极化对锆钛酸铅陶瓷力学性能的影响

doi:10.15541/jim20140360

摘要/Abstract

摘要：

本工作所采用的样品为锆钛酸铅陶瓷PZT-5H与PZT-8, 用动态力学分析仪(DMA)测试了极化前后PZT-5H与PZT-8在不同力学荷载频率下的杨氏模量和内耗与温度的关系。结果表明: PZT-5H和PZT-8的铁电-顺电相变温度(T_c)分别为438 K和550 K。极化前后PZT-8的杨氏模量都高于PZT-5H, 这是由于硬性取代导致PZT-8的内应力大于PZT-5H。极化后, PZT-5H与PZT-8的杨氏模量增大, 本文研究了极化前后压电效应对模量变化的影响。测试得出两种样品都存在一个弛豫内耗峰。分析表明, PZT-8的弛豫内耗峰由氧空位的扩散引起, 而PZT-5H弛豫内耗峰的形成机制则比较复杂, 与畴壁运动及畴壁在运动过程中与点缺陷的相互作用有关。计算得出极化后两种样品的弛豫激活能增加, 原因是极化导致局部内应力升高, 空间电荷沿极化电场排列, 两种因素都会对畴壁及空位的运动产生钉扎效应, 从而使弛豫过程更加困难。

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关键词: 杨氏模量, 内耗, DMA, PZT, 极化

Abstract:

This study concerns two following commercial lead zirconate titanate (PZT) materials, “soft” PZT-5H and “hard” PZT-8 piezoelectric ceramics. Young’s modulus and internal friction versus temperature at different vibration frequencies were investigated by means of Dynamic Mechanical Analysis (DMA) before and after polarization. The phase transition temperatures (T_c) of PZT-5H and PZT-8 ceramics were 438 K and 550 K. PZT-8 ceramic had higher Young’s modulus than PZT-5H ceramic at ferroelectric phase, which resulted from the increase of internal local stress in PZT-8 ceramic. After polarization, the Young’s modulus of both PZT ceramics increased, the influence of the piezoelectric effect was investigated. A relaxation peak emerges in internal friction curve of each PZT sample. Considering the hard ceramic, this peak is a pure relaxation mechanism controlled by oxygen vacancies diffusion. Considering the soft ceramic, the relaxation peak can be related to viscous motion of domain walls and the interaction between domain walls and point defects. The activation energy of the relaxation peak increased after polarization, which resulted from the increased local internal stress and directional arranged space charges caused by polarization.

Key words: Young’s modulus, internal friction, DMA, PZT, polarization

中图分类号:

TQ174

于瑶, 王旭升, 李艳霞, 姚熹. 极化对锆钛酸铅陶瓷力学性能的影响[J]. 无机材料学报, 2015, 30(2): 219-224.

YU Yao, WANG Xu-Sheng, LI Yan-Xia, YAO Xi. Effect of Polarization on Mechanical Properties of Lead Zirconate Titanate Ceramics[J]. Journal of Inorganic Materials, 2015, 30(2): 219-224.

图/表 8

Fig. 1 Temperature dependent Young’s modulus of unpoled and poled PZT-5H at different frequencies

Fig. 2 Temperature dependent Young’s modulus of unpoled and poled PZT-8 at different frequencies

Fig. 3 Temperature dependent internal friction of unpoled (a) and poled (b) PZT-5H at different frequencies

Fig. 4 Temperature dependent internal friction of unpoled (a) and poled (b) PZT-8 at different frequencies

Fig. 5 Arrhenius plots and fitting lines for Pr in PZT-5H (a) and PZT-8 (b)

Table 1 Relaxation internal friction peak temperatures of PZT ceramics at different frequencies

T_p/K f/Hz	PZT-5H (Unpoled)	PZT-5H (Poled)	PZT-8 (Unpoled)	PZT-8 (Poled)
0.1	363	365	422	426
0.5	379	381	445	450
1	386	387	459	460
5	402	400	485	486
10	409	407	497	496

Table 2 Relaxation parameters for the relaxation internal friction peaks of PZT ceramics

	PZT-5H (Unpoled)	PZT-5H (Poled)	PZT-8 (Unpoled)	PZT-8 (Poled)
H/eV	1.28	1.43	1.10	1.19
τ₀/s	2.6×10^-18	3.7×10^-20	1.1×10^-13	1.2×10^-14

Fig. 6 Relationship of the Pr strength (Δ) and temperature in PZT-5H (a) and PZT-8 (b)

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