Formation of Microstructure of Lithium-Titanium Ferrite during its Synthesis in a 2.4 MeV Electron Beam
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BRIEF COMMUNICATIONS FORMATION OF MICROSTRUCTURE OF LITHIUM-TITANIUM FERRITE DURING ITS SYNTHESIS IN A 2.4 MeV ELECTRON BEAM A. P. Surzhikov,1 E. V. Nikolaev,1 E. N. Lysenko,1 S. A. Nikolaeva,1 D. Zh. Karabekova,2 and A. S. Ghyngazov3
UDC 539.2
Keywords: Li–Ti-ferrite, electron beam, structure, atomic-force microscopy.
INTRODUCTION Ferrite materials are the key elements of most modern radio-engineering, electronic and computational devices. [1, 2]. In particular, lithium ferrites are extensively applied in microwave devices and as cathode materials for lithium cells [3, 4]. Lithium-substituted ferrites, where Fe3+ ions are substituted for titanium ions are characterized by low dielectric loss values and high temperature stability and are therefore widely applied in microwave engineering [5–7]. Today, ceramic technology of ferrite production is quite common, including the synthesis of ferrite powders at high temperatures. Given the fact that ferrites generally have complex compositions, their synthesis involves the formation of transient products of solid-phase interaction including monoferrite phases and solid oxide solutions. Such solid-phase interactions occur in a diffuse regime and therefore for a complete synthesis reaction require an inclusion of multiple grinding and compaction procedures into the technological process, followed by many-hour annealing at high temperatures. It is for this reason that the ceramic technology of ferrite manufacturing belongs to multi-operation and power-consuming processes and does not yield a large percentage of useful products. Furthermore, using this technology it is impossible to manufacture ultrafinegrained ferrite powders because of high synthesis temperatures. Within recent time, new methods of synthesizing ferrite materials have been extensively used, which rely on heating the reagents in a high-energy electron beam (110 MeV) [8–10]. In our works [11, 12] we showed that using this heating approach it is possible to accelerate solid-phase interaction in the reaction mixture by a few factors and considerably reduce the synthesis temperature and time. The ferrites manufactured via the electron-beam heating are characterized by high values of residual magnetization, saturation magnetization, electrical resistivity and Curie temperature. It is well known that the properties of ferrites are largely determined by their microstructure. Therefore it is critical to know how heating of the initial mixture in the beam of high-energy electrons would affect the formation of the resulting ferrite microstructure. The use of electron microscopy for examination of microstructure of lithium ferrites is limited due to their high specific resistivity. Charging of the surface prevents from obtaining high-resolution images. The atomic-force microscopy (AFM) is void of this disadvantage. The purpose of this study is using the AFM method
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National Research Tomsk Polytechnic University, Tomsk, Russia, e-mail: [email protected]; [email protected]; [email protected]; [email protected]; 2Buketov K
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