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1.
利用脉冲激光沉积方法制备出了具有室温铁磁性的Ni1-xFexO(x=0.02,0.05)稀磁半导体.X射线衍射(XRD)结果表明Ni1-xFexO的晶体结构为NaCl结构,并且在Fe含量较高的Ni0.95Fe0.05O中出现了少量的α-Fe2O3物相.X射线吸收近 关键词: 1-xFexO')" href="#">Ni1-xFexO XANES 脉冲激光沉积方法  相似文献   

2.
利用X射线吸收精细结构、X射线衍射和磁性测量等技术研究脉冲激光气相沉积法制备的Zn1-xCoxO (x=0.01,0.02)稀磁半导体薄膜的结构和磁性.磁性测量结果表明Zn1-xCoxO样品都具有室温铁磁性.X射线衍射结果显示其薄膜样品具有结晶良好的纤锌矿结构.荧光X射线吸收精细结构测试结果表明,脉冲激光气相沉积法制备的样品中的Co离子全部进入ZnO晶格中替代了部分Zn的格点位置,生成单一相的Zn1-xCoxO 稀磁半导体.通过对X射线吸收近边结构谱的分析,确定Zn1-xCoxO薄膜中存在O空位,表明Co离子与O空位的相互作用是诱导Zn1-xCoxO产生室温铁磁性的主要原因. 关键词: 1-xCoxO稀磁半导体')" href="#">Zn1-xCoxO稀磁半导体 X射线吸收精细结构谱 脉冲激光气相沉积法  相似文献   

3.
刘强  程新路  范勇恒  杨向东 《物理学报》2009,58(4):2684-2691
采用密度泛函理论下的第一性原理平面波超软赝势方法,对Zn1-xMgxO超晶胞和掺杂Al,N后的Zn1-xMgxO超晶胞分别进行了优化计算.结合广义梯度近似计算了Al和N共掺杂后Zn1-xMgxO的能带结构、电子态密度和Mulliken电荷布居分布.计算表明:掺入N原子的2p态电子为Zn1-xMgxO价带顶提供空穴载流子,使Zn1-xMgxO价带顶向高能方向移动;掺入Al原子的3p态电子则与N原子的2p态电子在费米能级附近发生轨道杂化,使费米能级处价带能级展宽,Al和N共掺杂可获得p型Zn1-xMgxO. 关键词: 密度泛函理论 1-xMgxO')" href="#">Zn1-xMgxO 电子结构 共掺杂  相似文献   

4.
ZnCoO稀磁半导体的室温磁性   总被引:1,自引:0,他引:1       下载免费PDF全文
采用固相反应法,将ZnO和Co2O3粉末按不同的成分配比混合,制备了稀磁半导体Zn1-xCoxO (x=0.02,0.06,0.10)材料.并使用H2气氛退火技术对样品进行了处理,得到了具有室温铁磁性的掺Co氧化锌稀磁半导体.利用全自动X射线衍射仪、X射线光电子能谱仪、高分辨透射电子显微镜和超导量子干涉器件磁强计对样品的结构、晶粒的尺寸、微观形貌以及磁性等进行了测量和标度. 关键词: 稀磁半导体 氧化锌 掺杂 固相反应法  相似文献   

5.
史力斌  李容兵  成爽  李明标 《物理学报》2009,58(9):6446-6452
采用基于密度泛函理论和平面波赝势技术的CASTEP程序对Zn1-xBexO合金电子结构和光学性质进行了计算.当0≤x≤1,其带隙从0.963 eV变化到7.293 eV.分析了晶格畸变和能带间排斥效应对带隙的影响.当Be含量x=0.125,0.25,0.375,0.5,0.625,0.75时,a/b轴压应变控制着带隙变化;当x=0.875,1时,c轴压应变控制着带隙变化.能带间的p-d排斥影响价带顶变动,Γ1vΓ1c之间排斥影响导带底变动.这些能带间的排斥效应被用来分析Zn1-xBexO带隙变动.另外,也分析了Zn1-xBexO介电函数虚部ε2. 关键词: 带结构 光学性质 应变 排斥  相似文献   

