稀土Fe-B超细非晶合金的表征

采用化学还原法制备了添加稀土元素Nd的超细Fe-B非晶合金,研究了离子浓度对产物组成的影响和反应过程中溶液pH值的变化,分析了反应过程中pH值的变化规律对金属离子还原机理的影响.采用电感偶合等离子光谱(ICP) 、光电子能谱(XPS)、X射线衍射 (XRD)和电子透射显微境(TEM)等手段对产物的组成、表面原子的价态、晶相和形貌及颗粒大小进行了表征.结果表明,调节离子浓度可以得到组成不同的非晶合金,溶液中Fe2+和Nd3+ 相对独立反应,分别生成Fe-B物相与Nd(BO2)3和Nd(OH)3的混合物相,表明Nd3+的存在没有直接对BH-4还原Fe2+的过程产生影响.非晶Fe-B物相呈链球状,粒径约为250nm,非晶Nd(BO2)3和Nd(OH)3的混合体颗粒粒径＜100*!nm,呈网络絮状分布.样品表面Fe和Nd原子分别呈+2价和+3价,B以B0和B+3混合价态的形式存在.

Characterization of ultrafine Fe-B amorphous alloy with rare earth element

Ultrafine Fe-B amorphous alloy particles with rare-earth element were chemically prepared in aqueous solutions. Through analyzing the pH change of the reaction in aqueous solutions , it is found that Nd³⁺ and Fe²⁺ carry out with different mechanisms: Fe²⁺ is reduced by BH₄^- while Nd³⁺ turned into Nd(BO₂)₃ and Nd(OH)₃ by precipitating. Element contents in the particles can be varied by changing the ionic concent ration of the aqueous solution according with the result of ICP. The XRD、TEM and XPS results show that the particles are amporphous sphere , consisting of two parts: one is ball of 250 nm Fe-B particle , the other is floccule of Nd(BO₂)₃ and Nd (OH)₃ with size less than 100 nm. And it is also found that Fe²⁺ is detected in the alloy surface , but Fe , Nd(BO₂)₃ and Nd (OH)₃ are detected in the alloy bulk , which is according with the conclusion of analyzing of pH changing during the reaction.