Resonance scattering and RBS from non-stoichiometric oxides

Abstract

Rutherford back scattering (RBS) and elastic nuclear resonance (non-RBS resonance scattering of 3.05 MeV α-particles from oxygen atoms of a sample, for example) have been used for non-destructive characterization of differently fired samples of cadmium oxide (a II–VI semiconductor), Bi 2Sr 2CaCu 2O (8+ x) and (Bi 0.92Pb 0.17) 2Sr 2CaCu 2O (8+ x) high temperature superconductors, and practically useful films of a composite of diamond nanoparticles and Si–O made by CV deposition on Si substrate. In the RBS spectrum, steps for light elements like O and Ca are practically not visible, while steps for heavy elements like Bi and Cd are clear and large. In contrast, there is a clear resonance peak due to oxygen allowing easy detection of oxygen in a sample. Most important of our present RBS findings is reduction of O-content from cadmium oxide on firing (here for 36 h) at higher and higher temperatures up to 800 °C. Large variations of room temperature (300 K) electrical resistivity of CdO after heat treatments at different temperatures for 36 h have been explained on basis of variation in O-content. Its room temperature resistivity of 26.4 mΩ cm for firing at 275 °C reduces to only 2.15 mΩ cm for firing at 800 °C.