6.
高茜  娄晓燕  祁阳  单文光 《物理学报》2011,60(3):36401-036401
基于Zn1-xMnxO纳米薄膜磁性研究的实验结果及相关理论,建立了一个包含多种交换作用的Ising多层膜模型,采用Monte Carlo模拟的Metropolis算法对于其铁磁序的成因进行了模拟研究.结果表明,Mn掺杂浓度(x)越低越有利于铁磁序的形成,但是x越低,系统的磁化强度越小,居里温度越低.载流子对铁磁序的形成所起的调节作用随着x的增大而增强,又随着磁各向异性常数(K)的增大而弱化.本 关键词: 稀磁半导体(DMS) 1-xMnxO纳米薄膜')" href="#">Zn1-xMnxO纳米薄膜 Ising多层膜 Monte Carlo模拟  相似文献   

7.
唐晶  陈长乐  金克新  赵省贵 《物理学报》2008,57(2):1166-1170
分别采用溶胶-凝胶法和脉冲激光沉积的方法制备了La067Sr033FexMn1-xO3(x=0, 005, 010, 015)系列块材和薄膜,研究了Fe部分替代对La067Sr033FexMn1-xO3薄膜 关键词: 光诱导 Fe掺杂 晶格效应  相似文献   

8.
利用X 射线衍射(XRD)和X射线吸收精细结构(XAFS)方法研究了磁控共溅射方法制备的MnxGe1-x薄膜样品的结构随掺杂磁性原子Mn含量的变化规律.XRD结果表明,在Mn的含量较低(7.0%)的Mn0.07Ge0.93样品中,只能观察到对应于多晶Ge的XRD衍射峰,而对Mn含量较高(25.0%, 36.0%)的Mn0.25Ge0.75和Mn关键词: 磁控溅射 XRD XAFS xGe1-x稀磁半导体薄膜')" href="#">MnxGe1-x稀磁半导体薄膜  相似文献   

9.
张忻  李佳  路清梅  张久兴  刘燕琴 《物理学报》2008,57(7):4466-4470
采用机械合金化制备了n型(Bi1-xAgx)2(Te1-ySey)3合金粉体,对其进行XRD分析表明Bi,Te,Ag,Se单质粉末,经2h球磨后实现了合金化;SEM分析表明随着机械合金化时间延长粉体颗粒变得均匀、细小,颗粒尺寸在微米至亚微米数量级.采用放电等离子烧结制备了块体样品,研究了合金成分和球磨时间对热电性能的影响.结果表明材料的热电性能与掺杂元素有密切关系,Ag有利于提高功率因子和降低晶格热导率,球磨10h的(Bi0.99Ag0.01)2(Te0.96Se0.04)3合金粉末的烧结块体具有最大的功率因子和最低的晶格热导率,并在323K取得最高ZT值0.52. 关键词: 1-xAgx)2(Te1-ySey)3合金')" href="#">(Bi1-xAgx)2(Te1-ySey)3合金 机械合金化 放电等离子烧结 热电性能  相似文献   

10.
邱东江  王俊  丁扣宝  施红军  郏寅 《物理学报》2008,57(8):5249-5255
以NH3为掺N源,采用电子束反应蒸发技术生长了Mn和N共掺杂的Zn1-xMnxO:N薄膜,生长温度为300℃,然后在O2气氛中400℃退火0.5 h.X射线衍射测量表明,Zn0.88Mn0.12O(Mn掺杂)薄膜或Zn0.88Mn0.12O:N(Mn和N共掺杂)薄膜仍具有单一晶相纤锌矿结构,未检测到杂质相 关键词: ZnO薄膜 Mn和N共掺杂 电学特性 磁特性  相似文献   

