共查询到20条相似文献,搜索用时 250 毫秒
1.
用脉冲激光沉积技术(PLD)在MgO(100)基底上生长了嵌埋Co纳米晶的BaTiO3复合薄膜. 分别利用x射线衍射(XRD)、原子力显微镜(AFM)以及拉曼光谱(Raman)对薄膜的微观结构、表面 形貌进行了表征. 结果表明该薄膜为c轴取向的四方晶体结构,薄膜表面均匀、致密、 具有原子尺度的光滑性,其均方根表面粗糙度(RMS)达到015nmCo以纳米晶形式嵌埋BaTi O3基体中,呈单分散性均匀分布,其粒径随激光脉冲数的增加而增大. Co:BaTiO3纳米 复合薄膜拉曼峰的强度随钴纳米晶粒径的增加明显减弱,但是峰的宽度逐渐增加.
关键词:
Co:BaTiO3
纳米复合薄膜
脉冲激光沉积 相似文献
2.
制备出具有室温单轴磁晶各向异性的非间隙型Co基Gd3Co29-xCrx化合物(x=65和70),x射线衍射和磁性测量表明所有单相化合物均属于单斜晶系,Nd3(Fe,Ti)29型结构和A2/m空间群.Gd3Co29-xCrx化合物的居里温度在x=65时为412 K,x=70时为359 K. Gd3Co29-xCrx化合物在x=65 时磁化强度随温度的变化曲线表明,在居里温度以下的某一温度处有一补偿点,在补偿点处求得晶格分子场系数nRT=33 T f.u./μB.
关键词:
Gd3Co29-xCrx化合物
x射线衍射
磁晶各向异性 相似文献
3.
采用溶胶 凝胶自燃烧法制备了纳米尺度的锌钴铁氧体Zn06CoxFe24- xO4(x=0—030)粉体,分别在不同温度下进行了热处理,利用x射线衍射仪(XRD) 和振动样品磁强计(VSM)对其物 相结构和磁性进行了测量和分析.实验结果表明,锌钴铁氧体Zn06Co015Fe 225O4在550—800℃温度区间出现α Fe2O3过渡相,在高于800℃温度时生 成 单一尖晶石相锌钴铁氧体;随钴含量的增加,Zn06CoxFe2
关键词:
锌钴铁氧体
磁性
结构
相变
溶胶 凝胶 相似文献
4.
用磁过滤脉冲真空电弧沉积方法制备了CoPt(FePt) C纳米复合薄膜,并在不同温度下进行了退火处理,研究了薄膜中碳的含量以及退火温度对薄膜结构与磁性能的影响.制备态薄膜经过足够高的温度退火后,x射线衍射和磁力显微镜分析发现,在碳基质中生成了面心四方相的CoPt(FePt)纳米颗粒.对于特定组分为Co24Pt31C45和Fe43Pt35C22的薄膜,矫顽力以及颗粒尺寸都随退火温度的升高而增大,当退火温度为700℃时,Co24Pt31C45薄膜的矫顽力为21×105A/m,晶粒尺寸为17nm;当退火温度为650℃时,Fe43Pt35C22相应值分别为28×105A/m和105nm.
关键词:
磁记录材料
磁性薄膜
CoPt
FePt纳米复合薄膜 相似文献
5.
通过x射线衍射分析和磁性测量对(Nd1-xErx)3Fe273Ti17化合物的结构与磁性进行了研究.单相(Nd1-xErx)3Fe273Ti17化合物的成相范围为x=00—05之间,所有化合物均属于单斜晶系、Nd3(Fe,Ti)29型结构和A2/m空间群.着Er含量的增加,(Nd1-xErx)3Fe273Ti17化合物的晶胞体积、居里温度TC和5K下的饱和磁化强度Ms均单调减小,而5K下的饱和磁化强度Ms和Er含量的关系与稀释模型所描述的结果相一致.(Nd1-xErx)3Fe273Ti1
关键词:
(Nd1-xErx)3Fe273Ti17化合物
磁晶各向异性
自旋重取向
磁相图 相似文献
6.
用第一性原理基础上的超软赝势方法的总能计算,研究了3d过渡金属(Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn)在Pd(001)表面的单层p(1×1)和c(2×2)结构的表面磁性和总能. 所得结果表明:对于Sc, Ti, V和Cr只存在p(1×1)的铁磁性结构,而Mn只有c(2×2)的反铁磁结构存在. Fe, Co和Ni这三种元素上述两种结构都存在,但是总能上p(1×1)的铁磁结构要低些,因此是比较稳定的结构. 而Cu和Zn在该表面上的单层中不存在上述两种结构. 对于V的p(1×1)铁磁结构,计算得到的每个V原子磁矩为2.41μB,大于用全电子方法得到的0.51μB. 两种计算方法得到其他金属原子 (Cr,Mn,Fe,Co,Ni)的表面磁矩比较相近,都比孤立原子磁矩略小.
