金属-自由基分子基铁磁体的设计合成进展

金属一自由基分子基铁磁体的设计和合成，是近年发展起来的新课题，本文介绍这一课题的研究现状与发展趋势。     

纳米BaFe12O19永磁铁氧体的制备、结构和磁性的研究

In this paper, the nanometer permanent magnetic BaFe₁₂O₁₉ powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO₃)₂, Fe(NO₃)₂ and NH₄HCO₃·NH₂COONH₄ were used as starting materials. The effect of crystallization process and heat treatment conditions on the particle size, microstructure and magnetic properties of powder was studied by using XRD, TEM and vibration sample magnetometometer techniques.XRD results showed that the hematite, α-Fe₂O₃, was the main phase in the powder at heat treatment temperatures below 650℃ and its amount in the powder was decreased with increasing temperature and small amount of α-Fe₂O₃ was still remained after being heated at 900℃ for 8hrs. BaFe₁₂O₁₉ was formed about 650℃ and its amount increased in the powder as temperature raised and the higher temperature was needed to attain considerable amount of BaFe₁₂O₁₉ and ideal nanometer BaFe₁₂O₁₉ particle in the powder. The temperature between 40℃～60℃ in the crystallization process was favor to the formation of good BaFe₁₂O₁₉ crystal and to the good magnetic properties of the powder. TEM showed that the particle size in the powder increased with the enhancement of the temperature and the powder crystallized at 40℃ and heated at 800℃ for 8hrs afterwards had a very homogenous particle size distribution, and that the powder heated at 900℃ for 8hrs with the same crystalline condition as the former had a typical hexagonal shape and a chain aggregation. Specific saturation and residential magnetizations and coercive force of the powder increased mono-tonically with the increase of temperature, and reached 39.86A·m²·kg^-1, 23.96A·m²·kg^-1, 480kA·mg^-1 at 900℃, respectively.     

有机磁体--新世纪的新材料

有机磁性材料是最近二十多年发展起来的新型的功能材料 ,因为其结构的多样性 ,可用化学方法合成 ,可得到磁性能与机械、光、电等方面结合的综合性能等特点 ,在超高频装置、高密度存贮材料、吸波材料、微电子工业和宇航等需要轻质磁性材料的领域有很大的应用前景。本文综述了有机磁性化合物的发展和研究近况。     

MgFe2O4纳米粉体的水热合成及其表征(英)

MgFe₂O₄ nanoparticles were hydrothermally synthesized at 150 ℃ using iron nitrate [Fe(NO₃)₃·9H₂O], magnesium nitrate [Mg(NO₃)₂·6H₂O] and sodium hydroxide (NaOH) as starting materials by carefully controlling the reaction conditions. The influences of several factors such as presence or absence of Na⁺, molar ratio of Fe³⁺ / Mg²⁺, concentration of mental ions, temperature and reaction time on resultant products were investigated in the hydrothermal process. The sample was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its magnetic properties were measured using vibrating sample magnetometer (VSM).     

具有螺共轭效应的有机电性及磁性材料研究进展

螺共轭术语是1967年由Simmons和Fukunaga首次提出的, 由于其特殊的立体电子效应而引起了科学家们的广泛关注. 综述了近年来具有螺共轭效应的有机导电材料及磁性材料研究进展, 并提出了一些新的设想.     

非晶态RE—TM(RE=Nd,Pr,TM=Fe,Co,Ni)薄膜的磁性和Pr的变价行为

本文通过对非晶态轻稀土Pr,Nd和过渡族金属Fe,Co,Ni薄膜合金的低温磁性研究,分别得到了(Pr,Nd)_x-(Fe,Co,Ni)_1-x合金中Pr,Nd和Fe,Co,Ni金属磁矩随成份x的变化,并且通过对磁矩的研究得到Pr离子的4f电子可能有退局域化的结论。 关键词：     

磁感生各向异性的一个新模型

本文通过分析金属-金属型非晶合金中磁感生各向异性随成分的变化关系,提出了四面体元方向有序的模型。与实验拟合结果表明此模型与实验符合较好。 关键词：