共查询到20条相似文献,搜索用时 328 毫秒
1.
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
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.
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
4.
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
5.
6.
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
7.
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
8.
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
9.
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
10.
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
11.
利用飞秒时间分辨光谱,可观测叠加在电子态动力学上的相干振动动力学. 从金团簇的相干振动中,不仅能提取电子与振动的耦合信息,也能得到力学性质和电子结构,进而有望实现微小质量探测等应用. 本文利用飞秒时间分辨的瞬态吸收探测了[Au25(SR)18]-团簇的相干振动动力学,通过对相干振动的频率、相位、波长分布的详细分析进一步揭示了其来源. 在[Au25(SR)18]-团簇的飞秒瞬态吸收动力学中可以观测到频率为40 cm-1和80 cm-1的两种振动,均来源于团簇中心Au13核的振动. 通过对相干振动的相位分析发现频率为80 cm-1的振动来自于对电子态之间吸收频率的调制,而频率为40 cm-1的振动来源于对电子态之间吸收强度的调制. 同时,研究发现[Au25(SR)18]-团簇相干振动的频率对其表面配体不敏感,该振动是来源于Au13核的本征性质. 相似文献
12.
O. Lopez-Acevedo H. H?kkinen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(2):311-314
Loss of small fragments (like AuL, Au2L3,
Au4L4) have been found systematically in several MALDI and FAB
experiments on thiolate-protected gold clusters of different sizes. When using the cluster
Au25L18
-1 as
parent cluster, the fragmented cluster
Au21L14
-1 has
been reported to be obtained in high proportion (L = SCH2CH2Ph).
Here we analyse a few possible fragmentation patterns of the well-known parent cluster
Au25L18
-1 (L =
SCH3). Using DFT calculations we study the different atomic configurations
obtained after a AuL fragment is lost from
Au25L18
-1. We
found energetically favourable configurations that can be written as
Au13 [Au2L3]6-z
[AuL2]
z
-1,
where the modification can be described as a replacement of the long protecting unit by a
short one (Au2L3 → AuL2). A full replacement
(z = 6) gives rise to a protected
Au19L12
-1
cluster. This mechanism does not modify the super-atomic electronic structure of the gold
core, i.e., all these fragments remain an 8 electron super-atom clusters exactly like the
parent Au25L18
-1. We
suggest that the Au19L12
-1 cluster
could be realized by using a bulky thiolate, such as the tert-butyl thiolate
SC(CH3)3
. 相似文献
13.
M. A. Khodorkovskii T. O. Artamonova S. V. Murashov D. Michael L. P. Rakcheeva A. A. Belyaeva N. A. Timofeev A. S. Mel’nikov A. L. Shakhmin I. A. Dement’ev 《Technical Physics》2009,54(1):1-6
Signals from ions forming in a supersonic molecular beam consisting of an argon-water vapor mixture are measured as functions
of the exciting electron energy in the range to 120 eV. The thresholds of electron impact excitation of (H2O)
n − 1H+ and Ar
n
(H2O
m
+ clusters are determined for the first time. It is found that the proton-hydroxyl group binding energy decreases considerably
both in the case of water molecule clustering and when mixed Ar
n
(H2O)
m
clusters arise. 相似文献
14.
CO adsorption on small Aun(n=1-7) clusters supported on a reduced rutile TiO2(110) surface:a first-principles study 下载免费PDF全文
CO adsorption on small Au n(n = 1-7) clusters which are supported by a partially reduced rutile TiO 2(110) surface has been investigated by the first-principles method.The low coordinated sites of Au clusters are favorable for CO adsorption.CO-Au n-TiO 2 system displays surface magnetism.There is a strong interaction between the adsorbed CO molecule and the supported Au clusters. 相似文献
15.
Ligand-protected gold clusters are widely used in biosensors and catalysis. Understanding the structural evolution of these kinds of nanoclusters is important for experimental synthesis. Herein, based on the particle swarm optimisation algorithm and density functional theory method, we use [Au1(SH)2]n, [Au2(SH)3]n, [Au3(SH)4]n (n?=?1–3) as basic units to research the structural evolution relationships from building blocks to the final whole structures. Results show that there is a ‘line-ring-core’ structural evolution pattern in the growth process of the nanoclusters. The core structures of the ligand-protected gold clusters consist of Au3, Au4, Au6 and Au7 atoms. The electronics and optics analysis reflects that stability and optical properties gradually enhance with increase in size. These results can be used to understand the initial growth stage and design new ligand-protected nanoclusters. 相似文献
16.
