A recent study published in Advanced Photonics Research examines the potential of nickel-aluminum (Ni-Al) intermetallic compounds as high-temperature plasmonic materials for infrared (IR) thermophotonic applications.
By combining theoretical modeling with experimental validation, the research aims to improve material selection and device design, ultimately enhancing the performance of IR microdevices.
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Evolving Thermophotonics for High-Temperature Applications
Thermophotonics—the conversion of thermal radiation into usable energy—continues to attract interest for its role in boosting energy efficiency across sectors like automotive and aerospace.
However, conventional plasmonic materials, including noble and base metals, tend to fall short in high-temperature environments due to low thermal stability and significant losses in the IR spectrum.
To overcome these limitations, researchers are turning to alternative materials with more favorable thermal and optical properties. Among them, Ni-Al intermetallic compounds show strong promise.
Their excellent thermal stability and tunable optical characteristics make them well-suited for IR applications, particularly in nano- and microscale devices designed for energy harvesting, sensing, and thermal management. These qualities also align with broader sustainable development goals (SDGs), offering potential pathways to more efficient thermophotonic systems.
Exploring Ni-Al Intermetallic Compounds
The study focused on evaluating the optical behavior and device performance of various Ni-Al compounds, with a particular emphasis on NiAl due to its well-documented thermal resilience.
Using Kohn-Sham density functional theory (DFT) and the Vienna Ab initio Simulation Package (VASP), the researchers employed the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) to analyze crystal structures, chemical compositions, and dielectric functions.
To validate their theoretical findings, the team conducted experimental measurements on single-crystal NiAl samples. These included X-ray diffraction (XRD) and spectroscopic ellipsometry, allowing them to compare empirical data with simulation results.
They also drew on resources like the Inorganic Crystal Structure Database (ICSD) and the Materials Project to assess electronic and structural properties. Optical response modeling was carried out using the Drude model, while rigorous coupled-wave analysis (RCWA) supported detailed electromagnetic simulations.
Key Findings and Takeaways
The results reveal that NiAl offers excellent optical performance in the IR range, positioning it as a strong alternative to conventional plasmonic materials like silver (Ag) and gold (Au). NiAl, in particular, achieved a high-quality factor of 692, underscoring its suitability for advanced IR microdevices. Modeling of plasmonic metamaterials based on NiAl demonstrated its effectiveness as both a spectroscopic absorber and emitter.
Further investigation showed that device absorptivity could be fine-tuned through thoughtful structural design, enhancing performance in applications such as thermal emitters and molecular sensors. The strong correlation between theoretical and experimental results confirmed the reliability of the DFT models.
Importantly, NiAl exhibited both localized surface plasmon resonance (LSPR) and surface plasmon polariton (SPP) characteristics comparable to those found in noble metals within the mid-IR spectrum.
The study also examined how geometry impacts device performance, identifying optimal configurations for maintaining high absorptivity and thermal stability. Three NiAl-based designs were proposed: gratings, microtrenches, and metal-insulator-metal (MIM) stripes, each suited to different IR applications.
Notably, the grating structure peaked in absorptivity at 4.25 μm, closely matching the absorption band of carbon dioxide (CO2), making it a strong candidate for nondispersive infrared (NDIR) sensors in environmental monitoring.
Real-World Potential of NiAl-Based Devices
This research opens new doors for high-efficiency thermophotonic devices, particularly in energy and environmental monitoring. NiAl-based microdevices could support high-temperature IR sensing, thermal emission, and energy harvesting. Their high absorptivity at specific wavelengths makes them ideal for gas detection, including CO2 monitoring using NDIR technology.
The high-temperature stability and superior optical properties of NiAl make it a suitable candidate for integration into IR sensors and surface-enhanced infrared absorption (SEIRA) platforms. These capabilities are relevant to applications requiring precise thermal control, such as industrial process monitoring, chemical detection, and certain diagnostic tools.
Future work should focus on bridging theoretical models with fabrication processes. Challenges such as achieving precise patterning of NiAl metastructures must be addressed to develop reliable and scalable thermophotonic devices. Continued exploration of their performance in energy and sensing applications will help define their role in emerging IR technologies.
Journal Reference
Ngo, TD., et al. (2025). Infrared Thermophotonics: Theoretical Benchmarking of Ni-Al Superalloys. Advanced Photonics Research. DOI: 10.1002/adpr.202400093, https://advanced.onlinelibrary.wiley.com/doi/10.1002/adpr.202400093
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