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以硝酸铋、硝酸铁以及硝酸镝等无机硝酸盐为原料通过化学液相法在Pt(111)/Ti/SiO_2/Si上制备了Dy~(3+)掺杂的BiFeO_3薄膜,研究了Dy~(3+)掺杂量的变化对Bi_(1-x)Dy_xFeO_3薄膜的晶体结构和磁性的影响.Dy~(3+)掺杂量不高于10%的Bi_(1-x)Dy_xFeO_3薄膜可以得到与纯BiFeO_3相同的晶体结构.随着Dy3+掺杂量的进一步增大,Bi_(1-x)Dy_xFeO_3薄膜的晶体结构发生变化,晶格从菱心结构转变为单斜或四方结构.磁性测试显示:随着Dy~(3+)掺杂量的增加Bi_(1-x)Dy_xFeO_3薄膜的磁性增强,同时从无饱和磁化强度和零磁滞的S型磁化曲线的形状判断,薄膜由于铁磁反铁磁转变时两磁性相竞争表现出自旋玻璃态的特征. 相似文献
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对R2Co17-xSix(R=Ce,Gd和Y)化合物的X射线衍射和磁性测量研究结果表明,Si原子的加入使R2Co17化合物的室温磁晶各向异性由易面转变为易轴,各向异性常数随Si原子浓度的增加而出现极大值、重点讨论了Si原子在Co次晶格四个不同晶位择优占位与Co次晶格磁晶各向异性演化的关系,其中18h晶位对Co次晶格各向异性负贡献起重要作用 相似文献
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唐树伟吴孟修罗东明王鑫林白树林 《中国有色金属学报》2023,(1):138-148
采用第一性原理计算方法研究了铝钒合金Al_(3)V及其C、Fe、Si取代掺杂的Al_(24)V_(7)X、Al_(23)V_(8)X (X=C,Fe,Si)合金晶体结构的稳定性、电子结构和力学性能。计算结果表明,X (X=C,Fe,Si)掺杂对Al_(3)V合金晶体结构的影响较小,Al_(24)V_(7)X和Al_(23)V_(8)X (X=C,Fe,Si)仍然保持明显的Al_(3)V金属特征。Mulliken电荷布居和重叠布居分析显示X (X=C,Fe,Si)会与周围Al和V原子产生键合作用,提高Al_(24)V_(7)X和Al_(23)V_(8)X (X=C,Fe,Si)的稳定性和抗变形能力。X (X=C,Fe,Si)的取代掺杂对Al_(3)V合金晶体的刚度影响较小,但能使Al_(3)V合金材料的塑性有所提升,有望能有效解决Al_(3)V合金的脆性问题,拓宽Al_(3)V合金的应用范围。 相似文献
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采用基于密度泛函理论的第一性原理方法,研究掺杂单个Al、Zn、Cu、Ni、Li、Zr原子对3C-SiC/Mg体系界面结合的影响,选取代表性的Zn原子和Zr原子进行Mulliken电荷、重叠布居数和态密度计算分析。结果表明,3C-SiC/Mg界面模型最稳定的堆垛结构是将5层的Mg(0001)堆垛在10层的 3C-SiC(111)面上,C封端的中心型模型在6种3C-SiC/Mg模型结构中分离功最大,界面间距最小,界面的润湿性最好;掺杂Zn原子后,3C-SiC/Mg-Zn体系的分离功减小,掺杂的Zn原子与Mg原子成反键,态密度中赝能隙变小使得3C-SiC/Mg-Zn体系的共价键性减弱,不利于3C-SiC/Mg-Zn界面结合; 掺杂Al、Cu、Ni、Li、Zr原子后,体系的分离功增大,Zr原子对界面润湿性的改善效果最好。掺杂Zr原子后,界面层Mg原子与Si原子的反键消失,与C原子在界面处形成Zr-C强共价键,态密度离域性增强,成键能力增强,导致3C-SiC/Mg-Zr体系的分离功增大最多。 相似文献
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采用溶胶-凝胶法在LaNiO3/Si衬底上制备Er3+掺杂BaTiO3薄膜.通过XRD、AFM和PL图谱分别研究薄膜的晶体结构、形貌以及上转换发光性能.结果表明,薄膜的微观结构和发光性能与Er3+掺杂晶格的位置有关.A位掺杂薄膜较B位掺杂薄膜具有较小的晶格常数和较好的结晶.PL光谱表明:A位掺杂的薄膜和B位掺杂的薄膜都于528 nm和548nm处获得较强的绿色上转换发光以及在673 nm处获得较弱的红光,分别对应Er3+离子的2H11/2→4I15/2,4S3/2→4I15/2和4F9/2→4I15/2能级跃迁.相对于B位掺杂的薄膜,A位掺杂样品有较强的绿光发射积分强度以及较弱的红光发射相对强度.这种差异可以通过薄膜的结晶状况和交叉弛豫机制来进行解释. 相似文献
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采用溶胶-凝胶法在LaNiO3/Si衬底上制备Er3+掺杂BaTiO3薄膜。通过XRD、AFM和PL图谱分别研究薄膜的晶体结构、形貌以及上转换发光性能。结果表明,薄膜的微观结构和发光性能与Er3+掺杂晶格的位置有关。A位掺杂薄膜较B位掺杂薄膜具有较小的晶格常数和较好的结晶。PL光谱表明:A位掺杂的薄膜和B位掺杂的薄膜都于528nm和548nm处获得较强的绿色上转换发光以及在673nm处获得较弱的红光,分别对应Er3+离子的2H11/2→4I15/2,4S3/2→4I15/2和4F9/2→4I15/2能级跃迁。相对于B位掺杂的薄膜,A位掺杂样品有较强的绿光发射积分强度以及较弱的红光发射相对强度。这种差异可以通过薄膜的结晶状况和交叉弛豫机制来进行解释。 相似文献
