For my master’s thesis in Chemical Engineering, I have been working with optical hydrogen sensors. During my studies I have specialized in the properties and characterization of materials and this project challenges me to use my obtained knowledge in a more experimental context. I am pleased to introduce my master’s thesis project:
‘Tantalum-Hafnium: Optical Hydrogen Sensor for High Temperature Applications.’
Tantalum is one of the most promising optical hydrogen sensing materials, due to its large hydrogen partial pressure detection range, excellent sensitivity, fast response time, and great stability [1]. However, tantalum still has a few challenges. One of these challenges is the loss of sensitivity at higher temperatures for low hydrogen concentrations. This makes tantalum less suitable for high temperature applications. The loss of sensitivity can be contributed to a shift in the detection range to higher pressures for increasing temperatures. A similar shift in detection range is found by alloying tantalum with ruthenium or palladium [2, 3]. However, this also means that at higher temperatures the detection range of the alloys experience a shift to even higher pressures.
The aim of this research is to identify an alloy of tantalum that has higher sensitivity for low partial hydrogen pressures at high temperatures compared to tantalum itself. Hafnium is selected as alloying metal based on the properties and its ability to form a solid solution with tantalum. Both structural, including X-ray diffraction, X-ray reflection and atomic force microscopy, and optical measurements are performed to assess the performance of tantalum-hafnium alloys with varying compositions.
Preliminary results show that alloying tantalum with hafnium shift the detection range to lower pressures. At higher temperatures the detection range still shifts to higher pressures, however this is partially compensated making the total shift smaller compared to tantalum. This means that the sensitivity of the tantalum-hafnium alloys is higher compared to tantalum at high temperatures. This shows that tantalum-hafnium alloys have the potential to become optical hydrogen sensors for high temperature applications.
1. Bannenberg, L. J., Boelsma, C., Schreuders, H., Francke, S., Steinke, N. J., van Well, A. A., and Dam, B. (2019) Optical hydrogen sensing beyond palladium: Hafnium and tantalum as effective sensing materials. Sens Actuators B Chem, 283 538–548, doi: 10.1016/j.snb.2018.12.029.
2. Bannenberg, L. J., Schreuders, H., van Beugen, N., Kinane, C., Hall, S., and Dam, B. (2023) Tuning the Properties of Thin-Film TaRu for Hydrogen-Sensing Applications. ACS Appl Mater Interfaces, 15 (6), 8033–8045, doi: 10.1021/acsami.2c20112.
3. Bannenberg, L., Schreuders, H., and Dam, B. (2021) Tantalum-Palladium: Hysteresis-Free Optical Hydrogen Sensor Over 7 Orders of Magnitude in Pressure with Sub-Second Response. Adv Funct Mater, 31 (16), doi: 10.1002/adfm.202010483.
TU Delft Optical Hydrogen Sensing & Thin Film Energy Materials 