CS263772B1 - Method of treatment of surfaces of aluminiumtoytrit perovskit monocrystal and aluminiumtoytrit granate for low-energy beta ratiation - Google Patents

Abstract

A method for treating surfaces of scintillation detectors of low energy beta radiation and electrons, the active part of which consists of a single crystal of an aluminate aluminate garnet or a cerium activated aluminate perovskite which is in the form of a semi-finished product in a mixture of 18-30% by weight. hydrochloric acid (HCl) and 10 to 40 wt. nitric acid (HNO3), the remainder being water (H2O), after washing with water (H2O), is placed in phosphoric acid (H3PO4) at a concentration of 80-99% by weight, with which it is heated to 180-400 ° C for 50 to 150, after washing with water (H 2 O), is heated under a hydrogen (H 2) atmosphere at 1500 to 1750 ° C for 15 to 20 hours. After tempering, the workpiece is processed to the desired shape, and the surface is again treated in the same manner as before hydrogenation with 50 to 70% by weight of nitric acid (HNO3). for 10 to 30 min at 50 to 70 ° C followed by washing with water (H 2 O) and drying at 50 to 70 ° C for 20 to 30 hours. The scintillation material prepared in this way exhibits high luminescence efficiency for low electron energies and beta radiation.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of a single crystal aluminoyltrium perovskite and cerium-activated aluminoyltrium garnet material for scintillation detectors with high detection efficiency of low energy beta radiation and electrons with enhanced luminescence efficiency.

At present, detectors in the form of platelets and powders are used for the detection of low-energy beta and electrons with energy in the range of 0 to 220 keV in liquid and gaseous environments. and yttrium silicates. For a number of applications, such as tritium isotope detection in aqueous solutions where electron range with a maximum energy of 18 keV is very small 0.05 to 0.1 µm, precise scintillator preparation with surface layer optimization is critical for detection and luminescence efficiency.

By etching and subsequent washing the mechanically damaged layer is removed after processing, but the surface is not sufficiently chemically passive, it absorbs the ions from the environment, degrades the transmission of the surface layer and thus degrades the luminescence properties of the scintillator.

Said drawbacks are eliminated preparation scintillation detector of low energy beta radiation, electrons for use in liquid and gaseous environments based on single crystals hlinitoytritého garnet (YjAlgO ^ SCE DT. YAGiCe) or hlinitoytritého perovskite (YA10 _3: Ref. YAFsCe) activated by cerium, the essence of the invention consists in that the single crystal YAG: Ce,

YAPsCe is cut or crushed into pieces after cultivation. The blanks thus formed are formed in a mixture of 18 to 30 wt. % hydrochloric acid (HCl) and 10 to 40 wt. nitric acid (HNO _3), the remainder being water (Hjo), then washed with water (Hjo) and put in phosphoric acid (HjPO ^) of 80 to 99 s by weight. and heated for 50 to 150 s at a temperature of 180 to 400 ° C, and after washing with water (H ₂ O), heat in a hydrogen atmosphere (H ₂ ) at a temperature of 1500 to 1750 ° C for 15 to 20 hours. After tempering, the blanks are further machined in the form of wafers 0 2 to 50 mm x 0.05 to 3 mm or crushed to a powder having a grain size of 1 to 100 µm. The plates or powder thus formed are reprocessed in the same manner as before hydrogenation, supplemented with 50 to 70% by weight nitric acid (HNO ₃ ). for 10 to 30 min at 50 to 70 ° C followed by washing in water (H 2 O) and drying at 50 to 70 ° C for 20 to 30 hours.

In the first stage, the preparation process does not cause the ions of the various elements, in particular the iron, to be diffused during tempering of the etched blanks, which occur on the surface after processing into blanks. These ions cause non-luminescence transitions and thus lower luminescence efficiency. Etching of the finished powder or pad causes the broken layer that contains the polish residues to be removed. This increases the transparency of the surface layer and the resulting layer of yttrium and cerium phosphates forms a transition antireflective layer for the output light.

Such scintillation detector material exhibits 1.5 to 3 times higher luminescence efficiency than scintillation materials prepared by other methods.

He did

Of 0.1 per cent by weight of peroxyite aluminoyltrium (YAPiCe) single crystal. A sheet of less than 3 mm was prepared and the blank thus obtained was purified in a 20 wt. % hydrochloric acid (HCl) and 15 wt. nitric acid (HNO _3), the remainder being water (Hjo) and washed with water (HJO) is inserted into the phosphoric acid (I ^ POJ) at a concentration of 80% by weight. and etched for 100 s at 400 ° C and, after washing with water, tempered in a hydrogen atmosphere (Hj) at 1720 ° C for 17 hours. After tempering, the preform was further crushed to a desired grain size of 50-80 µm and the surface was again treated in the same manner as before tempering, supplemented with 50 wt.% Nitric acid (HNO ₃ ). for 20 min at 70 ° C followed by washing with water (H 2 O) and drying at 70 ° C for 20 hours. The scintillation material thus prepared was used as a tritium isotope detector in aqueous solution. Compared to the YAP: Ce detector which was prepared by another method without double etching, this material showed 2.4 times higher luminescence efficiency.

Example 2

Of a single crystal of aluminoyltrium garnet (YAGiCe) containing 0.08 wt. cerium (Ce) was prepared with a 0 30x1.5 mm plate and the thus formed stock was boiled in a 30 wt. % hydrochloric acid (HCl) and 10 wt. nitric acid (HNO 3, the remainder being water), the plate was washed with water (H 2 O), placed in 95% w / w phosphoric acid (H 2 PO 4) and heated for 50 s at 300 ° C. washed with water (Hjo and washing tempered in an atmosphere of hydrogen (H ₂₎ for 15 hours at 1620 ° C. after tempering, the plate was worked into the shape of a scintillation detector 0 20x1 mm, and the thus formed detector was adjusted in the same manner as before tempering supplemented with 50 wt% nitric acid (HNO 4) for 30 min and dried at 50 ° C for 30 h. The scintillation detector thus generated was used to detect electrons with an energy of 30 keV and was 2.5 times higher luminescence efficiency over a detector that was only etched after tempering.

Claims (1)

Process for treating the surfaces of a single crystal of aluminoytric perovskite and aluminotritic garnet for detecting low energy beta radiation and electrons, characterized in that the semifinished product made of single crystals is cooked in a mixture of 18 to 30% by weight. % hydrochloric acid (HCl) and 10 to 40 wt. nitric acid (HNO ^), the remainder being water (Hjo), then washed with water (H ₂ O) is inserted into phosphoric acid (HjPO ^) at a concentration of 80 to 99% by weight. with which it is heated at a temperature of 180 to 400 ° C for 50 to 150 s after washing with water (H 3 O), tempered in a hydrogen atmosphere (H 3), at a temperature of 1500 to 1 750 ° C for 15 to 20 hours, after which the semi-finished product is machined to the desired shape and its surface is re-treated in the same way as before hydrogenation, supplemented by the action of nitric acid (50 to 70% by weight of HNO3) for 10 to 30 min at 50 to 70 ° C followed by washing in water (H 2 O) and drying at 50 to 70 ° C for 20 to 30 hours.