晶内微孔PZT95/5铁电陶瓷制备、成孔过程及极化增强机理

PZT95/5 ferroelectric ceramics have found important practical application in the area of pulsed power supply.Porous PZT95/5 ferroelectric ceramics are promising new generation materials of pulsed power supply because they are mechanically stronger under shock wave compression than dense ceramics and thus improving the reiliability of the power. However,the intentionally-introduced pores degrade their electrical properties significantly. Recently, we observed a unique phenomenon in the sintering process of PZT95/5 ferroelectric ceramics that the formation of a quantity of small pores within grains (hereafter we called intragrannular pores)by adding carbon nanotubes(CNTs)as pore former,leading to an enhancement of the remanent polarization. However, the formation process of the intragrannular pores and physical mechanism underlying the enhanced remanent polarization is still unclear yet. In this proposal,firstly, PZT95/5 ferroelectric ceramics with intragrannualr pores will be fabricated by varying the CNTs content,extent of PbO excess, sintering atmospheres. Secondly, based on the mircrostructural characterization and sintering dynamics theory, the formation mechanism of the intragrannular pores will be tentatively investigated. Thirdly, the local structure and influence of the intragrannular pores on the electrical properties, the phase transition behavior,and especially on the domain switching behavior will be investigated, so as to find out the underlying physical mechanism for the enhanced remnant polarization. The forthcoming results and conclusions of this proposal will show potentials for realizing the simutaneous optimization of compressibility under shock wave and storage energy density enhancement of PZT95/5 ferroelectric ceramics in the pusled power supply application.

PZT95/5 铁电陶瓷是铁电高功率脉冲电源的核心材料，在尖端技术领域具有重要应用。多孔PZT95/5 铁电陶瓷由于具有更优异的抗冲击性能，可显著提高电源的可靠性而成为第二代铁电脉冲电源的首选。然而，气孔的引入降低了陶瓷材料的铁电性能。最近，申请人利用碳纳米管作为造孔剂在PZT95/5铁电陶瓷的晶粒内部形成数量较多的微小气孔（晶内微孔），展现了独特的剩余极化强度增强效应，但其成孔过程和极化增强机制尚不明确。本项目拟在前期工作的基础上，通过调控碳纳米管添加量、PbO过量度、烧结气氛等制备具有晶内微孔的PZT95/5铁电陶瓷；结合显微结构表征和烧结动力学研究晶内微孔的成孔机制；研究晶内微孔局域特征及其对电畴翻转行为的影响，揭示极化强度增强效应的微观机理。本项目研究结果有望实现多孔PZT95/5铁电陶瓷在铁电脉冲电源应用中抗冲击性能和储能密度的同步优化，满足国家战略需求。

PZT95/5 铁电陶瓷是铁电高功率脉冲电源的核心材料，在尖端技术领域具有重要应用。本项目首次以晶内微孔的PZT95/5铁电陶瓷铁电陶瓷为研究对象，研究了不同组分和工艺条件对于晶粒内微孔形成的影响，结合烧结动力学理论研究了晶粒内微孔的形成机制，并探讨了极化强度增强效应的物理机制。具体研究结果如下：.(1) 利用碳纳米管作为造孔剂，可以实现在PZT95/5铁电陶瓷的晶粒内引入微孔。0.1%重量百分比的碳纳米管添加量在PZT95/5铁电陶瓷内产生1.5 %的孔隙率。晶粒内微孔的分布较为均匀，尺寸在~1μm的数量级。.(2) 通过比较研究PbO过量度、ZrO2过量度、碳纳米管添加量以及Zr/Ti比对于PZT95/5铁电陶瓷的微结构的影响，发现PbO过量度、ZrO2过量度以及碳纳米管添加量对于PZT95/5铁电陶瓷材料晶粒内微孔的形成起重要作用，而烧结温度以及Zr/Ti比对于PZT95/5铁电陶瓷材料晶粒内微孔的形成没有显著影响。 结合烧结动力学理论，研究了PZT95/5铁电陶瓷材料晶粒内微孔的形成机制：碳纳米管、PbO的不足量和ZrO2过量，都可以通过不同的方式造成PbO不足，减缓烧结过程中元素扩散速率，进而影响PZT95/5铁电陶瓷材料烧结阶段的致密化过程，从而在晶粒上形成微孔结构。.(3) 在PZT95/5铁电陶瓷材料中，不论是PbO不足量或者ZrO2的过量，还是碳纳米管造成的气孔，都会显著造成晶格中的铅缺位，铅空位的产生使得畴壁运动容易进行，有利于自发极化非180°畴的取向，从而提高陶瓷材料的剩余极化强度。.本项目的研究结果有望实现多孔PZT95/5铁电陶瓷在铁电脉冲电源应用中抗冲击性能和储能密度的同步优化，满足国家战略需求。