Effects of trivalent gadolinium and cobalt co-substitution on the crystal structure, electronic transport, and ferromagnetic properties of bismuth ferrite

• Published in: Materials science in semiconductor processing Vol. 27; pp. 899 - 908
• Main Authors: Song, G.L., Su, J., Ma, G.J., Wang, T.X., Yang, H.G., Chang, F.G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2014; Elsevier
• Subjects: BiFeO3; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Diamagnetism, paramagnetism and superparamagnetism; Domain effects, magnetization curves, and hysteresis; Electronic transport properties; Exact sciences and technology; Ferromagnetic properties; Magnetic properties and materials; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Physics; Small particles and nanoscale materials; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Studies of specific magnetic materials; The magnetic hysteresis loops; The magnetic phase transition temperature; BiFeO3; The magnetic phase transition temperature; The magnetic hysteresis loops; 77. 80. −e; Electronic transport properties; 75. 60. Ej; Ferromagnetic properties; 77. 84. −s; Grain size analysis; Iron oxide; Transport properties; Doping; Ferromagnetic materials; Gadolinium; XRD; Liquid phase sintering; Leakage currents; Cobalt; Phase transitions; Ferrites; Hysteresis loop; Ferroic material; Ferrite; 77. 80. -e; Bismuth; BiFeO; 77. 84. -s; Electrical characteristic; Crystal structure; Grain size; Scanning electron microscopy; Magnetization; Electrical properties; Doped materials; Electron microscopes; Magnetic hysteresis; Ceramics; Electron microscopy; Transport processes; Codoping
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2014.09.004

Multiferroic trivalent gadolinium and cobalt co-substituted bismuth ferrite Bi0.95Gd0.05Fe1−xCoxO3(x=0, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by rapid liquid phase sintering method. The results showed that all the peaks of X-ray Diffraction (XRD) for Bi0.95Gd0.05Fe1−xCoxO3 samples can be indexed according to the crystal structure of pure BiFeO3. XRD analysis revealed a phase transition in Gd3+ and Co3+ co-doped BiFeO3 when x was larger than 0.1. The Scan Electron Microscope (SEM) images indicated that Gd3+ and Co3+ doping significantly decreased the grain sizes of BiFeO3 ceramic. Gd3+ and Co3+ co-doping BiFeO3 enhanced the electrical properties with lower leakage current. The magnetic hysteresis loops and the magnetization were greatly improved in co-substituted specimens at room temperature. The Mr of Bi0.95Gd0.05Fe1−xCoxO3 (x=0, 0.05, 0.1, 0.15, 0.2) was 34, 60, 105, 103 and 180 times of that of BiFeO3 at 30kOe, respectively. All the samples exhibited ferromagnetic behavior at 750K and paramagnetic behavior at 900K, indicating a high temperature magnetic phase transition of BiFeO3 at 870K, which shifted to 780K by Gd3+ and Co3+ doping. This can be attributed to the Fe3+–O2−–Fe3+ super-exchange strength and the relative stability of the magnetic structure.