温度、压力和时效时间对Bi0.9 Gd 0.1 Fe 0.9 Mn 0.1 O3体系弛豫动力学的影响：玻璃态和压致弛豫行为的直接证据
Effect of Temperature, Pressure and Aging time on the Relaxation Dynamics of Bi0.9Gd0.1Fe0.9Mn0.1O3 System: Direct Evidence of Glassy State and Pressure Induced Relaxor Behavior
Satya N. Tripathy, Zaneta Wojnarowska, Justyna Knapik, Arthur Chrobak, Dillip K. Pradhan, Sebastian Pawlus, Marian Paluch
The fundamental aspects of relaxation dynamics in Bi0.9Gd0.1Fe0.9Mn0.1O3 multiferroic system have been reported. The study was carried out employing dielectric relaxation spectroscopy covering eight decades in frequency 0.01 to106 Hz and in a wide range of temperature 423 K to 153 K, hydrostatic pressure 0.1 MPa to 1765 MPa and aging time 0 s to 80000 s. The temperature dependent dielectric response indicates three relaxations processes in the dynamic window of modulus formalism. Variable range hopping model of small polarons manifests the bulk conduction mechanism. The bulk and grain boundary contributions have been estimated using impedance spectroscopy analysis and reveal that localized process dominates the relaxation. The direct evidence of glassy feature is established below 200 K by aging experiments. Our findings provide a potential connection between nearly constant loss features appearing below 200 K with fastest relaxation of magnitude 0.16 eV. We also discuss the time temperature superposition behavior using modulus scaling. A pressure driven normal ferroelectric to relaxor behavior is witnessed above a critical pressure as a result of relative competition between short range and long range forces. Our findings focus the role of high pressure as a fundamental bridge between normal ferroelectrics and relaxors. Intriguingly, there exists a direct connection between chemical pressure induced by substitution and external hydrostatic pressure. These findings have robust fundamental importance on theoretical elucidation of relaxation dynamics in perovskite systems.
Stability of Glassy and Ferroelectric States in the Relaxors PbMg1/3Nb2/3O3 and PbMg1/3Nb2/3O3-12% PbTiO3
无序玻璃相的稳定性在弛豫PbMg 1/3 Nb 2/3 O 3和（PbMg 1/3 Nb 2/3 O 3）0.88（PbTiO 3）0.12，称为PMN和PMN-PT，研究通过制备部分极化样品，并允许他们在零场的温度范围内的阶段是历史依赖的老化。PMN-PT的极化会自发地增加，直到形成长程序，首先出现巨极化噪声。因此，PMN-PT中的结晶稳定相似乎是铁电的。与此相反，PMN样品缺乏尖锐的一阶场驱动的转变，发现在其他一些样品自发去极化，其玻璃态是化学稳定的一致。详细的热去极化结果表明，在PMN两个不同的宽峰，以及一小部分的材料与突然熔化转变的分布。
弛豫铁电体（PbMn $_{1/3}$ Nb $_{2/3}$ O $_3$）$_{1-x}$（PbTiO $_3$）$_{x}$，$x=0.1$，（PMN/PT（90/10））表现出几种复杂的时效行为。就在敏感性峰值之下，有一种状态表现出年轻化，但几乎没有记忆。在较低的温度下，有一个政权，主要是累积老化，预计简单的域增长。在更低的温度下，有一个既有恢复活力又有记忆的机制，让人想起旋转眼镜。PMN/PT（88/12）也被发现表现出一些这些老化制度。这种定性的老化行为让人想起在重入铁磁体中所看到的，重入铁磁体在较低温度下表现出从畴生长铁磁制度到重入自旋玻璃制度的交叉。这些惊人的相似之处表明，在PMN/PT（90/10）之间的竞争的铁电相关形成的畴生长制度与玻璃相关形成的自旋玻璃制度。PMN/PT（90/10）也被发现表现出频率老化时间缩放的时间依赖性的一部分，温度为260 K及以下的相位敏感性。还报道了老化效应对热循环和场扰动的稳定性。
