Speciation of Tellurium During Volatilization from Lead-Bismuth Eutectic and Its Chemical Transport Properties.

Tellurium (Te) volatilization from lead-bismuth eutectic (LBE) was investigated by thermosublimatography to resolve the chemical form of Te transported from a Pb-rich liquid metal and its subsequent surface-mediated transformations. For dilute Te in LBE (x Te ≈ 10-3), the dominant transported species was assigned to PbTe-(g), which deposited at high temperature in both fused-silica and 316L stainless-steel columns. This indicates that lead-based coolants intrinsically suppress Te release, as Te bound in PbTe is less volatile than elemental Te. In fused-silica columns, deposited PbTe partially decomposed under more oxidizing carrier-gas conditions, causing secondary release and low-temperature deposition of elemental Te, most consistently explained by Te2(g) formation. In contrast, PbTe remained stable on 316L stainless-steel surfaces even under water-saturated conditions, consistent with local redox buffering by the steel surface. These results demonstrate that Te transport from Pb-rich liquid metal is governed not only by its chemical form, but also by gas-phase conditions and surface-mediated processes. The findings provide insight into chalcogen transport at liquid metal/material interfaces and demonstrate how surface selection and carrier-gas redox conditions can influence Te mobility.