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1.
In the EPR of (La1––x
Gd
y
Ce
x
)Al2 a bottleneck in the relaxation of the conduction electrons to the lattice is present at sufficiently high Gd-concentrations. The bottleneck can be broken by decreasing the Gd-concentration or by adding Cerium as a spin-flip-scatterer.g-factor and line broadening are measured for (La1–y
Gd
y
)Al2 and (La1––x
Gd
y
Ce
x
)Al2 as a function of temperature and Gd- and Ce-concentrations. The Cerium induced relaxationsrate
eL
(Ce) increases linearly with Ce-concentration up tox0.025. This corresponds to the fact, well known by measurements of the Kondo anomalies, that Cerium impurities show no significant interaction up to rather high concentrations. 相似文献
2.
利用射频磁控溅射的方法在SrTiO3(001) 基片上制备了(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格结构.对所制备的超晶格结构进行了50—150℃温度范围内的电流-电压测试分析.结果表明,随着BiFeO3薄膜的厚度减小,温度的升高,(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格结构的电流变大.进一步根据介质导电模型对(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格结构的导电特性做了分析.在温度较低或者电场较弱时,所制备的(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格结构表现为欧姆导电,而在高温,高电场的情况下,其导电行为由空间电荷限制电流机理主导.
关键词:
超晶格薄膜
多铁
空间电荷限制电流 相似文献
3.
R. S. Iskhakov E. A. Denisova S. V. Komogortsev L. A. Chekanova Yu. E. Kalinin A. V. Sitnikov 《Physics of the Solid State》2010,52(11):2263-2266
This paper reports on the results of the investigation of the relation between the magnetic microstructure and ferromagnetic
resonance (FMR) in ferromagnetic metal-insulator composites by using granular alloys (Co41Fe39B20)
x
(SiO2)1 − x
and Co
x
(SiO2)1 − x
as an example. A comparative analysis of the properties of FMR spectra and parameters of random magnetic anisotropy leads
to correlations between these quantities. It has been found that the main mechanism that determines the FMR line width in
the films under investigation is the exchange narrowing mechanism. 相似文献
4.
5.
A. A. Demidov I. A. Gudim E. V. Eremin 《Journal of Experimental and Theoretical Physics》2012,114(2):259-272
The magnetic properties of ferroborate single crystals with substituted compositions Nd1 − x
Dy
x
Fe3(BO3)4 (x = 0.15, 0.25) with competing exchange Nd-Fe and Dy-Fe interactions are investigated. For each composition, we observed a
spontaneous spin-reorientation transition from the easy-axis to the easy-plane state and step anomalies on the magnetization
curves for the spin-flop transition induced by a magnetic field B | c. The measured parameters and effects are interpreted using a unified theoretical approach based on the molecular field approximation
and on calculations performed in the crystal-field model for the rare-earth ion. The experimental temperature dependences
of the initial magnetic susceptibility from T = 2 K to T = 300 K, anomalies on the magnetization curves for B | c in fields up to 1.8 T, and their evolution with temperature, as well as temperature and field dependences of magnetization
in fields up to 9 T are described. In the interpretation of experimental data, the crystal-field parameters in trigonal symmetry
for the rare-earth subsystem are determined, as well as the parameters of Nd-Fe and Dy-Fe exchange interactions. 相似文献
6.
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
7.
8.
I. V. Bodnar 《Journal of Applied Spectroscopy》2010,77(5):654-657
Single crystals of In2Se3 and CuIn5Se8 compounds and (In2Se3)1–x·(CuIn5Se8)x solid solutions have been grown from the melt using the Bridgman method and their composition and structure determined. It
is shown that the crystals have n-type conductivity. Their transmission spectra were studied in the self-absorption edge region
at 80 and 295 K. Based on the spectral measurements, the band gap width (Eg) was determined and the band gap concentration dependences were plotted. It is found that Eg varies with the x composition nonlinearly. Using the dielectric model of Van Vechten–Bergstresser and the Hill–Richardson
pseudo potential model, Eg(x) was calculated theoretically. 相似文献
9.
V. S. Rusakov N. I. Chistyakova I. A. Burkovsky A. M. Gapochka T. L. Evstigneeva 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(3):389-393
A M?ssbauer study of the structural and charge states of 57Fe and 119Sn atoms in the compounds of Cu3 −x
Fe
x
SnS4 and Cu2Fe1 − x
Zn
x
SnS4 systems was performed. It was shown that the iron atoms in the compounds of both systems were in the divalent and trivalent
states occupying the tetrahedral positions of the structure. The character of the changes of the degree of covalency of the
Fe2+-S, Fe3+-S and Sn4+-S bonds during the isomorphic substitution in the systems was established. 相似文献
10.
