Synthesis and Characterization of Single Crystals Y₃Fe₅O₁₂ and Bi₃Fe₅O₁₂ Prepared via Sol Gel Technique

Abstract

Abstract. Magnetic properties of nano-crystalline yttrium iron garnet, Y 3 Fe 5 O 12 and bismuth iron garnet, Bi 3 Fe 5 O 12 were studied. The samples were synthesized by using sol gel route. The gel were prepared using nitrates of yttrium and iron for the yttium iron garnet (YIG) and nitrates of bismuth and iron for the bismuth iron garnet (BIG). The raw materials were mixed and dissolved in citric acid and were stirred for 3 months in room temperature until the gel was observed. The X-ray diffraction pattern reveals the cubic structure of YIG and BIG samples at 700 0 C and 500 0 C respectively. From the M-H diagrams it was found that the YIG and BIG samples have saturation magnetization, Ms of 27.2 Gs with rectangular hysteresis loop and 24.4 Gs with S hysteresis loop, respectively. It is evident from the FESEM micrographs that the rectangular loop shape (YIG) arises from the homogeneous and rounded microstructure as compared to the inhomogenous and random orientation microstructure (BIG) of the samples. From the Electron diffraction done on Transmission Electron Microscope, both of the samples were shown to be single crystals. IntroductionMagnetic garnet, namely, yttrium iron garnet (Y 3 Fe 5 O 12 ) and bismuth iron garnet (Bi 3 Fe 5 O 12 ) that belongs to a group of magnetic oxides, is an attractive material for magneto-optical devices. They also have important applications within microwave frequencies, namely, optical isolators, oscillators, circulators and others, due to their large Faraday rotation and high saturation magnetization [1,2]. For these reasons, there are ongoing interests in investigating the chemical, physical and magnetic properties of these garnet materials. Extensive studies have been carried out on the synthesis of YIG nano-particles by coprecipitation technique. Due to the novel processing method, these oxides possess unique magnetic, magneto optical, thermal, electrical and mechanical properties such as excellent creep and radiation damage resistance, high thermal conductivity, high electrical resistivity, controllable saturation magnetization, moderate thermal expansion coefficient, energy transfer efficiency and narrow line width in ferromagnetic resonance [3]. Recently, YIG nanocrystals that were dispersed on glass have been investigated for high density magnetic or magneto-optical information storage [4].

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