The action of the monovalent M+ cations on the luminescent properties of the mixed M
x
(1)
M
1-x
(2)
UO2(NO3)3 crystals, where M is Na, K, Rb, Cs, or NH4 , has been investigated. It has been established that the spectral positions of the bands of vibronic transitions depend linearly on the ratio between the concentrations of the M(10) and M(2) cations. It is shown that the crystals considered are composed of l[RbUO2(NO3)3]n[CsUO2(NO3)3] clusters, where l/n = x/(1 - x). The spectral regularities revealed are determined by the partial contributions of the M(1) and M(2) cations to their combined, polarizing action on the uranyl complex and are explained by the ligand nature of its highest occupied molecular orbital.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 827–830, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
17.
L. A. Klinkova V. I. Nikolaichik N. V. Barkovskii 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(8):1103-1105
The phase composition of Y
z
Ba5Cu7O
y
(1) and Y
z
Ba3Cu5O
y
(2) samples with a variable percentage of yttrium up to the stoichiometric composition of the Y
n
Ba
m
Cu
m + n
O
y
series is investigated by X-ray phase and elemental analyses, electron diffraction, and high resolution imaging in a transmission
electron microscope at a temperature of 930°C in the crystallization field of a matrix oxide (Ba: Cu) of 5: 6 composition
on the phase diagram of the BaO-CuO
x
system at P(O2) = 21 kPa. The substantial effect of yttrium oxide’s presence on the phase composition of both objects is found, providing
evidence of a complex ionic equilibrium within the melt. The fine-domain oxide structure of the YBa2Cu3O6 tetragonal form, which is due to the coexistence of oxides of an Y
n
Ba
m
Cu
m+n
O
y
homologous series of (Y: Ba: Cu) 235, 123, and 257 composition is revealed. The domain size for these phases is 20–50 ?.
The domains are joined coherently along axis c. 相似文献
18.
采用密度泛函理论(DFT)中的B3LYP方法,在Lanl2dz基组水平上对WnNim(n+m=8)团簇的各种可能构型进行了几何参数全优化,得到了它们的基态构型;并对基态构型的平均结合能、Wiberg键级(WBI)、磁学性质、NBO进行了分析,结果表明:团簇随着W原子数的增多,稳定性增强,n≥5时,结构中都含有纯钨团簇的结构基元;W-W键级高于W-Ni键和Ni-Ni键;W5Ni3,W6Ni2团簇发生了"磁矩猝灭"的现象;在W,Ni原子内部,轨道电荷发生了转移,产生了"轨道杂化"现象,W,Ni原子之间也发生了电荷转移形成了较强的化学键.
关键词:
nNim(n+m=8)团簇')" href="#">WnNim(n+m=8)团簇
几何结构
电子性质
密度泛函理论 相似文献
19.
利用密度泛函理论在B3LYP/6-311G*水平上对叠氮化合物(HMgN3)n(n=1–5)团簇各种可能构型进行了几何优化,预测了各团簇的最稳定结构. 并对最稳定结构的成键特性、电荷分布、振动特性及稳定性进行理论研究. 结果表明:HMgN3团簇最稳定结构为直线型;(HMgN3)n(n=2,5)团簇最稳定结构为叠氮基中N原子和金属原子相连构成Mg–N–Mg结构;(HMgN3)n(n=3,4)团簇最稳定结构为叠氮基与Mg原子相互链接形成的环状结构. 团簇最稳定结构中金属Mg原子均显示正电性,H原子均显示负电性,叠氮基中间的N原子显示正电性、两端的N原子显示负电性,且与Mg原子直接作用的N原子负电性更强. Mg–N键和Mg–H键为典型的离子键,叠氮基内N原子之间是共价键. 团簇最稳定结构的红外光谱分为三部分,其最强振动峰均位于2258–2347 cm-1,振动模式为叠氮基中N–N键的反对称伸缩振动. 叠氮基在团簇和晶体中结构不变,始终以直线型存在. 稳定性分析显示,(HMgN3)3团簇相对于其他团簇更为稳定.
关键词:
3)n(n=1–5)团簇')" href="#">(HMgN3)n(n=1–5)团簇
叠氮基
密度泛函理论
结构与性质 相似文献
20.
Investigations of K3H(SO4)2 samples, which belong to the family of Me
m
H
n
(XO4)(m + n)/2 (Me = K, Cs, Rb, NH4; X = S, Se, As) crystals, revealed temperature anomalies in the dielectric and optical properties and in the heat capacity upon
phase transitions. X-ray diffraction studies confirmed that K3H(SO4)2 crystals undergo a structural phase transition from the monoclinic phase to the trigonal phase C2/c → R
m and that the high proton conductivity in the high-temperature phases of crystals belonging to this family is due to the formation
of a qualitatively new system of hydrogen bonds.
Original Russian Text ? A.A. Simonov, I.P. Makarova, V.V. Grebenev, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51,
No. 8, pp. 1477–1479. 相似文献