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M Synthesis and Magnetic Properties of Multiferroic BiFeO 3

Ivane Javakhishvili Tbilisi State University Institute of Condensed Matter Physics Giorgi Khazaradze. M Synthesis and Magnetic Properties of Multiferroic BiFeO 3 Tbilisi, 2012 A. Collaboration. M

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M Synthesis and Magnetic Properties of Multiferroic BiFeO 3

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  1. IvaneJavakhishvili Tbilisi State UniversityInstitute of Condensed Matter PhysicsGiorgiKhazaradze M Synthesis and Magnetic Properties of Multiferroic BiFeO3 Tbilisi, 2012 A

  2. Collaboration M Supervisor: Professor Alexander Shengelaya Dr. D. Daraselia Tbilisi State University Dr. D. Japaridze Tbilisi State University Z. GuguchiaUniversity of Zürich A

  3. IntroductionIn the 1960’s it was discovered a new class of materials, where ferromagnetic and ferroelectric ordering coexist. They were called multiferroics. FFerromagnetic ordering Ferroelectric ordering

  4. BiFeO3 has rhombohedrallyperovskite structure. At the same time quite diversified and uncommon properties: ferroelectric transition at Tc=1103 K and antiferromagnetic transition at TN=643 K. Crystal structure of BiFeO3. Pink-bismuth, Blue-iron, Green-oxygen.

  5. Problem BiFeO3 samples are usually obtained by thermal solid-state reaction method. It takes many hours to prepare these samples. However, impurity phases are usually present. Recently clean samples were obtained with rapid liquid phase sintering method. This method implies heating of the sample for a short time above its melting temperature. (During 5 minute at 8800C) Y.P. Wang et al. Appl.Phys.lett. 10, 11 (2004).

  6. New idea: Recently a new method was developed in our group at Tbilisi State University. The samples are irradiated wish strong beam of photons. It was called a photostimulated solid-state reaction method. With this method it takes only few minutes to prepare the samples. The negative effects of longtime thermal process are decreasing to a minimum due to small time. Also the energy consumption decreases significantly.

  7. Preparation of BiFeO3 1/2 Bi2O3 + 1/2Fe2O3 = BiFeO3 Mixing of starting materials. Pressing into pellet. Irradiation by photon-beam furnace with strong beam of photons, during two minutes at 8800 C.

  8. Experimental Methods A photon-beam furnace in switched mode. The furnace containes 10 halogen lamps with 1 kWt powereach.

  9. X-ray diffraction pattern of multiferroic BiFeO3

  10. Magnetization measurements were performed on the SQUID-magnetometer (Superconducting Quantum Interference Device) in the temperature range of 2-300 K and up to 7 Tesla magnetic field. Performed magnetic measurements: Temperature scan (TScan) in 2000 G applied magnetic field. Field scan (FScan) at 5 K and 300 K.

  11. Dependence of magnetic moment on temperature in 2000 G applied magnetic field

  12. Magnetization (M) versus field (H) curve for the BiFeO3 powder measured at 5 K. Inset shows the details of the M–H hysteresis loop displayed at a field of 1000 Oe.

  13. Magnetization (M) versus field (H) curve for the BiFeO3 powder measured at 300 K.

  14. EPR measurements For the study of microscopic magnetic properties of the prepared BiFeO3 the sample EPR spectra were measured in a broad temperature range. EPR spectrometer BRUKER ER 200D-SRC

  15. The intensity, linewidth and resonance fields for both EPR lines as a function of temperature was obtained and is plotted on the following graphs.

  16. Conclusions1. We prepared BiFeO3with photostimulated solid-statereactionmethod.2. We studied its magnetic properties using SQUID magnetometer.3. For the first time EPR spectra were measured in broad temperature range and sharp changes of EPR signal were observed at the antiferromagnetic transition temperature.4. Obtained results show that it is possible to synthesize quite good quality BiFeO3 compound usingphotostimulated solid-state reaction method.5. With further optimization of synthesis conditions it should be possible to synthesie 100 % phase pure BiFeO3 compound.

  17. Thanks for attention!

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