A rare-earth double perovskite ferroelastic for low-bias X-ray detection

Abstract

Developing lead-free X-ray detection materials that combine high sensitivity, low operating voltage, and environmental friendliness poses a significant challenge in the field of radiation detection. In this study, we rationally designed and synthesized a three-dimensional rare-earth double perovskite, (R-3-FP)₂RbCe(NO₃)₆ (1). 1 undergoes a first-order reversible ferroelastic phase transition around 400 K, primarily driven by the coordination distortion of Rb⁺, the breaking of F−Rb bonds, and the cooperative disordering of guest ions, accompanied by dielectric responses and reversible domain structure evolution. Furthermore, 1 possesses a wide indirect bandgap of approximately 3.13 eV, which effectively suppresses dark current noise. First-principles calculations further reveal that the density of states distribution in the conduction and valence bands of its electronic structure facilitates carrier separation and transport, providing favorable conditions for X-ray photoelectric conversion. Building on this, we systematically evaluated the radiation detection performance of 1. At a low bias voltage of 0.2 V, the device demonstrated a sensitivity of 184.5 μC·Gy_air⁻¹·cm⁻² and a detection limit of 0.716 µGy_air·s⁻¹, along with fast signal response and stability. This work not only reports on a distinct type of lead-free X-ray detection material based on ferroelastic phase transition behavior but also offers material design insights for developing low-power, high-stability X-ray detection devices.