压电声源驱动的微型热声制冷

有别于传统电动扬声器驱动的热声制冷系统,将以更高频的PZT换能器为驱动源达到谐振系统结构缩减的目的。考虑到热声制冷系统影响因素繁多,在对系统进行性能模拟分析的基础上提出优化设计方案,并建立PZT驱动的热声制冷系统开展实验研究。最后还为下一步工作提出改进思路。     

冲击波加载下PZT 95/5铁电陶瓷的电阻率研究

利用炸药爆炸产生的平面冲击波,研究了垂直模式冲击波加载下PbZr_0.95Ti_0.05O₃ (PZT 95/5)铁电陶瓷冲击波压缩区域的电阻率变化.在建立的模型中考虑了冲击波压缩区域的有限电阻率,计算结果表明：在压力约2.0GPa,负载短路的条件下,PZT 95/5铁电陶瓷冲击波压缩区域的电阻率从初始10⁷—10¹¹Ωcm迅速降到最小值约40Ωcm,然后基本保持在120—140Ωcm之间. 关键词： PZT 95/5铁电陶瓷 冲击波 电阻率     

PZT铁电薄膜纳米尺度铁电畴的场致位移特性

利用扫描力显微术的压电响应模式，并基于逆压电效应原理，研究了梯度组成的PZT铁电薄膜纳米尺度铁电畴的场致位移特性.获得了源于纳米尺度铁电畴的压电效应和电致伸缩效应贡献的场致位移回滞线，以及源于线性压电效应和电畴反转效应综合贡献的纳米尺度压电位移 场强蝶形曲线，证实了Caspari Merz理论在纳米尺度上的有效性.发现了梯度铁电薄膜存在纳米尺度印刻现象，认为该现象的内因源于薄膜中的内偏场. 关键词： PZT铁电薄膜 场致位移 纳米尺度 扫描力显微术     

Crack-Free,Thick Ceramic Coating Films via Non-Repetitive Dip-Coating Using Polyvinylpyrrolidone as Stress-Relaxing Agent

BaTiO₃ and PZT films were prepared from alkoxide-acetate solutions containing polyvinylpyrrolidone (PVP) by non-repetitive dip-coating. It was demonstrated that PVP incorporated in gel films suppresses crack formation during heating and increases the critical thickness, the maximum thickness achievable without crack formation via single-step deposition. Using PVP crack-free BaTiO₃ and PZT films 1.2 and 0.5 m in thickness could be prepared, respectively, via single-step dip-coating. The films were fairly transparent and dense in microstructure. The tensile stress in heat-treated BaTiO₃ films was also demonstrated to decrease significantly by incorporating PVP in gel films.     

含铜铁电电容器SrRuO3/Pb(Zr0.4Ti0.6)O3/SrRuO3/Ni-Al/Cu/Ni-Al/SiO2/Si异质结的研究

应用磁控溅射法以Ni-Al同时作为Cu与SiO₂/Si,Cu与SRO薄膜之间的阻挡层材料,将Cu与SiO₂/Si衬底和氧化物薄膜电极隔离,避免它们在高温氧气氛中发生化学反应和互扩散,实现了Cu薄膜与氧化物铁电电容器的集成.采用X射线衍射仪(XRD)和原子力显微镜(AFM)研究了不同温度下快速退火的SrRuO₃(SRO)/Ni-Al/Cu/Ni-Al/SiO₂/Si含Cu异质结的微结构和表面形貌,结果发现SRO/Ni-Al/Cu/Ni-Al/SiO₂/Si含Cu多层异质结薄膜在高达750 ℃仍然具有较强的Cu衍射峰和比较平整的表面,显示出了很好的高温热稳定性.研究了"室温长高温退"和"低温长高温退"两种工艺手段,发现在制备含Cu多层氧化物薄膜异质结时,低温长高温后退火的方式要优于常规的室温长高温后退火方式,通过低温长高温退工艺可以缓解应力、削弱界面粗化和避免高温生长对阻挡层和Cu薄膜结构的破坏.最后结合sol-gel法将Pb(Zr_0.4Ti_0.6)O₃(PZT)生长在该含Cu异质结上,制备得SRO/PZT/SRO/Ni-Al/Cu/Ni-Al/SiO₂/Si含Cu铁电电容器,研究了电容器的薄膜结构、铁电性能和漏电特性等,发现制备的含Cu铁电电容器具有很好的铁电性能,如电滞回线趋势饱和,剩余极化强度高达~42 μC/cm²,矫顽电压为~1.0 V,介电常数~1600,漏电流~1.83×10^-4 A/cm²,以及良好的抗疲劳特性和保持特性等,表明导电性优良的Cu薄膜可以应用于高密度高性能铁电电容器.对其漏电机理研究表明,SRO/PZT/SRO含Cu铁电电容器满足空间电荷限制传导机理. 关键词： Cu PZT 铁电电容器 Ni-Al     

Polymeric Macro-Molecular Piezoelectric Sensors for Evaluation of Structural Damage

Finding damages and their prevalence in structures is a very challenging problem. In order to identify potential structural damage, non-destructive methods are not very helpful. One of the most popular piezoelectric ceramic materials used worldwide is macromolecular lead zirconate titanate (PZT), also known as Pb[Zr(x)Ti(1-x)]O3. PZT transducers are proving to be a successful alternative for assessing the structure's health. The Macro-molecular PZT's self-actuating and sensing properties are utilized by the electromechanical impedance (EMI) method. In this capacity, the macro-molecular PZT patches serve as co-located actuators and sensors and make use of ultrasonic vibrations to produce a distinctive admittance “signature” of the structure. PZT patches perform exceptionally well in terms of damage sensitivity. The higher modes of vibration are locally activated by the local application of an AC source on the PZT transducers attached to the host structure. The alteration of the admittance response is a sign of injury to the transducer's vicinity. In the current study, the damage percentage and its location in a 150 × 150 × 150 mm concrete cube are being examined. Regression analysis is also used to determine the concrete cube's strength. This method also can identify hair-like cracks at an early stage, which explains how it can shield the building from serious failures.