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以石墨、碳化硅、硅粉体为原料,采用预处理工艺得到复合原料粉体,热压烧结制备C/Si 80/20 at%靶材。将制备的靶材在不同基片上溅射镀膜,分析薄膜的形貌及其生长模式。通过扫描电镜分析微观形貌、四探针测试电阻率、XRD结合拉曼光谱分析晶体结构,结果如下:(1)石墨和硅粉球磨混合48h可获得Si元素均匀分布的C/Si复合粉体;该粉体在1900 ℃下真空热处理时,C/Si通过互扩散生成等轴晶3C-SiC;(2)不同粒径的β-SiC粉体在1900 ℃真空热处理时,颈部生长速率和晶体结构转变存在显著差异。在高温下,纳米β-SiC粉体蒸汽压高,颈部增长速率快,通过蒸发-凝聚再结晶后可获得球形度良好的3C-SiC微米颗粒。(3)以C/Si/SiC 70/10/10 at%粉体为原料,采用球磨和高温真空热处理得到预处理粉体并热压制备C/Si 80/20 at%靶材,结果表明:与C/SiC 60/20 at%二元组分体系相比,三元组分预处理粉体制备靶材的均匀性好,平均电阻率3.9 mohm·cm,极差0.59,密度2.34 g/cm3,石墨化度0.17, 石墨晶体完整性好。(4)将制备的C/Si 80/20at%靶材分别在玻璃、硅片以及陶瓷基片上磁控溅射制备类金刚石薄膜,结果发现:在Si基体表面薄膜呈纵向生长模式,膜层微粒小于20 nm;在玻璃基体表面膜层呈层状生长模式且结合紧密;在陶瓷基体表面薄膜呈片状生长模式,膜层由微米级颗粒结合组成,与陶瓷基体的微观组织相似。 相似文献
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The magnetic properties and magnetocaloric effect in Fe4MnSi3Bx compounds with x=0, 0.05, 0.10, 0.15, 0.20, 0.25 have been investigated. X-ray diffraction study shows that all these compounds investigated crystallize in the Mn5Si3-type structure with space group P63/mcm. Boron insertion in the host ternary silicide Fe4MnSi3 does not change the crystal symmetry, only leads to an increase of the lattice parameters, indicating the B atoms entered the interstitial sites. With increasing B content, the Curie tem... 相似文献
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The structure and magnetic properties of CeMn2−xCoxGe2 (0.0≤x≤1.0) were studied by X-ray powder diffraction and magnetization measurements. All compounds crystallize in the ThCr2Si2-type structure with space group I4/mmm. Substitution of Co for Mn leads to a linear decrease in the lattice constants and the unit cell volume. Increasing substitution of Co for Mn shows a depression of ferromagnetic ordering. 相似文献
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目的 揭示飞秒激光加工参数对反应烧结碳化硅(Reaction-Bounded Silicon Carbide,RB-SiC)表面形貌的影响规律。方法 通过改变激光能量密度和有效脉冲数,研究RB-SiC表面烧蚀槽的形貌变化规律,确定飞秒激光加工RB-SiC的去除机理。采用扫描电镜、共聚焦显微镜、X射线能谱仪和拉曼光谱仪分析RB-SiC烧蚀前后的表面形貌演变行为。结果 激光能量密度在0.62~10.48 J/cm2时,Si富集区域形成凹陷结构,SiC颗粒区域形成周期性结构(Laser-Induced Periodic Surface Structures,LIPSS),周期约为970 nm。随着激光能量密度的增加,凹陷结构扩大加深,表面球形纳米颗粒增多,烧蚀槽宽度呈对数增长。有效脉冲数在69~ 1 379,Si富集区域的去除量高于SiC颗粒区域的去除量。随着有效脉冲数增加,烧蚀槽深度显著加深,凹陷结构扩展成深坑结构,飞溅至烧蚀槽外侧的纳米颗粒聚集成团簇物,由Si、SiC和非晶态SiO2构成的沉积物在烧蚀槽边缘形成堆积层。结论 降低激光能量密度能够减少RB-SiC表面凹陷和纳米颗粒,有助于提升烧蚀形貌的一致性。增加有效脉冲数会促进烧蚀槽底部深坑结构的产生,进而扩大Si与SiC去除量之间的差异。 相似文献
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The CuO doped with 5%-20% Mn(molar fraction) solids were sintered from CuO and MnO2 powder at high temperature (1 273 K) for 8 h. X-ray diffraction was used to determine the solid crystallinity and to address the formation of secondary phases. It is found that it is difficult to achieve pure Cu1-xMnxO phase using standard solid phase reaction. However, sintering under a pressure of 27.7 MPa significantly reduces the undesirable second phase CuMn2O4, providing a route to achieve pure Cu3-x MnxO phase. SQUID magnetometry was employed to characterize the magnetic properties. Mn-doped CuO presents ferromagnetic characteristics below 70 K. Electrical transport properties were measured in a current-perpendicular-to-plane(CPP) geometry using the PPMS, which suggests variable-range hopping mechanism. 相似文献
