Dense BaCe0.6Zr0.3Y0.1O3-Α Solid-State Electrolyte for Application in Hydrogen Sensors

Abella, Jordi

Fusion energy is a promising solution for the expected energy problems in the mid-term future. This technology is expected to use deuterium and tritium, two hydrogen isotopes, as fuel. Deuterium can be obtained from natural sources, but tritium, which is a non-stable hydrogen isotope, must be in situ generated. To assure the correct monitoring of both isotopes, it will be required the design and qualification of high-temperature sensors. The construction of H₂ sensors based on solid-state electrolytes can be the first step towards the development of new analytical tools able to monitor hydrogen isotopes in that aggressive environment.

In previous work [1], amperometric sensors based on BaCe_0.6Zr_0.3Y_0.1O_3-α (BCZY) solid-state electrolyte have shown good analytical parameters for hydrogen monitoring. However, these materials need high temperatures during sintering to obtain full density due to their refractory nature. This lack of densification can affect their electrochemical response due to their low ionic conductivity. The use of sintering aids, like ZnO, can improve the densification of these ceramics at lower temperatures.

In the present work, hydrogen sensors based on BCZY were constructed and evaluated in potentiometric mode. Different sintering conditions for this electrolyte were tested and their potentiometric response was compared. The following disk-shaped electrolytes were prepared for that purpose: 1400 ºC – 30 h, 1650 ºC – 6h. Simultaneously, BCZY was sintered at 1400 ºC -12 h with 5 mol% of ZnO as a sintering aid. Samples were characterized using XRD (to determine the crystallographic phases) and SEM (for microstructural defects and sintering). Then, disks were platinized and sealed with a glass binder to alumina tubes for sensor construction. Measurements were performed at 400 and 500 ºC. The hydrogen concentration in the RE was 1000 ppm H₂ in Ar. The response obtained with the three sensors was compared with the theoretical Nernst potential.

[1] A. Hinojo, I. Soriano, J. Abellà, S. Colominas, Evaluation of High-Temperature Hydrogen Sensors Based on BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α Perovskites for Industrial Applications, Sensors. 20 (2020) 7258. https://doi.org/10.3390/s20247258.