关键词:
Pd(001)表面
过渡金属原子单层
表面磁性 相似文献
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8.
9.
利用电弧熔炼制备了(Nd1-xErx)2Co15.5V1.5(x=0—1.0)化合物样品.通过x射线衍射分析和磁性测量研究了Er替代Nd2Co15.5V1.5中的Nd时对化合物结构和磁性的影响.研究结果表明,低Er含量(x<0.4),化合物为Th2Zn17型结构;高Er含量时(x>0.),化合物转变为Th2Ni17结构;Er含量为x=0.4和0.5时,两种结构共存.两种结构的晶胞参数a,c和晶胞体积V随着Er含量的增加都呈现递减的趋势.随着Er含量的增加,(Nd1-xErx)2Co15.5V1.5化合物的
关键词:
(Nd1-xErx)2Co15.5V1.5
结构转变
磁性 相似文献
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11.
Pure, Co doped and (Co, Cu) co-doped ZnO nanocrystals have been prepared by wet chemical route at room temperature to investigate the effect of Cu doping in Co doped ZnO nanocrystals . The nanocrystals have initially been characterized by X-ray diffraction, FTIR, Raman, optical absorption and EPR spectroscopy and the results were corroborated with DFT based electronic structure calculations. Magnetic properties of the samples have been investigated by studying their magnetic hysteresis behavior and temperature dependence of susceptibilities. Finally the local structure at the host and dopant sites of the nanocrystals have been investigated by Zn, Co and Cu K edges EXAFS measurements with synchrotron radiation to explain their experimentally observed magnetic properties. 相似文献
12.
Zhipeng Liu Jing Xue Yao Wang Fusheng Liu Xingjian Zhou Jixian Liu Jianguo Tang 《Particle & Particle Systems Characterization》2020,37(8):2000161
Small size and narrow distribution are the key factors to improve performances of metal nanocrystals due to nanosize effect. Here, a silver-alkylamine complex–mediated single micelle, a one-pot approach, for controlled synthesis of monodisperse silver nanocrystals, in which oleylamine molecules play key roles serving both as complex agent and as micellar coalescence blocker is reported. After the synthesis, monodisperse products can be directly collected through subsequent single-step separation as the particle size is finely adjusted during the synthesis. Dual-soluble silver oleylamine complex is prepared through liquid phase complexing and is used as oil-soluble precursor in single reverse micelle. The as-synthesized silver nanocrystals are very uniform with a controlled size of 6.00 ± 0.29 or 8.0 ± 0.40 nm and a narrow size distribution with a standard deviation (σ) of ≈5.0%. The protocol offers a general platform for fast synthesis of noble metal nanocrystals with rationally designed size and structure. 相似文献
13.
在氩气保护下,用三辛基亚磷酸和油酸分别作为Se和Cd的配位体,在260~300 ℃的十八烯溶液中合成了尺寸可控的CdSe纳米晶。该纳米晶不用进行进一步的提纯和尺寸分离就具有单分散性,其量子尺寸限域效应非常明显——吸收光谱的第一吸收峰峰位随着纳米晶的长大而发生红移;该纳米晶质量很高,具有很强的发光能力,其发射光谱对称的形状和合理的Stokes频移(13 nm)显示,该纳米晶的发光完全出自带隙,没有来自缺陷的发光。此外,实验结果表明,通过改变三辛基亚磷酸的浓度可以调节成核和生长的快慢,从而可以在不同的反应时间得到不同尺寸的单分散性CdSe纳米晶。 相似文献
14.
Pure and Cobalt doped zinc oxide were deposited on glass substrate by Ultrasonic spray method. Zinc acetate dehydrate, Cobalt chloride, 4-methoxyethanol and monoethanolamine were used as a starting materials, dopant source, solvent and stabilizer, respectively. The ZnO samples and ZnO:Co with Cobalt concentration of 2 wt.% were deposited at 300, 350 and 400 °C. The effects of substrate temperature and presence of Co as doping element on the structural, electrical and optical properties were examined. Both pure and Co doped ZnO samples are (0 0 2) preferentially oriented. The X-ray diffraction results indicate that the samples have polycrystalline nature and hexagonal wurtzite structure with the maximum average crystallite size of ZnO and ZnO:Co were 33.28 and 55.46 nm. An increase in the substrate temperature and presence doping the crystallinity of the thin films increased. The optical transmittance spectra showed transmittance higher than 80% within the visible wavelength region. The band gap energy of the thin films increased after doping from 3.25 to 3.36 eV at 350 °C. 相似文献
15.
