Department of Functional Materials, University of Bayreuth, 95440 Bayreuth, Germany.
Sensors (Basel). 2023 Apr 12;23(8):3914. doi: 10.3390/s23083914.
This study presents a resistive sensor concept based on Barium Iron Tantalate (BFT) to measure the oxygen stoichiometry in exhaust gases of combustion processes. The BFT sensor film was deposited on the substrate by the Powder Aerosol Deposition (PAD) method. In initial laboratory experiments, the sensitivity to in the gas phase was analyzed. The results agree with the defect chemical model of BFT materials that suggests the formation of holes h• by filling oxygen vacancies VO•• in the lattice at higher oxygen partial pressures . The sensor signal was found to be sufficiently accurate and to have low time constants with changing oxygen stoichiometry. Further investigations on reproducibility and cross-sensitivities to typical exhaust gas species (CO, HO, CO, NO, …) confirmed a robust sensor signal that was hardly affected by other gas components. The sensor concept was also tested in real engine exhausts for the first time. The experimental data showed that the air-fuel ratio can be monitored by measuring the resistance of the sensor element, including partial and full-load operation modes. Furthermore, no signs of inactivation or aging during the test cycles were observed for the sensor film. Overall, a promising first data set was obtained in engine exhausts and therefore the BFT system is a possible cost-effective alternative concept to existing commercial sensors in the future. Moreover, the integration of other sensitive films for multi-gas sensor purposes might be an attractive field for future studies.
本研究提出了一种基于钡铁钛酸盐（BFT）的电阻式传感器概念，用于测量燃烧过程废气中的氧化学计量比。BFT 传感器薄膜通过粉末气溶胶沉积（PAD）方法沉积在基底上。在最初的实验室实验中，分析了对气相中 的灵敏度。结果与 BFT 材料的缺陷化学模型一致，该模型表明在较高的氧分压下，通过在晶格中填充氧空位 VO••形成空穴 h•。发现传感器信号具有足够的准确性和低的时间常数，随着氧化学计量比的变化而变化。对重复性和对典型废气成分（CO、HO、CO、NO 等）的交叉灵敏度的进一步研究证实了传感器信号的稳健性，该信号几乎不受其他气体成分的影响。该传感器概念还首次在实际发动机废气中进行了测试。实验数据表明，通过测量传感器元件的电阻，可以监测空燃比，包括部分和满载运行模式。此外，在测试循环中，传感器薄膜没有出现失活或老化的迹象。总的来说，在发动机废气中获得了有前景的第一批数据集，因此 BFT 系统是未来替代现有商业传感器的一种有前途的经济型替代方案。此外，为了实现多气体传感器的目的而集成其他敏感薄膜可能是未来研究的一个有吸引力的领域。
