Influence of Shear Deformation on Carbon Onions Stability under High Pressure

The influence of shear deformation on carbon onions stability under high pressure up to 45 GPa was investigated in a Shear Diamond Anvil Cell (SDAC) by the Raman spectroscopy and the Transmission Electron Microscopy (TEM). At shear less then 40 degrees the carbon onions are stable up to 30 GPa. Biger shear deformation leads to increasing of size and destruction of the onions and to formation of sp3 C-C bonds. At pressure exceeded 45 GPa shear deformation leads to diamond-like carbon (DLC) formation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3501

Features of Formation of Cr³⁺ Paramagnetic Centers in Strontium Titanate (SrTiO<inf>3</inf>) Implanted with Chromium Ions

© 2020, Pleiades Publishing, Ltd. Abstract: We present results of structural (XPS) and magnetic resonance (EPR) studies of single-crystal plates of strontium titanate (SrTiO3) heavily doped with chromium utilizing ion implantation technique. It was shown that the temperature of the oxide matrix during ion implantation (300 or 900 K) significantly affects the valence state of the implanted chromium impurity (Cr0 or Cr3+) and the depth profiles of its distribution in the SrTiO3 matrix. Using the EPR method, it was established that as a result of implantation of chromium impurity at an elevated substrate temperature during irradiation, the dominating color centers in the surface implanted oxide layer appear in the form of trivalent chromium ions in a cubic environment with a g-factor g = 1.976 and the value of the hyperfine coupling constant with the magnetic nucleus of 53Cr isotope, A = 16.2 × 10–4 cm–1. From a comparison of these data with parameters for the cubic Cr3+ impurity center in the SrTiO3 single crystal, it was concluded that this center is localized in the structural positions of titanium. Upon implantation of a chromium impurity in SrTiO3 at room temperature of the substrate, in addition to cubic Cr3+ centers, new signals were detected in the EPR spectra, apparently associated with the formation of oxygen vacancies in the implanted oxide. However, the number of these additional centers does not change significantly even after high-temperature heat treatment of samples in air at temperatures up to 900 K. It is noted that signals of this type also appear in the spectra of SrTiO3 samples obtained as a result of hot implantation and then subjected to high-temperature thermal annealing

Radiation-induced modification of reflection spectra beyond the ion path region in polyimide films

Modification of the surface layers of polyimide films under γ-radiation and implantation with 30–100 keV Ni, Mn, Ag, Co, Fe and B ions in the dose range of 10¹⁵–1.5 × 10¹⁷ cm^–2 are investigated by reflection spectra measurements. Ion implantation is shown to lead to the modification of reflection from the rear (unimplanted) polymer side. Depending on the kind of ion and implantation mode a strong increase in the integrated reflection coefficient in the polymer opacity range is observed, as well as growth of the reflection intensity of optical bands λ1 = 254 and λ2 = 311 nm and their shifts to the short-wavelength region. The change in the reflection coefficient far beyond the implanted region is caused by the radiation-induced transformation of the polymer supermolecular structure near the surface and the relaxation of mechanical stress formed during film production