Prediction of the thermal neutron response of grain-boundary impedance in Gd-doped ceria based on the radiation-ionic effect
Abstract
The radiation-ionic effect was recently reported in 3 mol% Gd-doped CeO2 (3GDC): under 60Co gamma irradiation at 35 Gy/min, the grain-boundary (GB) ionic resistance of a bulk pellet decreased 680-fold at room temperature, because electrons trapped at the GB core lower the space-charge potential. The effect has been demonstrated only with photons. Gd has the largest thermal-neutron capture cross section of any stable element and is also the dopant that creates the GB barrier in GDC, so the same mechanism could link GB impedance to thermal-neutron sensing; whether it does, and under what conditions, has not been examined. Here the thermal-neutron response of 3GDC is modelled with the gamma-calibrated Mott-Schottky/Seager framework, with unmeasured parameters carried as intervals and propagated jointly. Each capture deposits about 50 keV by conversion and Auger electrons within 1 μm, the remaining 8 MeV leaving as prompt photons; Gd segregation to the GBs adds a factor of only 1-2 because the electron range exceeds the grain size. A thermal flux of 8×109 cm−2s−1 (6-12×109) matches the GB-effective generation rate of the 35 Gy/min calibration, and the predicted room-temperature GB resistance ratio is 110 (70-170) at 109 and 970 (600-1500) at 1010 cm−2s−1, falling to 2 at 61 (55-68) and 81 (73-92) ∘C. The neutron case differs from gamma irradiation in three respects: capture events are discrete, so the continuous-source approximation depends on the unmeasured trapped-charge lifetime; self-shielding (mean free path 0.27 mm) makes the response thickness dependent; and capture photons absorbed in the pellet add a gamma term comparable to the local term for pellets of 0.3 mm or more. The intervals are conditional on the model and exclude its structural error. The conditions under which the prediction can be tested are given.
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BibTeX
@misc{zhang2026prediction,
title = {{Prediction of the thermal neutron response of grain-boundary impedance in Gd-doped ceria based on the radiation-ionic effect}},
author = {Zhongming Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10191},
eprint = {2610.10191},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10191},
}
RIS
TY - UNPB
TI - Prediction of the thermal neutron response of grain-boundary impedance in Gd-doped ceria based on the radiation-ionic effect
AU - Zhongming Zhang
PY - 2026
DA - 2026/10/10
PB - arXiv
DO - 10.48550/arxiv.2610.10191
UR - https://arxiv.org/abs/2610.10191
AB - The radiation-ionic effect was recently reported in 3 mol% Gd-doped CeO_2 (3GDC): under ^60Co gamma irradiation at 35 Gy/min, the grain-boundary (GB) ionic resistance of a bulk pellet decreased 680-fold at room temperature, because electrons trapped at the GB core lower the space-charge potential. The effect has been demonstrated only with photons. Gd has the largest thermal-neutron capture cross section of any stable element and is also the dopant that creates the GB barrier in GDC, so the same mechanism could link GB impedance to thermal-neutron sensing; whether it does, and under what conditions, has not been examined. Here the thermal-neutron response of 3GDC is modelled with the gamma-calibrated Mott-Schottky/Seager framework, with unmeasured parameters carried as intervals and propagated jointly. Each capture deposits about 50 keV by conversion and Auger electrons within 1 μm, the remaining 8 MeV leaving as prompt photons; Gd segregation to the GBs adds a factor of only 1-2 because the electron range exceeds the grain size. A thermal flux of 8×10^9 cm^−2s^−1 (6-12×10^9) matches the GB-effective generation rate of the 35 Gy/min calibration, and the predicted room-temperature GB resistance ratio is 110 (70-170) at 10^9 and 970 (600-1500) at 10^10 cm^−2s^−1, falling to 2 at 61 (55-68) and 81 (73-92) ^∘C. The neutron case differs from gamma irradiation in three respects: capture events are discrete, so the continuous-source approximation depends on the unmeasured trapped-charge lifetime; self-shielding (mean free path 0.27 mm) makes the response thickness dependent; and capture photons absorbed in the pellet add a gamma term comparable to the local term for pellets of 0.3 mm or more. The intervals are conditional on the model and exclude its structural error. The conditions under which the prediction can be tested are given.
ER -