Rubidium-Exchanged NASICON Ceramic Electrolytes for Rapid and Reversible Electrochemical Vapor Control

Developing solid electrolytes with high rubidium (Rb) ion transport activity and reversible exchange capability is a crucial material pathway for electrically controlled alkali-metal atom supply in compact atomic clocks and atomic magnetometers. In this research, Rb was introduced into Na3Zr2Si2PO12 ceramics via molten-salt exchange and mixed-powder sintering to construct a Rb-functionalized NASICON solid electrolyte (Rb-ex NASICON). Its overall electrical transport was examined by electrochemical impedance spectroscopy, while its field-driven Rb migration and reversible electrochemical activity were evaluated in an electrochemical Rb atom source device using Rb-specific atomic absorption spectroscopy. Although Rb-ex NASICON exhibits a lower overall apparent conductivity than pristine NASICON (apparent activation energy: 0.44 eV), it generated a net Rb vapor density increment exceeding 2 × 1010 cm−3 under release bias—nearly two orders of magnitude higher than that of the pristine device (2.3 × 108 cm−3) under identical conditions. After sufficient Rb recovery loading, +5 V actuation yielded rapid net Rb density increments of 9 × 109 cm−3 at 1 s and 3.8 × 1010 cm−3 at 4 s, alongside stable release–recovery cycling via polarity switching. The results demonstrate that the Rb incorporated into NASICON is electrochemically active and capable of rapid, reversible transport, establishing Rb-ex NASICON as an effective solid electrolyte for electrochemical Rb atom source devices.