CN100412157C - A tungstate scintillation material doped with rare earth ions excited by X-rays and its preparation method - Google Patents

Abstract

The invention relates to a scintillation luminescent material with large light output and slow attenuation under the excitation of X-rays or other high-energy rays and a preparation method thereof, belonging to the field of scintillation luminescent materials. The scintillation luminescent material is trivalent rare earth ion (Eu)³⁺) The activated rare earth tungstate has a chemical composition formula: RE_2(1-x)Eu_2xWO₆Wherein RE is at least one rare earth ion of Y, La, Gd and Lu, and x is an activator Eu³⁺The content of (b) is more than 0.05 and less than 0.3. Is prepared by a solid-phase synthesis method. Under the excitation of X-ray, the luminous intensity is about that of the inorganic scintillator Lu₂O₃:Eu³⁺1.14 times of that of red light emitting about 610nm, andthe spectral sensitivity of the CCD detector is well matched, and the CCD detector can be used in the medical fields of Positron Emission Tomography (PET), X-ray Computed Tomography (CT), X-ray fluorescence intensifying screens and the like and other static imaging technical fields of high-energy ray detection.

Description

A tungstate scintillation material doped with rare earth ions excited by X-rays and its preparation method

technical field

The present invention relates to a tungstate scintillation material doped with rare earth ions excited by X-rays and a preparation method thereof, more particularly to a rare earth tungstate scintillation material doped with rare earth europium ions (Eu ³⁺ ) and its preparation method. The scintillation luminescent material has strong red luminescence under the action of X-rays, and can be used in technical fields such as X-ray medical imaging, high-energy ray safety detection and the like.

Background technique

Scintillation materials belong to a class of materials that can emit part of the absorbed energy in the form of ultraviolet light or visible light after being irradiated by X-rays, γ-rays and other high-energy rays. The greater the number of photons emitted by the scintillation material after being irradiated with a specific energy, the more it helps to improve the accuracy of the detection signal, and the greater the density can increase the energy absorption of high-energy particles and effectively convert them into visible photons. The luminescence decay time of the scintillation material should be as short as possible in order to distinguish radiation excitation events with very short time intervals and improve the accuracy of high-energy ray detection. The most important thing is that the luminescence peak position of the scintillation material must be able to match with the existing photodetector, so that the luminescence signal of the scintillation material can be converted into an electrical signal through the photoelectric effect for conventional display imaging, signal analysis and other applications, and its imaging With high contrast and high resolution (Xu Xurong, Su Mianzeng. Luminescent Optics and Luminescent Materials, Beijing: Chemical Industry Press, 2004; S.E.Derenzo, M.J.Weber, et al, Nucl.Instru.and Meth.A 505(2003) 111).

Due to the development and requirements of high technology such as nuclear physics, space physics, positron emission tomography (PET) and X-ray computer tomography (CT), inorganic scintillation materials have achieved remarkable development since the late 1980s, and there have been Single crystal Bi ₄ Ge ₃ O ₁₂ , PbWO ₄ and a series of Ce ³⁺ activated luminescent scintillation materials such as Lu ₂ SiO ₅ :Ce ³⁺ and Gd ₂ SiO ₅ :Ce ³⁺ etc. In recent years, scintillation materials have also emerged in security inspections (container rapid inspection systems) and industrial inspections (such as oil well nuclear detection, non-destructive testing of important components such as rockets, missiles, and aircraft, etc.), which will generate tens of billions of dollars in output value. High-tech industry. The currently used scintillation materials are mainly NaI:Tl, PbWO ₄ , Bi ₄ Ge ₃ O ₁₂ , etc. However, they all have some disadvantages, such as NaI:Tl is easy to deliquescence, long afterglow, PbWO ₄ has low luminous efficiency, Bi ₄ Ge ₃ O ₁₂ afterglow is long.

In ceramic scintillators, Lu ₂ O ₃ :Eu ³⁺ has high luminous intensity (23010ph/MeV) and high density (9.4g/cm ³ ), and the main peak of the emission spectrum is around 610nm, matching the spectral sensitivity of CCD detectors It is good, so it has high contrast and high resolution for imaging, and some basic performances have surpassed the existing scintillation crystals, but its decay is slow (1.3ms), so it is not suitable for dynamic fast imaging and can only be used It is used for static imaging, and it uses rare earth oxide (Lu ₂ O ₃ ) as the matrix doped with rare earth ions (Eu ³⁺ ), which makes its raw material cost high, which greatly limits its wide application (FADiBianca ; JP J.Georges; DACusano; CD Greskovich, Rare earthceramic scintillator, US patent 4525628, 1985; Lempicki A., Brecher C., Szuprycznski, P., et al.Nucl.Instr.Meth.in Phy.Res.A, 488 (2002) 579-590). Therefore, it has become an urgent task to develop a new type of scintillating luminescent material with reasonable price and excellent luminescent properties.

