Discover all scientific publications including scientific papers, posters and more.
Discover all scientific publications including scientific papers, posters and more.
Authors: Daniel Freidzon, Ellen Wachtel, Anna Kossoy, Hagai Cohen, Ayelet Vilan, David Ehre, Isaac Abrahams, Igor Lubomirsky
Abstract: Proton conductors are essential for a wide range of applications including solid oxide fuel cells, sensors and resistivity switches. However, commonly used proton-conducting materials such as Nafion, doped barium zirconate, and cesium dihydrogen phosphate suffer from significant limitations – including poor long-term stability and microfabrication compatibility. Recent work has shown that bulk La2Ce2O7 (LCO50) ceramics hydrate in moist environments and exhibit increased conductivity at temperatures below 473 K. In this work, we investigate the hydration behavior of magnetron-sputtered LCO50 thin films. We demonstrate that water can be incorporated into the crystal lattice, leading to an approximately fivefold increase at 363 K in the total conductivity of the as-deposited film. Extrapolating the exponential temperature dependence to room temperature, yields an approximately 103 fold conductivity enhancement, in agreement with values derived from XPS/CREM. To confirm that the total conductivity of the hydrated film is at least partially protonic, and to demonstrate that LCO50 can function as a mixed ion conductor, we demonstrate its use as the electrolyte in a layered tungsten oxide electrochromic device.
Journal: Solid State Ionics, Volume 438, 1 April 2026, 117150
Authors: Daniel Friedzon, Ellen Wachtel, Olga Brontvein, Anna Kossoy, Leonid Chernyak, David Ehre, Igor Lubomirsky
Abstract: We present a three-terminal resistive switching device with a 20 mol% gadolinium-doped ceria (20GDC) thin film as the solid state electrolyte. The device features a top Ta-metal gate electrode and bottom Ta-metal source and drain electrodes, separated by a 1 mm gap filled with 20GDC. Its operation relies on the redox reaction of cerium, specifically the reduction of cerium (IV) to cerium (III) at the interface between the Ta-gate and the 20GDC electrolyte. Under positive gate bias, the Ta gate electrode undergoes oxidation, while cerium is reduced, forming a conductive layer between the source and drain electrodes. Applying a negative gate bias reverses this effect. To confirm that resistivity changes originate from interface redox reactions, we conducted cyclic voltammetry at 403 K. The results demonstrate that peak current is inversely proportional to the scan rate, a characteristic of reaction at a surface. Additionally, we demonstrated that sputtering a TaOx blocking layer beneath the gate electrode suppresses resistive switching. While the resistance changes only by a factor of two, the proposed device operates near equilibrium, is simple to fabricate, and exhibits high robustness. These characteristics make the concept of interface oxidation/reduction appealing for further exploration.
Journal: Solid State Ionics, Volume 430, November 2025, 116999