Accurate Determination of Oxygen in Superconducting Ceramics by Charged Particle Activation Analysis

Abstract

The oxygen content in Ba-Y-Cu superconducting ceramics was determined by the charged particle activation analysis using the 16O(3He, p)18F reaction. Firstly, the accuracy of the method was evaluated by determining the oxygen contents in Al2O3, SrTiO3 and BaTiO3 with SiO2 as the standard sample. The oxygen content in the materials of densities and average atomic numbers approximating those of SiO2 was accurately determined by irradiation with 3He of various energies. Furthermore, with 3He of more than 15.2MeV, the determination of oxygen with 1% error was possible and independent of the density and the average atomic number. Secondly, thick target yields were measured for interfering nuclides produced by other constituent elements in the ceramics. The interference to the measurement of 18F radioactivity was significant with more than 15.2MeV of 3He, and the chemical separation of 18F was necessary for accurate determination of the oxygen content in the ceramics. The charged particle activation analysis with 18F chemical separation was used to determine the oxygen content in Ba-Y-Cu and Ba(Sr)-Y-Cu superconducting oxide ceramics. These ceramics were confirmed to be in a single phase by the X-ray diffraction method. The oxygen concentrations were determined to be 16.3% in Ba-Y-Cu and 16.5% in Ba(Sr)-Y-Cu; the molar ratio between Ba(Sr), Y, Cu and O was calculated to be 1.96:1.00:3.08:6.90 for the former, and 1.96:1.00:3.11:6.99 for the latter.