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《Acta Materialia》2007,55(6):2129-2135
Nanocomposite CrAlSiN compounds prepared by the cathodic arc evaporation technique were subjected to structural and mechanical characterization tests. X-ray diffraction, X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) were employed to investigate the effects of Si addition on the structure and phase development of the metastable NaCl structure of high aluminum CrAlN films. TEM studies revealed that partial substitution of the metal component by Si in CrAlN results in the nucleation of a wurtzite h-AlN phase even for amounts of silicon as low as ∼2–3 at.%. XAS measurements at the Cr and Si K-edges indicated that the local environment of Cr atoms is strongly affected by the Si addition, and that silicon may also be part of the crystalline phase. These results indicate the formation of complex Cr–Si–X compounds, where X can be N, Al or both, and the formation of composite nanocrystalline CrAlSiN films. 相似文献
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1 Introduction Nowadays, there is much interest in magnetic refrigeration materials, as they offer the prospect of an energy-efficient and environment friendly alternative for the traditional vapour cycle refrigeration technique. Magnetic refrigeration is… 相似文献
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Hailing Yang Xiaoguang Xu Guoqing Zhang Jun Miao Xin Zhang Shizhe Wu Yong Jiang 《稀有金属(英文版)》2012,31(2):154-157
We have observed room temperature ferromagnetism in Mn-doped and (Fe, Mn)-codoped ZnO thin films grown under different oxygen partial pressures by pulsed laser deposition. The X-ray diffraction and optical transmission spectra studies demonstrate the natural incorporation of Fe and Mn cations into wurtzite ZnO lattices. The effects of transition metal doping and defects on the magnetic properties was investigated. It is found that room temperature ferromagnetism is sensitive to oxygen vacancy and Zn vacancy. The absence of ferromagnetism in pure ZnO films grown under different oxygen partial pressures reveals that the transition metal ions should also play an important role in inducing the ferromagnetism. 相似文献
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THEEFFECTOFSILICONADDITIVEONTHESTRUCTURE ANDPROPERTIESOFC-B_4C-SiCCOMPOSITEHUANGQizhong;YANGQzaoqinandWULijun(PowderMetallurg?.. 相似文献