A CsPbBr 3 single crystal exhibits great potentials in X-ray/gamma-ray spectroscopy and imaging. Here, an inverse temperature crystallization (ITC) method with modified precursor composition is proposed to prepare CsPbBr 3 single crystals. The introduction of adduct PbBr 2 •2DMSO, synthesized by the antisolvent vaporassisted crystallization method, in the precursor solution gives rise to superior crystallization with a lower impurity concentration and higher resistivity of 6.37 × 10 9 Ω•cm, as well as a higher hole mobility (50.7 cm 2 •V −1 •s −1 ). Furthermore, a low dark current of 2.3 nA is obtained at a bias of −100 V based on an as-grown crystal with a thickness of 1 mm, according to the asymmetric Au/CsPbBr 3 /Sn structure. The resulting asymmetric planar detectors achieve the high peak-to-valley ratio pulse height spectra with an energy resolution of 7.66%, illuminated by an uncollimated 241 Am@5.5 MeV α particle. Simultaneously, an energy resolution of 13.5% is realized when irradiated by a 59.5 keV 241 Am γ-ray source at room temperature. The thermally stimulated current (TSC) spectra indicate that the density of deep energy-level trap is significantly reduced in the CsPbBr 3 crystals grown by PbBr 2 •2DMSO-modified precursor solution, which is consistent with the high performance in radiation detection.
Molecular dynamic (MD) simulations were used to study threshold displacement energy (TDE) surface and Si displacement cascades in 4H-SiC system. To figure out the role of different Wyckoff sites in determining the TDE values, both Si and C atoms in 2a and 2b Wyckoff sites were separately considered as the primary knocked atoms (PKA). The initial kinetic energy was then distributed along 146 different crystallographic directions at 10 K. TDE surface appeared highly anisotropic for Si and C displacements along different crystallographic directions. The TDE was determined as 41 eV for Si and 16 eV for C. The average values of TDE over two Wyckoff sites were estimated to 66 eV for Si PKA and 24 eV for C PKA. The displacement cascades produced by Si recoils of energies spanning varied from 5 keV to 50 keV at 300 K. To count the number of point defects using Voronoi cell analysis method, the crystal structure of 4H–SiC was transformed from hexagonal to orthorhombic. It was found that the surviving defects at the end of cascades were dominated by C vacancies and interstitials due to low displacement energies of C atoms and greater number of C interstitials when compared to C vacancies.
The uniaxial strain-induced electronic structure variations in intrinsic and Al doped (3C-, 4H-) SiC are studied by using first-principle calculations. The main findings are summarized as follows: (I) the tensile strain leads to a structural transformation in Al doped 3C-SiC, which is signed by the total energy and lattice characteristics; (II) the band gap Eg modulation with large reductions is achieved by applying strains up to 2% in all compounds; (III) The high-symmetry points of valence band maximum and conduction band minimum in intrinsic and Al doped 4H-SiC show the abnormal characteristic under strain, corresponding to the maximum Eg as the strain is ∼-1%. These results suggest that the strain approach could be used to tune the electronic structures of SiC compounds.
Z-pinch dynamic hohlraums (ZPDHs) could potentially be used to drive inertial confinement fusion targets. Double- or multishell capsules using the technique of volume ignition could exploit the advantages of ZPDHs while tolerating their radiation asymmetry, which would be unacceptable for a central ignition target. In this paper, we review research on Z-pinch implosions and ZPDHs for indirect drive targets at the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics. The characteristics of double-shell targets and the associated technical requirements are analyzed through a one-dimensional computer code developed from MULTI-IFE. Some key issues regarding the establishment of suitable sources for dynamic hohlraums are introduced, such as soft X-ray power optimization, novel methods for plasma profile modulation, and the use of thin-shell liner implosions to inhibit the generation of prior-stagnated plasma. Finally, shock propagation and radiation characteristics in a ZPDH are presented and discussed, together with some plans for future work.
All-inorganic perovskite CsPbBr3 serving as an ionizing radiation material exhibits tremendous potential in many fields. However, the applications are limited by the poor energy resolution (ER), which is significantly associated...
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