4 research outputs found
Investigation and Generation of Vacancies in Alpha Quartz by Soft X-Rays
In this paper we applied the soft-X-ray radiation for generation of point defects, vacancies, and chemical reactions in quartz , taking into account our earlier made similar experiments with crystal silicon and importance of quartz for applications in many fields. In this case only radiative Auger's effects with electrons and electric dipole of atoms transitions can generate metastable vacancies, point defects, and induce chemical reactions. Usually, for point defects generation doses of gamma rays are used. We measured values of the Bragg reflections of X-rays and calculated mean square deviations of atoms in crystal lattice for defining the dynamics of irradiated point defects. We accomplished infrared measurements for establishing of generated chemical reactions, and conductivity measurements were also done
Investigation and Generation of Vacancies in Alpha Quartz by Soft X-Rays
In this paper we applied the soft-X-ray radiation for generation of point defects, vacancies, and chemical reactions in quartz , taking into account our earlier made similar experiments with crystal silicon and importance of quartz for applications in many fields. In this case only radiative Auger's effects with electrons and electric dipole of atoms transitions can generate metastable vacancies, point defects, and induce chemical reactions. Usually, for point defects generation doses of gamma rays are used. We measured values of the Bragg reflections of X-rays and calculated mean square deviations of atoms in crystal lattice for defining the dynamics of irradiated point defects. We accomplished infrared measurements for establishing of generated chemical reactions, and conductivity measurements were also done
Phase transitions, screening and dielectric response of CsPbBr3
Cesium–lead–bromide (CsPbBr3) is the simplest all inorganic halide perovskite. It serves as a reference material for understanding the exceptional solar cell properties of the organic–inorganic hybrid halide perovskites and is itself discussed as an alternative absorber material. Broadband dielectric spectroscopy has proven to yield an in depth understanding of charge screening mechanisms in the halide solar cell absorbers based on methylammonium and modifications hereof. For a deeper understanding of charge carrier screening, we have investigated CsPbBr3 across wide temperature (120 K–450 K) and frequency ranges. Besides the two known phase transitions at 403 K and 361 K, the dielectric data show another
anomaly around 220 K, which can be interpreted as another phase transition. XRD and EPR studies confirm the presence of this anomaly, but Raman scattering spectra do not show any lattice anomalies in the vicinity of 220 K. This additional anomaly is of first order character (different transition temperatures upon cooling and heating) but hardly influences the lattice dynamics. Our broadband dielectric investigations of CsPbBr3 display the same microwave limit permittivity as for MAPbX3 (3r z 30,
X ¼ Cl, Br, I, MA ¼ CH3NH3 +) but do not afford a second permittivity relaxation up to this frequency. Our prior assignment of the second contribution in the methylammonium compounds being due to the relaxation dynamics of the methylammonium ion as a dipole is herewith proven. Nevertheless, CsPbBr3 shows large charge carrier screening up to very high frequencies which can still play a vital role in charge carrier dynamics and exciton behaviour in this material as well.publishe
Reply to the comment on “Phase transitions, screening and dielectric response of CsPbBr3” by Š. Svirskas, S. Balčiūnas, M. Šimėnas, G. Usevičius, M. Kinka, M. Velička, D. Kubicki, M. E. Castillo, A. Karabanov, V. V. Shvartsman, M. R. Soares, V. Šablinskas, A. N. Salak, D. C. Lupascu and J. Banys, J. Mater. Chem. A, 2020, 8, 14015
In this reply, we address the concerns that were raised about our paper on CsPbBr3 single crystals. M.
Szafranski criticized the dielectric and DSC data in our original paper claiming that they were a ´ ffected by
the experimental artefacts or poor quality of the investigated single crystals, as his DSC and dielectric
data did not show any low temperature anomalies in CsPbBr3. We argue in this reply that our main
conclusions were not made based on the DSC and dielectric experiments. Here, we emphasize the
importance of other experiments like EPR and XRD that were performed to understand if there are any
structural transformations of CsPbBr3 at low temperatures. We believe that M. Szafranski did not take ´
into account all the discussion that was presented in our original paper. We hope to clear the doubts in
this reply.publishe