In-situ TEM analysis of the degradation processes in Ru-Al electrodes for high-temperature SAW devices on CTGS substrates under impact of temperature and varying mechanical stress using passivated TEM lamellas

使用钝化 TEM 薄片对 CTGS 基底上高温 SAW 器件的 Ru-Al 电极在温度和变化的机械应力影响下的降解过程进行原位 TEM 分析

• 批准号: 470028346
• 负责人: Dr. Marietta Seifert
• 金额: --
• 依托单位: Institut für Materialchemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/470028346?language=en
• 关键词: situ; TEM; analysis; degradation; processes

There is a high demand for wireless high-temperature sensors to monitor processes and equipment parts (e.g. turbine blades) at high temperatures up to 900°C, especially in aggressive atmospheres and at locations which are difficult to access. Such miniature sensor devices require substrates and metallizations which can be highly loaded, since the high temperatures strongly promote processes like oxidation and creep. A very promising system is the RuAl metallization in combination with the high-temperature stable piezoelectric Ca3TaGa3Si2O14 substrate. The sensors made of these materials work on the principle of surface acoustic waves (SAW), so that the metallization is not only exposed to the high temperature, but in addition also to a high-frequency mechanical load caused by the SAW. To understand the resulting mechanisms of degradation which lead to a failure of the devices and to improve the electrode systems accordingly, local investigations are required to reveal the starting points of the degradations. In this project, the required in-situ characterizations on the nano-scale during thermal and high-frequency mechanical load are carried out for the first time.The microstructure is investigated with high lateral resolution in a scanning transmission electron microscope (STEM). The in-situ annealing and application of a high-frequency mechanical load will be performed in combination with a special sample holder and an appropriate sample geometry. A special feature is the realization of the high-frequency load of the metal electrode via the piezoelectric effect of the SAW substrate. Furthermore, the actual heat-induced diffusion conditions within the electrodes of a SAW based sensor will be reconstructed in the thin TEM lamellas to realize a good comparability with the real operating conditions. Therefore, in addition, a new procedure is developed to realize a passivation of the free surfaces of the electron transparent samples to suppress a diffusion along the surfaces of the TEM lamellas during the in-situ annealing. To estimate the transferability of the results achieved with the in-situ experiments to the real bulk devices additional FEM simulations are carried out.With these combined in-situ techniques, a procedure which has not yet been applied for the investigations of the changes of the microstructure which take place within the electrodes is developed and applied to access the local causes of these processes which impede the application of the devices. The knowledge gained about these mechanisms is relevant for future industrial applications of the RuAl-based electrodes. The increased basic understanding as well as the models of the degradation processes which are developed are an important basis for the improvement of the high-temperature stability of the SAW devices.

对无线高温传感器的需求很高，以在高达900°C的高温下监视工艺和设备零件（例如涡轮叶片），尤其是在侵略性的气氛和难以进入的位置。这种微型传感器设备需要底物和金属化，这可以高度载荷，因为高温强烈促进氧化和蠕变等过程。一个非常有前途的系统是Rual Meltallization与高温稳定的压电CA3TAGA3SI2O14底物结合使用。这些材料制成的传感器以表面声波原理（SAW）的原理起作用，因此金属化不仅暴露于高温下，而且还暴露于由SAW引起的高频机械载荷。要了解导致设备失败并相应地改进电极系统的降解机制，该项目的本地调查，在热和高频机械载荷期间纳米级上所需的原位特征是首次进行微观结构。高频机械载荷的原位退火和应用将与特殊的样品持有人和适当的样品几何形状结合进行。一个特殊的特征是通过锯底物的压电效应实现金属电子的高频负载。此外，将在薄的TEM层中重建基于电子的传感器内的实际热诱导的扩散条件，以实现与实际操作条件的良好可比性。因此，此外，开发了一种新的程序，以实现对电子透明样品的自由表面的钝化，以抑制沿TEM层中沿TEM层的扩散的渗透。为了估计通过原位实验到实际散装设备实现的结果的可传递性，进行了其他FEM模拟。通过这些合并的原位技术，开发并应用了一种尚未应用于电子在电子中发生的微观结构变化的过程，并应用于访问阻碍设备应用的这些过程的局部原因。关于这些机制获得的知识与基于Rual的电极的未来工业应用有关。开发的基本理解以及降解过程的模型是改善锯设备高温稳定性的重要基础。