Structure, phase diagram and magnetic properties of Bi1−xLaxFeO3 solid solution
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- 作者：Q.R. Yaoa ; b ; c ; qingry96@guet.edu.cn" class="auth_mail" title="E-mail the corresponding author ; Y.H. Shenb ; P.C. Yangb ; H.Y. Zhoub ; c ; G.H. Raob ; c ; Z.M. Wangb ; c ; J.Q. Dengb ; c
- 关键词：C. Magnetic properties ; Phase diagram ; Phase transition ; X-ray diffraction ; Crystal structure
- 刊名：Ceramics International
- 出版年：2016
- 出版时间：April 2016
- 年：2016
- 卷：42
- 期：5
- 页码：6100-6106
- 全文大小：2426 K
文摘
A series of polycrystalline Bi1−xLaxFeO3 (0≤x≤1.00) solid solution were synthesized by sol–gel method. The effects of lanthanum concentration on the phase formation, phase transition and magnetic properties were studied. The XRD results displayed that there is a clear indication of structural modification and symmetry change brought about by La doping. At room temperature the crystal structure of the solid solution transforms from rhombohedral R3c (x≤0.15) to tetragonal P4mm (0.15<x <0.40), then to cubic issn=02728842&md5=34ed39e41f75ed0c199a5c6d58e8dd4f">
(0.40≤x<0.50), and finally to orthorhombic Pbnm (0.50≤x ≤1.00). In situ high temperature X-ray powder diffraction studies reveal that phase transformations of the rhombohedral R3c and the cubic issn=02728842&md5=34ed39e41f75ed0c199a5c6d58e8dd4f"> to the orthorhombic Pbnm occur in the temperature regions of 680–730 °C and 300–680 °C,respectively. The phase transformations of the tetragonal P4mm to the cubic issn=02728842&md5=34ed39e41f75ed0c199a5c6d58e8dd4f"> occurs in the temperature region of 200–230 °C, whereas the phase structure of orthorhombic Pbnm keeps unchanged below 850 °C. Based on careful characterization of crystal structure and phase transition as a function of temperature, the phase diagram of the pseudo-binary BiFeO3–LaFeO3 system has been constructed. The phase diagram manifests that the Bi1−xLaxFeO3 (0≤x≤1.00) solid solution provides more options to tune the magnetism and multiferroism, as the crystal structures with polarity feature occur in a wide doping concentration of La (x≤0.30). We then selectively studied the magnetic properties of possible multiferroic phases, i.e. R3c and P4mm phases. The results revealed that both the magnetic remanence and the coercive field of Bi1−xLaxFeO3 (0<x≤0.30) increased with the La content.
(0.40≤x<0.50), and finally to orthorhombic Pbnm (0.50≤x ≤1.00). In situ high temperature X-ray powder diffraction studies reveal that phase transformations of the rhombohedral R3c and the cubic issn=02728842&md5=34ed39e41f75ed0c199a5c6d58e8dd4f"> to the orthorhombic Pbnm occur in the temperature regions of 680–730 °C and 300–680 °C,respectively. The phase transformations of the tetragonal P4mm to the cubic issn=02728842&md5=34ed39e41f75ed0c199a5c6d58e8dd4f"> occurs in the temperature region of 200–230 °C, whereas the phase structure of orthorhombic Pbnm keeps unchanged below 850 °C. Based on careful characterization of crystal structure and phase transition as a function of temperature, the phase diagram of the pseudo-binary BiFeO3–LaFeO3 system has been constructed. The phase diagram manifests that the Bi1−xLaxFeO3 (0≤x≤1.00) solid solution provides more options to tune the magnetism and multiferroism, as the crystal structures with polarity feature occur in a wide doping concentration of La (x≤0.30). We then selectively studied the magnetic properties of possible multiferroic phases, i.e. R3c and P4mm phases. The results revealed that both the magnetic remanence and the coercive field of Bi1−xLaxFeO3 (0<x≤0.30) increased with the La content.