# Deuterium permeation in Er$_2$O$_3$ thin film fabricated on a type 316L stainless steel substrate

## TL;DR

This study demonstrates the fabrication of Er$_2$O$_3$ thin films on stainless steel for hydrogen isotope permeation barriers, showing effective reduction at specific high temperatures but degradation at higher temperatures.

## Contribution

It introduces a new Er$_2$O$_3$ thin film fabrication method for permeation barriers and evaluates its performance at high temperatures.

## Key findings

- Permeation reduction most effective at 650°C.
- Film quality confirmed by microscopy and spectroscopy.
- Degradation occurs above 800°C.

## Abstract

A metal-oxide film can be used as a hydrogen-isotope permeation barrier in the fuel circulation system for nuclear fusion. We fabricated Er$_2$O$_3$ thin film on a type 316L stainless-steel substrate by using a metal-organic chemical vapor deposition technique for the purpose of hydrogen-isotope permeation barrier. Electron microscopy based imaging and energy-dispersive X-ray spectroscopy measurements indicate a sound film quality together with X-ray diffraction experiments. We also measured deuterium permeation in the film at high temperatures ranging from 600 $^{\circ}$C to 800 $^{\circ}$C. The permeation reduction was most apparent at 650 $^{\circ}$C. Above 800 $^{\circ}$C, we confirmed that the film was damaged and did not work as a permeation barrier.