Co3O4纳米晶的制备和表征 总被引:3,自引:0,他引:3
发现了一种新制备Co3O4纳米晶的新方法。这种方法是先将高分子聚乙烯吡咯烷酮(PVP)和乙酸钴溶解到溶剂中缓慢蒸发溶剂,然后干燥形成的前驱体,最后在400℃温度下煅烧制备了Co3O4纳米晶。生成的产物用XRD,SEM,TEM等测试方法进行了表征。结果发现在不同的溶剂中形成前驱体所制备的Co3O4纳米晶具有不同的形貌特征,使用乙醇溶剂时生成了大量的由Co3O4纳米晶自组装形成的Co3O4微米球;而使用水溶剂时则生成的全都是Co3O4纳米晶。实验结果表明在不同溶剂中形成的前驱体对于最终制备的Co3O4纳米晶形态有着很大的影响。 相似文献
16.
Cobalt/gold (Co/Au) bimetallic nanoparticles are prepared by chemically reducing gold (III) chloride to gold in the presence of pre-synthesized Co nanoparticles. Transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectrometry, and a superconducting quantum interference device (SQUID) magnetometer have been used to characterize as-prepared bimetallic nanoparticles. Our findings demonstrate Au not only grows onto Co nanoparticles, forming a surface coating, but also diffuses into Co nanoparticles. The introduction of Au alters the crystalline structure of Co nanoparticles and changes their magnetic properties. Dodecanethiols induce a reorganization of as-prepared Co/Au bimetallic nanoparticles. 相似文献
17.
D. Ma A. D. Stoica X.-L. Wang Z. P. Lu T. Proffen 《Applied Physics A: Materials Science & Processing》2010,98(3):537-542
In this paper, we report the structure, optical, and gas-sensing properties of Co-doped ZnO nanocrystals prepared by a simple
solvothermal route. The red-shift of the band-gap edge is attributed to a merging of donor and conduction bands due to Co
doping. Photoluminescence (PL) spectra were used to study the dependence of doping on the deep-level emission, which show
obvious enhanced blue-green emission after Co doping. Gas sensors were prepared and tested for the detection of C2H5OH in air. It is found that the Co-doped nanocrystals have a significantly better sensing performance than pure ZnO, which
is comparable to the Au-functionalized ZnO sensors. We provide a possible explanation in terms of the sensing mechanism of
the surface reaction process. 相似文献
18.
Faraci G Pennisi AR Balerna A Pattyn H Koops GE Zhang G 《Physical review letters》2001,86(16):3566-3569
Cobalt was introduced into a silver matrix by ion implantation and observed by extended x-ray absorption fine structure (EXAFS) spectroscopy. In the range 0.10--0.70 at. % evidence of Co dimers dispersed in the matrix was found. The dimers are somewhat contracted with respect to the bulk Co nearest neighbor distance and distributed in a chainlike configuration with each dimer at 90 degrees from each other along opposite square faces of the Ag fcc lattice. 相似文献
19.
《Current Applied Physics》2001,1(2-3):169-173
We synthesized nearly monodisperse bare ZnSe nanocrystallites having luminescence which ranges in wavelength from 340 to 430 nm via nucleation due to supersaturation and growth followed by size selective precipitation. Bare ZnSe dots' outermost surface is passivated with organic HDA/TOP. In order to enhance the radiative emission from the semiconductor nanocrystals, we capped the bare ZnSe quantum dots with ZnS semiconductor materials of a wider band gap and 5% of lattice mismatch and produced highly luminescent core-shell (ZnSe)ZnS quantum dots. The core-shell (ZnSe)ZnS nanocrystals show 20 times or more as greatly enhanced luminescence quantum yields as those of bare ZnSe nanocrystals. The ZnSe bare dots and the (ZnSe)ZnS core-shell dots have cubic zinc blende structures as expected from the bulk structure. The observed shapes of bare ZnSe and core-shell (ZnSe)ZnS dots are nearly spherical or ellipsoidal with the aspect ratios of 1.2 and 1.4, respectively. They are not faceted. 相似文献
20.
《Journal of magnetism and magnetic materials》2005,293(1):265-270
Heating rates generated by superparamagnetic particles deteriorate quickly with particle polydispersity. We prepared highly uniform, monodisperse, single-crystal magnetite nanoparticles of tailorable size via organometallic decomposition. As-synthesized nanocrystals were coated with phospholipids to form biocompatible magnetoliposomes. Modeling of AC-magnetic field parameters indicates that 11 nm nanocrystals have maximum heating rates within the biologically safe frequency range. 相似文献