Ionic-Conduction Based Polycrystalline Oxide Gamma Ray Detection - Radiation-Ionic Effects.

Newly discovered opto-ionic effects in metal oxides provide unique opportunities for functional ceramic applications. We generalize the recently demonstrated grain boundary opto-ionic effect observed in solid electrolyte thin films under UV irradiation to a radiation-ionic effect that can be applied to bulk materials and used for gamma ray (γ-rays) detection. Near room temperature, lightly doped Gd-doped CeO 2 , a polycrystalline ion conducting ceramic, exhibits a resistance ratio change ∼ 10 3 $\sim \;{10^3}$ and reversible response in ionic current when exposed to 60 Co γ-ray (1.1 and 1.3 MeV). This is attributed to the steady state passivation of space charge barriers at grain boundaries, that act as virtual electrodes, capturing radiation-induced electrons, in turn lowering space charge barrier heights, and thereby exclusively modulating the ionic carrier flow within the ceramic electrolytes. Such behavior allows significant electrical response under low fields, i.e., < 2 V/cm, paving the way to inexpensive, sensitive, low-power and miniaturizable solid-state devices, uniquely suited for operating in harsh (high temperature, pressure & corrosive) environments. This discovery presents opportunities for portable and/or scalable radiation detectors benefiting geothermal drilling, small modular reactors, nuclear security and waste management. This article is protected by copyright. All rights reserved.