Scintillation materials based on solid solutions ZnSxSe1–x

Composite materials based on ZnSxSe1–x solid solutions are promising materials for gamma and X-ray detectors. However, influence of compositions and particle size on scintillation properties is unclear, which prevents their application. This paper reports on the complex study of microcrystalline ZnSxSe1–x powdered scintillations, prepared by solid phase synthesis from ZnS and ZnSe initial compounds. ZnSxSe1–x solid solutions were obtained in the range of x from 0.07 to 0.86 and in the following sizes: 200—250 μm, 140—200 μm, 140—80 μm, and less than 80 μm. X-ray diffractions of powder ZnSxSe1–x shows formation of a cubic lattice of sphalerite structure. ZnSxSe1–x powders demonstrate a presence of a luminescence band in the 590-615 nm regions, while an increase in sulfur concentration leads to a shift of the maximum intensity of X-ray induced luminescence to the short-wave region, which is associated with an increase of the band gap width. The best parameters of X-ray induced luminescence are obtained for the solid solution with 39 at.% of sulfur. The ZnS0,39Se0,61 solid solutions obtained under these conditions have an X-ray induced luminescence intensity that is 4 times higher than that of ZnSe(Al) single crystal and a relatively low level of afterglow. In ZnSxSe1–x solid solutions, increasing of particle size leads to shifts of the X-ray induced luminescence to the longwave region. The highest intensity of the X-ray induced luminescence corresponds to the ZnS0,39Se0,61 composition with the particle size of less than 80 μm. Also, ZnS0,39Se0,61 solid solutions, with particle size less than 80 microns, are more homogeneous in composition, which is why the process of solid phase reaction in them passes more efficiently. It is shown that the ZnSxSe1–x composite scintillators can be used as gamma and X-ray detectors. It has been established that the effectiveness of these materials depends on their composition. ZnS0,5Se0,5 and ZnS0,39Se0,61 composites demonstrate the best scintillation characteristics, with twice as high an efficiency as that of the «commercial» ZnSe(Al) composite

Effect of sulfur on the scintillation properties of mixed ZnSxSe1–x crystals

ZnSxSe1–x based luminescent materials are promising for use as X-ray and γ-ray detectors. The main advantage of ZnSxSe1–x crystals is the possibility of making of solid solutions over an entire X-range. It was found that varying the composition of ZnSxSe1–x crystals can change their luminescent properties. Many studies were focused on obtaining ZnSxSe1–x mixed crystals, most using a vapour phase growth methods, and only some of works used the directional solidification. The directional solidification techniques allow growing large ZnSxSe1–x crystals for high-energy particles detectors. Practical use, however, requires the knowledge about luminescent properties of ZnSxSe1–x bulk crystals. This study reports the effect of sulfur content on basic properties of ZnSxSe1–xx bulk crystals grown by Bridgman- Stockbarger method. Six different compounds were studied: ZnS0.07Se0.93, ZnS0.15Se0.85, ZnS0.22Se0.78, ZnS0.28Se0.72, ZnS0.32Se0.68, ZnS0.39Se0.61. The ZnSe(Al) and ZnSe(Te) crystals grown at the similar conditions were used as reference. X-ray luminescence was studied using РЕИС-И (REIS-I) X-ray source (Cu, U = 10—45 kV). КСВУ-23 (KSVU-23) spectrophotometer was used to analyse the emission spectra. The afterglow level η (%) was determined by Smiths Heimann AMS-1 spectrophotometer at excitation by such X-ray and γ-ray sources as 123Cs and 241Am (59.5 keV). Light output is one of the main characteristics of the scintillator, which determines its quality as a detector. The ZnSxSe1–x crystals demonstrated increase in the intensity of X-ray induced luminescence spectra with increasing of sulfur content and reached maximum for ZnS0.22Se0.78 composition. Light output of ZnSxSe1–x bulk crystals are higher than those of ZnSe(Te) and ZnSe(Al) commercial crystals. Moreover, thermal stability of scintillation light output of ZnSxSe1–x bulk crystals are also better than those. This investigation has revealed that basic properties of ZnSxSe1–x based scintillation detectors are better than those of ZnSe(Te) and ZnSe(Al)

10_indutnyi

Abstract. Relationship between preparation conditions of the raw charge, crucible material, growth regimes and structure defectness and electrophysical properties of crystals Cd 1-x Zn x Te has been studied. The crystals were grown both from the raw material which had been pre-synthesized in quartz ampoules and from the raw material synthesized from the elements directly in the growth furnace. It is shown that the best values of electric resistivity ρ (up to 10 11 Ohm⋅cm) and sensitivity to X-ray and gammaradiation are obtained for crystals grown in crucibles of highly pure coal-graphite material from the presynthesized raw charge. Correlation has been established between values of ρ and crystal defectness: decrease of dislocation density by 10 4 times led to 10 7 times higher values of resistivity. Concentration of dislocation etching pits regularly decreased with higher purity of the raw material and optimization of crystal preparation technology

Wide-band chalcogenide scintillators on the basis of AIIBVI compounds

The formation characteristics of chalcogenide scintillators (CS) based on zinc sulfide and selenide are considered. The research has shown that such scintillators have high specific light yield, low afterglow level, short luminescence time, low value of the effective atomic number (Zeff=26—33), large band gap (Eg=2,8—3,6 eV), high thermal stability of output parameters. The prospects of use of such scintillators in various devices of modern radiation instrumentation has been shown