Rajan Soumya, Gazzali P M Mohammed, Chandrasekaran G
Magnetism and Magnetic Materials Laboratory, Department of Physics, Pondicherry University, Pondicherry 605014, India.
Magnetism and Magnetic Materials Laboratory, Department of Physics, Pondicherry University, Pondicherry 605014, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2017 Jan 15;171:80-89. doi: 10.1016/j.saa.2016.07.037. Epub 2016 Jul 27.
BaFeTiO (x=0, 0.005, 0.01) polycrystalline ceramics are prepared using solid state reaction method. Structural studies through XRD, Raman and XPS confirm single tetragonal phase for BaTiO whereas a structural disorder tends to intervene with the introduction of smaller Fe ions which reduces the tolerance factor and tetragonality ratio. Grain size of the samples is estimated using SEM micrographs with ImageJ software and chemical composition is confirmed using EDX spectra. Raman spectra measured in the temperature range of 303K to 573K showers light on the structural phase transition exploiting a significant disappearance of the 306cm mode. Further, structural analyses suggest the entry of Fe into the B-site upon increasing its concentration in BaTiO. The dopant sensitive modes lying at around 640cm and 650cm are assigned to lattice strain. A reduction in ferroelectric to paraelectric transition temperature is observed with a transformation from diffused type to normal ferroelectric upon the increased Fe content. The oxidation state of Fe in the BaTiO lattice has been decided using EPR Spectra precisely. Room temperature magnetic ordering is observed in Fe substituted BaTiO using PPMS. The coexistence of ferroelectric and magnetic ordering is established in the present study for optimized Fe substituted BaTiO.
采用固态反应法制备了BaFeTiO（x = 0、0.005、0.01）多晶陶瓷。通过X射线衍射（XRD）、拉曼光谱和X射线光电子能谱（XPS）进行的结构研究证实，BaTiO为单一四方相，而较小的Fe离子的引入往往会导致结构无序，这降低了容差因子和四方度比。使用带有ImageJ软件的扫描电子显微镜（SEM）显微照片估算样品的晶粒尺寸，并使用能量色散X射线光谱（EDX）确认化学成分。在303K至573K温度范围内测量的拉曼光谱，利用306cm模式的显著消失揭示了结构相变。此外，结构分析表明，随着Fe在BaTiO中浓度的增加，Fe进入B位。位于640cm和650cm附近的掺杂剂敏感模式归因于晶格应变。随着Fe含量的增加，观察到铁电-顺电转变温度降低，并且从扩散型转变为正常铁电体。利用电子顺磁共振（EPR）光谱精确确定了Fe在BaTiO晶格中的氧化态。使用物理性质测量系统（PPMS）在Fe取代的BaTiO中观察到室温磁有序。在本研究中，对于优化的Fe取代的BaTiO，确定了铁电和磁有序的共存。