11.
Zn1–xFexO (x=0–0.05) nanoparticles were synthesized without a catalyst by a two-step method. Fe was doped into ZnO by a source of metallic Fe sheets in a solid–liquid system at 80 °C, and the Zn1−xFexO nanoparticles were obtained by annealing at 300 °C. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy were used to characterize the structural properties of the as-grown Zn1−xFexO. The optical properties were determined by Infrared and Ultraviolet–visible spectroscopy. The results confirm that the crystallinity of the ZnO is deteriorated due to Fe-doping. XPS results show that there is a mixture of Fe0+ and the Fe3+ in the representative Zn0.95Fe0.05O sample. The optical band gap of Zn1−xFexO is enhanced with increasing of Fe-doping. Room temperature ferromagnetism was observed in all the Fe-doped ZnO samples.  相似文献   

12.
We have investigated the magnetic and optical properties of chemically low temperature-synthesized Zn1– x Fe x O (x = 0.05 and 0.10) diluted magnetic semiconducting nanoparticles (~7 nm). Observed magnetic behaviour of x = 0.05 samples showed that the net magnetic interaction was antiferromagnetic-like, a feature established by Curie–Weiss fit, concave Arrott–Belov–Kouvel (ABK) plots with the absence of spontaneous magnetization even at 5 K and stretched exponential-type time-dependent magnetization behaviour. Optimization of the Fe(x) dopant concentration in Zn1– x Fe x O gave the most favourable room-temperature ferromagnetism for x = 0.10, as supported by finite coercive field (~94.4 Oe) and remanent magnetization (0.011 µB/Fe ion) from strong hysteretic magnetization vs. magnetic-field curves at room temperature. The Curie temperature of the x = 0.10 sample was estimated at ~388 K. The existence of a room-temperature ferromagnetic phase was further established by the convex nature of the ABK plots with finite spontaneous magnetization. The observed magnetic behaviour for different x values is best explained by a magnetic polaron model.  相似文献   

13.
郝延明  王玲玲  严达利  安力群 《物理学报》2009,58(10):7222-7226
通过X射线衍射、磁测量等手段对电弧炉制备的不同热处理条件的Sm2Fe17-xCrxx=1—3)化合物的结构和磁性进行了研究.结果表明1050 ℃下退火5 d的Sm2Fe17-xCrxx=1—3)化合物具有菱方相的Th2Zn17型结构,同样温度下退 关键词: 2Fe17-xCrx化合物')" href="#">Sm2Fe17-xCrx化合物 磁体积效应 居里温度 磁晶各向异性  相似文献   

14.
Co掺杂对ZnO薄膜结构和性能的影响   总被引:9,自引:0,他引:9       下载免费PDF全文
采用PVA溶胶-凝胶方法,在玻璃衬底上制备了Zn1-xCoxO薄膜,利用X射线衍射仪(XRD)研究了不同Co含量对其微结构的影响.采用振动样品磁强计(VSM)测量了Zn0.88Co0.12O样品室温下的磁性.采用荧光光谱仪研究了Zn1-xCoxO样品室温下的发光特性,分析掺杂含量对其发光性能的影响,发现随着掺杂含量的增加,蓝光发光峰有一定的红移现象. 关键词: PVA方法 ZnO 掺杂  相似文献   

15.
范军峰  张宁 《物理学报》2007,56(10):6056-6060
用溶胶-凝胶法制备了Fe掺杂BaTiO3粉体,在1350℃下烧结成圆片状多晶样品,并与Tb1-xDyxFe2-y胶合成磁电(ME)双层膜或三层膜.实验分析表明Fe:BaTiO3依然是四方相钙钛矿结构,但是居里温度及相变潜热均略低于纯净BaTiO3.研究了Tb1-xDyxFe2-y-Fe∶BaTiO3双层膜和Tb1-xDyxFe2-y-Fe∶BaTiO3-Tb1-xDyxFe2-y三层膜的ME效应.在2.8×104A/m的磁场下,两者的横向ME电压系数均达其峰值,分别为6.225和26.25mV·(A·m-1)-1·cm-1.并且,用掺杂BaTiO3制备的双层膜和三层膜的横向ME电压系数均为相同条件下用纯净BaTiO3制备的双层膜和三层膜的横向ME电压系数的1.5倍.另外由于不含铅,锆等有害物质,符合环保要求,因此采用掺杂BaTiO3制备的磁电效应器件具有深入研究和应用价值.  相似文献   

