压应力场下PLZT铁电陶瓷的原位Raman观测

In-Situ Raman Observations for PLZT Ferroelectric Ceramics under Compressive Stresses

铁电陶瓷材料在外场加载下的畴变所引起的材料结构变化,是导致材料性能衰变和破坏的主要原因,Raman光谱技术是一种研究铁电材料畴变和微结构变化的无损伤性及原位微区的观测方法。采用传统固相法合成Zr/Ti原子比为53/478的掺镧锆钛酸铅(PLZT)铁电陶瓷材料,采用X射线衍射仪和扫描电子显微镜及Precision_LC铁电测试系统分别对试样进行结构形貌表征和铁电物理性能测试,利用自制的应力加载装置与Raman光谱仪联用,实现不同压应力场作用下试样的原位Raman谱测试,考察和分析Raman谱软模E(2TO)和E(3TO+2LO)+B1的峰强和峰位随散射偏振方向的变化规律。结果表明,不同压应力场下Raman软模E(2TO)和E(3TO+2LO)+B1的峰强均随散射偏振角度呈现正弦式的变化规律,在60°偏振角度上软模峰强最大,在150°偏振角度上软模峰强最小。随着压应力场的增加,在0°和60°偏振角度获得的软模峰强随应力场的增加呈现明显的下降趋势,而在90°和150°偏振角度获得的软模峰强基本不变。压应力场变化对PLZT陶瓷的Raman软模E(2TO)和E(3TO+2LO)+B1的峰位均不产生影响。

The change in material microstructure caused by ferroelectric domain switching under an alternative mechanical and electrical field is considered to be a major cause for degradation and failure of ferroelectric materials.It is shown that Raman spectroscopy could be used as a nondestructive,micro-regional and sensitive technique for in-situ observations of domain switching and microstructure changes for polycrystalline ceramics with home-made experimental apparatuses.The lanthanum-doped lead zirconate titanate（PLZT）ceramics with atomic ratio Zr/Ti=53/47 were prepared with conventional solid state reaction technique.The crystal phase and morphology of the PLZT specimen were characterized with XRD and SEM techniques,with the ferroelectric physical properties with PrecisionLC system.The compressive stress was applied to the PLZT specimen and in-situ Raman measurements were carried out through the self made microtest mechanical loading device.The effects of stresses and polarization directions of the scattered light on the Raman spectra intensity and peak position for E（2TO）and E（3TO＋2LO）＋B1soft modes were discussed and analyzed.The results revealed that both variations of peak intensity with the polarization degree for E（2TO）and E（3TO＋2LO）＋B1soft modes showed an periodicity in a sine type law,which increased to the highest value at60°and decreased to the lowest value at 150°.With the increase of the compressive stress,the peak intensity for E（2TO）and E（3TO＋2LO）＋B1soft modes showed a significant decrease at the polarization degree of 0°and 60°,whiel it remained unchanged at 90°and 150°.The compressive stress has no effects on the peak position for E（2TO）and E（3TO＋2LO）＋B1soft modes.