Papers by Keyword: Isotope

Abstract: The kinetics of the isotope exchange between gaseous oxygen enriched with the 18O isotope and two LaMnO3+δ oxide samples – a nanopowder and a bulk nanocrystal – has been studied. The 18O isotope concentration has been measured by the acceleration nuclear microanalysis method. The coefficients of the volume and the nanograin boundary self-diffusion of oxygen have been evaluated at 500 °C. They are equal to 3.5·10 −20 and 1.5·10 −13 cm2/s, respectively.

Abstract: A betavoltaic cell in 4H SiC is demonstrated. An abrupt p-n diode structure was used to collect the charge from a 1mCi Ni-63 source. An open circuit voltage of 0.95V and a short circuit current density of 8.8 nA/cm2 were measured in a single p-n junction. An efficiency of 3.7% was obtained. A simple photovoltaic type model was used to explain the results. Good correspondence with the model was obtained. Fill factor and backscattering effects were included. Efficiency was limited by edge recombination and poor fill factor.

Abstract: The spectrometric characteristics of the detectors based on 4H-SiC using 4.8-7.7 MeV a-particles were determined. The Cr Schottky barriers with areas of 1×10-2 cm2 were performed^by vacuum thermal evaporation on 4H-SiC epitaxial layers grown by chemical vapor deposition (CVD) with thickness 26 and 50 µm. The concentrations of the uncompensated donors into CVD epitaxial layers were (6-10) ×1014 cm-3, that allowed to develop a detector depletion region up to 30 µm using reverse bias of 400 V. The energy resolution less than 20 keV (0.34%) for lines of 5.0- 5.5 MeV was achieved that is twice as large of the resolution of high-precision Si-based detectors prepared on specialized technology. The maximum signal amplitude of 4H-SiC - detectors corresponding to the average electron-hole pair generation energy was found to be 7.70 eV.