Chemical expansion of praseodymium-cerium mixed oxide films at high temperatures

镨-铈混合氧化物薄膜的高温化学膨胀

• 批准号: 404875250
• 负责人: Professor Dr.-Ing. Holger Fritze
• 金额: --
• 依托单位: Institut für Elektrische Informationstechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/404875250?language=en
• 关键词: Chemical; expansion; praseodymium; cerium; mixed

The primary objective of the research project is to investigate the chemical expansion of thin films at high temperatures. The material to be studied is praseodymium-cerium mixed oxide (PCO) in the temperature range from 400 °C to 700 °C. The choice is motivated by considerably higher mechanical expansion upon insertion or removal of oxygen in comparison to e.g. high-temperature piezoelectric crystals. Compared to bulk material, PCO films offer the advantage of low time constants as short transport distances for oxygen occur. In addition to the chemical expansion, the defect structure in the layers and the time-determining atomic transport mechanisms have to be determined. The development, realization and test of a special interferometer or more precisely vibrometer, which is able to measure changes of the layer thickness in the sub-nanometer range even at frequencies of a few millihertz, represents an essential technical task. Through the development of a differential vibrometer and the use of signal diversity, the noise of the signal should be drastically reduced. The results and the new measuring method can be applied to other materials than the PCO model system, so that further insights into chemical expansion and small displacements in other mechanical systems can be obtained.The topic is highly relevant. However, hardly any data on the chemical expansion of thin films is available. They have been determined largely indirectly and show some contradictions. In contrast to structural materials and electronic functional materials, high-temperature actuator materials require extensive research. Such high temperature "artificial muscles" are e.g. demanded for energy conversion and space exploration.The applicants have complementary competences in the field of high-temperature materials and the development of vibrometers, which are well suited for solving the scientific challenge and which are unique in this combination. Furthermore, the work will be carried out in close cooperation with an author of the apparently only available publication on mechanical determination of PCO film expansion, so that the planned sample exchange provides comparable results.The preliminary work has shown that vibrometers are generally able to detect changes in the thickness of PCO films which are caused by electrochemical pumping of oxygen. A significant restriction, however, is the signal noise of standard vibrometers at low frequencies. Oxygen-equilibrium in the PCO films requires excitation frequencies of a few millihertz, where no meaningful measurements are possible so far. On the instrumentation side, for example, it has been shown that signal diversity significantly reduces noise.

该研究项目的主要目标是研究薄膜在高温下的化学膨胀，所研究的材料是镨铈混合氧化物（PCO）在400°C至700°C的温度范围内。与高温压电晶体相比，PCO 薄膜在插入或去除氧时具有相当高的机械膨胀，因此具有时间常数低、氧传输距离短的优点。除了化学膨胀之外，还必须确定层中的缺陷结构和决定时间的原子输运机制。 开发、实现和测试能够测量原子变化的特殊干涉仪或更精确的振动计。即使在几毫赫兹的频率下，层厚度也能达到亚纳米范围，这也是一项重要的技术任务。通过开发差分振动计和使用信号多样性，可以显着降低信号的噪声。新的测量方法可以应用于除 PCO 模型系统之外的其他材料，从而可以进一步了解其他机械系统中的化学膨胀和小位移。该主题具有很强的相关性。但是，几乎没有任何有关薄膜化学膨胀的数据。与结构材料和电子功能材料相比，它们主要是间接确定的，并且需要对这种高温“人造肌肉”进行广泛的研究。具有互补的能力高温材料领域和振动计的开发非常适合解决科学挑战，并且在这种组合中是独一无二的。此外，这项工作将与显然是唯一可用出版物的作者密切合作进行。 PCO 薄膜膨胀的机械测定，以便计划的样品交换提供可比较的结果。初步工作表明，振动计通常能够检测由电化学泵送氧气引起的 PCO 薄膜厚度的变化，但是存在很大的限制。 ，是信号噪声PCO 薄膜中的标准振动计需要几毫赫兹的激励频率，例如，在仪器方面，信号多样性可以显着降低噪声。