Deuterium retention in doped graphites

Abstract

The retention behaviour of deuterium (3 keV D3+ yielding 1 keV/D+) in doped graphites (produced by Ceramics Kingston Ceramique, with dopants: B, Si, Ti and W) has been studied for temperatures in the range 300–1000 K, and for fluences of 1021 to ∼ 4 × 1024 D/m2. Retention was measured using thermal desorption spectroscopy (TDS). The undoped reference graphite material showed similar behaviour to EK98, an isotropic fine-grain graphite produced by Ringsdorff, while the doped graphites showed a tendency to increased trapping, especially the Si- and W-doped specimens. For low fluence D+ implantation, TDS spectra for most of the doped graphites are altered as compared to the undoped reference material. In particular, a titanium-doped specimen displayed a clear two-peaked spectrum with ∼ 20% of the implanted D released at temperatures below the onset of desorption in the case of the undoped specimens. Similarly, the amount of D retained as a function of temperature is altered, most noticeably in the case of the Ti-doped material, in agreement with the lower trapping energy implied by the TDS spectra.