采用脉冲激光沉积(PLD)镀膜技术在倾斜10°的LaAlO3(100)单晶衬底上制备了(SrTiO3)n/(SrTi0.8Nb0.2O3)m系列超晶格.在超晶格薄膜的XRD图谱中清楚地观察到周期调制的卫星峰结构.从卫星峰的分布计算了超周期,进而得到了在生长SrTiO3和SrTi0.8Nb0.2<
关键词:
3)n/(SrTi0.8Nb0.2O3)m]20/LAO(100)超晶格')" href="#">[(SrTiO3)n/(SrTi0.8Nb0.2O3)m]20/LAO(100)超晶格
激光感生热电电压
各项异性Seebeck系数
原子层热电堆 相似文献
11.
本文采用高温有机溶剂法制备了(Fe1-xCox)3BO5纳米棒, 通过控制反应物中乙酰丙酮钴的含量合成了不同Co含量的(Fe1-xCox)3BO5. 利用高分辨透射电子显微镜(HRTEM)、超导量子干涉磁强计(SQUID)对其形貌和磁性能进行了表征. 高分辨透射电子显微镜结果表明制备出的纳米(Fe1-xCox)3BO5为多晶棒状, 且具有多折孪晶结构; 磁性测量的结果表明,(Fe1-xCox)3BO5纳米棒在室温下表现出铁磁性, 随着Co含量的增加, 纳米棒的铁磁性逐渐增加, 该纳米棒有望用来研究生物大分子的机械性能. 相似文献
12.
采用基于柠檬酸体系的溶胶-凝胶法制备了Pr0.7(Sr1-xCax)0.3MnO3系列的多晶块材, 同时还用脉冲激光沉积技术(PLD)在SrTiO3(100)衬底上外延生长了同一系列的薄膜, 系统研究了它们的晶格结构和电输运行为. 多晶和薄膜样品都具有正交晶格结构, 电输运行为在居里温度TC以上的高温顺磁相都很好
关键词:
0.7(Sr1-xCax)0.3MnO3')" href="#">Pr0.7(Sr1-xCax)0.3MnO3
绝热小极化子模型
双交换作用
Jahn-Teller晶格畸变 相似文献
13.
Microporous (TiO2)
x
–(SiO2)100 − x
(0 < x < 40) xerogels have been produced by sol–gel methods either by partial pre-hydrolysis or reflux of tetraethoxysilane and
titanium isopropoxide. These have been characterised by 29Si nuclear magnetic resonance, X-ray diffraction, EXAFS at the Ti–K edge, X-ray photoelectron spectroscopy, temperature-programmed
reduction, FT infrared, N2 adsorption at 78 K (BET), transmission electron microscopy and dynamic light scattering (DLS). These were dip coated onto
fused silica and characterised by atomic force microscopy and UV–visible absorption. Their photoactivity in removal of alkylphenol
ethoxylate TX100 from water was less than for less porous titania. The advantages of including thermally removable PEG or
PPG templates in terms of increasing surface, meso-porosity and photon absorbance at visible wavelengths to give nanoengineered
photocatalytic films are described. 相似文献
14.
A. V. Ivanov Yu. E. Kalinin V. N. Nechaev A. V. Sitnikov 《Physics of the Solid State》2009,51(12):2474-2479
The concentration dependences of the electrical resistivity and complex permeability of [“(Co45Fe45Zr10)
x
(Al2O3)100 − x
”/“α-Si: H”]
n
multilayer structures and (Co45Fe45Zr10)
x
(Al2O3)100 − x
composites have been studied. It has been established that introduction of a semiconductor interlayer into the (Co45Fe45Zr10)
x
(Al2O3)100 − x
composites substantially decreases the electrical resistivity of [“(Co45Fe45Zr10)
x
(Al2O3)100 − x
”/“α-Si: H”]
n
multilayer structures. The concentration dependences of the real and imaginary parts of the complex permeability of the [“(Co45Fe45Zr10)
x
(Al2O3)100 − x
”/“α-Si: H”]
n
nanomultilayer structures substantially differ from those of the (Co45Fe45Zr10)
x
(Al2O3)100 − x
composites. The real part of the complex permeability of the [“(Co45Fe45Zr10)
x
(Al2O3)100 − x
”/“α-Si: H”]
n
nanomultilayer structures follows the curve with a minimum near the percolation threshold of the composite, and the imaginary
part smoothly decreases as the ferromagnetic phase concentration increases. The results obtained are explained by the increase
in the bifurcation temperature due to the conduction electrons of the semiconductor interlayer, which favor magnetic ordering
of ferromagnetic grains. 相似文献
15.
Jie Song Bing-Lin Hong Jun Zheng Pei Lin Ming-Sen Zheng Qi-Hui Wu Quan-Feng Dong Shi-Gang Sun 《Applied Physics A: Materials Science & Processing》2010,98(2):455-460
Ti-substituted LiMn2O4 (LiMn2−x
Ti
x
O4, x=0, 0.15, 0.30, 0.45, 0.60, and 0.75) has been synthesized using solid-state reactions. Their crystal and electronic structures
were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy
(UPS). XRD data suggested that the lattice parameters of LiMn2−x
Ti
x
O4 increase due to the replacement of Mn by Ti ions. XPS results indicated that the substituted Ti ions were in +4 oxidation
state; consequently, the normal oxidation state of Mn ions has been detected by measuring the binding energy splitting of
Mn 3s states, which decreases with the content of substituted Ti. The valence band spectra suggested that the intensity of
e
g
level of Mn 3d orbitals increased due to the increase of the Mn3+/Mn4+ ratio. 相似文献
16.
