Bannenberg Lars J, Veeneman Isa M, Straus Folkert I B, Chen Hsin-Yu, Kinane Christy J, Hall Stephen, Thijs Michel A, Schreuders Herman
Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, JB Delft 2629, The Netherlands.
ISIS Neutron Source, Rutherford Appleton Laboratory, STFC, UKRI, Didcot OX11 0S8X, United Kingdom.
ACS Omega. 2024 Sep 26;9(40):41978-41989. doi: 10.1021/acsomega.4c06955. eCollection 2024 Oct 8.
This paper studies the structural and optical properties of tantalum-iron-, tantalum-cobalt-, and tantalum-nickel-sputtered thin films both ex situ and while being exposed to various hydrogen pressures/concentrations, with a focus on optical hydrogen sensing applications. Optical hydrogen sensors require sensing materials that absorb hydrogen when exposed to a hydrogen-containing environment. In turn, the absorption of hydrogen causes a change in the optical properties that can be used to create a sensor. Here, we take tantalum as a starting material and alloy it with Fe, Co, or Ni with the aim to tune the optical hydrogen sensing properties. The rationale is that alloying with a smaller element would compress the unit cell, reduce the amount of hydrogen absorbed, and shift the pressure composition isotherm to higher pressures. X-ray diffraction shows that no lattice compression is realized for the crystalline Ta body-centered cubic phase when Ta is alloyed with Fe, Co, or Ni, but that phase segregation occurs where the crystalline body-centered cubic phase coexists with another phase, as for example an X-ray amorphous one or fine-grained intermetallic compounds. The fraction of this phase increases with increasing alloyant concentration up until the point that no more body-centered cubic phase is observed for 20% alloyant concentration. Neutron reflectometry indicates only a limited reduction of the hydrogen content with alloying. As such, the ability to tune the sensing performance of these materials by alloying with Fe, Co, and/or Ni is relatively small and less effective than substitution with previously studied Pd or Ru, which do allow for a tuning of the size of the unit cell, and consequently tunable hydrogen sensing properties. Despite this, optical transmission measurements show that a reversible, stable, and hysteresis-free optical response to hydrogen is achieved over a wide range of hydrogen pressures/concentrations for Ta-Fe, Ta-Co, or Ta-Ni alloys which would allow them to be used in optical hydrogen sensors.
本文研究了钽铁、钽钴和钽镍溅射薄膜在非原位以及暴露于各种氢气压力/浓度下的结构和光学性质，重点关注光学氢传感应用。光学氢传感器需要传感材料在暴露于含氢环境时吸收氢气。反过来，氢气的吸收会导致光学性质发生变化，可用于制造传感器。在这里，我们以钽为起始材料，将其与铁、钴或镍合金化，旨在调整光学氢传感特性。其原理是与较小的元素合金化会压缩晶胞，减少吸收的氢气量，并将压力组成等温线移向更高压力。X射线衍射表明，当钽与铁、钴或镍合金化时，体心立方相的钽晶体没有实现晶格压缩，但会发生相分离，即体心立方晶体相与另一相共存，例如X射线非晶相或细晶金属间化合物。该相的比例随着合金元素浓度的增加而增加，直到合金元素浓度达到20%时不再观察到体心立方相。中子反射测量表明，合金化仅使氢含量有有限的降低。因此，通过与铁、钴和/或镍合金化来调整这些材料传感性能的能力相对较小，且不如用先前研究的钯或钌替代有效，钯或钌确实可以调整晶胞尺寸，从而实现可调的氢传感特性。尽管如此，光学透射测量表明，钽铁、钽钴或钽镍合金在很宽的氢气压力/浓度范围内对氢气实现了可逆、稳定且无滞后的光学响应，这使得它们可用于光学氢传感器。
