ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 48.00 gram CeI ₃(99.9%) 2.75 gram.

Processing step: basic identical with Comparative Examples 1.Different is that the temperature of high-temperature zone is 830 ℃ when step (3).

Embodiment 10

90%LaBr ₃6%GdBr ₃4%CeCl ₃The growth of single crystal

Raw materials used: LaBr ₃(99.99%) 45.00 gram; GdBr ₃(99.9%) 2.10 gram CeCl ₃(99.99%) 1.30 gram.

Processing step: basic identical with Comparative Examples 1.Different is, the temperature of high-temperature zone is 830 ℃ when step (3), and constant temperature at least 3 hours.

The manufacture method of scintillator powder of the present invention has multiple, as sintering process, method of fusion.Wherein, the way of vacuum melting is a kind of effective means, the utensil that the crucible that can select materials such as silica glass, platinum, graphite, vitreous carbon to make melts as raw material.According to kind and its content difference of substrate material and activator material, generally the temperature with fusing is controlled at 750 ℃～950 ℃, and the time was controlled at 0.5～2 hour.The same with the method for single crystal growth, melting raw materials must be carried out in a vacuum or under rare gas element (for example high pure nitrogen or the argon gas) protection of drying and anaerobic, to prevent the generation of following side reaction:

2ReX ₃+O ₂→2ReOX+2X ₂

ReX ₃+H ₂O→ReOX+2HX

In the formula, Re represents rare earth element (comprising Ce), and X represents halogen (comprising Br).

Embodiment 11 to 14

98%LaBr ₃2%CeF ₃(embodiment 11), 90%LaBr ₃10%CeF ₃(embodiment 12), 80%LaBr ₃20%CeF ₃(embodiment 13), 70%LaBr ₃30%CeF ₃The preparation of (embodiment 14) powder.

(1) prepares crucible.It is that 0.18-0.20mm, external diameter are that 19mm, length are the platinum crucible at the bottom of the band of 5-6cm that platinum is processed into thickness.Simultaneously, prepare an internal diameter and be 20mm, wall thickness and be 2mm, length and be 14-15cm, and the silica tube of an end closure, platinum crucible and silica tube are cleaned up and dry.

(2) except that the raw material difference that takes by weighing, all the other processing steps (2) with embodiment 6.(embodiment 11:LaBr ₃49.00 gram, CeF ₃0.52 gram; Embodiment 12:LaBr ₃49.00 gram, CeF ₃0.52 gram; Embodiment 13:LaBr ₃49.00 gram, CeF ₃0.52 gram;

Embodiment 14:LaBr ₃49.00 gram, CeF ₃0.52 gram).

(3) the band material silica tube of vacuum-packed liner platinum crucible is vertically packed in the resistance furnace, be rapidly heated (being advisable) to be no more than 200 ℃/hour be warmed up to (embodiment 11:860 ℃ of temperature that certain determines, embodiment 12:880 ℃, embodiment 13:910 ℃, embodiment 14:940 ℃) back constant temperature 1-2 hour, all melt to guarantee raw material.

(4) cooling makes the melt cooling in the platinum crucible, until room temperature.To expect that piece pulverizes in the exsiccant gloves, promptly obtain the scintillator of white powder form.

Table 1 has been listed light output, energy resolution and the time characteristic data of the crystal prototype of embodiments of the invention 1-5 and Comparative Examples 1-3.As can be found from Table 1:

(1) scintillation properties that mixes the lanthanum bromide crystal prototype (embodiment 1 to embodiment 5) of Cerium II Chloride is better than pure lanthanum bromide crystal (Comparative Examples 1) comprehensively, and advantage is obvious especially.

(2) be that the lanthanum bromide crystal prototype (embodiment 3) of activator material has more outstanding scintillation properties than the lanthanum bromide crystal prototype (Comparative Examples 3) that is the activator material with the Cerium II Chloride with the comprise cerium bromide of identical molar fraction, comprise higher light output, better energy resolving power (referring to Fig. 4) and better time response (referring to Fig. 5).The difference of sample light output facet also can be confirmed from the relative intensity of excitation of X-rays emmission spectrum shown in Figure 2.

(3) be the lanthanum bromide crystal prototype (embodiment 1-5) of activator material with the Cerium II Chloride, what be better than too is activator material and be the scintillation crystal sample (Comparative Examples 2) of matrix with the mixture of lanthanum bromide and Lanthanum trichloride with the Cerium II Chloride.

(4) be that the lanthanum bromide crystal prototype (embodiment 4) of activator material can have very high light output, very high energy resolution (～3%) and very fast attenuation characteristic (for example 2.5 nanoseconds of rise time, 16.4 nanoseconds of fall time) concurrently with the Cerium II Chloride.

The scintillation properties of the embodiment sample of scintillation crystal of the present invention may not represented the top performance of scintillator of the present invention.However, the scintillation properties that the crystal prototype of embodiments of the invention 2 to 4 is showed also is very outstanding.Its scintillation properties is better than the basic metal scintillation crystals comprehensively.Particularly, the crystal prototype of embodiment 4 also has outstanding especially time response (referring to Fig. 7) except the energy resolution (referring to Fig. 6) that has the output of high light and become reconciled, and this is general LaBr ₃: Ce crystal, especially LaCl ₃: the Ce crystal is incomparable.

