Self-Healing Cs3Bi2Br3I6 Perovskite Wafers for X-Ray Detection

Self-healing of defects imposed by external stimuli such as high energy radiation is a possibility to sustain the operational lifetime of electronic devices such as radiation detectors. Cs₃Bi₂Br₃I₆ polycrystalline wafers are introduced here as novel X-ray detector material, which not only guarantees a high X-ray stopping power due to its composition with elements with high atomic numbers, but also outperforms other Bi-based semiconductors in respect to detector parameters such as detection limit, transient behavior, or dark current. The polycrystalline wafers represent a size scalable technology suitable for future integration in imager devices for medical applications. Most astonishingly, aging of these wafer-based devices results in an overall improvement of the detector performance—dark currents are reduced, photocurrents are increased, and one of the most problematic properties of X-ray detectors, the base line drift is reduced by orders of magnitude. These aging induced improvements indicate self-healing effects which are shown to result from recrystallization. Optimized synthetic conditions also improve the as prepared X-ray detectors; however, the aged device outperforms all others. Thus, self-healing acts in Cs₃Bi₂Br₃I₆ as an optimization tool, which is certainly not restricted to this single compound, it is expected to be beneficial also for many further polycrystalline ionic semiconductors.     

Compact soft x-ray spectrometer for plasma diagnostics at the Heidelberg Electron Beam Ion Trap

A compact flat-field soft x-ray grazing-incidence grating spectrometer equipped with a cryogenically cooled back-illuminated charge-coupled device camera was built and implemented at the Heidelberg Electron Beam Ion Trap. The instrument spans the spectral region from 1 to 37 nm using two different gratings. In slitless operation mode, it directly images a radiation source, in this case ions confined in an electron beam ion trap, with high efficiency and reaching hereby a resolving power of lambda/Deltalambda approximately =130 at 2 nm and of lambda/Deltalambda approximately =600 at 28 nm. Capable of automatized operation, its low noise and excellent stability make it an ideal instrument not only for spectroscopic diagnostics requiring wide spectral coverage but also for precision wavelength measurements.     

Effective technical solutions for the refining of steel from nonmetallic inclusions in continuous caster tundishes

The technical solutions proposed for modifying the internal structure of the tundishes in slab continuous casters and intended to increase the quality of slabs and sheet rolled products are subjected to pilot tests.     

Use of Texture-Dependent Ultrasonic Parameter as Indicator of Degradation of Hot-Rolled Thin-Sheet Steel Under Uniaxial Tension

Journal of Nondestructive Evaluation - Centrifugal pumps (CPs) are mainly composed of impeller and bearings. The operation of the CPs is disturbed if any of its components is faulty. Bearings...     

Modern aspects of surgical treatment of myopia

The Doppler laser flowmetry was used in order to study the microcirculation in the skin, muscles and bone marrow at different stages of obliterating atherosclerosis of the lower extremity arteries. Progress of the disease is characterized by a decrease of the absolute indices of blood flow in combination with disturbed regulation of vascular tension. The lumbar sympathectomy causes intensification of microcirculation not only in the skin, but also in the muscular and bone marrow tissues.     

Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching

Films of nanocrystalline silicon (nc-Si) were prepared from hydrogenated amorphous silicon (a-Si:H) by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics.     

Hydrodynamics and optimization of bottom-tuyere parameters for steel injection in the intermediate ladle

Physical simulation of steel injection in the intermediate ladle of a continuous slab-casting machine permits the determination of the supply channels for the bottom tuyere such that bubble injection of the metal extends over the whole bath depth in the intermediate ladle and the gas bubbles reliably pass through the slag coating layer. Practical results are presented for the proposed tuyere.