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Cerium Trifluoride Powder

#0768


Polycrystalline Powder and Monocrystal Synthesis of Cerium Trifluoride for Detectors

Tech Area / Field

  • MAT-SYN/Materials Synthesis and Processing/Materials

Status
3 Approved without Funding

Registration date
24.10.1996

Leading Institute
VNIIKhT (Chemical Technology), Russia, Moscow

Supporting institutes

  • ITEF (ITEP), Russia, Moscow\nInstitute of General Physics named after A.M. Prokhorov RAS, Russia, Moscow

Collaborators

  • Technische Universität Darmstadt / Institut für Ferstkörperphysik, Germany, Darmstadt\nUniversity of Georgia / Department of Physics and Astronomy, USA, GA, Athens

Project summary

Project objective

The objectives of project are to develop the technology of synthesis of high-purity poly-crystalline powders of anhydrous cerium trifluoride (CeFs) and to develop the growth technology of large optically homogeneous single crystals of cerium trifluoride, which is a new promising material for fast-response and high-efficient detectors of ionizing radiation. This project is a result of the joint effort of three institutes: АН-Russian Research Institute of Chemical Technology (ARRICT), General Physics Institute (GPI), the State Scientific Center" Institute for Theoretical and Experimental Physics" (ITEP) on the basis of their technological and scientific potential.

The importance of the project is due to demand for new improved scintillates and high potential of the CeF3 crystal. CeF3 crystal luminescence has high light yield, which is close to the record value of light yield of well-known BGO crystal, short decay time (less than 30 ns), high thermal stability of luminescence parameters (temperature alterations no more then 0,14% per degree) and high radiation resistance. Up to now the commercial production of the CeF3 single crystals is not developed, they are grown only in laboratory conditions as the samples for research purposes.

As a result of the project performance the following valuable scientific and engineering problems will be solved:


1. The technology of synthesis of polycrystalline high-purity anhydrous СеF3 powders to produce super pure single crystals will be developed;
2. The growth technology of large (up to 20 mm in diameter and more than 150 mm in length) optically uniform single crystals of CeF3 using directional solidification method will be developed.
3. The methods of quality control of the grown CeF3 single crystals will be developed. It will be based on modern physical methods of investigations including electron and X-ray techniques of crystal structure study, absorption, fluorescent and kinetic spectral analysis.
4. The experimental series of large CeF3 single crystals with stable and controlled parameters will be produced. The experimental nuclear particle detectors with high service parameters for positron thomographs, accelerators, electronic-magnetic calorimeters and spectrometers will be developed.

The synthesis technology of anhydrous polycrystalline powders of cerium fluoride will be worked out on the basis of the original method, developed in ARRICT. Unlike traditional method of precipitation from water solution the anhydrous method allows one to obtain a ready-made fluoride during a single operation without implementation of additional impurities. Using the experimental installation the unique batches of the polycrystal CeF3 powders with fluorination level not less than 99.98 %, containing 99.95 % of the basic material and the sum of metal impurities (12 elements) less than 0.003 % have been obtained.

In the frames of the project it is planned to:


- conduct researches aimed at increasing of СеF3 powders purity up to 99.99 % of the basic material and higher and the fluorination level up to 99.995 %;
- conduct researches on synthesis of anhydrous polycrystalline cerium fluoride from different starting raw materials to control the duplication and quality of outcoming material;
- conduct researches on technological parameters of the process to develop the highly-efficient industrial installation for polycrystalline CeF3 powder synthesis.

The synthesis technology of large uniform CeF3 single crystals will be developed on the basis of technological potential and long-term experience of GPI in the field of fluoride single crystal growth. The laboratory prototype of growth installation have been successfully developed, allowing one to obtain the experimental samples of CeF3 single crystals up to 10 mm in diameter and 80 mm length. Cerium fluoride single crystals synthesis will be performed using the method of directional solidification. The growth technology of high quality CeF3 single crystals from polycrystalline powder requires some specific technological processes:


- preliminary melting in fluorinating atmosphere;
- growth in active fluorinating atmosphere;
- group growth, allowing to increase significantly the rate and productivity of the process.

The optimal technological parameters of the mentioned processes will be found and the technological installation allowing to obtain uniform CeF3 single crystals up to 20 mm in diameter and more than 150 mm in length with desired crystallographic orientation will be developed. GPI have all basic equipment required for successful realization of this part of the project including chamber furnaces with power up to 4 kW and automatic temperature adjustment from 30 to 1200 °C for mixture annealing; a vacuum chamber with a furnace for deeper mixture purification and annealing; a furnace with temperature up to 1100 °C for mixture fluoridation; growth furnaces with specific configuration of a crucible and a heater and all necessary accessories for management and control of growth process.

To control the quality of the grown CeF3 single crystals their various physical properties, including optical absorption, fluorescence and excitation spectra, fluorescence decay, scintillation and light yield characteristics, irradiation resistance, optical and structural homogeneity, impurity composition, will be studied. The dependence of these properties on the conditions of crystal synthesis and polycrystalline material fabrication will be established. Modern physical methods of investigation and a number of unique experimental installations, developed in GPI and ITEP will be applied for these purposes.

The annual demand for CeFs single crystals can reach tens of tons. The current price of 1 cm3 of the crystal is about 5 $. The new technology developed by Russian scientists will allow one to decrease it to 2-3 $ in case of industrial production.

The project will be realized in close collaboration with the following foreign partners:


- University of Georgia, Athens, USA, laboratory of Prof. William M. Yen;
- Institute of Nuclear Research in Trieste, Italy, directed by Prof. Guido Barbiellini;
- Institute of Solid State Physics, Technical University of Darmstadt, Germany, laboratory of Prof. Dr. Johann Heber;
- Institute of Nuclear Physics, Technical University of Darmstadt, Germany, Dr. Karl-Manfred Mutterer;
- Institute of Heavy-Ion Acceleration, Darmstadt, Germany, Dr. Jurgen Gerl;
- Uni-Export Instruments Limited, Stokenchurch, UK.

During the project performance we are ready to discuss the results and exchange high pure CeF3 polycrystalline and single crystal samples for comparison tests and scientific applications in Universities and Scientific Centers of the European Community, USA and Japan. In case these organizations are interested we can exchange sample tests procedures and programs and offer engineering specifications of the equipment used for CeFs polycrystalline powder synthesis and single crystals growth.


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