The scintillation properties data of table 1 part embodiment of the present invention and Comparative Examples scintillation crystal sample

Annotate: ^*Previous data are that (unit is a photoelectron number/MeV) to the photoelectric yield number, and back data are light output data relatively in the light output data hurdle.What adopt in the light output measurement is the XP2020Q photomultiplier.

Can know by inference from the emmission spectrum (referring to Fig. 3) of powdered sample under excitation of X-rays of part embodiment of the present invention, wherein be no lack of the higher scintillator of light output.This can be from the intensity data (can simply compare according to the relative height of luminous main peak) of they and crystal prototype.

The spectral signature of table 2 part embodiment scintillator powder of the present invention sample

With CeCl ₃The luminous main peak of lanthanum bromide crystalline for activator is positioned at about 358nm place.Mix CeCl ₃Lanthanum bromide crystallo-luminescence main peak along with CeCl ₃There is red shift in various degree in the increase of concentration.With CeF ₃Be the luminous main peak of the lanthanum bromide powder of activator, be positioned at and be about 386nm.The latter's luminous peak wavelength is longer than the former, even is longer than with CeBr ₃Lanthanum bromide (LaBr for activator ₃: Ce) crystal.CeCl among the scintillation crystal embodiment 3 for example ₃Molar fraction be 0.9%, luminous main peak is positioned at about 356nm; And CeCl among the embodiment 5 ₃Amount be 10%, its luminous main peak red shift is to about 364nm.Mix CeF ₃The luminous main peak of lanthanum bromide powder, have more tangible red shift.This red shift of wavelength is useful for using.

Cerium activated rare earth halide bromide of the present invention is that a kind of and present optimum scintillator performance is suitable, even more excellent scintillator.The scintillator that it has not only avoided having the highest light output and least energy resolving power is formed and is had the scintillator of fast attenuation characteristic and forms inconsistent problem, and the lower (CeCl of manufacturing cost ₃Compare CeBr ₃Cheaply).

Scintillator of the present invention can be used as the parts of scintillation detector, is used for fields such as industry, medical science, safety check and geological prospecting, for example oil well logging, x-ray tomography instrument (XCT), PET (positron emission tomography) scanner (PET).

Claims

1. cerium activated rare earth halide bromide scintillator is characterized in that:

Described scintillator is to be substrate material with Brominated rare earth compound or mixture, with the cerium halide compound of non-bromine or mixture is the activator material, wherein the total amount of the halogens of Ce elements and non-bromine such as is at a mole number, the halogens of described non-bromine comprises fluorine, chlorine, iodine, and the cerium halide of non-bromine comprises cerium fluoride, Cerium II Chloride, cerous iodide;

The chemical constitution general formula of described scintillator is (1-a) ReBr ₃ACeX ₃, wherein, Re be in lanthanum, gadolinium, lutetium, the yttrium one or both to four kinds mixing, X be in fluorine, chlorine, the iodine one or both to three kinds mixing, a is CeX ₃Molar fraction, 0＜a≤0.4.

2. cerium activated rare earth halide bromide scintillator according to claim 1 is characterized in that: Re is a lanthanum, or a kind of X that mixes to three kinds in lanthanum and gadolinium, lutetium, the yttrium is that in fluorine, chlorine, the iodine one or both are to three kinds mixing.

3. cerium activated rare earth halide bromide scintillator according to claim 2 is characterized in that: Re=La, X=C1,0＜a≤0.1.

4. cerium activated rare earth halide bromide scintillator according to claim 3 is characterized in that: 0＜a≤0.01.

5. cerium activated rare earth halide bromide scintillator according to claim 2 is characterized in that: Re=La, X=F, 0＜a≤0.2.

6. cerium activated rare earth halide bromide scintillator according to claim 2 is characterized in that: Re=La, X=I, 0＜a≤0.3.

7. according to the described scintillator of arbitrary claim in the claim 1 to 6, it is characterized in that: the form of described scintillator is greater than 50 millimeters ³The transparent single crystal body.

8. according to the described scintillator of arbitrary claim in the claim 1 to 6, it is characterized in that: the form of described scintillator is powder or polycrystal.

9. the growth method of the single crystal of cerium activated rare earth halide bromide scintillator as claimed in claim 1, it is characterized in that: this single crystal adopts vacuum-packed quartz crucible, or employing is sealed in the platinum crucible in the silica tube, or be sealed in plumbago crucible or vitreous carbon crucible in the silica tube, in the resistive heating growth furnace, use the decline technology to obtain.

10. the cerium activated halogen bromination crystalline growth method described in claim 9 is characterized in that:

1) bottom of crucible is a taper, and cone angle is between 20～60 degree, and the vacuum tightness in the crucible is 10 ^-3More than the Pa;

2) burner hearth of growth furnace from top to bottom is separated into three different zones, and its vertical temperature ladder is respectively 0～30 ℃/centimetre, 5～30 ℃/centimetre and 0～20 ℃/centimetre;

3) lowering speed of crucible is controlled in 0.1～2.0 millimeter/hour scope;

4) after crucible stopped falling, the cooling rate of growth furnace was controlled in 10～30 ℃ of/hour scopes.