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Superheavy scintillators based on REAO4 compounds (RE= rare earth element, A= V, Ta and Nb)
|Olesia Voloshyna 1, Vyacheslav N. Baumer 2, Svetlana Neicheva 1, Nikolay Starzhinskiy 1, Igor Zenya 1, Sergey Gridin 1, Oleg Sidletskiy 1|
1. Institute for scintillation materials of NAS of Ukraine (ISMA), Lenin avenue, 60, Kharkov 61158, Ukraine
Materials based on compounds with common formulae REAO4 (RЕ – rare earth element, A – element of the 5th group of Periodic table) are widely applied in optics, X-ray visualization and proposed for usage as scintillators for registration of X- and γ-rays [1, 2]. Rare earth orthotantalates due to high density from 7,8 g/cm3 for LaTaO4 up to 9,75 g/cm3 for LuTaO4 can be considered as promising scintillators for high-energy physics. During recent 5 years materials based on yttrium tantalate-niobates with common formulae Y(Ta1-xNbx)O4 attracted great interest [3, 4] from both scientific and technical points of view.
In the present work, methods of obtaining, luminescent and scintillation properties of compounds with common formulae REAO4 (A=V, Ta and Nb) were explored. Optimal regimes of raw material solid-state synthesis were determined; content of the main phase after solid-state synthesis was up to 99%. Ceramic samples of both undoped orthotantalates (RETaO4) and tantalate-niobates (RE(Ta1-xNbx)O4) and doped with familiar dopant (Eu, Pr и Ce) for scintillation materials were obtained. Single crystals of undoped orthovanadates (REVO4) were grown by Czochralski technique. Optimal regimes of after-growth annealing for elimination of oxygen vacancies forming during the crystal growth in inert atmosphere, were determined.
YVO4 and GdVO4 single crystals demonstrate light yield up to 11500 ph/MeV, energy resolution about 16 % at 662 KeV, and microsecond decay after X- and γ -radiation. Light yield increases by 3 – 5 times at lowering the temperatures down to 77 K.
Among orthotantalates, the biggest light yield is observed with YTaO4 and GdTaO4 (110 % and 43 % compared to BGO). Significant light yield is observed for Eu- and Pr- doped samples as well (for example, for GdTaO4:Eu light yield is 136 % compared to BGO). Orthotantalates demonstrate faster luminescence with decay times around 300 - 1000 ns.
With modifying of cation composition in yttrium and gadolinium tantalate-niobate samples luminescent and scintillation characteristics of material significantly change. Light yield in some mixed compositions rises by up to 2 times compared to their constitutents. Brightest luminescence was observed for Eu-doped samples.
1. Patent WO 2008/094184 A3, publ. 07.08.2008.
2. O.V. Voloshina, V.N. Baumer, et al.,NIM A, 664 (2012) 299 – 303.
3. E.-J.Popovici, M. Nazarov, et al., Physics Procedia 2 (2009) 185–190.
4. I.D. Arellano, M.V.Nazarov, et al., J. of Lumin., 132 (2012) 2479–2483.
Presentation: Poster at 15th Summer School on Crystal Growth - ISSCG-15, by Olesia Voloshyna
See On-line Journal of 15th Summer School on Crystal Growth - ISSCG-15
Submitted: 2013-05-28 10:45 Revised: 2013-05-28 10:45