| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 97 === One-dimensional nano-structures have generated considerable interest, due to their unique and superior qualities opposite bulk structures. The investigation in BiFeO3(BFO) material is to transform its morphology into nanowires. The BiFeO3 compound is one of the few materials with coexistent ferroelectricity (TC =810℃) and antiferromagnetism (Neel temperature TN =380℃) at room temperature. Therefore, BFO material is considered to have the great potential for applications in magnetic as well as in ferroelectric devices.
Though BiFeO3 was discovered in the 1960’s, but it has the week use in the field of electronics for several reasons: one is that Bi and Fe atoms make it hard form BiFeO3 single phase and ionic iron valence changes from tervalency to bivalence easily result in BiFeO3 has quite high leakage current. In the other hand BiFeO3 its low dielectric constant and resistance make it hard to measure hysteresis loop; furthermore BiFeO3 single phase cannot be synthesized by solid state method and it often includes Bi2Fe4O9、Bi25FeO40 etc impurity phases. Recently, it has generated considerable interest, being a material with great potential applications, by a combination of its magnetic and electric properties in the field of electronics: radio, television, audio-video and digital recording, and as permanent magnets. Thus, the synthesis of bismuth ferrite materials subject of renewed research and attempts have been made to obtain a pure phase. There are two major preparation technique, solid-state reactions based on Bi2O3 andFe2O3 have been used, with thermal treatments around 800°-830℃, but unreacted Bi2O3/ Bi2Fe4O9 were present and removed by washing with HNO3.. Another chemical method includes simultaneous precipitation / coprecipitation involving starting solutions such as Bi and Fe nitrates with ammonium hydroxide and sol-gel method to obtain pure-phase BiFeO3 .Nano-stucture synthesis is the new technique for the last decades. So, the subject of the research is to change BFO material structure by recently nano-techniques and hope to get better physical qualities. In the literature[40], BFO nanowires synthesis has successful done by NCA (porous nanochannel alumina) template, but in the study represents another BFO nanowires synthesis in Si substrate without using NCA template.
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