ABSTRACT

A series of single-phase rare earth-doped bismuth ferrites were prepared by the solid state reaction method. After characterizing the samples with XRD, the bulk density measurements were carried out by the immersion method. The ultrasonic longitudinal (V_l) and shear (V_s) wave velocities were measured using 1 MHz quartz transducers with the help of the pulse transmission technique. Using the ultrasonic velocity values, Young’s and rigidity moduli along with Poisson’s ratio and Debye temperatures were calculated. As the materials are porous, the zero porous moduli have also been calculated using the Hasselman and Fulrath model. The observed variation of elastic moduli with different dopants has been explained qualitatively. The low-temperature behavior of ultrasonic longitudinal (V_l) wave velocities was also measured. A small change of slope was observed at 208 K in BFO, BLFO and BSFO samples. Finally, the ultrasonic attenuation coefficient values of all the samples were also measured.

摘要

采用固相反应法制备了一系列单相稀土掺杂的铋铁氧体。在用 XRD 表征样品后，通过浸没法进行体积密度测量。超声纵向 ( V _l ) 和剪切 ( V _s) 波速度是在脉冲传输技术的帮助下使用 1 MHz 石英传感器测量的。使用超声波速度值，计算杨氏模量和刚度模量以及泊松比和德拜温度。由于材料是多孔的，因此还使用 Hasselman 和 Fulrath 模型计算了零多孔模量。观察到的弹性模量随不同掺杂剂的变化已定性解释。还测量了超声波纵向 ( V _l ) 波速度的低温特性。在 BFO、BLFO 和 BSFO 样品中，在 208 K 处观察到斜率的微小变化。最后，还测量了所有样品的超声衰减系数值。