16.
To make p-type diluted magnetic semiconductor (DMS), Ni1−xFexO nanofibers with different Fe doping concentrations have been successfully synthesized by electrospinning method using polyvinyl alcohol (PVA) and Ni(CH3COO)2·4H2O as starting materials. The nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, superconductivity quantum interference device (SQUID) and X-ray photoelectron spectroscopy (XPS) test. The results show that Fe doping has no influence on the diameter and surface morphology of NiO nanofibers, and the nanofibers are polycrystalline with NaCl structure. All Fe-doped samples show obvious ferromagnetic properties and the saturation magnetization is enhanced with increase of the doping concentration of Fe, which indicates that the doped Fe has been incorporated into the NiO host and results in room-temperature ferromagnetism in the Ni1−xFexO nanofibers.  相似文献   

17.
Mn掺杂ZnO稀磁半导体材料的制备和磁性研究   总被引:3,自引:0,他引:3       下载免费PDF全文
采用共沉淀方法制备了名义组分为Zn1-xMnxO(x=0.001,0.005,0.007,0.01)的Mn掺杂的ZnO基稀磁半导体材料,并研究了在大气气氛下经过不同温度退火后样品的结构和磁性的变化.结果表明:样品在600℃的大气条件下退火后, 仍为单一的六方纤锌矿结构的ZnO颗粒材料;当样品经过800℃退火后,Mn掺杂量为0.007,0.01的样品中除了ZnO纤锌矿结构外还观察到ZnMnO3第二相的存在.磁性测量表明,大气条件下600℃退火后的样品,呈现出室温铁磁性;而800℃退火后的样品,其室温铁磁性显著减弱,并表现为明显的顺磁性.结合对样品的光致发光谱的分析,认为合成样品的室温铁磁性是由于Mn离子对ZnO中的Zn离子的替代形成的. 关键词: ZnO 掺杂 稀磁半导体 铁磁性  相似文献   

18.
By the electrospinning and calcination techniques, we have prepared uniform nanofibers of Co1−x Zn x Fe2O4 (0.0≤x≤0.5) ferrites with diameters of 110–130 nm. The Co1−x Zn x Fe2O4 nanofibers are single-phase spinels and the lattice constant with Zn content deviates from the Vegard’s law for these Co1−x Zn x Fe2O4 nanofibers. The Co1−x Zn x Fe2O4 nanocrystal grains by which are built nanofibers increase with calcination temperature. Variations of coercivity and saturation magnetization with calcination temperature can be explained in terms of the grain-size (D) effect. The coercivity (H c) of Co0.5Zn0.5Fe2O4 nanofibers varies as D 0.65 and basically follows the predicted D 2/3 dependence based on the random anisotropy model in a D range below the single-domain size around 40 nm. The saturation magnetization of Co1−x Zn x Fe2O4 nanofibers initially increases with increasing Zn content, reaches a maximum value at x=0.3 and then decreases with further increase of Zn content, while the coercivity exhibits a continuous reduction with the increase of Zn content.  相似文献   

19.
This paper is focusing on the synthesis of Zn1−xFexS nano-particles with x = 0, 0.1 and 0.2 by chemical co-precipitation method, the prepared of which are characterized by XRD, EDS, TEM, PL, magnetization versus field behavior and M-T curve. In the XRD patterns, Zn1−xFexS nano-particles are shown of cubic zinc blende structure, and the broadening diffraction peaks consistent with the small-size characteristic of nano-materials. The diameter of nano-particles is between 3.3 and 5.5 nm according to the HR-TEM images. The EDS data confirm the existence of Fe ions in Fe-doped ZnS nanoparticles. There we found that Fe-doping did not import new energy bands or defect states, but reduced the intensity of PL peaks. The magnetization versus field behaviors were illustrated by the M-H curves at both 5 K and 300 K, respectively, where no remanence or coercive force was observed. This phenomenon indicates that the Zn1−xFexS (x = 0.1) nano-particles are superparamagnetic. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves further reveal that the blocking temperature (TB) of the superparamagnetic behavior might be below 5 K.  相似文献   

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