Room Temperature Ferromagnetismin Co-doped ZnO Bulks

Pure single phase of Zn0.95Co0.05O bulks were successfully prepared by solidstate reaction method.The effects of annealing atmosphere and temperature on the room temperature ferromagnetic behavior were investigated. The results show that the airannealed samples has similar weak ferromagnetic behavior with the assintered samples, but the obvious ferromagnetic behavior is observed for the samples annealed in vacuum or Ar/H2 gas, indicating that the strong ferromagnetism is associated with high oxygen vacancies density. High saturation magnetization Ms=0.73 μB/Co and eoercivity Hc=233.8Oe are obtained for the Ar/H2 annealed samples with pure single phase structure when annealing temperature is 600 ℃.     

注入剂量对300℃下Mn+注入p型GaN薄膜的结构和磁性影响

在(0001)面的蓝宝石衬底上用低压MOCVD法生长p型GaN外延层.对p型GaN薄膜用180keV的Mn 离子注入进行磁性粒子掺杂,注入时GaN薄膜处于300℃,注入剂量分别为5.0×1015、1.0×1016和5.0×1016cm-2.对注入的样品在N2气流中进行快速热退火处理,温度为850℃,时间为30s.用超导量子干涉仪(SQUID)对样品的磁性进行了分析,在5.0×1015cm-2的注入样品中发现了较强的铁磁性;而1.0×1016和5.0×1016cm-2的Mn 离子注入样品中铁磁响应有所减弱.结合用X射线衍射(XRD)和扫描电子显微镜(SEM)对在不同剂量下Mn 注入GaN薄膜的结构、形貌和成分的分析,揭示了不同剂量磁性离子注入给GaN薄膜带来的结构、形貌和相应的铁磁性变化规律,发现只有适当的注入剂量(5.0×1015cm-2)才有利于在300℃下用180keV的Mn 注入对p型GaN薄膜进行磁性离子掺杂.     

Cu掺杂ZnO纳米结构的室温铁磁性研究

采用柠檬酸盐法合成了一系列Zn1-xCuxO(x=0.01,0.02,0.03,0.04)纳米粒子,XRD结果表明Zn1-xCuxO样品为单一的ZnO纤锌矿结构.磁性测试结果表明Zn1-xCuxO(x=0.01,0.02,0.03,0.04)在室温下表现为铁磁性.XRD,TEM与XPS的测试结果表明,样品中没有具有铁磁性的第二相出现.经分析Zn1-xCuxO(x=0.01,0.02,0.03,0.04)的铁磁性是Cu掺杂ZnO纳米结构的本质特征.     

Mn注入 n型 Ge单晶的特性研究

采用离子能量为 100keV,剂量为 3× 1016cm- 2的离子注入技术,室温下往 n型 Ge( 111)单晶 衬底注入 Mn+离子,注入后的样品进行 400℃热处理.利用 X-射线衍射法 (XRD)和原子力显微 镜( AFM)对注入后的样品进行了结构和形貌分析, 俄歇电子能谱法 (AES)进行了组分分析,交变 梯度样品磁强计( AGM)进行了室温磁性测量.结果表明原位注入样品的结构是非晶的,热处理后 发生晶化现象.没有在样品中观察到新相形成. Mn离子较深的注入进 Ge衬底,在 120 nm处 Mn原子百分比浓度达到最高为 8%.热处理后的样品表现出了室温铁磁特性.     

Sn掺杂对(In0.95-xSnxFe0.05)2O3薄膜的结构、电学及磁特性的影响

我们利用脉冲激光沉积的方法制备了一系列(In0.95-xSnxFe0.05)2O3 (x=0~0.09)薄膜,并在其中发现了室温铁磁性。X射线衍射结果表明锡与铁离子已掺入氧化铟晶格。随着锡的掺入,样品内的载流子浓度得到了很大的提高,但相应的铁磁性却几乎没有变化。我们认为氧空位相关的束缚磁极化子模型能够跟好的解释我们的铁掺杂氧化铟薄膜中的铁磁耦合的机制,而载流子传导的RKKY相互作用则不适用于这一系统。     

基于虚拟仪器技术的金属磁记忆检测与故障诊断系统

以铁磁性杆件为对象建立模型,从理论上研究了金属磁记忆的检测和故障诊断方法,并设计了以虚拟仪器技术为基础的金属磁记忆的检测和故障诊断系统,采用小波变换对传感器输入信号进行处理,消除噪声干扰。实现了离线或在线检测与诊断,有效地判断出受载试件上的应力集中部位,找出了应力集中线的位置。     

Ferromagnetic properties of Cu- and Fe-codoped nanocrystalline CdO powders: Annealing in hydrogen promote long-range ferromagnetic order

A mixture of cadmium acetate dihydrate, bis(acetylacetonato)copper, and tris(acetylacetonato)iron complexes is thermally co-decomposition to synthesizes Cu and Fe-codoped CdO (CdO:Cu:Fe) powders. The aim of this study is to examine the effect Fe doping on the appearance and development of room temperature ferromagnetism (RT-FM) in the presence of Cu ions as catalyst. X-ray diffraction (XRD) and X-ray fluorescence (XRF) measurements were carried out to study powders purity and crystalline structure. The XRD results show that Cu and Fe ions are incorporated in the ZnO crystal lattice by occupying Zn sites thereby forming ZnO:Cu:Fe solid solution (SS), whereas XRF confirms the purity of the obtained SS. The magnetic properties of the as-prepared and H-annealed (CdO:Cu:Fe–H) SS powders was investigated as a function of %Fe doping level. It was observed that the magnetic behaviour of pure as-synthesised CdO is mainly diamagnetic with slight FM phase. However, its behaviour with Cu and Fe codoping transforms to the mostly paramagnetic overlapped with small FM behaviour. More importantly, it was found that that annealing under H₂ atmosphere induces the reduction of CdO to form pure Cd metal, resulting in total transformation to FM behaviour with strength increases consistently with doping. Furthermore, with hydrogenation a tremendous enhancement of FM parameters takes place so that the M_s increases by about 1230% reaching a very high value of 1.43 emu/g for 1.8%Fe doping level of CdO.     

二维Fe5GeTe2单晶的大量制备及吸波性能研究

目的 快速制备克量级、高质量的二维磁性Fe₅GeTe₂单晶,并开发具有范德华结构、室温铁磁性及优异微波吸收性能的新型吸波材料。方法 通过调控输运剂的含量,并缩短化学气相传输法的恒温段时长,以探索高质量Fe₅GeTe₂单晶的快速、制备量大的方法。将Fe₅GeTe₂单晶与石蜡按不同质量分数混合后,通过同轴线测试法分析其微波性能。结果 成功制备了克量级、高质量的Fe₅GeTe₂单晶样品。借助矢量分析仪的同轴线测试法研究Fe₅GeTe₂单晶的微波损耗性能发现,当Fe₅GeTe₂的质量分数为30%时,Fe₅GeTe₂的吸波特性较差,最佳反射损耗值仅为-4.8dB;当Fe₅GeTe₂的质量分数达到70%时,Fe₅GeTe_...