Contents of the invention

The object of the present invention is to provide a scintillation material suitable for emitting red light under the excitation of high-energy rays and a preparation method thereof, which has luminescence, superior performance, and a price significantly lower than that of rare earth lutetium oxide-based materials.

The present invention uses rare earth tungstate RE ₂ WO ₆ as the substrate, and uses Eu ³⁺ to partially replace the substrate rare earth ion as the activator. Its chemical composition formula is: RE _2(1-x) Eu _2x WO ₆ , wherein RE is at least One kind of rare earth ion among Y, La, Gd and Lu, x is the content of activator Eu ³⁺ , and the content is 0.05<x<0.3.

The present invention adopts the traditional solid-phase synthesis method, and the raw materials are: Eu ₂ O ₃ , WO ₃ and at least one rare earth oxide in Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ and Lu ₂ O ₃ (both Commercially available analytical pure or chemically pure), according to the above chemical composition formula ingredients, then use ethanol as medium, fully grind and mix in agate mortar or high-density Al ₂ O ₃ mortar, then put the mixture after drying Put it into an alumina crucible, cover the crucible lid, and then synthesize in a high-temperature furnace. The synthesis temperature is 1100 ° C, and the temperature is kept for 24 hours; the heating rate is 5-10 ° C / min, and the high-temperature furnace is a horse heated by Fe-Cr-Al wire. Furnace or other such as silicon carbide rod furnace.

The red scintillation material prepared by the present invention has the following advantages:

(1) The luminous intensity of the prepared scintillation material is high, which is 1.14 times that of Lu ₂ O ₃ :Eu ³⁺ ; (2) The luminous peak is located at about 610nm, which matches well with the spectral sensitivity of the CCD detector, so Imaging with it has high contrast and high resolution; the luminescence of the scintillation material is mainly due to the fact that the WO ₆ group can effectively transfer energy to Eu ³⁺ ions when excited, resulting in Eu ³⁺ luminescence; (3) has Satisfactory activator concentration range, the best concentration is about 15%, that is, x=0.15; (4) has a relatively high density (9.7g/cm ³ ), which can better absorb incident high-energy particles; (5) Rare earth tungstate is used as the substrate, which greatly reduces the cost of raw materials compared with expensive lutetium oxide; (6) the equipment is simple, the operation is safe and convenient, the raw materials are easy to obtain, the cost is low, and it is convenient to produce in large quantities; (7) the present invention The provided Eu ³⁺ doped tungstate scintillation materials can be used in medical fields such as positron emission tomography (PET), X-ray computed tomography (CT) and X-ray fluorescence intensifying screens and other high-energy ray detection field of static imaging technology.

The following table shows the performance comparison between the present invention and the commercial scintillation material Lu ₂ O ₃ :Eu ³⁺ .

Description of drawings

Figure 1 shows the X-ray excitation emission spectra of the commercial scintillation material Lu ₂ O ₃ :Eu ³⁺ luminescent powder sample and Lu ₂ WO ₆ powder sample doped with 15% Eu ³⁺ under the same conditions. It can be seen from the figure that the luminescent region of Lu ₂ WO ₆ doped with 15% Eu ³⁺ is the red light region around 610nm, which matches well with the spectral sensitivity of the CCD detector. The light output of the obtained powder sample is about 114% of that of Lu ₂ O ₃ :Eu ³⁺ under X-ray excitation.

Figure 2 shows the X-ray excitation emission spectra of the commercial scintillation material Lu ₂ O ₃ :Eu ³⁺ luminescent powder sample and Y ₂ WO ₆ powder sample doped with 10% Eu ³⁺ under the same conditions.

Figure 3 shows the X-ray excitation luminescence intensity curve of Lu ₂ WO ₆ :Eu ³⁺ as a function of Eu ³⁺ doping concentration. It can be seen that the concentration quenching effect occurs when the concentration exceeds 15%, and the optimal doping concentration should be 15% %nearby.

Fig. 4 shows the pulsed X-ray excitation luminescence decay curve of Lu ₂ WO ₆ :Eu ³⁺ (15%). The decay curve was fitted according to the double exponential decay model to obtain the luminescence decay time of the sample τ ₁ =1.0ms, τ ₂ =5.5ms, and the percentage of each luminescent component in the total luminescence τ ₁ (30%), τ ₂ (70% ) (the solid line is the fitted curve). As a comparison, the luminescence decay time of the commercial scintillation material Lu ₂ O ₃ :Eu ³⁺ is about 1.3ms.