A. K. Zvezdin A. M. Kadomtseva Yu. F. Popov G. P. Vorob’ev A. P. Pyatakov V. Yu. Ivanov A. M. Kuz’menko A. A. Mukhin L. N. Bezmaternykh I. A. Gudim 《Journal of Experimental and Theoretical Physics》2009,109(1):68-73
Magnetic and magnetoelectric properties of ferroborate single crystals with complex composition (Tb1 − x
Er
x
Fe3(BO3)4, x = 0, 0.75) and with competing exchange Tb-Fe and Er-Fe interactions are investigated. Jumps in electric polarization, magnetostriction,
and magnetization are observed as a result of spin-flop transitions, as well as a considerable decrease in the critical field
upon an increase in the Er concentration, in a field H
c
parallel to the c axis. The observed behavior of phase-transition fields is analyzed and explained using a simple model taking into account
anisotropy in g factors and exchange splitting of funda-mental doublets of the easy-axis Tb3+ ion and easy-plane Er3+ ion. It is established that magnetoelectric and magnetostriction anomalies under spin-flop transitions are mainly controlled
by the Tb subsystem. The Tb subsystem makes a nonmonotonic contribution ΔP
a
(H
a
, T) to polarization along the a axis: the value of ΔP
a
reverses its sign and increases with temperature due to the contribution from the excited states of the Tb3+ ion.
Original Russian Text ? A.K. Zvezdin, A.M. Kadomtseva, Yu.F. Popov, G.P. Vorob’ev, A.P. Pyatakov, V.Yu. Ivanov, A.M. Kuz’menko,
A.A. Mukhin, L.N. Bezmaternykh, I.A. Gudim, 2009, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2009, Vol.
136, No. 1, pp. 80–86. 相似文献
17.
Gold(I) thiolate compounds (i.e. AuI-SR) are important precursors for the synthesis of atomically precise Aun(SR)m nanoclusters. However, the nature of the AuI-SR precursor remains elusive. Here, we report that the Au10(TBBT)10 complex is a universal precursor for the synthesis of Aun(TBBT)m nanoclusters (where TBBT=4-tertbutylbenzenethiol/thiolate). Interestingly, the Au10(TBBT)10 complex is also found to be re-generated through extended etching of the Aun(SR)m nanoclusters with excess of TBBT thiol and O2. The formation of well-defined Au10(TBBT)10 complex, instead of polymeric AuI-SR, is attributed to the bulkiness of the TBBT thiol. Through 1D and 2D NMR characterization, the structure of Au10(TBBT)10 is correlated with the previously reported X-ray structure, which contains two inter-penetrated Au5(TBBT)5 rings. The photophysical property of Au10(TBBT)10 complex is further probed by femtosecond transient absorption spectroscopy. The accessibility of the precise Au10(TBBT)10 precursor improves the efficiency of the synthesis of the Aun(TBBT)m nanoclusters and is expected to further facilitate excellent control and understanding of the reaction mechanisms of nanocluster synthesis. 相似文献
18.
19.
Ihor Studenyak Yuriy Neimet Csaba Cserháti Sándor K?kényesi Edvardas Kazakevi?ius Tomas ?alkus Algimantas Ke?ionis Antanas Orliukas 《Central European Journal of Physics》2012,10(1):206-209
Structural studies of (Ag3AsS3)
x
(As2S3)1−x
chalcogenide superionic glasses in the compositional range x = 0.3–0.9 were performed by scanning electron microscopy. Temperature and compositional dependences of transmission coefficient,
electrical conductivity, and activation energy were investigated 相似文献
20.
We have investigated the structure, optical and magnetic properties of ferroelectric KNb1-xFexO3-δ (X=0, 0.01, 0.03, 0.05, 0.10, 0.15, 0.20, 0.25) synthesized by a traditional solid-state reaction method. According to the X-ray diffraction and the results of Rietveld refinement, all the samples maintain orthorhombic distorted perovskite structures with Amm2 space group without any secondary phase, suggesting the well incorporation of Fe ions into the KNbO3 matrix. With the increase of Fe concentration, the band gap of each sample is decreased gradually, which is much smaller than the 3.18 eV band gap of pure KNbO3. Through X-ray photoelectron spectrum analysis, the increased density of oxygen vacancy and Fe ions may be responsible for the observed decrease in band gap. Compared with the pure KNbO3, Fe doped samples exhibit room-temperature weak ferromagnetism. The ferromagnetism in KNb1-xFexO3-δ with low-concentration dopants (X=0.01-0.10) can be attributed to the bound magnetic polaron mediated exchange. The enhancement of magnetism for the high-concentration (X=0.10-0.20) doped samples may arise from the further increase of magnetic Fe ions. 相似文献