铁电单晶Pb(Mg1/3Nb2/3)O3-0.32PbTiO3的实验及本构模型研究

对压力作用下沿001]晶向极化的Pb(Mg弛豫型铁电单晶;极化旋转(相变);黏塑性模型;本构;细观力学国家自然科学基金，教育部全国优秀博士学位论文作者专项基金2006-11-06对压力作用下沿001]晶向极化的Pb(Mg1/3Nb2/3)O3-0.32PbTiO3(PMN0.32PT)弛豫型铁电单晶的应力应变行为进行了实验研究,实验结果表明铁电单晶〈001〉晶向的应力应变行为和铁电多晶有本质的不同,是传统的电畴翻转机理所难以解释的,所提出的极化旋转(相变)模型合理地解释了实验中观察到的现象;基于提出的极化旋转(相变)模型,采用细观力学方法建立了铁电单晶的细观本构模型.在模型中采用黏塑性公式描述铁电单晶可能的8个相变系统的相变行为.为了验证模型的可靠性,用该模型模拟了铁电单晶〈001〉晶向的应力应变实验曲线.计算表明,该模型能较好地模拟铁电单晶〈001〉晶向的相变行为.

EXPERIMENTAL AND CONSTITUTIVE MODEL STUDY OF Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 RELAXOR FERROELECTRIC SINGLE CRYSTAL POLED ALONG〈001〉CRYSTALLOGRAPHIC DIRECTION

The stress and strain properties of $\langle 001 \rangle$ oriented PMN-0.32PT relaxor ferroelectric single crystals have been investigated. Obtained results show that the stress and strain behavior along $\langle 001 \rangle$ crystallographic direction is different from that of the ferroelectric polycrystal. Polarization rotation models are developed to explain the observed behaviors of PMN-0.32PT. Based on the experimental phase transformation mechanism of ferroelectric single crystal, a constitutive model of ferroelectric single crystal is proposed based micromechanical method. In the model, the phase transformation systems on 8 possible sliding planes are characterized by a viscoplastic law. The behavior of ferroelectric single crystal is then derived from phenomenal crystallographic theory through the transformation strain on sliding planes. The developed model has been applied to simulate the experimental stress-strain curve of $\langle 001 \rangle$ oriented PMN-0.32PT. It is shown that the developed model can faithfully capture the key characteristic of the observed constitutive behavior of $\langle 001 \rangle$ oriented PMN-0.32PT.