Detailed ways

Example 1

Weigh Lu ₂ O ₃ (99.99%) 0.716 grams, WO ₃ (analytical pure) 0.464 grams, Eu ₂ O ₃ (99.99%) 0.070 grams, add absolute ethanol (analytical pure) as a medium, fully Grinding and mixing, put the obtained mixture into a 30mm×Φ30mm alumina crucible, cover the crucible, put it into a Fe-Cr-Al wire heating muffle furnace, and heat up from room temperature at a rate of 5°C per minute. Raise the temperature to 1100°C, keep it warm for 24 hours, take it out after natural cooling, and get a white product after grinding, which is the red luminescent scintillation material of Lu _1.80 Eu _0.20 WO ₆ .

Example 2

Weigh 0.637 grams of Lu ₂ O ₃ (99.99%), 0.464 grams of WO ₃ (analytical pure), 0.141 grams of Eu ₂ O ₃ (99.99%), and use ethanol as a medium to grind in an Al ₂ O ₃ mortar, Make it mix evenly, then place it in an _Al2O3 crucible, cover it, put it _into a silicon carbide rod furnace and increase the temperature to 1100°C at a rate of 8°C/min for synthesis, and the rest are the same as in Example 1. The white product obtained is the red luminescent scintillation material of Lu _1.60 Eu _0.40 WO ₆ .

Example 3

Weigh 0.644 g of Y ₂ O ₃ (99.99%), 0.696 g of WO ₃ (analytical pure), 0.053 g of Eu ₂ O ₃ (99.99%), and the rest are the same as in Example 1. The white product obtained is Y _1.90 Eu _0.10 WO ₆ red luminescent scintillation material.

Claims (9)

1. A tungstate scintillation material doped with rare earth ions excited by X-rays, characterized in that the doped rare earth ion is Eu ³⁺ , and the chemical composition of the scintillation material is: RE _{2(1-x )} Eu _2x WO ₆ , wherein RE is at least one rare earth ion among Y, La, Gd, and Lu, x is the doping content of activator Eu ³⁺ , and the doping concentration is 0.05<x<0.3. 2. The tungstate scintillation luminescent material doped with rare earth ions excited by X-rays according to claim 1, wherein said luminescent material excites red light with a wavelength of 610nm under X-ray excitation conditions. 3. The tungstate scintillation material doped with rare earth ions excited by X-rays according to claim 1, characterized in that the doping amount of Eu ³⁺ x=0.15. 4. The method for preparing the tungstate scintillation material doped with rare earth ions excited by X-rays as claimed in claim 1 is characterized in that it adopts a high-temperature solid-phase synthesis method, and the concrete process steps are: (a) Using Eu ₂ O ₃ , WO ₃ and at least one rare earth oxide among Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ and Lu ₂ O ₃ as raw materials, according to RE _2(1-x) Eu _2x WO ₆ , 0.05<x<0.3 ingredients, using absolute ethanol as the medium, grinding and mixing, then put it in a crucible and cover it, and synthesize it in a high-temperature furnace by high-temperature solid-phase method at a synthesis temperature of 1100°C and keep it warm for 24 hours; (b) Naturally cooled with the furnace and obtained by crushing. 5. The preparation method of the tungstate scintillation material doped with rare earth ions excited by X-rays as claimed in claim 4, characterized in that the adopted Lu ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , WO ₃ , and Eu ₂ O ₃ raw materials are commercially available chemically pure or analytically pure. 6. The preparation method of the rare earth ion-doped tungstate scintillation material excited by X-rays as claimed in claim 4, wherein the grinding and mixing are carried out in an agate mortar or an Al ₂ O ₃ mortar. 7. The preparation method of the tungstate scintillation material doped with rare earth ions excited by X-rays as claimed in claim 4 is characterized in that the mixture of grinding and mixing is placed on Al ₂ O ₃ in a crucible, and then Fe-Cr- It is synthesized by solid-state method in a muffle furnace heated by Al wire or a silicon carbide rod furnace. 8. According to the preparation method of the rare earth ion-doped tungstate scintillation material excited by X-rays as claimed in claim 4 or 7, it is characterized in that the heating rate is 5-10°C/min during solid phase synthesis. 9. The application of the tungstate scintillation material doped with rare earth ions excited by any one of rights 1-3 is characterized in that it is used for positron emission tomography, X-ray computed tomography and X-ray fluorescence intensifying screen.

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