【作者】 姚飞；

【导师】 曾亦可；

【作者基本信息】 华中科技大学 ， 微电子学与固体电子学， 2013， 硕士

【摘要】 锆钛酸铅（PZT）材料因其优异的铁电、压电、热释电性，被广泛的用于制备各种传感器、换能器和驱动器。富锆型PZT在铁电低温三方相到高温三方相转变时，拥有较高的热释电系数，是重要的热释电材料之一。与体材料和薄膜相比厚膜在加工的过程中成品率高、性能稳定、成膜面积大有利于器件的微型化、集成化。丝网印刷法作为一种工艺简单、成本低、成膜面积大的厚膜制备技术被广泛应用。然而PZT材料致密成瓷温度较高（≥1200℃），PZT厚膜若在此高温下烧结易引起铅挥发和电学性能恶化。另外，随着电子器件向微型化、集成化和多功能化方向发展，低温共烧技术（LTCC）得到了广泛的关注，该技术要求电子材料能与银（Ag）、铜（Cu）等金属电极共烧。因此，降低厚膜烧结温度意义重大。本文的目标是将PZT厚膜的烧结温度降低到银的熔点以下，减少铅挥发，提高厚膜致密度，提升厚膜的电性能。首先，本文采用丝网印刷技术，通过添加Bi₂O₃-Li₂CO₃助烧剂将Pb(Zr_0.9Ti_0.1O₃厚膜制备在氧化铝基片上。研究了Bi₂O₃-Li₂CO₃的含量对厚膜的烧结温度、微观形貌、相结构、介电性能和热释电性能的影响。结果表明：适量Bi₂O₃-Li₂CO₃的添加，可以将PZT厚膜的烧结温度降低到1050℃，促进了晶粒的生长和厚膜的致密化，提高PZT厚膜的介电常数和热释电系数。当Bi₂O₃-Li₂CO₃的含量为6wt%时，厚膜样品在30℃时，热释电系数达到4.5×10^-8Ccm^-2K^-1，热释电探测率优值达到2.3×10^-5Pa^-1/2。在此基础上，为了进一步降低PZT厚膜的烧结温度以及抑制铅挥发，选用PbO和Bi₂O₃-Li₂CO₃作为共同助烧剂。研究了助烧剂含量对厚膜微观形貌、相结构、介电性能和热释电性能的影响。研究表明：随着PbO和Bi₂O₃-Li₂CO₃含量的增加，烧结温度从1100℃降低到了900℃，晶粒尺寸和晶格常数减小。当PbO含量为6.4wt%，Bi₂O₃-Li₂CO₃含量为5.4wt%时，PZT厚膜可在900℃下烧结，在30℃时具有最大的热释电系数10.51×10^-8Ccm^-2K^-1和最大的热释电探测率优值10.58×10^-5Pa^-1/2。针对富锆型PZT厚膜在应用过程中热释电温区过窄的问题，通过设计制备梯度厚膜得到了热释电温区较宽的PZT厚膜。热处理PZT粉体以抑制不同层组分粉体间的相互反应。制备出的梯度PZT厚膜在17℃³5℃宽温区内热释电系在5.5×10^-8Ccm^-2K^-1以上、热释电探测率优值在5×10^-5Pa^-1/2以上。更多还原

【Abstract】 Lead zirconate titanate（PZT） materials has been widely used to prepare sensors,transducer and actuator for its excellent ferroelectric, piezoelectric and pyroelectricperformance. Zr-rich PZT is a promising candidate to make infrared detectors because ithas a high pyroelectric coefficient when the transition from rhombohedral ferroelectric lowtemperature phase （FRL） to rhombohedral ferroelectric high temperature phase （FRH） takesplace. Recently, PZT thick films have drawn much attention because they have betterelectrical properties than thin films and it is unnecessary to grind or polish them likepyroelectric ceramics, which is good for miniaturization and integration of device.Compared with other existing methods, screen printing is flexible, cost-effective fabricationmethod for fabrication of thick films.However, the processing temperatures required to obtain dense PZT ceramics areabout1200℃, which is too high for most of substrates and incompatible with the infraredfocal plane array technologies. The LTCC technique also needs to reduce the sinteringtemperature to co-sintered with Ag electrode. With this end in view, reducing the sinteringtemperature is essential for the fabrication and practical application of high performancePZT thick films. The main aim of our research is to reduce the sintering temperature of PZTthick film to below the melting point of silver and improve the electrical of PZT thick films.First of all, the Pb(Zr_0.9Ti_0.1O₃thick films were fabricated on Al2O3substrate via thescreen printing technology by using Bi₂O₃-Li₂CO₃additions as liquid-phase sintering aids.The dependence of microstructure, dielectric and pyroelectric properties on the content ofsintering aids has been studied. When a proper quantity of Bi₂O₃-Li₂CO₃doped in the thickfilms, the sintering temperature of the thick films decreases to1050℃, and the grain size,density and electrical of the thick films increase. The Pb(Zr_0.9Ti_0.1O₃thick film with6wt%Bi₂O₃-Li₂CO₃has the maximum pyroelectric coefficient4.5×10^-8Ccm^-2K^-1and the highestfigure-of-merit2.3×10^-5Pa^-1/2at30℃.Then, in order to reduce the sintering temperature of the PZT thick films to900℃,PbO and Bi₂O₃-Li₂CO₃were chose as liquid-phase sintering aids. The effects of sintering aids doped on the microstructures, phase compositions, dielectric properties andpyroelectric properties of the thick films were systematically investigated. It was found thatwhen the amount of Bi₂O₃-Li₂CO₃increases, the sintering temperature of the thick filmsdecreases from1100℃to900℃, and the grain size and the lattice constant decrease either.In addition, the Pb(Zr_0.9Ti_0.1O₃thick film with6.4wt%PbO and5.4wt%Bi₂O₃-Li₂CO₃sintered at900℃has the maximum pyroelectric coefficient10.51×10^-8Ccm^-2K^-1and thehighest figure-of-merit10.58×10^-5Pa^-1/2.In order to solve the problem that the pyroelectric temperature zone was too narrowwhen PZT thick film was used in infrared sensor, the multilayer thick film with widepyroelectric temperature zone was prepared. To prevent the reacting between componentsin the different layer, the starting materials were pretreated. The multilayer PZT thick filmhas the pyroelectric coefficient larger than5.5×10^-8Ccm^-2K^-1, the figure-of-meritapproximately6×10^-5Pa^-1/2, in the pyroelectric temperature zone（17℃³5℃）.更多还原