水热合成与溶胶凝胶自蔓延法制备纳米钡铁氧体粉末的研究

【作者】 黄涛；

【导师】 黄英；

【作者基本信息】 西北工业大学 ， 应用化学， 2003， 硕士

【摘要】 铁氧体是目前广泛应用与隐身领域的吸波材料之一。铁氧体既具有亚铁磁性又有介电特性，对简谐微波电磁场来说，其相对磁导率和相对介电系数均呈现复数形式。它既能产生磁滞损耗又能产生电致损耗，因而是一种优良的微波吸收材料。以各种铁氧体为基的复合型吸波材料涂层已经引起广泛的重视和研究，但是传统铁氧体材料普遍存在粒径大的缺点。纳米铁氧体是一种性能优良的吸波剂，它不仅能吸收电磁波，而且能偏转、散射电磁波，吸波性能较一般铁氧体更佳。而且纳米铁氧体的比重小，在应用时更为方便。对传统铁氧体材料进行改造，以减小其粒径，是非常重要的研究工作。 本研究的重要工作是纳米铁氧体吸收剂的合成。纳米粒子由于具有特殊的表面效应、体积效应、量子隧道效应，表现出与常规材料不同的物理化学性质，对纳米吸波材料而言，其具有极好的吸波特性，同时具备吸波频带宽、兼容性好、质量轻和厚度薄等特点。纳米吸波材料是吸波材料研究的趋势。 纳米尺寸的铁氧体是对传统铁氧体的改造。通过探索适当的西北工业大学硕士论文摘要合成条件，使铁氧体达到纳米级的要求，从而为制备新型铁氧体晶体开辟一条新途径。铁氧体的合成方法有很多，我们选用了水热合成法与溶胶凝胶自蔓延燃烧法，此两种方法都是目前合成铁氧体的活跃方法，通过对不同条件的探索，确定最佳的合成工艺条件。同时，我们又对合成的纳米晶体进行检测与表征。使用X一射线衍射鉴别晶体结构，通过透射电子显微镜观察粒子的形貌与大小，X一射线衍射鉴别晶体是钡铁氧体，透射电子显微镜观察粒子的形态与大小，，发现粒子分散性较好，结晶性良好，形貌为六角型，通过统计计算粒子粒径，粒子大小处于纳米级，平均粒径为70nm。更多还原

【Abstract】 Hexa-ferrites have been used widely in the engineering field because of theirs superior performance. Especially, they are characteristic of low price and perfect absorbability, so they can be an important absorbent in Radar Absorbing Materials. Hexa-ferrites are characteristic of ferromagnetism and conductance, so that they can produce magnetic hysteresis loss and electricity loss. Nano-hexa-ferrites are of good absorbents. Because they can not only absorb electromagnetic wave but also deflect and scatter electromagnetic wave, their absorbability was improved. Moreover, the density of nano-hexa-ferrites was reduced, so they are very easily to be applied.The purpose of this paper is to synthesize nano-hexa-ferrites. Comparision with normal materials, Nano-materials have special performance because of their special surface effect, volume effect, and quantum effect. A kind of proper template was found in order to synthesis novel nano-ferrites. Various preparation methods have been used to obtain ferrites. In order to meet the requirement of nano-hexaferrites, hydrothermal method and sol-gel self-propagating high-temperature synthesis method were applied. By studying the effects of different precursors, pH value, temperature and time, the optimum conditions were determined, the structure of crystals was studied by X-diffract aat the same time the morphologic and the diameter of crystals were studied by TEM .更多还原